Rice Heavy Ions News

Temperature Measurements - News coverage

Frank Geurts — 2025-11-18T12:30:31-06:00

A collection of news releases concerning our recent paper to Nature Communications.

Scientific American - Nov. 15
https://www.scientificamerican.com/article/scientists-create-3-3-trillion-degree-particle-soup-to-mimic-the-universe/

BNL Press Release:
https://www.bnl.gov/newsroom/news.php?a=122624

Rice University:
https://news.rice.edu/news/2025/rice-physicists-probe-quark-gluon-plasma-temperatures-helping-paint-more-detailed-picture

Interview with Physics World

Frank Geurts — 2025-10-11T16:14:49-05:00

This was an interesting interview with Physics World. Explaining the relevance of a critical point in layman's terms …

https://physicsworld.com/a/hints-of-a-boundary-between-phases-of-nuclear-matter-found-at-rhic/

YouTube appearances ��

Frank Geurts — 2025-10-11T16:00:00-05:00

A couple of back-to-back features in the recent Rice Magazine with YouTube videos in which you can see me enthusiastically waving my hands. 👋😀👋

The Heart of Matter: Rice researchers are part of a decades-long, international scientific experiment peering into the beginnings of the universe.

Brilliang Minds, Different Perspectives: The Rice Global India Initiative brings two worlds together to create a powerful research ecosystem.

Building your own detector ... with LEGOs

Frank Geurts — 2025-08-27T15:30:58-05:00

Here's a great article from a recent CMS Newsletter on how to build your own detector at home, using LEGOs or a 3D printer, if you happen to have one idling at home … (i now know I really need one!)

https://cms.cern/news/build-cms-detector-home?mtm_campaign=Newsletter&mtm_kwd=news_engage

‘Oscars of Science’ Breakthrough Prize honors Rice physicists

Frank Geurts — 2025-04-10T19:49:14-05:00

source: Rice News by Marcy de Luna

‘Oscars of Science’ Breakthrough Prize honors Rice physicists

Faculty and alumni share award for pioneering research at CERN

An international team of physicists, including Rice University’s Paul Padley, Frank Geurts, Karl Ecklund, Wei Li and Darin Acosta, this week was awarded the 2025 Breakthrough Prize in Fundamental Physics for research on the Higgs boson and the exploration of nature at the shortest distances and under the most extreme conditions.

The prize, which honors the world’s top scientists in fundamental physics, life sciences and mathematics, was awarded to more than 13,000 physicists who contributed to the four large experiments at the Large Hadron Collider (LHC), including the Compact Muon Solenoid (CMS) experiment at the European Organization for Nuclear Research (CERN). The Rice researchers were recognized for their pioneering work in particle physics, including precise measurements of Higgs boson properties that confirm the symmetry-breaking mechanism of mass generation and their studies of the quark-gluon plasma, a state of extremely hot and dense matter that existed shortly after the big bang.

“This recognition underscores the power of international collaboration in scientific discovery,” said Padley, professor of physics and astronomy. “To be part of the team helping unlock nature’s fundamental secrets is deeply rewarding.”
The CMS experiment, one of four major LHC detectors, played a pivotal role in verifying the mechanism by which fundamental particles acquire mass through interaction with the Higgs field. Breakthroughs by the CMS team include precise measurements of the Higgs boson’s properties, the discovery of rare particle interactions and new insights into symmetry breaking — a fundamental aspect of the standard model of particle physics.
Their work also offers a window into the extreme conditions that existed moments after the big bang. While the Higgs boson’s discovery was announced in 2012, uncovering its complete characteristics remains an active and ongoing scientific pursuit.

Numerous Rice students, postdoctoral researchers and alumni contributed to the project, including Antony Adair, Bora Akgün, Austin Baty, Ulf Behrens, Zhenyu Chen, Osvaldo Miguel Colin, Sven Dildick, Sarah Freed, Parker Gardner, Maxime Guilbaud and Iason Krommydas.
Additional contributors include Matthew Kilpatrick, Arun Kumar, Andre Govinda Stahl Leiton, Jiazhao Lin, Pedro Fernandez Manteca, Ben Michlin, Ted Nussbaum, Radia Redjimi, Jamal Rorie, John Rotter, Wei Shi, Benjamin Tran, Zhoudunming Tu, Shuai Yang, Zaochen Ye, Efe Yigibasi, James Zabel, Yousen Zhang and the late Jay Roberts.
The Breakthrough Prize, often called the “Oscars of Science,” was founded in 2012 by tech leaders including Sergey Brin, Priscilla Chan, Mark Zuckerberg, Anne Wojcicki, Julia Milner, and Yuri Milner. Open to all physicists whether theoretical, mathematical or experimental, the prize recognizes those advancing our understanding of the universe’s most profound mysteries.
The $3 million prize is shared among all recipients. The prize money supports grants for doctoral students from member institutions to conduct research at CERN.
“The questions these laureates are asking are among the deepest questions there are about the workings of life, the nature of the universe and the abstract landscapes of mathematics,” Yuri Milner said. “It’s inspiring to see scientists seeking and finding answers to these questions.”

RHIC Run 25 - preparations

Frank Geurts — 2025-03-18T11:36:28-05:00

Preparations for RHIC Run 25 are in full swing. In the past week(s), the superconducting magnets are all lowered to the temperatures where we can start to use liquid helium for the last step to 4K. In the status plot, below, you can see how each of the sectors sequentially sees its temperatures lowered to about 70-80K. Liquid helium will do the rest, and by March 23 we expect to see the full RHIC ring at 4K operating conditions.

Meanwhile, we are preparing the detectors of the STAR experiment. For starters, we make sure that we can ramp up the solenoidal magnet (the S in STAR) and flow the flammable gas in our tracker (the T in STAR), called the TPC. Without actual beam collisions we are able to set up our detectors to trigger for cosmic rays, i.e. the muons that are the decay products of energetic protons hitting the earth's atmosphere, leading to large particle showers that include many pions (the lightest mesons). These pions subsequently decay into muons (and neutrinos, which the STAR detector does not see). Even muons don't have eternal life, but thanks to special relativity (and their high velocity) we can still see them as they zap through our detector before turning into electrons. The video below shows our detector registring single muons. If you look carefully then you can see some of the tracks have some curvature. That's the magnetic field acting upon the charged particles! You also see that some tracks appear broken up in pieces. Well, that's why we start this testing well ahead of our operations using beam collisions: we are using these tracks to check each and every piece of our detectors!

Click on the picture below to see a ~45second GIF of incoming cosmic rays.

STAR Collaboration Meeting

Frank Geurts — 2025-03-07T17:36:04-06:00

The STAR collaboration meeting is a great opportunity to learn about the many exciting analyses that are performed by as many students and postdocs. Two days of parallel sessions, for each PWG, are followed by two days of plenary discussions on physics and our future endeavours were preceded by a dedicated workshop on the endcap TOF detector and a Junior's Day.

More details, including the agenda can be found on this page: https://indico.bnl.gov/event/26119/

No meeting without a group picture!

(courtesy BNL 2025)

Confinement and Symmetries in the QCD Phase Diagram

Frank Geurts — 2025-02-16T06:24:59-06:00

I asked ChatGPT to summarize our current understanding of the Quark-Gluon Plasma, and this is what it wrote for me (see below). While I can understand that it blissfully “forgets” the foundational work that facilities like CERN’s SPS, BNL’s AGS, and GSI’s SIS have done, its description has a few other intriguing, let’s say, inaccuracies. Lattice QCD, a powerful tool in the theory community, still faces significant challenges in describing conditions that more realistically correspond to energy regimes, typically at and below those provided by RHIC. Additionally, the notion of two distinct phases, such as a gas of hadrons versus free quarks and gluons, remains a debatable and potentially inaccurate description of the so-called phase diagram of hot and dense nuclear matter.

So, workshops like this one attempt to address this from a purely theoretical perspective: “Confinement and symmetry from vacuum to QCD phase diagram.” I was fortunate enough be invited to this workshop as the sole experimentalist, presenting experimental observations that should provide theoretical guidance, although it often requires that as well. While it was undoubtedly a very technical workshop, and I must admit that I often lost track of most talks after their introductory slides, I thoroughly enjoyed listening to the discussions and their physical motivations and constructs. Of course, convincing experimentalists that there are more than three color charges in QCD, let alone an infinite number, will be challenging. Additionally, extracting an imaginary chemical potential from our particle yields and spectra may seem difficult. Nevertheless, the underlying physical reasoning and mathematical concepts are relevant and inspiring.

Unfortunately, I don't ski, so I did miss out as some of the discussions continued in ski lifts and, presumably, downhill slopes.

ChatGPT:

Current Understanding of Quark-Gluon Plasma (QGP)
Introduction:
Quark-Gluon Plasma (QGP) is a state of matter in which quarks and gluons, the fundamental constituents of protons and neutrons, are not confined within hadrons, but exist freely. This state is believed to have existed microseconds after the Big Bang and can be recreated in high-energy heavy-ion collisions in particle accelerators such as the Large Hadron Collider (LHC) at CERN.

Properties of QGP:

High Temperature and Energy:

QGP is formed at extremely high temperatures, exceeding 2 trillion Kelvin, where quarks and gluons are free from the strong force that typically binds them inside protons and neutrons.

Color Confinement and Deconfinement:

In normal conditions, quarks are confined within hadrons. In QGP, they are deconfined, allowing quark-gluon interactions to be studied without confinement.

Fluid-Like Nature:

Experiments have shown that QGP behaves like a nearly perfect fluid with very low viscosity, unlike traditional gases or plasmas.

Thermalization and Collective Motion:

QGP undergoes rapid thermalization, leading to collective flow patterns, which are studied through observables like elliptic flow.

Experimental Observations:

Heavy-Ion Collisions:

Experiments at the LHC and RHIC (Relativistic Heavy Ion Collider) have recreated QGP conditions by colliding heavy ions at near-light speeds.

Jet Quenching:

The suppression of high-energy jets in QGP serves as a probe of its density and the interactions within.

Direct Photon and Dilepton Production:

Photons and dileptons, unaffected by the strong force, provide insight into the initial conditions and temperature of the QGP.

Theoretical Developments:

Lattice QCD:

Quantum chromodynamics (QCD) simulations on lattice frameworks provide theoretical insights into the properties of QGP at different temperatures and densities.

Hydrodynamic Models:

These models mimic the QGP's fluid-like behavior, aiding in understanding its evolution and observable phenomena in collisions.

Challenges and Future Directions:

Despite advances, understanding the precise mechanisms of QGP formation, its thermalization, and transition back to hadronic matter remains challenging.

Future research aims to explore QGP properties at even higher temperatures, study its behavior in smaller systems, and understand the quark-hadron phase transition.

In summary, the study of QGP provides critical insights into the fundamental forces and early universe conditions. With ongoing experiments and theoretical advancements, our understanding continues to grow, revealing the complex dynamics of this unique state of matter.

Hard Probes 2024

Frank Geurts — 2024-09-30T11:22:49-05:00

The Hard Probes 2024 conference has been exceptionally successful for STAR, with many talks and posters on behalf of the collaboration. Tthe STAR Highlights talk by Isaac Mooney (Yale) gives a very nice overview. Chenliang Jin presented his results from the dielectron analyses from the BES Phase 2.

His results were shown in a couple of overview talks that followed, as well as in the physics motivation for the JPARC-HI efforts in Japan.

Rice nuclear physics team tapped to lead $15 million Large Hadron Collider upgrade project

Frank Geurts — 2024-03-23T12:11:06-05:00

Under the direction of Wei Li, our heavy groups will build time-of-flight detectors for the CMS experiment at CERN. Our groups have vast experience with these types of detector using Multi-Gap Resistive Plain Chambers (MRPCs). What makes this project especially interesting is the use of a new technology, based on Low Gain Avalanche Diodes (LGADs). Accurate timing is all-important for time-of-flight detectors, and LGADs can deliver such timing with a precision of 30 picoseconds. What's more, these detectors are silicon based and thus can be very thin, possibly situated relatively close to the beam line without having too much of an effect on detectors that are mounted further away.

A Rice Media press release can be found at this link.

In the spotlight: QuarkNet

Frank Geurts — 2023-09-29T18:10:32-05:00

Our Rice/UH QuarkNet center made it in this week's QuarkNet Friday Flyer. Take a look at this URL: Friday Flyer Sept.28, 2023 or look at the picture, below.

QuarkMatter 2023

Frank Geurts — 2023-09-04T08:00:00-05:00

The QuarkMatter 2023 conference wrapped up with many group pictures. Below is a small collage of pictures, including Yiding Han's presentation.

Yiding Han's presentation on BES-2 Thermal Dielectron Measurements

Co-chairs of the QuarkMatter conference at The Rustic

The STAR Collaboration at QM23

STAR PreQM'23 Meeting

Frank Geurts — 2023-09-02T00:00:00-05:00

Almost 70 STAR collaborators descended on the Rice campus to participate in the Pre-QuarkMatter meeting. Within a 3-day, jam-packed agenda the collaboration rehearsed all its oral contributions to the QuarkMatter conference, which followed the next week. While outdoor temperatures were consistently about 100F, the campus provided for a welcoming environment in part thanks to the graduate student bar Valhalla and the neighboring Rice Village. Of course, no self-respecting workshop can end without a group picture and below, you'll see an energized STAR collaboration in the Kyle Morrow room on the 3rd floor of the Fondren Library at Rice University. On the big screen you will recognize a few of our online participants, and all the way in the front you can see some of our (very) junior, future collaborators. 😀

Rice Thresher interview

Frank Geurts — 2023-08-23T00:00:00-05:00

The Rice Thresher is consistently listed in Princeton Review's top-10 of best college newspapers. I was honored to get an online feature. Many thanks to Molly Kyles for a great conversation and her professional work!

https://www.ricethresher.org/article/2023/08/frank-geurts-to-lead-worlds-longest-running-nuclear-collider-experiment

Frank Geurts to lead world’s longest running nuclear collider experiment
By Molly Kyles 8/22/23 11:41pm

Rice University physicist Frank Geurts has been named co-spokesperson for the Solenoidal Tracker at Relativistic Heavy Ion Collider collaboration, the world’s first heavy-ion collider located at Brookhaven National Laboratory. Alongside Brookhaven Lab physicist Lijuan Ruan, Geurts will lead STAR for the next three years to collect data on nuclear collisions and study the matter that was present at the origin of the universe.

“The neutrons and protons inside atoms melt into their substructure: quarks and gluons,” Geurts said. “We slam nuclei to smithereens and look at what comes out of it. [We] deduce what we had in [early universe] conditions.”

The STAR experiment can replicate the extreme conditions that existed just microseconds after the Big Bang with detailed control over the data collected.

“In the lab, you can have these kinds of collisions many, many times. You can study the conditions and properties created in a lab in a very detailed way,” Ruan said.

For Geurts, these questions surfaced in his life earlier than most. The Netherlands-born scientist can trace his love for physics back to the stars.

“As a kid, I was always very interested in astronomy. I woke up at two o’clock in the morning, looking at the stars,” Geurts said. “The rabbit hole was there, I just went deeper and deeper, and figured that nuclear particle physics was my thing. There was this drive in asking, I went from the large objects in the sky to zooming in and understanding why things are what they are.”

Geurts went on to study physics in his undergraduate and graduate years in the Netherlands. During that time, Geurts had the opportunity to work at CERN, the European Organization for Nuclear Research, before applying for a postdoctoral position at Rice and beginning his involvement with STAR.

“I [selected] Rice because [of] its reputation in designing, development and research in detectors for particle physics,” Geurts said. “I grew into [the STAR] experiment. I was a co-convener, then I was a Physics Analysis Coordinator, then I was a deputy spokesperson and as of recently, I am, together with Lijuan, a co-spokesperson.”

Ramamoorthy Ramesh, Rice’s vice president of research, emphasized the significance of Rice’s affiliation with STAR.

“At the end of the day, you want our faculty to be competing for the biggest discoveries. And the biggest discoveries invariably mean the biggest recognition,” Ramesh said. “We need to be a part of that big conversation, where discoveries are being made.”

Ramesh analogizes the scope of scientific discovery to the vastness of a boba tea shop menu.

“The origins are still being discovered. In the beginning there were just protons, electrons, neutrons,” Ramesh said. “Now, we know there are maybe 33 subatomic particles, with different flavors. It’s exactly like going to a boba tea shop. It’s just tea with boba, but there are 60 different varieties.”

The public funding that the STAR collaboration relies on requires its findings to be communicated to the general public.

“We’re the longest running nuclear colliding experiment. That is, to a substantial degree, thanks to taxpayers. We need to make sure that high school kids, undergrads and middle school [students] know the science so they can have the same enthusiasm we have,” Geurts said.

STAR plans to record its final collisions in 2025, before being converted into an electron-ion collider. However, STAR’s work will continue after its last collision.

“STAR will likely continue another five or eight years just digesting and analyzing,” Geurts said. “We basically redesign a new experiment each time we look at the data.”

From a curiosity in the stars to colliding particles at super speeds, for Geurts, all discoveries come back to collaboration.

“To students that want to make big discoveries, talk about science,” Geurts said. “Discuss it with your peers, with your professors, discuss it with your parents for all I care. Big discoveries come not out of single minds. Big discoveries come out of humans talking to each other.”

Team STAR 2nd in the BNL Basketball

Frank Geurts — 2023-07-16T17:12:15-05:00

The BNL Basketball Tournament saw Team STAR beat all BNL teams, only to meet its victor in the SULI Summer student team!

In addition Kong Tu and Zhengqiao Zhang both from BNL, this STAR-studded team consisted of Rice's own Chenliang Jin and Zaochen Ye!

🏀🏀🏀
Congratulations STAR Team on your 2nd place!!!
🏀🏀🏀

h/t Kong Tu for the picture!

STAR Pre-QM2023 meeting registration is open

Frank Geurts — 2023-07-10T13:43:08-05:00

Today the registration of the STAR Pre-QuarkMatter meeting has opened. STAR Collaborators who plan on attending are invited to join this 3-day meeting at Rice University. Collaborators who have been selected to give either oral or poster presentations are strongly encouraged to attend this meeting in person. Information on registration, accomodations, how to get to and around town, and much more can be found at this link https://bit.ly/STARpreQM23

Twitter bird not tweeting ...?

Frank Geurts — 2023-07-10T09:38:42-05:00

Hmm, it looks like the little twitter bird @NuclearRiceU -feature in the right column of this News page- is not tweeting much. Even though it is. This may be another victim of the "turmoil" called Twitter. We'll try to get it back again. (Soon?)

Quick update: embedded twitter feeds are currently all disabled. Even Twitter's own webpages suffer from it: https://developer.twitter.com/en/docs/twitter-for-websites/timelines/overview. With 80% of Twitter's workforce terminated, it's yet to be seen if this feature ever returns, let alone get any priority …

Rice News feature

Frank Geurts — 2023-07-10T09:17:14-05:00

This feature made it to the front page of the Rice website. Many thanks to Silvia Cernea Clark, Gustavo Raskosky, and Brandon Martin for their very professional work!

https://news.rice.edu/news/2023/rice-u-physicist-lead-worlds-longest-running-nuclear-collider-experiment

Rice U. physicist to lead world’s longest-running nuclear collider experiment

Frank Geurts named co-spokesperson of the STAR collaboration

Rice University physicist Frank Geurts is one of two scientists elected to lead the world’s longest-running nuclear physics experiment at a particle collider facility, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory.
Together with Brookhaven Lab physicist Lijuan Ruan, Geurts will serve a three-year term as co-spokesperson for the STAR collaboration. This group of over 740 scientists from 74 institutions across 15 countries uses a 1,200-ton, building-sized instrument ⎯ the Solenoidal Tracker at RHIC, or STAR detector ⎯ to study what happens when gold ions, protons, or a wide range of other atomic nuclei collide into or zoom past each other at ultrahigh speeds.
As co-spokesperson, Geurts will help manage operations for the STAR collaboration and detector system, acting as a representative of its technical and scientific activity.

The STAR detector at the Department of Energy’s Brookhaven National Laboratory (Courtesy of Brookhaven National Laboratory)

“We want to make sure that students and institutes across the collaboration can work efficiently with the data collected by the detector and help disseminate our exciting results to the scientific community and the public,” Geurts said.
RHIC, a 2.4-mile-circumference particle accelerator that is the world’s second-largest after the Large Hadron Collider, re-enacts on a subatomic scale cosmic events such as the aftermath of the Big Bang or neutron star collisions. The STAR detector system captures and analyzes data generated by the particle collisions inside RHIC to gain insight into the behavior of nuclear matter under extreme conditions.
“We're investigating very fundamental properties of nuclear matter and the best way to do that is by pushing it to its very extremes,” Geurts said. “Under extreme conditions like the Big Bang, but also when we have neutron star collisions or potentially even in supernovae, nuclear matter can melt into quarks and gluons ⎯ the substructure of these particles.”
Data collected from the collisions offers scientists a snapshot of a primordial state of matter present in the first instants of the universe’s existence known as quark-gluon plasma.

A computer rendering of a collision in the STAR detector (Courtesy of Brookhaven National Laboratory)

“It's basically a soup made up of the particles that form the substructure of protons and neutrons,” Geurts said. “In this soup, these so-called quarks and gluons are effectively liberated, not knowing anymore to what neutron or proton they originally belonged. On top of that, because of the high energies, many more quarks and antiquarks are created in this hot soup. There's a high degree of collectivity in these multiparticle systems.”
Using STAR, scientists learn about difficult-to-study fundamental forces that govern matter in the universe, such as the strong nuclear force. “From early experimental results, we learned that quark-gluon plasma is not so much a hot gas of liberated quarks,” Geurts said. “Instead, it has the characteristics of a hot and strongly interacting fluid with nearly no viscosity, behaving almost like an ideal liquid. This is very interesting, because ⎯ even though we are looking at what is truly the hottest place in the universe ⎯ we find effects of strongly interacting systems that at times look very similar to what you see in matter at ultracold temperatures.”

Frank Geurts, a Rice University physics and astronomy professor, has been elected co-spokesperson of the STAR experiment, the world’s longest-running nuclear physics collider experiment at a particle accelerator facility. (Photo by Gustavo Raskosky/Rice University)

The strongest of the four fundamental forces in nature (with gravity, electromagnetism and weak force being the other three), the strong force is what holds matter together both inside and outside the nucleons in atoms.
“Let’s take a gold nucleus, for example,” Geurts said. “You have a lot of neutrons ⎯ which carry no electrical charge ⎯ and protons packed together at the center of an atom. Because protons are positively charged, these particles repel one another, so something else must be way stronger than this electromagnetic force in order to keep them all together. That’s the strong force at work.”
Geurts’ leadership role foregrounds Rice’s long-standing contribution as one of STAR’s founding members. Not only have Rice scientists been actively involved in the collaboration over its near-quarter-century duration, but the university has also helped improve the detector’s particle identification capabilities.
“We can now say with much better precision what kind of particles we see being created in these collisions,” Geurts said.

The STAR detector at the Department of Energy’s Brookhaven National Laboratory (Courtesy of Frank Geurts/Rice University)

Geurts, who joined STAR in 2000 as a postdoctoral researcher, highlighted its role as a training ground for generations of scientists.
“We have graduate students who were not born when we started the experiment. We have professors who started their careers as graduate students in this experiment and now are leading new groups throughout the world in this endeavor. The data collected by STAR will continue to serve as an invaluable resource for many more doctoral theses and papers to come.”
Both the detector and the collider are scheduled to run experiments and continue recording data through the end of 2025, after which they will cease operations. Components of RHIC will be transformed into an Electron-Ion Collider, which is expected to begin operation in the early 2030s.
“Our responsibility as a management team is to pave the way for STAR to continue being an innovative and productive scientific enterprise during its post-operational phase,” Geurts said. “We expect that STAR will continue to come up with very exciting science for five, eight, maybe ten years after we record our last heavy-ion collision in 2025.”

src: https://news.rice.edu/news/2023/rice-u-physicist-lead-worlds-longest-running-nuclear-collider-experiment

QuarkNet 2023 Summer Workshop for High-School Teachers

Frank Geurts — 2023-06-03T07:43:29-05:00

In the last week of June, the UH/Rice University QuarkNet Center will hold its annual workshop for high-school teachers. We have a stimulating program thanks to a new collaboration with the IRIS-HEP, we will add a 3-day coding component to our program but also will have sufficient resources to expand the number of teachers that can attend.

In addition to that, we will dedicate a day to the upcoming Worldwide Data Day and learn how to analyze actual data from the CMS detector, and spend another day with "Oopsies in Science" to discuss things that can go wrong in the Edison's "98% perspiration" (which should be contributed to Kate Sanborn.)

We will also feature daily lectures from Rice and UH faculty on a wide range of topics in physics and astronomy.

Look at our agenda (which is still in development) at this link: QuarkNet Summer 2023 Workshop.

Below is the announcement that was sent to the teachers in the Greater Houston Area. There is still some space left, so contact our lead teacher Mary Yarbray if you are a science teacher interested in participating.

Quarknet is a week-long $120/day paid stipend 30-credit hour workshop that allows “teachers and physicists to work together on physics research projects exploring the hidden nature of matter, energy, space, and time”.Quarknet | Our funding and support comes from entities like NSF, University of Notre Dame, Fermilab, and the US Department of Energy.

Who: All secondary science teachers with an emphasis on Physics. This year, we have additional funding from NSF through the Institute for Research and Innovation in Software for High Energy Physics (IRIS-HEP), which allows us to include up to 30 participants this summer. We are interested in reaching out to Houston ISD and Aldine ISD (Title 1 schools), so if you can help spread the word, we would thank you. All Houston area schools are welcome to attend Quarknet.

How teachers can prepare:

What teachers should bring:
Computer, Notebook, writing utensils, and calculators.

Parking:
Parking will be covered by Rice University with a priority to carpools. We usually park in the lot of Rice Blvd and entrance 21.

Class Location: The workshop will take place in Herman Brown Hall room 227. (see agenda for map)

Lunch:
The department of Physics and Astronomy will provide lunch boxes for us. Soda machines may be found about the campus, but you may want to bring extra drinks. The menu is linked to the registration form. If you are bringing your own food, please indicate that on the form.

Agenda: https://star.rice.edu/outreach/quarknet/summer2023/
Introduction to particle physics.
·       The first three days (Mon-Wed) will be a coding workshop and the last two days will be filled with a couple of Quarknet activities and preparing for Worldwide Data Day this Fall.World Wide Data Day | Quarknet
·       Teachers will need to have a google account with colab access. Colab is not a part of the education suite, so IT might need to flip the switch for it to open. Even then, the district's firewall might still cause issues so please work with your district's IT.
·       Fabulous speakers from Rice and UH.
Registration: click here to register.

Thank you for your time,
Dr. Frank Geurts, Rice University Faculty Sponsor
Shane Wood, Quarknet Fellow
Mary Yarbray, Rice University Quarknet Lead Teacher

GRASP Workshop and the connection between Rice and Utrecht

Frank Geurts — 2023-05-23T06:53:22-05:00

This week the Institute for Gravitational and Subatomic Physics, cleverly abbreviated to GRASP, holds its inaugural workshop. GRASP, formally known as SAP (you can guess what that stands for), previously known as Vakgroep Kernfysica, is a research institute within Utrecht University's Departement Natuurkunde (Physics Department).

Its history is impressive, going back to people like Ornstein at a time when the department was still situated in the old city center of Utrecht at the Bijlhouwerstraat, built in 1875 upon insistence by Buys Ballot (who was a meteorologist with a remote interest in experimental physics). There is much more to read about this beautiful building at this link. What is interesting is to read the comments by Prof. Jan Kuperus: unbeknown to me and likely many people that walk in the park on top of it, the lab hosted a small particle accelerator. Raimond Snellings delivered a great historical account in his opening talk.

The GRASP Opening Workshop was held in yet-another-impressive building in the old inner city of Utrecht: the Paushuis, a building built in the early 16th century for the Dutch pope to live. But never ended up doing so. Ah well, a great place for a very informative workshop on the aspects of gravitational waves and heavy-ion physics, the two main pillars of the GRASP institute.

Run 23 cooldown finished

Frank Geurts — 2023-05-13T14:11:17-05:00

Run 23 is about to start. Its overall length is determined by the number of so-called cryoweeks; or, the number of weeks that the superconducting magnets are in operating conditions, i.e. below 4.6K. This important milestone was set to happen for May 11, and in the figures you can indeed see that from the ambient, "room" temperature throughout the early part of the spring cooling with liquid nitrogen brought the magnets down to about 60-80K, followed by the final step which involves liquid helium.
The graphs, which anybody can follow from CAD's website, show that the blue beam (which runs clockwise) was the first to reach this milestone, followed by the yellow beam (which runs counterclockwise).

Zooming in, above, on the last days as the blue ring drops first to operating temperatures, followed by the supercolliding magnets of the yellow beam. Below, zooming in even a bit more to the May-11 start of cryo-weeks, you can now see the blue-ring temperatures hover around and below 4.8K

May The Fourth Be With You

Frank Geurts — 2023-05-04T14:12:29-05:00

#TBT May 4th, 2018, at the #STAR Control Room, view from the Shift Leader's desk waiting for beam …

A Spokesperson's Welcome

Frank Geurts — 2023-05-01T22:30:23-05:00

Starting today, May 1, I will join Lijuan in our new co-spokespersons' team of the STAR Collaboration. Earlier today, we made the following announcement to the collaboration. We are excited to work with our new management team and very grateful to an excellent team that got us where we are. Those are big shoes to fill!

This morning the outgoing and incoming management teams held their last joint management meeting. As we announced to Council, starting today, May 1, the new management team will take on its responsibilities. Before introducing the new team to you, we’d like to take this opportunity to express on behalf of the Collaboration our sincere gratitude to all the members of the old team who have dedicated so much of their time in the past years to help steer our collaboration through BES-2, the forward upgrades, and have now put us in the best position to run for three more years at top energies.

Please join us in thanking Helen, Ken, Xin, Rongrong, and Takafumi !!

With the transition now complete [1], Lijuan and I would like to introduce the new management team. We have included their email address and would like to ask you to direct your management queries to them.

Spokesperson: Lijuan Ruan (BNL, ruan@bnl.gov)
Spokesperson: Frank Geurts (Rice University, geurts@rice.edu)

Deputy Spokesperson: ShinIchi Esumi (University of Tsukuba, esumi.shinichi.gn@u.tsukuba.ac.jp)
Deputy Spokesperson: Qinghua Xu (Shandong University, xuqh@sdu.edu.cn)

Physics Analysis Coordinator: Sooraj Radhakrishnan (Kent State University, skradhakrishnan@lbl.gov)
Deputy Physics Analysis Coordinator: Barbara Trzeciak (Czech Technical University, barbara.trzeciak@gmail.com)

Best regards,

Frank & Lijuan

[1] https://www.star.bnl.gov/welcome.php

QuarkNet Masterclass 2023

Frank Geurts — 2023-03-27T09:05:02-05:00

On Saturday, March 23, we welcomed more than 30 students and teachers from 8 high schools on our campus for the annual QuarkNet Master Class. Starting at 8h30am, we had a full day with a wide range of activities culminating in a Zoom call with particle physicists at Fermilab (Chicago) and other schools in Oklahoma to discuss the results of our hands-on analyses of real CMS data.

The morning started with an exercise in which we tried to organize a card deck with many fundamental particles. What organizational principle would you choose? And why? Mass, charge, spin, year of discovery? Darin Acosta (the leader of a similar QuarkNet program at the University of Florida) explained in his presentation how physicists now believe the Standard Model provides a good description of our current understanding of fundamental particles. But, quoting Darin here, "who knows what this will look like 100 years from now?"

Talking about particles is one thing, "seeing" them is a whole other endeavor. In the advanced teaching lab located in Brockman Hall 120, graduate student Jaanita Mehrani demonstrated the workings of a real scintillator-based cosmic ray detector similar to what many schools operate through the QuarkNet CRD program. She also demoed a very small, ultra-portable cosmic ray "watch." She allowed the students to peak at an ongoing physics experiment in which junior undergraduate students measured the lifetime of muons. A Cloud Chamber, located in a dark area of the lab, gave a real sense of muons passing through, as well as other particles, each leaving their signature trails.

More lectures on what it takes to actually measure particles were followed by two more lab tours and a boxed lunch, kindly provided by the Department of Physics & Astronomy.

The two tours took the students and teachers to the labs of Dr. Morosan and Dr. Killian (Dean of Natural Sciences). In Dr. Morosan's lab the students experienced the wondrous world superconducting materials that under very cold conditions will levitate. In Dr. Killian's lab carefully tuned lasers were able to almost stop atoms from vibrating thus creating the literally coolest place in the universe (yes, outer space is on average almost a million times hotter!)

After about an hour of actual physics analyses of real CMS data, all students joined a Zoom meeting with another school in Oklahoma analyzed at the same time ATLAS data and a panel of expert physicists at Fermilab in Chicago.

The agenda, links to resources that we used, and some more pictures can be found at this 2023 MasterClass's page.

Spring '23 STAR Collaboration Meeting

Frank Geurts — 2023-03-04T12:00:00-06:00

t's been a while since I attended a STAR Collaboration meeting in person, let alone visited Berkeley's LBNL. In fact, I was looking forward to visiting LBNL back in March 2020 when COVID reared its ugly head. At that time, it had already been more than 3 years since my last trip to LBNL. A rather memorable meeting that took place in the wake of a rather dramatic US presidential election. I am digressing. It was good to be back in Berkeley again and meet with friends and colleagues, and sunsets across the Bay are still impressive, even in cloudy conditions.

Among the many physics discussions, a few items stood out. The STAR Juniors coordinated lunch parties with senior scientists. My lunch with students from Yale, UC Riverside, and CTU was an absolute delight and I hope these lunches will become a staple in future meetings. Another important event was the opportunity we had as a collaboration, but also as individuals to bid one of our most esteemed colleagues and long term STAR collaborator, Bill Christie a happy start of his retirement. I particularly like the picture in which you can see Bill holding a certificate under the watchful eyes of Tim Hallman (Assoc. Director DOE Office of Nuclear Physics), Spyros Margetis (DOE/NP Prog.Director), and Flemming Videbaek (BNL/STAR retiree). Bill's commitment to STAR serves as an excellent example to all of us - somebody who I have called at early hours from the STAR Control Room, or often somebody who'd be calling me asking why we weren't taking data.

Oh, and then there was one more important item that had to be decided by the STAR Council at this collaboration meeting and that was the election of the next co-spokespersons. I am thankful to the Council for the trust that they put in Lijuan Ruan (BNL) and me to lead the STAR collaboration for the next three years.

Visiting CERN

Frank Geurts — 2022-12-07T16:45:19-06:00

It's been about 14 years ago since I last visited CERN. The city of Geneva has appeared a few times on past itineraries, but this was the first time since the "LHC incident" in September 2008 that I visited the CERN Meyrin site. Some things have changed, but many things did not, and it was pretty amazing to find myself walking the same shortcuts through an all-familiar maze of interconnected buildings. While the main motivation for my visit was to discuss our contributions to the construction of CMS's "MIP Timing Detector" (MTD), or rather its Endcap Timing Layer (ETL), it was a great opportunity to attend some of the meetings that took place in the context of the CMS Week and visit "Point 5," the experimental site for the CMS detector to see in-person how the installation efforts in a few years will look like.

It was also a great opportunity to meet old friends (Tapan!) going back to my days as an undergraduate and graduate student at the WA93 and WA98 experiments, respectively.

Unfortunately, the Netherlands lost that same week from Argentina in the quarter finals of the World Cup ...

Strangeness in QuarkMatter 2022

Frank Geurts — 2022-06-17T12:07:20-05:00

At the 20th International Conference on Strangeness in Quark Matter, Zaochen Ye was invited to present at one of its plenary sessions an overview of thermal dilepton measurements in heavy-ion collisions The conference typically focusses on experimental an theoretical developments with respect to strange and heavy-flavored quarks in high-energy heavy-ion collisions as well as in astrophysical phenomena. Dilepton measurements essentially straddle this range of topics as such measurements include decays of phi mesons (strangeness), contributions from charm mesons through J/psi and weak D-meson decays. Temperature measurements extracted from dilepton measurements further more give insight to the conditions inside a QGP, which is a state of matter that arose early after the Big Bang and potentially in neutron-star collisions.

(slide from Zaochen Ye's SQM'22 plenary presenation, summarizing temperature measurements)

QuarkNet 2022 Summer Workshop for Teachers

Frank Geurts — 2022-06-11T14:52:47-05:00

With the support of the QuarkNet leadership and Rice's Physics & Astronomy department the yearly QuarkNet workshop took place in June 2022.

Over the span of a full week from June 6-10, we were able to about a dozen teachers from various campus across Greater Houston. Equally exciting is that we saw a record number of five QuarkNet fellows travel to Houston to lead a great set of mini-workshops as well as a couple of fellows that joined remotely. A special shout-out goes to Houston center's lead teacher Mary Yarbray and QuarkNet fellow Shane Wood who both have been instrumental in bringing together an exciting program and great group of enthusiastic teachers.

This year's program saw three components, all new, that included a coding workshop, a neutrino workshop, and a brand-new Higgs@10 workshop on the imminent 10yr anniversary of the discovery announcement of the Higgs boson. With the introduction to coding, using Python-based code in Jupyter notebooks, the teachers learned about exciting new ways in which students could deeper engage with physics measurements (or simulations). The neutrino workshop further build on top of this by pulling in real MINERvA data and manipulating these data to learn more about the observation of neutrino oscillations. Finally, the Higgs@10 workshop allowed everybody to re-familiarize eachother with the powerful iSpy environment in which teachers and students can pull in real CMS or ATLAS data. For this workshow, these curated data sets provided great opportunities to observe the Higgs peak arise from an analysis of 4-lepton LHC p+p events.

In addition to the mini-workshops, faculty and scientists from both UH and Rice gave hour-long lectures on a range of topics that included an overview of exciting new detector upgrades in anticipation for LHC Run3 (prof. Ecklund), how heavy-ion collisions and neutron-star collisions related (prof. Ratti), what we've learned in the past 10 years since the Higgs discovery (prof. Acosta), and how nuclear physics is applied in radiation therapies (prof. Yepes).

We are very grateful to the QuarkNet leadership for their support - specifically to Shane, Chris, Adam, Mike-1, Mike-2, Maria, and Ken! We thank the Rice Physics & Astronomy Dept. for its in-kind contributions, not in the least providing lunch to all that attended (thank your Barbara!).

RHIC & AGS Users' Meeting 2022 Merit Award

Frank Geurts — 2022-06-11T14:23:28-05:00

Congratulations to Zaochen Ye!
At the 2022 virtual RHIC and AGS Users' Meeting, Zaochen received a prestigious Merit Award from BNL's ALD for Nuclear and Particle Physics, dr. Haiyan Gao. He was honored for “his dedication to STAR time-of-flight detector operation and calibration, and breakthrough analysis of dielectron continuous spectra related to the QGP (quark-gluon plasma) radiation.”

(picture: Zaochen Ye in his office, right before the virtual ceremony)

Heaps Prize 2022

Frank Geurts — 2022-05-09T14:12:02-05:00

The Heaps Prize is one of the top awards with which the Physics & Astronomy department each year honors an undergraduate physics student on the basis of excellence in a recent research project, often one leading to the senior thesis. The Distinction in Research in Physics and Astronomy is given for a research accomplishment of exceptional quality, as judged by a committee of faculty based on one or more scientific documents describing a contribution to physics, astronomy, or related field. The recipient of both honors this year is Jaanita Mehrani for her excellent work in our group on "Hydrodynamics calculations of Beam Energy Scan Au+Au data, taken by the STAR experiment." I am not sure any pictures were taken but if there are I will update this post. Needless to say that we look forward to see her continue her work in our group as a graduate student. Congratulations Jaanita!

DIS 2022 - Santiago de Compostela, Spain

Frank Geurts — 2022-05-06T12:00:00-05:00

In the week of May 2, the DIS 2022 conference was held (in person!) in historical pilgrimage town of Santiago de Compostela in Spain. This is the 29th in the series of annual workshops on Deep-Inelastic Scattering (DIS) and Related Subjects. Our Rice group member Isaac Upsal attended in person and presented on behalf of the STAR collaboration work, including his, on "Nuclear Tomography with Polarized Photon-Gluon Collisions".

Isaac presented STAR measurements from diffractive photo-nuclear interactions in ultra-peripheral Au+Au and p+Au collisions at √𝑠_𝑁𝑁=200 GeV and from U+U collisions at √𝑠_𝑁𝑁=193 GeV. These measurements are used to measure the strong interaction radius of gold and uranium nuclei at high energy. He showed first measurements of the neutron skin of uranium measured at high energies and discussed the implications for experiments at the future Electron Ion Collider, where similar diffractive photo-nuclear interactions are an essential component in the planned physics program.

You can find his slides at this link.

QuarkNet Masterclass 2022

Frank Geurts — 2022-05-05T09:22:26-05:00

On Saturday April 30 we organized our first do-i-dare-to-say-it "post-pandemic" QuarkNet Masterclass.

Almost 30 students from five high schools attended a pretty full day of lectures, demos, tours, and hands-on analysis of real data from the Large Hadron Collider at CERN. A special thank-you goes out to the US QuarkNet leadership for their support and the Rice Physics & Astronomy department who sponsored the lunches. I also appreciate NSCI's Dean Tom Killian, and his students for allowing us to tour their lab and showing the exiting physics at temperatures of about 0.00000001 (10^-9) K when we earlier in the morning talked about temperatures of 1000000000000 (10^12)K and in between had a lot of fun of some left-over liquid nitrogen which boils at 77K!

More details on this and other QuarkNet activities in my group can be found at this link. Here I will also post some more pictures, including the by-now traditional "hold-your-favorite particle" group photos.

QuarkMatter 2022 - Krakow, Poland

Frank Geurts — 2022-03-10T12:00:00-06:00

What a way to jump more than 2 years and talk about -again- about QuarkMatter. The 2022 edition, or rather the one that was originally planned for 2021. This year the meeting was able to take a few of us out from Zoom to "IRL". It allowed us to bring together again over coffee breaks, lunches, dinners, and the occasional beer the science and friendships that had been insulated by screens and microphones.

Anyways, a few points about this year's conference. First of, Zaochen Ye's hard work over the past years paid of beautifully in an excellent presentation on the first thermal dilepton based temperature measurement using STAR Au+Au data from the 2018 run at 27GeV and the 2017 run at 54GeV.
His results did not go unnoticed and reappeared in three more plenary overview presentations throughout the week. The 2022 QuarkMatter conference ended with a the invitation from the co-chairs of the 2023 QM meeting which will be held in ... Houston, TX! Yes, we look forward to seeing all our colleagues here in Houston in September 2023!

QuarkNet 2021 Summer Workshop for Teachers

Frank Geurts — 2021-06-19T12:00:00-05:00

As more and more schools and universities tried to return mid-2021 to in-person classes, the Rice/UH #QuarkNet center saw opportunities to return to an in-person workshop for high school teachers. With the support of the QuarkNet leadership and Rice's Physics & Astronomy department the very first "post" pandemic on-campus QuarkNet workshop took place in June 2021.

Over the span of a full week from June 14 - 18, we were able to invite eleven teachers from various campus across Greater Houston. We are especially trilled to see no less than three staff members from QuarkNet travel to Houston for an exciting range of mini-workshops. Special thanks go out to the center's lead teacher Mary Yarbray! In a continuation of the 2019 CMS E-Lab workshop, Shane Wood (QuarkNet National Staff) introduced the teachers to CMS Data Workshop. Our ultimate goal is to expand our center's attendance of future MasterClasses. We asked those teachers who host one of QuarkNet's Cosmic Ray Detectors (CRD) to bring them to our campus while QuarkNet Cosmic Fellow Nate Untermann brought his wonderful expertise back to our campus. Under his guidance several projects were discussed that teachers could bring back to their schools. One of the Rice undergraduate seniors, Jaanita Mehrani, who works with professor Geurts (QuarkNet mentor and PI of the Rice/UH center) shared her expertise and showed a neat demonstrator based on MIT's CosmicRayWatch project.

Mixed in between the muons studied in the CMS mini workshop and the muons detected with QuarkNet's own CRD's, we were especially thrilled to see a couple of afternoons dedicated to QuarkNet's STEP UP program. In this interesting mini-workshop, based on an APS program, Michael Wadness (QuarkNet's STEPUP Lead) together with Shane Wood discussed efforts to engage young women in physics, how to recognize and change deep-seated cultural views about physicists, and how teachers could help inspire young women to pursue physics in college.

In addition to the mini-workshops, faculty and scientists from both UH and Rice gave hour-long lectures on a range of topics that included application of nuclear and particle physics through MediPix (prof. Pinksy), Medical Physics (dr. Wang), the latest news from CMS (prof. Ecklund), what we learned hot nuclear matter (prof. Geurts), and what know -and don't know- about Dark Matter (prof. Long).

In all, this first national in-person high school teacher workshop was a welcome return of staple QuarkNet program and came with a jam-packed program full of exciting physics and ideas. We are very grateful to the QuarkNet leadership for their support - specifically to Shane, Nate, and Mike. We thank the Rice Physics & Astronomy dept. for its in-kind contributions, not in the least providing lunch to all that attended. QuarkNet activities in our center are back again and we look forward to inviting high school students for MasterClasses soon!

[from the 2021 Annual Report]

QuarkMatter 2019 - Wuhan, China

Frank Geurts — 2019-11-25T21:58:17-06:00

In 2019 the Quark Matter Conference took us to Wuhan, China. Zaochen Ye presented a poster on dielectron measurements in the new and much larger 2017 data set of Au+Au collisions at 27GeV. His results were also presented in Florian Seck's (TU Darmstadt) parallel presentation. The statistical uncertainties on these preliminary results promise rather exciting opportunities of measuring thermal radiation in the invariant mass range between the phi and J/psi vector mesons. On Friday during the last plenary session before the banquet, Frank Geurts gave the experimental overview of electromagnetic and weak probes. An exciting amount of new results on these subjects were shown at the conference. On the last day, Rice graduate Daniel Brandenburg (now at BNL) received Elsevier's Young Science Award for Best Experimental Talk.

Poster presentation from Zaochen.

Frank speaking on the ginormous stage set for the plenary sessions on Friday.

A clear view on the city of Wuhan from my hotel room.

Rice Physics & Astronomy Brownbag lunches for graduate students

Frank Geurts — 2019-09-12T12:00:00-05:00

Each Fall semester provides a great opportunity to tell a new class of physics & astronomy students about the exciting research that we do in the high-energy nuclear physics groups. My favorite opening slide of these Brownbag Lunches is the one that shows one of the pillars in the corridor of the Brockman Hall for Physics. The pillar has a big bronze plaque showing a typical event display of the many particles ("tracks") that are produced in a high-energy collision of gold on gold nuclei as seen by STAR's Time Projection Chamber.

STAR Collaboration Meeting in Cracow

Frank Geurts — 2019-08-23T09:22:28-05:00

In August the AGH UST group hosted the STAR Collaboration Meeting in Cracow, Poland. The organizers should be congratulated on a perfectly organized meeting (with excellent coffee!) as can be seen from the many smiles on the obligatory collaboration meeting picture. It was a well-attended meeting with many familiar faces from across the globe. I look forward returning to Cracow for the 2021 QuarkMatter conference!

Congratulations James (Daniel) Brandenburg

Frank Geurts — 2019-06-18T11:35:29-05:00

Congratulations to Daniel Brandenburg who who received an Honorable Mention in the RHIC/AGS Thesis Award. The purpose of the award is to recognize the most outstanding thesis related to research conducted at the RHIC, AGS, NSRL, Tandem, BLIP or ATF facilities. This year there were 16 submissions with two winners and two honorable mentions.

RHIC and STAR are preparing for BES-2

Frank Geurts — 2019-01-04T10:11:32-06:00

It's been a while since I've sent out updates, so let me share the following press release from BNL while I start filling you in on what has happened in the past couple of months! -fg

Source: Brookhaven National Laboratory

19th year of operations at the Relativistic Heavy Ion Collider will continue search for critical point in transition from protons and neutrons to quark-gluon plasma.

The Relativistic Heavy Ion Collider (RHIC) is actually two accelerators in one. Beams of ions travel around its 2.4-mile-circumference rings in opposite directions at nearly the speed of light, coming into collision at points where the rings cross.

UPTON, NY—January 2 marked the startup of the 19th year of physics operations at the Relativistic Heavy Ion Collider (RHIC), a U.S. Department of Energy Office of Science user facility for nuclear physics research at Brookhaven National Laboratory. Physicists will conduct a series of experiments to explore innovative beam-cooling technologies and further map out the conditions created by collisions at various energies. The ultimate goal of nuclear physics is to fully understand the behavior of nuclear matter—the protons and neutrons that make up atomic nuclei and those particles’ constituent building blocks, known as quarks and gluons.
Many earlier experiments colliding gold ions at different energies at RHIC have provided evidence that energetic collisions create extreme temperatures (trillions of degrees Celsius). These collisions liberate quarks and gluons from their confinement with individual protons and neutrons, creating a hot soup of quarks and gluons that mimics what the early universe looked like before protons, neutrons, or atoms ever formed.
“The main goal of this run is to turn the collision energy down to explore the low-energy part of the nuclear phase diagram to help pin down the conditions needed to create this quark-gluon plasma,” said Daniel Cebra, a collaborator on the STAR experiment at RHIC. Cebra is taking a sabbatical leave from his position as a professor at the University of California, Davis, to be at Brookhaven to help coordinate the experiments this year.
STAR is essentially a house-sized digital camera with many different detector systems for tracking the particles created in collisions. Nuclear physicists analyze the mix of particles and characteristics such as their energies and trajectories to learn about the conditions created when ions collide.

The STAR collaboration's exploration of the "nuclear phase diagram" so far shows signs of a sharp border—a first-order phase transition—between the hadrons that make up ordinary atomic nuclei and the quark-gluon plasma (QGP) of the early universe when the QGP is produced at relatively low energies/temperatures. The data may also suggest a possible critical point, where the type of transition changes from the abrupt, first-order kind to a continuous crossover at higher energies. New data collected during this year's run will add details to this map of nuclear matter's phases.

By colliding gold ions at various low energies, including collisions where one beam of gold ions smashes into a fixed target instead of a counter-circulating beam, RHIC physicists will be looking for signs of a so-called “critical point.” This point marks a spot on the nuclear phase diagram—a map of the phases of quarks and gluons under different conditions—where the transition from ordinary matter to free quarks and gluons switches from a smooth one to a sudden phase shift, where both states of matter can coexist.

STAR gets a wider view
STAR will have new components in place that will increase its ability to capture the action in these collisions. These include new inner sectors of the Time Projection Chamber (TPC)—the gas-filled chamber particles traverse from their point of origin in the quark-gluon plasma to the sensitive electronics that line the inner and outer walls of a large cylindrical magnet. There will also be a “time of flight” (ToF) wall placed on one of the STAR endcaps, behind the new sectors.
“The main purpose of these is to enhance STAR's sensitivity to signatures of the critical point by increasing the acceptance of STAR—essentially the field of view captured in the pictures of the collisions—by about 50 percent,” said James Dunlop, Associate Chair for Nuclear Physics in Brookhaven Lab’s Physics Department.

RHIC's STAR detector tracks the thousands of particles produced by each ion collision. It weighs 1,200 tons and is as large as a house.

“Both of these components have large international contributions,” Dunlop noted. “A large part of the construction of the iTPC sectors was done by STAR’s collaborating institutions in China. The endcap ToF is a prototype of a detector being built for an experiment called Compressed Baryonic Matter (CBM) at the Facility for Antiproton and Ion Research (FAIR) in Germany. The early tests at RHIC will allow CBM to see how well the detector components behave in realistic conditions before it is installed at FAIR while providing both collaborations with necessary equipment for a mutual-benefit physics program,” he said.

Tests of electron cooling
Before the collision experiments begin in mid-February, RHIC physicists will be testing a new component of the accelerator designed to maximize collision rates at low energies.
“RHIC operation at low energies faces multiple challenges, as we know from past experience,” said Chuyu Liu, the RHIC Run Coordinator for Run 19. “The most difficult one is that the tightly bunched ions tend to heat up and spread out as they circulate in the accelerator rings.”
That makes it less likely that an ion in one beam will strike an ion in the other.

A schematic of low-energy electron cooling at RHIC, from right: 1) a section of the existing accelerator that houses the beam pipe carrying heavy ion beams in opposite directions; 2) the direct current (DC) electron gun and other components that will produce and accelerate the bright beams of electrons; 3) the line that will transport and inject cool electrons into the ion beams; and 4) the cooling sections where ions will mix and scatter with electrons, giving up some of their heat, thus leaving the ion beam cooler and more tightly packed.

To counteract this heating/spreading, accelerator physicists at RHIC have added a beamline that brings accelerated “cool” electrons into a section of each RHIC ring to extract heat from the circulating ions. This is very similar to the way the liquid running through your home refrigerator extracts heat to keep your food cool. But instead of chilled ice cream or cold cuts, the result is more tightly packed ion bunches that should result in more collisions when the counter-circulating beams cross.
Last year, a team led by Alexei Fedotov demonstrated that the electron beam has the basic properties needed for cooling. After a number of upgrades to increase the beam quality and stability further, this year’s goal is to demonstrate that the electron beam can actually cool the gold-ion beam. The aim is to finish fine-tuning the technique so it can be used for the physics program next year.
Berndt Mueller, Brookhaven’s Associate Laboratory Director for Nuclear and Particle Physics, noted, “This 19th year of operations demonstrates once again how the RHIC team — both accelerator physicists and experimentalists — is continuing to explore innovative technologies and ways to stretch the physics capabilities of the most versatile particle accelerator in the world.”

Research at RHIC is funded primarily by the DOE Office of Science (NP) and by these agencies and organizations.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

Follow @BrookhavenLab on Twitter or find us on Facebook.

STAR eTOF installation nears completion

Frank Geurts — 2018-11-22T14:53:27-06:00

With the installation of the lower 6 sectors, the endcap Time-of-Flight (eTOF) detector, a joint CBM/STAR project, has been fully installed as of Wednesday Nov.21. With the gas, high voltage, low voltage, clock and DAQ connections all in place the next step will follow in the commissioning efforts towards STAR's Beam Energy Scan Phase 2 which is scheduled to start late February/early March. Geary Eppley of Rice together with collaboration members from Heidelberg and with the excellent support from STAR's Technical Support Group have been working in the past couple of weeks getting the 36 modules -all shipped from Heidelberg, Germany- mounted to the endcap.

DOE Office of Science Highlight: Heavy Particles Get Caught Up in the Flow

Frank Geurts — 2018-09-07T11:29:16-05:00

Today, the DOE's Office of Science highlighted STAR's heavy-flavor program on its "Science Highlights" web page. Take a look at the following direct link to the release: Heavy Particles Get Caught Up in the Flow

The STAR Heavy Flavor Tracker, located in the center of STAR at the Relativistic Heavy Ion Collider at BNL.
Image courtesy of Brookhaven National Laboratory.

2018 APS April Meeting

Frank Geurts — 2018-05-08T16:50:53-05:00

This year's APS April Meeting took place in ... April (not always a given) and was my first opportunity to visit the city of Columbus OH. Julia Velkovska (Vanderbilt) and Romana Vogt (LBL) organized a couple of topical workshops on heavy ion physics. One workshop discussed "High Baryon
Density Physics in Nuclei and the Cosmos". I was invited to talk what we can learn about high baryon density QCD from low energy nuclear collisions. Other talks in this (obviously very interesting!) session looked on the one hand at the nuclear equation of state from cosmological measurements such as gravitational waves from neutron star-black holes and binary neutron star mergers, while at the other hand looked at high
baryon density QCD from lattice calculations.

On the third day of the conference, the DNP section met and the nuclear physics leadership of the DOE Office of Science and NSF brought all up to speed on the current funding challenges and opportunities. Tim Hallman (Associate Director of the DOE Office of Science for Nuclear Physics, and former STAR spokesperson) highlighted a couple of times STAR in this presentation. Very nice!

QuarkNet Masterclass

Frank Geurts — 2018-03-26T10:54:48-05:00

On Saturday we organized the first QuarkNet Masterclass for high school students on the campus of Rice University. Several students and teachers attended a physics-filled day with lectures, demos, in-class activities, and hands-on analysis of data from the CMS experiment. We concluded the masterclass with a videoconference with a few other QuarkNet centra to discuss our work and answer any questions from the organizers or other students.

One of the teachers, Alain Harvey, shared a wonderful story on his Facebook feed about this which he kindly allowed me to share. I look forward to seeing more teachers and there students join in future returns of his great initiative. Of course, I should thank Umbe Oliveira-Cantu and the department for providing us all with lunch!

In Alain Harvey's words:
"Once a year, high school classes from around the world can participate in QuarkNet masterclasses.

These students spent an entire day on the Rice University campus, visiting the physics laboratories, and hearing faculty member Dr. Frank Geurts discuss his current research and the field of particle physics. The capstone activity was the analysis of real high energy physics data, and the exchange and comparison of the results with the other classes around the world via video-conference. As a result, students gained valuable insights relating to the topics and methodology of particle physics.

During the day students:

• Attended lectures on the Standard Model and learned how to analyze events;

• Analyzed events from various CERN or Fermilab particle physics experiments; and,

• Discussed their results with other student teams via international videoconferencing moderated by physicists.

MasterClass is a means for Quarknet high school teachers to share their enthusiasm for cutting edge science research and expertise with their own students. Rice University’s Physics and Astronomy Department generously hosted teacher-led teams for an entire day of engaging activities. Students examined actual CMS image data focused on Z- and W-bosons measurements, firsthand. Students also engaged with researchers and staff, toured available labs and meet others with similar interests from around the world!

During the morning session, students learned about the components of a particle accelerator and how to pick out identifying characteristics of particles from event data. This was a great opportunity for students to learn about cutting edge research and engage with physicists doing it!

The Physics Lab was followed by a leisurely lunch generously provided by Rice University.

The afternoon session culminated with teachers and their students participating in a live video conference with high school students and researchers from other QuarkNet centers located in the U.S. and other countries.

The QuarkNet Masterclass Program

QuarkNet is a long-term, research-based program in the United States jointly funded by the National Science Foundation and the U.S. Department of Energy.

Since 1999, QuarkNet has established centers at universities and national laboratories conducting research in particle physics (also called high-energy physics) across the United States.

Mentor physicists and physics teachers collaborate to bring cutting-edge physics to high school classrooms. QuarkNet offers research experiences for teachers and students, teacher workshops and sustained follow-on support.

Through these activities, teachers enhance their knowledge and understanding of scientific research and transfer this experience to their classrooms, engaging students in both the substance and processes of contemporary physics research.

In 2007, QuarkNet first piloted U.S. Masterclasses, modeled on a program offered by EPPOG and studying Large Electron-Positron Collider-era CERN data. Today masterclasses study ALICE, ATLAS or CMS data. Masterclasses are one-day national events in which teams of students visit a nearby university or research center to gain insight into topics and methods of particle physics.

2011 was the first year that LHC data were incorporated into the masterclass There were exercises for ATLAS (Z- and W-bosons measurements), ALICE (for stranger particles), and CMS (J/ψ meson).

2012 saw the incorporation of expanded CMS data (W/Z measurement.)

Quarknet MasterClasses are held annually in February or March, and are open to high school teachers participating the QuarkNet program, just one of the perks for the joint Quarknet Summer Institute at Rice University and the University of Houston!

What my students had to say:

"Not only did the MasterClass introduce me to an exciting new college scene, but it also introduced me to intelligent people, who have a desire to participate in activities concerning particle physics as I do. It was informative; and even exciting; how we spoke about what we were going to look at and determine through observing electronic diagrams.

We looked at various similar yet classifiably different diagrams and determined what exactly they were using only a set of notes we established earlier and our wit! It was awe-inducing to work and compare results with other students my age on the same project, from across the country and the world. As a junior in high school, I have considered taking general physics in college, and this course gave me some experience that will help me decide how to consolidate on what kind of physics I would like to accomplish working with. I will recall this experience for years to come, and look forward to more like this one."

Harris Khan, Jersey Village High School, Houston, Texas

"One of the most memorable things of the project was how when we had conflicting data (such as two muons and one electron) and no one would know what to classify the collision as being. This showed me how even today physicists are still seeking answers to events at subatomic size. I gained a lot from the Quarknet MasterClass, and I hope I can do more things like it next year."

Anthony Luu, Cypress-Woods High School, Houston, Texas"

Ruthenium & Zirconium

Frank Geurts — 2018-03-13T09:00:00-05:00

IT IS ON!!! After a couple of weeks of taking data from cosmic rays crossing through the STAR detectors, we have now officially changed to "Physics Mode" and are back again taking collider data from heavy-ion collisions. But, this year is special. This year we are looking at collisions between ruthenium (Ru-96) and Zirconium (Zr-96). As you can tell both isotopes carry the same total number of nuclei (protons + neutrons). The difference is in how the atomic mass is distributed between the protons and neutrons. Zirconium has an atomic number (read: number of protons) of Z=40, while Ruthenium has Z=44.

The physics motivation for running these two species lies in the subtle but significant difference in that number and the effect that it may have on the very strong magnetic fields that develop in the initial stages of a collisions. Recall that these highly electrically charged heavy ions speed with ultrarelativistic velocities thus generating a very strong electrical current and magnetic field perpendicular to the collision plane. See this nice figure taken from a recent comment in Nature

The magnetic field is expected to have a subtle but measurable effect on the behavior of fundamental particles that created in the hot and dense quark-gluon plasma. The effect, called the Chiral Magnetic Effect, is different from what one would expect under "normal" conditions and tied to fundamental symmetries in nature. Testing the strength of this effect for different magnetic fields while keeping all other conditions more or less similar is one of the main drivers of this year's run period.

A nice write-up can be found at Brookhaven National Lab's website at this link.

The Rice group is working hard on making sure that the main working horses, the BTOF and VPD detectors as well as the MTD detector are fully functional and take high-quality data. At the same time, we work on testing a first sector of the endcap Time-of-Flight detector commissioned in anticipation of next year's continuation of the Beam Energy Scan program.

STAR eTOF Software Workshop at Rice

Frank Geurts — 2018-02-25T21:48:54-06:00

The endcap Time-of-Flight detector is a detector upgrade for the STAR experiment that will improve particle identification capabilities significantly in the more forward region of its rapidity coverage. It will be an essential component that will take advantage of the other important upgrade, i.e. replacement of the inner sectors of STAR's decades old workhorse, the TPC. The second phase of the Beam Energy Scan is scheduled to take place in 2019-2020. The iTPC and eTOF upgrades will need to be installed and ready to go before that time. As the hardware installation and commissioning efforts are all well under way, it is important that the software developments ramp up and all be ready to analyze the data that we register, even if only from the first few modules that are installed for the 2018 run.

In the week of February 19, a group of students from Rice, Heidelberg, Darmstadt, and UC Davis met to discuss what is needed and how to seed the various development tasks that lie ahead. In the picture, below, you see Geary Eppley (with his back towards the camera), and from left to right Florian Seck (UT Darmstadt), David Tlusty (Rice), Daniel Brandenburg (Rice), and Philipp Weidenkaff (Heidelberg) in a small windowless conference room ...

Picture courtesy of Joey Butterworth.

THIS Fall 2017

Frank Geurts — 2017-11-11T18:00:00-06:00

On November 10 and 11, after many years of talking about it, we finally had a first regional Texas Heavy-Ion & Spin physics symposium at our very own Rice campus. Within less than 2.5hr drive we have five institutes that are involved in heavy-ion and spin physics related research. Our goal is to bring graduate students and postdocs together and present their work to their peers in a friendly setting. Thirty-nine faculty, postdocs, and students showed up for this 2-day event and listened to sixteen very well prepared presentations. This was a great success and we hope next year to see a repeat of this. For more information go to THIS2017.

On the picture you can see all participants nicely lined up in front of the Brockman Hall for Physics. If you carefully zoom in on the column in the back you will see a bronze(!) event display of a Au+Au collision in the STAR detector.

Santa Monica "SMASH" Elementary School (outreach part 2!)

Frank Geurts — 2017-10-25T17:00:00-05:00

Ask a nuclear physicist!
What a great idea! Using FaceTime I talked for more than half an hour (was it a full hour?) to an elementary school 3rd/4th grade class in Santa Monica, CA. The children had all prepared themselves and provided the fantastic teacher (Alejandra Santini) with a big stack of questions. And, boy, those were some good questions!! Thankfully I had already done some calculations so that I could help the students answer the questions of the energy of TNT (Minecraft!) vs. that of a QGP ... This was also a great time to show of my Particle Zoo pluche puppets.

And, at the end the whole class sang their Periodic Table Song to me. I could not stop laughing (and they could not stop singing!). A special shout-out to Alejandra Santini, her excellent class, Guido Faas (who was instrumental in setting this up), and of course my best friend ... Archer!

Klein High School - (outreach part 1)

Frank Geurts — 2017-10-24T17:00:00-05:00

Klein ISD is all but small (as the German/Dutch word "Klein" would imply). It serves more than 50,000 students in 32 elementary schools, 9 intermediate schools, and 5 high schools (source: Wikipedia). The auditorium at Klein High School nicely filled up and resulting in a lot of questions from everybody who came and listen in. A special shout out to Mary Yarbray (she's a high school physics teacher who is actively involved in the QuarkNet program) who invited me. You can see me hold this wonderful "particles in a physics box" tissue box that one of her students had made.

Strangeness in Quark Matter 2017 (Utrecht, The Netherlands)

Frank Geurts — 2017-07-17T15:39:25-05:00

On July 10, Utrecht University in the Netherlands hosted the 17th edition of the International Conference on Strangeness in Quark Matter -a.k.a. by its acronym SQM 2017. Over a 6-day long timespan, more than 200 physicists met and discussed strange quarks and hadrons in hot and cold nuclear matter. This year, the organizers decid

ed to broaden the spectrum by including contributions on the heavier quarks, charm and bottom. David Tlusty presented in his invited plenary presentation an overview of recent strangeness results from two collaborations that actively probe the intermediate baryon chemical potential range of the QCD phase diagram: NA61 at CERN, and STAR at RHIC. A direct link to his slides can be found here. Frank chaired one of the parallel sessions that took place on Friday.

PhD Thesis defense Joey Butterworth

Frank Geurts — 2017-04-11T10:55:57-05:00

Congratulations to Joey Butterworth for his successfull defense on April 11 of his PhD thesis on "Electron-positron pair production in Au+Au collisions at √sNN= 27 GeV as part of the Beam Energy Scan Program at STAR"

From the official announcement:

This thesis reports the e+e- pair production in the top 80% most central Au on Au collisions at √sNN = 27 GeV from the STAR experiment. The production exhibits an excess yield, in the low invariant mass region (M(e+e-) ≤1.2 GeV/c2), when compared to a hadronic cocktail without ρ-meson contributions. This excess yield is shown to be successfully described by model calculations that include a broadening of the ρ-meson spectral function in a hot, dense medium, and similar agreement to the excess yield, after applying an acceptance-correction, is also exhibited. These results are a part of a systematic study of the e+e- pair production in Relativistic Heavy Ion Collider Beam Energy Scan Program and are presented with data from Au on Au collisions at √sNN = 19.6, 39, 62.4, and 200 GeV. Each collision energy e+e- pair measurement has an excess with respect to a hadronic model without ρ-meson contributions, and each excess yield is described by model calculations that include a broadening of the ρ-meson spectral function in a hot, dense medium. This suggests that the ρ meson is modified by the hot, dense medium. The acceptance-corrected excess yields are also reported as a function √sNN, charged particle multiplicity, and predicted lifetimes. Given uncertainties, no statistically significant excess yield dependence on √sNN, charged particle multiplicity, and predicted lifetimes are observed for Au on Au collisions with a 0-80% centrality.

Joint CBM/STAR Meeting

Frank Geurts — 2017-03-23T00:00:00-05:00

[based on STAR Newsletter contribution by Geary Eppley]

The STAR Collaboration and the Compressed Baryonic Matter Collaboration held a joint workshop in the historic art deco clock tower auditorium at the Technische Universitat Darmstadt on Saturday March 18. CBM
and STAR are collaborating on an endcap time-of-flight detector for the Beam Energy Scan phase II at RHIC, scheduled for 2019-2020. The eTOF upgrade will greatly enhance the physics reach for BES-II and provide a full-scale integration and systems test for almost 10% of the planned CBM TOF system. The joint CBM-STAR project is part of the FAIR Phase 0 program to test detector components prior to the completion of CBM and the Facility for Antiproton and Ion Research accelerator at GSI Darmstadt, scheduled for 2025.

This first CBM-STAR joint workshop attracted 48 physicists from the US, China, and Europe. The sixteen presentations during the one-day Saturday session covered topics of interest for BES-II, CBM, and HADES from both an experimental and theory point of view. Geary Eppley convened the opening session which mostly focussed on some of the relevant hardware advances towards BES-II. Daniel Brandenburg and Florian Seck (who visited Rice in the Fall of 2016) presented the plans for dilepton measurements and recent theory developments, respectively. Frank Geurts discussed improvements and opportunities in bulk spectra.

The workshop was delicious as well. The organizers provided a sumptuous Italian buffet for lunch and a traditional Hessian buffet Saturday evening. There was also a productive discussion session Sunday morning following the workshop. The CBM Collaboration meeting began Monday. There was a construction readiness review of MRPC production for the eTOF modules. Construction of the first batch, about 10% of the 108 MRPCs needed for the full eTOF, is scheduled to begin this May. A complete sector of eTOF, covering one TPC sector, will be installed at STAR for Run 18. The second CBM-STAR joint workshop is scheduled in conjunction with the next CBM collaboration meeting in Wuhan, September 25-29.

Quark Matter 2017 (Chicago)

Frank Geurts — 2017-02-11T00:00:00-06:00

In an icy cold yet not snow-covered Chicago, a group of seven Rice students, postdocs, and faculty presented exciting results from the STAR and CMS heavy-ion programs at the XXVI international conference on ultrarelativistic heavy-ion collisions, also know as Quark Matter 2017. This conference is considered one of the, if not the, most important conferences in the field. The conference series is typically held on a 18-month schedule. This year more than 700 participants joined from all over the world to listen to the many plenary and parallel sessions, as well as discuss the approximately 400 posters.

Daniel Brandenburg gave an oral presentation on some recent, exciting results in low-transverse momentum dielectron spectra which appear to show a consistent and significant excess as a function of the (virtual) dielectron mass. He also showed some first preliminary results of a dilepton analysis that involves muons instead of electrons and is based on the output of the MTD detector.

David Tlusty presented a poster on his recent results the measurement of directed flow from proton, Lambda and K0s in fixed-target collisions measured by the STAR detector (which is designed for collider mode, so this is a rather unconventional way of using the detector!).

Frank Geurts presented a posted on the Endcap Time-of-Flight detector, one of the future detector upgrades that STAR together with the CBM Collaboration (in the context of FAIR Phase 0) envision for the upcoming second phase of the RHIC Beam Energy Scan.

The direct links to the presentations are listed below.

Daniel Brandenburg on Dilepton production in p+p, Au+Au collisions at sqrt(sNN)=200GeV and U+U collisions at sqrt(sNN)=193GeV
David Tlusty on Strange Hadrons Spectra and Directed Flow in STAR Fixed target Experiment
Frank Geurts on The STAR eTOF Upgrade

Winter Workshop on Nuclear Dynamics (Snowbird, Utah)

Frank Geurts — 2017-01-20T12:00:00-06:00

David Tlusty and Frank Geurts both traveled earlier this month to Snowbird (Utah) to attend the 33rd Winter Workshop on Nuclear Dynamics.This long-standing workshop series takes up a unique position amongst high energy nuclear and particle physics workshops in that it sees an attendance of of theorists and experimental scientists from US and European institutes as well as Asian and African institutes!

The combination including representations from almost all major experimental heavy-ion collaborations provide for an ideal environment to discuss current developments in the field. The format of morning and evening presentations further allow for ample time for in-person discussions in the afternoon, either in the ski lift (Frank does not ski) or when strolling along the beach when the workshop is held at warmer locations.
David (see picture) presented a set of first results on directed flow measurements from the fixed-target data that was taken in a, short, dedicated run in 2015. Frank talked about exciting new opportunities that the STAR collaboration recently proposed in a joint detector upgrade effort with the CBM collaboration in Germany in what is generally referred to as FAIR Phase 0.

The Winter Workshop on Nuclear Dynamics is organized by Rene Bellwied (UH), Anthony Timmins (UH), and Frank Geurts (Rice).

Daniel Brandenburg Junior Representative STAR Council

Frank Geurts — 2017-01-09T09:06:36-06:00

The results from last December's elections are in and Daniel Brandenburg has been elected Junior Representative for the STAR Council. Congratulations! He follows what by now is a tradition of very active junior involvement from the Rice group. STAR Council's Junior representatives (2 students and 1 postdoc) provide for an important voice in the Council. They also organize the Junior days that typically take place the day before a STAR Collaboration Meeting.

Mini-workshop on TOF and MTD in STAR at NCKU (Tainan, Taiwan)

Frank Geurts — 2016-12-13T16:48:03-06:00

A mini-workshop was organized from December 8 until 10 on the TOF and MTD detectors that are used in STAR. Both sub detectors have already been part of the STAR detector system for some time. The Barrel TOF system was full commissioned in 2010 and played an essential role in the RHIC Beam Energy Scan (2010-2011, and in 2014). The Muon Telescope Detector was fully commissioned in 2013, ahead of schedule, and ready to participate in the STAR Heavy Flavor campaign from 2014-2016. Both detectors have a lot in common as both are based on Multigasp Resistive Plate Chamber technology. The TOF/MTD workshops are a regular set of meetings in which not only the detector aspects but also the physics results are discussed. In November 2013, our group organized such a workshop at Rice. This year the workshop was organized by the NCKU group and took place on their campus in Tainan, Taiwan.

In addition to a review of the existing detectors and the great results that have come out or our starting to come out of these systems, we also discuss future upgrades. At this workshop, Frank presented the plans and current status of the STAR Endcap TOF system (see photo). This detector will feature during the second phase of the Beam Energy Scan (currently scheduled for 2019-2010) and like the BTOF and MTD is based on MRPC technologies.

David Tlusty appointed STAR Physics Working Group convener

Frank Geurts — 2016-11-23T15:17:58-06:00

After consultations from the physics working group (PWG) members and with unanimous agreement from the STAR management team, David Tlusty (Rice) has been appointed by the STAR spokesperson as convener of the recently merged Light-Flavor Spectra/Ultra-Peripheral Collisions PWG. David is the first person who is appointed for this newly merged PWG and will join the current LFS/UPC convener team of Dr. Bingchu Huang (UIC) and Dr. Wlodek Guryn (BNL).

Picture: David presenting his fixed-target analysis at the STAR Analysis Meeting at LBNL (November 2016)

STAR's Event Plane Detector - a first glimpse

Frank Geurts — 2016-11-09T15:42:02-06:00

During the STAR Analysis Meeting at LBNL we got a great opportunity to look at one of the sectors of the Event Plane Detector (EPD) before it got boxed up and shipped to BNL. The EPD is a very important detector upgrade in anticipation of the Run 18 (2018) and the BES Phase-2 which is currently scheduled to take place 2019-2020. The detector allows for an independent determination of the collision geometry by measuring the so-called event plane. The event plane effectively spans between the beam direction and the impact parameter, i.e. the line between the centers of both incoming nuclei.

In the picture that I took one can see such an EPD tile and from left to right Zhangbu Xu (STAR spokesperson), Xu Sun, and Alex Schmah (project co-leader). If you look careful, you can see in the back a wooden box in which another EPD tile is already nicely bundled up and ready for shipment.

The tiles will be installed ahead of RHIC Run-17 in order to gain further insights when operating this subdetector in a typical collisions environment.

STAR Analysis Meeting at LBNL

Frank Geurts — 2016-11-06T14:13:43-06:00

The STAR Analysis Meeting, scheduled for November 10 - 12, 2016 has been announced. This meeting will see in-depth discussions on the results that the collaboration prepares for the upcoming QuarkMatter conference. It also will see discussions on the status of several of the papers that it plans to release in the near future. Three of those papers (including dielectron measurements in the RHIC Beam Energy Scan, and Nuclear Modification Factors for ideatedied particles from the RHIC Beam

Energy Scan) involve analyses and principle authors from the Rice group.

Link to the registration page: https://sites.google.com/lbl.gov/star2016

STAR's Endcap TOF: installation of a prototype

Frank Geurts — 2016-10-19T16:08:40-05:00

In the week of October 17 two members of the Rice group, Geary Eppley and David Tlusty traveled to BNL to work with our colleagues from CBM (Ingo Deppner and Norbert Herrmann, both from Heidelberg) and with assistance from the local STAR STSG crew to install a prototype Endcap Time-of-Flight detector (eTOF). Our CBM colleagues brought two 32-strip Multigap Resistive Plate Chamber (MRPC) to BNL. Both detectors are mounted such that they completely overlap and thus provide signal redundancy for the upcoming tests that are planned during the RHIC Run-17 beam. This week was used to hook up gas connections as well as the low-voltage, high-voltage systems such that a basic in-situ module check could be performed.

In January next year, shortly before the cooling of the RHIC accelerator, the team will further integrate the eTOF system with STAR's trigger and DAQ systems, as well as connect the clock feed to the common TOF clock that is used for the Barrel TOF and MTD systems.

These eTOF test will provide very relevant data on the its operation inside STAR's environment during actual beam collisions. The final eTOF detector will involve 36 CBM TOF modules and be an essential upgrade for STAR towards the BES phase-2 program (scheduled for 2019-2020). It will extend STAR's particle identification (PID) capabilities to higher momentum in the forward pseudorapidity range provided by the iTPC upgrade. Furthermore, the upgrade will enable a fixed-target program which extends the energy scan to much lower center-of-momentum energies.

Identified Light and Strange Hadron Spectra at √sNN=14.5 GeV [...] (QM2015 proceedings), J.D. Brandenburg

Frank Geurts — 2016-10-05T00:00:00-05:00

Proceedings for The XXV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions: Quark Matter 2015 published in Nucl. Phys. A 956 (2016) 445

Abstract:
With the recently measured Au+Au collisions at √sNN=14.5 GeV, STAR completed its first phase of the Beam Energy Scan (BES) program at RHIC. The main motivation of the BES program is the study of the QCD phase diagram and the search for a conjectured critical point. Amongst the various collision energies of 7.7, 11.5, 19.6, 27, and 39 GeV, that have been previously presented by STAR, collisions at 14.5 GeV will provide data set in the relatively large chemical potential gap between the 11.5 and 19.6 GeV center-of-mass energies. In this contribution, we report new STAR measurements of Au+Au at √sNN=14.5 GeV that include identified light particle RCP and spectra, as well as measurements of the strange hadrons (Ks0, Λ, Ξ, Ω, and φ). The spectra from both light and strange particles cover a significant range of the intermediate transverse momentum (2 < pT < 5 GeV/c) in all beam energies. This provides a unique set of data for a systematic study of the baryon-to-meson ratio at intermediate pT from BES Phase I. We will discuss its physics implications and whether hadronic interactions at late stage dominate the collision dynamics.

Rice Science Café: The Hottest Thing in the Universe

Frank Geurts — 2016-10-04T00:00:00-05:00

Come on over for some #physics, #beers, and a few #quarks …. Churchill room in the Black Lab opens shortly after 6pm, and I start talking shortly after my first beer.

Hard Probes 2020: the Texas Edition

Frank Geurts — 2016-09-27T13:11:12-05:00

Earlier this week, the International Advisory Committee of the 8th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2016) announced that the 10th installment of this important conference series will be held in 2020 at UT Austin and involves the collaborative effort of the four main heavy-ion institutes in that region: UT Austin, Texas A&M, Univ. of Houston, and our group at Rice University

The picture below, courtesy of Joey Butterworth, shows the presentation at Wuhan (China) yesterday.

Identified Light and Strange Hadron Spectra at √sNN = 14.5 GeV with STAR at RHIC BES I (WWND16 proceedings), J.D. Brandenburg

Frank Geurts — 2016-08-24T00:00:00-05:00

Proceedings for 32nd Winter Workshop on Nuclear Dynamics (WWND 2016) published in J.Phys.Conf.Ser. 736 (2016) no.1, 012005

Abstract:
With the recently measured Au+Au collisions at √sNN =14.5 GeV, RHIC completed its first phase of the Beam Energy Scan (BES) program. The main motivation of the BES program is the search for a conjectured critical point and possible first order phase transition. Amongst the various collision energies of 7.7, 11.5, 19.6, 27, and 39 GeV, that have been previously presented by STAR, collisions at 14.5 GeV will provide data set in the relatively large chemical potential gap between the 11.5 and 19.6 GeV center-of-mass energies. In this contribution, we report new STAR measurements of Au+Au at sNN=14.5 GeV that include identified light particle RCP and spectra, as well as measurements of the strange hadrons (Ks0, Λ, Ξ, and Ω). The spectra from both light and strange particles cover a significant range of the intermediate transverse momentum (2 < pT < 5 GeV/c) in all beam energies. We will discuss the physics implications of these observables and whether hadronic or partonic interactions dominate the collision dynamics at a given center-of-mass energy.

STAR Collaboration Meeting at OSU

Frank Geurts — 2016-08-15T11:53:27-05:00

This week STAR will have its semi-annual Collaboration Meeting. It will be held at Ohio State University in Columbus, OH. Several members of our group will attend the meeting and present research updates ranging from strangeness measurements in fixed-target collisions, to intermediate-invariant-mass dimuon measurements in p+p collisions.

A link to the Collaboration Meeting's webpage can be found here.

#iamaphysicist

Frank Geurts — 2016-05-27T13:25:07-05:00

Happy #iamaphysicist day …

happy #iamaphysicist day ... working to understand the quark gluon plasma with @RHIC_STAR at @BrookhavenLab 🎓👍 pic.twitter.com/PBULRH28Us
— Frank Geurts (@frankgeurts) May 26, 2016

Daniel Brandenburg 2016 Chuoke Award

Frank Geurts — 2016-05-13T18:26:32-05:00

Congratulations to Daniel Brandenburg for receiving the 2016 Chuoke Award in recognition of "graduate students who show the greatest promise in physics as evidenced by performance in course work and speedy progress in research"!

PhD Thesis defense Kefeng Xin

Frank Geurts — 2015-11-23T03:46:00-06:00

Date & Time: November 23, 2015 at 1pm-4pm
Location: 300 Brockman Hall for Physics

Abstract: Dileptons, e.g. dimuons, have been proved to be very important tools to explore the hot and dense matter created at heavy-ion collider experiments. The first dimuon excess observation at the STAR experiment from Au + Au collisions at sqrt(sNN) = 200 GeV/c will be presented. Muonic atoms are bound hadron-muon states. In ultrarelativistic heavy-ion experiments, muonic atoms can be a perfect tool to access the muon thermal emission of a hot quantum chromodynamics (QCD) system as only thermal muons or muons from short-lived resonances are able to form muonic atoms. Among muonic atoms, the antimatter muonic hydrogen and the hyper-muonic atom, K^0_L, have been predicted but not yet discovered. STAR’s first measurement of muonic atom production will be presented.

Antimatter not so different after all

Frank Geurts — 2015-11-04T19:16:00-06:00

reproduced from Rice News

Rice University scientists help make first measurement of antiproton attraction.
Due to the diligence of a Rice University student and his calculations, humanity now knows a little more about the universe.
Kefeng Xin, a graduate student at Rice, is one of a handful of primary authors who revealed evidence this week that the attractive force between antiprotons is similar to that between protons — and measured it.
Specifically, the team measured two important parameters: the scattering length and the effective range of interaction between two antiprotons. This gave scientists a fundamental new way to understand the force that holds together the nuclei in antimatter and how this compares to matter.
“This is about the subtle difference in the way matter and antimatter interact with each other,” said Rice physicist Frank Geurts.

Rice University physicist Frank Geurts, left, and graduate student Kefeng Xin are part of the team that made the first measurements of the attractive force between antiprotons. Xin is a primary author of the paper that appears this week in Nature. Photo by Jeff Fitlow

Antiprotons carry the opposite electrical charge and spin that protons do. Like all matter and antimatter, both were created at the instant of the Big Bang. Physicists are still trying to understand why they see so few antiparticles in nature even though particles and antiparticles were produced in equal amounts and annihilate each other on contact.
“It could have been that antimatter didn’t have the same attractive force as matter and would have helped explain how these differences, during the initial part of the Big Bang, might have resulted in antimatter not having survived in the shape of stars and planets, as matter did,” Geurts said.
“That’s where this research is helpful. The interactions between two antimatter particles turn out to be quite similar to matter particles. It may not give us a solution to the bigger problem, but we most definitely removed one option,” he said.
The find was reported in Nature on behalf of the more than 500 scientists, including Geurts, who work on the STAR experiment, part of the Relativistic Heavy Ion Collider (RHIC) at the U.S. Department of Energy’s Brookhaven National Laboratory. Brookhaven’s story on the discovery appears here.
The scattering length is a measurement of how particles deviate as they travel from source to destination; their paths are visible as three-dimensional traces captured by STAR (which is short for Solenoid Tracker at RHIC). The effective range indicates how close particles need to be for their charges to influence each other, like magnets.
Both are measured in femtometers. One femtometer is one-millionth of a nanometer; a nanometer is one-billionth of a meter.
For antiprotons measured at RHIC, the scattering length was roughly 7.41 femtometers, and the effective range was 2.14 femtometers, nearly equivalent to their proton counterparts. Measuring distances that small involves both sophisticated equipment and sophisticated calculations.
Scientists working at Brookhaven National Laboratory, including physicists at Rice, have announced the first measurements of the attractive force between antiprotons.

Scientists working at Brookhaven National Laboratory, including physicists at Rice, have announced the first measurements of the attractive force between antiprotons. The discovery gives physicists new ways to look at the forces that bind matter and antimatter. Courtesy of Brookhaven National Laboratory

“This discovery isn’t a surprise,” said Xin, whose Ph.D. thesis focuses on rather exotic systems called muonic atoms. “We’ve been studying the interaction between nucleons (particles that make up an atom’s nucleus) for decades, and we’ve always thought the forces between antimatter particles are the same as for matter. But this is the first time we’ve been able to quantify it.”
Xin, a student of Geurts, applied methods developed in his thesis to the analysis. The first task was to determine which particles produced in a collision were indeed antiprotons and whether any two were in close enough proximity to influence each other. Then came correlating their momentum from creation to destruction, typically a few nanoseconds.
“All of the data we collected in 2011 is from 500 million events (collisions between two heavy gold ions),” Xin said. “Pretty much every event can contribute.”
Antimatter can be created in small amounts with a collider like RHIC and analyzed. The collider accelerates the nuclei of heavy atoms to nearly the speed of light and smashes them together to produce elemental particles, antiparticles and exotic materials like quarks, muons and plasmas. All of these can be characterized by tools built at Rice and elsewhere as part of STAR.
RHIC smashed gold ions to produce hundreds of millions of particles, which can be detected by the ionization traces they leave in a gas-filled cylinder that surrounds the collision and a “time-of-flight” sensor. The instrument, the construction of which was led by Rice, tells researchers how many nanoseconds it takes particles to travel from the point of impact to sensors at the outer boundaries of the collider.
“RHIC is ideal for this kind of experiment because it allows us to dump a boatload of energy into a very small volume and have many particles come out of it,” Geurts said. “The multiplicity is important. If you don’t make a lot of particles, the odds of having them interact with each other is slim.”
Researchers from 52 institutions that are part of the STAR collaboration are co-authors of the Nature paper. Rice co-authors include graduate students Daniel Brandenburg, Joey Butterworth and Nick Luttrell; research scientist Geary Eppley; and Pablo Yepes, a senior faculty fellow in physics and astronomy. Geurts is an associate professor of physics and astronomy.
The research is funded primarily by the Department of Energy Office of Science.
– See more at: http://news.rice.edu/2015/11/04/antimatter-not-so-different-after-all-2/#sthash.MJ7A84cH.dpuf

MS defense by James Daniel Brandenburg

Frank Geurts — 2015-10-30T10:51:00-05:00

Date & Time: October 30, 2015 at 1pm-3pm

Location: 223 Herman Brown Hall

Physicists Narrow Search for Solution to Proton Spin Puzzle

Frank Geurts — 2014-11-05T21:15:00-06:00

New RHIC results reveal that gluons make a significant contribution to spin, an important intrinsic particle property; transient sea quarks also play a role.

BNL press release at http://www.bnl.gov/newsroom/news.php?a=25112

How the spins of the building blocks of matter add up: Measurements from RHIC's STAR and PHENIX experiments reveal that gluons (yellow corkscrews) contribute about as much as quarks (red, green, and blue) to the overall spin of a proton. But there is still a mystery to explain what accounts for the rest of the "missing" spin.
Image/caption courtesy Brookhaven National Lab

Search for Muonic Atoms at RHIC (PANIC'14 proceedings), K. Xin

Frank Geurts — 2014-10-30T23:51:00-05:00

Proceedings for International Conference on Particles and Nuclei (PANIC 14) are on arXiv: http://arxiv.org/abs/1410.8037 and at Journal of Physics: Conference Series

Abstract:
We present the search results for muonic atoms on √sNN=200 GeV Au+Au collisions collected by the STAR experiment at RHIC. With the muon identification at low momentum, the invariant mass spectra were reconstructed. Clear signals are observed at the expected atom masses. Two particle correlations show that the production of the daughter particles happens at the same space-time point, presenting the signature of atom ionization. The fraction of primordial muons is extracted from π-μ correlations.

Dielectron production in Au + Au collisions from STAR (HardProbes '13 proceedings), J. Butterworth

Frank Geurts — 2014-10-30T12:03:00-05:00

Proceedings for the 2013 Hard Probes conference published in Nucl.Phys.A 932(2014)318 doi:10.1016/j.nuclphysa.2014.09.080

Abstract: We present the systematic study of dielectron production from minimum bias Au + Au collisions at √sNN=19.6, 39, and 62.4 GeV along with the production from minimum bias Au + Au collisions at 200 GeV for reference. The spectra are compared to simulated hadronic contributions that do not contain ρ-meson contributions. In each comparison, there is an excess in the dielectron yield that is consistent with a medium modified ρ -meson and shows no dependence on √sNN. To further understand the excess, the spectra are compared to the simulated hadronic contributions plus model calculations that include contributions from the medium and ρ-mesons with a broadened spectral function. These comparisons are consistent within uncertainties.

RHIC featured at NPR's Science Friday: How to Make Quark Soup

Frank Geurts — 2014-10-20T15:48:00-05:00

Watch at this direct link to PRI's video. Or, go to PRI's Science Friday website at How to Make Quark Soup and find audio and video links.

RHIC featured on the Science Channel

Frank Geurts — 2014-08-15T09:20:00-05:00

The Relativistic Heavy-Ion Collider (RHIC) featured in "How The Universe Works" on the Science Channel. With STAR's Mike Lisa (OSU) explaining RHIC's role in exploring the building blocks of matter.

Fluctuations & Particle Identification Workshop

Frank Geurts — 2014-05-23T00:00:00-05:00

The STAR Fluctuations & Particle Identification workshop, at Rice University on May 23-25, 2012, will focus on the topics of fluctuations in heavy ion collisions and the techniques used for particle identification in the analysis of these collisions. At this workshop, STAR experimentalists and invited theorists will discuss the theory, the analysis methods, and the results, with the goal of further developing the plan towards the publication of final results. The consistent and effective use of the particle identification capabilities of the TPC dE/dx, the Time of Flight system, and the calorimeters, is a particularly crucial part of fluctuation analyses and will also be discussed at this meeting.

The Impact of the US on CMS

Frank Geurts — 2014-03-20T16:50:00-05:00

A couple of videos that advertise the role of the US in CMS h/t Don Lincoln (FNAL)

A short (3:30m) version: https://www.youtube.com/watch?v=Zjg9CMVhbbU
A longer (7:30min) version https://www.youtube.com/watch?v=9Imeiu83-iM

STAR experiment featured in Apple's "30 years of Mac" commercial

Frank Geurts — 2014-03-04T21:40:00-06:00

The STAR experiment at Brookhaven National Lab is featured in one of the fifteen locations of Apple's tribute to "30 years of Mac". It starts 46 seconds into the video clip at the link below.

http://www.apple.com/30-years/1-24-14-film/

Look for two of our BNL colleagues in front of the detector (Paul and Bill) and for one of the T.W. Bonner Lab's contributions to the experiment, the VPD (vertex position detector).

The other contribution, the TOF, is a bit more difficult to find behind all the tubes and cables …

STAR MTD/EndcapTOF Workshop

Frank Geurts — 2013-11-20T00:00:00-06:00

In November 2013, our group hosts the 2013 MTD Workshop. In addition to discussions on the physics and the commissioning progress of the MTD system, we will also discuss the R&D plans towards the eSTAR detector, specifically the proposed Endcap TOF.

The Muon Telescope Detector (MTD) is expected to be fully installed and commissioned for the upcoming RHIC Run 14 (starting Feb.'14). Together with the Heavy Flavor Tracker (HFT) which is also scheduled for operations during that run, the STAR detector will be in an excellent position to significantly improve its measurements on quarkonia, and lower invariant mass dileptons.

The meeting website can be found at this link: MTD/eTOF 2013 Workshop

The Muon Telescope Detector (MTD) is one of the important upgrades to the STAR detector enabling the detection of and online triggering of muons over a large phase space. This, together with the HFT upgrade, will put the STAR detector in an excellent position to measure heavy-flavor hadrons and improve our understanding of the production of such hadrons in the environment of hot nuclear matter.

The MTD construction project involves several institutes from China, India, and the United States. At the time of this workshop, the construction project will enter into its final phase in which the remaining modules are installed and the full system further commissioned in anticipation of the 2014 RHIC heavy-ion run.

The proposed Endcap TOF (ETOF) detectors will enabled the future eSTAR detector to further extend its particle identification capabilities for the semi-inclusive deep inelastic scattering processes at the proposed eRHIC. The ETOF will be mounted on both the east and west side poletips of the STAR magnet. On the east side, the ETOF will provide, in combination with a proposed Transition Radiation Detector, and the upgraded TPC, essential (scattered) electron identification. In addition, both the east and west systems will further extend kinematic coverage in Bjorken-x and Q2 range.

Rice physicists help discover new particle that may be Higgs

Frank Geurts — 2012-07-04T16:00:00-05:00

[take from Rice News]

HOUSTON — (July 4, 2012) — Rice University physicists participating in the search for the elusive Higgs particle joined their colleagues at the European Organization for Nuclear Research (CERN) today in announcing the observation of a never-before-seen particle. The particle may turn out to be the Higgs boson or something new and equally important.
The search for the Higgs particle is at the heart of the most expensive science project in history — CERN’s $6 billion Large Hadron Collider (LHC). In an announcement today, LHC officials in Geneva, Switzerland, stopped short of declaring a victory in the Higgs search, saying instead that they have found a new particle with properties that make it a likely match for the supermassive Higgs particle.

The particle tracks from this collision and others show LHC scientists what they would expect to see from the decay of a Higgs boson. © CERN 2012

“To use an analogy from CSI: We’ve found a body, but we need to wait for the DNA results to declare it the Higgs,” said Rice particle physicist Paul Padley, a co-investigator on the LHC Compact Muon Solenoid (CMS) experiment. “We’re not calling this the Higgs for the same reason the police don’t guess about the identity of a body. It’s our responsibility to be sure.”
The search for the Higgs particle marks a historic turning point in physics: The particle is the final unobserved piece of a puzzle called the Standard Model (SM), a model which jibes with every particle physics experiment ever performed. The Higgs, a type of particle known as a boson (pronounced “BOH-sahn”), is one of the linchpins of the SM.
“In our current understanding, all of the fundamental particles of nature get their mass through the Higgs mechanism,” said Frank Geurts, assistant professor of physics and astronomy at Rice and a co-investigator on the CMS experiment. “So, if we don’t find the Higgs particle — if that’s not there — then we seriously have to rethink why we exist at all.”

Paul Padley at the CMS dector

Padley, who returned to Rice from the LHC near Geneva late last week, said the search for the Higgs at LHC is one of the greatest endeavors in human history. “There are multiple experiments at LHC, and on the CMS experiment alone there are more than 3,000 scientists from 179 institutions in 41 countries. The experiment recreates conditions that existed in the first billionth of a second after the Big Bang.”
In addition to Padley and Geurts, Rice Department of Physics and Astronomy faculty co-investigators at LHC include Professor Jay Roberts, Assistant Professor Karl Ecklund and Assistant Professor Wei Li. More than two dozen Rice staff and students have also worked on the 13,000-ton CMS detector. For example, Rice physicists played a key role developing some of the electronic systems that sort CMS data in real time and select what to keep for future analysis. That’s no simple task because the CMS experiment produces 40 terabytes of data — enough to fill more than 8,500 DVD discs — each second. And a single run of the machine can last for weeks or even months.

Frank Geurts

Rice personnel also contributed to the CMS pixel detector, which is like a 66-megapixel camera that snaps a photo 40 million times per second. Located just 4 centimeters from the head-on proton collisions in the LHC, the pixel detector records the trajectories of hundreds of particles that are produced in the collisions, and it helps sort through the debris of the collisions so that CMS physicists can reconstruct which particles are produced in any given collision.
Rice faculty, engineers, postdocs and students helped build and maintain some of the electronics that mine collision data in real time and flag collisions, which are often referred to as “events,” that should be saved for future analysis. These stored events provided the data that scientists needed to confirm today’s announcement about the likely candidate for the Higgs particle.
“The science unveiled today could not have happened without Rice’s hardware and software as well as hundreds of other critical components that were conceived and created at universities and national laboratories the world over,” said Ecklund, who is at CERN for today’s announcement.

Karl Ecklund

Ecklund, Geurts and Padley, who have each devoted many years to the search for the Higgs boson, say the only prospect more exciting than finding the long-anticipated Higgs is finding something completely unexpected.
“When I was a physics undergraduate, we were taught that the expansion of the universe was slowing,” Padley said. “Whether or not the universe would one day collapse upon itself was an open question, and the Hubble Space Telescope was launched, in part, to answer that question.
“What the Hubble found was utterly shocking,” Padley said. “The Hubble found the universe was expanding faster and faster every second. It was completely new and totally unexpected knowledge, and that is exactly the sort of unpredictable discovery we expect to find with the LHC once it ramps up to full power.”

- See more at: http://news.rice.edu/2012/07/04/rice-physicists-help-discover-new-particle-that-may-be-higgs/#sthash.MMjUxN3D.dpuf

Rice-born detector finds heaviest antimatter

Frank Geurts — 2011-04-25T16:00:00-05:00

[taken from Rice News]

Physicists at Rice University and their collaborators have detected the antimatter partner of the helium nucleus, antihelium-4. This newly observed particle is the heaviest antimatter nucleus ever detected.
Scientists at Rice’s Bonner Lab designed and built the new time-of-flight detector that identified antihelium-4. The $7.5 million detector was built by a U.S.-China collaboration led by Rice, with Chinese scientists contributing $2.5 million to the project. The new detector was installed as part of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in New York. STAR scientists announced their find today in the journal Nature.

Antimatter is the yang to matter’s yin. Both were created in ostensibly equal amounts at the time of the Big Bang, but because matter and antimatter annihilate each other upon contact, most of it disappeared almost instantly. But there was an apparent imbalance that favored matter, which makes up nearly all that we see (and are) today.
Why this is so remains one of the great mysteries in physics. Scientists hope the study of antimatter created in particle accelerators, which attempt to mimic conditions at the beginning of the universe, will offer clues to why nature allows humans to exist.

Last year at Brookhaven, shortly after the long-planned time-of-flight detector was fully installed, evidence of 15 antihelium-4 nuclei (aka anti-alphas) was found among the trillions of particles released when heavy gold ions were collided at nearly the speed of light. These nuclei contain two antiprotons and two antineutrons and do not undergo radioactive decay.

The collisions produce a quark gluon plasma which, when cooled, transitions into a hadron gas that contains protons, neutrons and their antimatter equivalents among many other fundamental particles. This rapidly expanding cloud of particles is where the team found antihelium-4.

“These are massive clumps of antimatter,” said Frank Geurts, a Rice assistant professor of physics and astronomy and one of the lead authors of the paper. “The fact that two antineutrons and two antiprotons find each other, produce an anti-alpha, travel two to three meters of air and give us a measurable signal when they pass through the time-of-flight detector is astounding.”

Just as astounding was the ability of the STAR detector to capture and identify these heavy antimatter particles among the trillions of particles created in collisions at Brookhaven each year. It would be far easier, Geurts said, to find the proverbial needle in a haystack, but the new time-of-flight detector, which Rice scientists designed and built over the course of a decade, was up to the task. Jabus Roberts, a Rice professor of physics and astronomy, and research scientist Geary Eppley, both co-authors on the new paper, started the research that led to the detector more than 10 years ago. Eppley and William Llope, senior faculty fellow in physics and astronomy and also a co-author, managed the construction and installation of the apparatus.
The detector is a set of 23,000 sensors that surround STAR, short for Solenoidal Tracker at RHIC. These sensors identify the types of subatomic particles released when heavy nuclei collide. The detector tells researchers how long it takes a particle to travel from its creation to the point it passes through one of the sensors and is accurate to a 10th of a billionth of a second.

Rice played a role in the discovery even beyond its creation of the critical detector. A Rice graduate student found the first evidence that antihelium-4 was being created in collisions at RHIC. Jianhang Zhou, now working in private industry in Houston, “dedicated a chapter in his thesis to the fact that he had found two candidates (for antihelium-4),” Geurts said. “At that time, we needed more statistics and a time-of-flight detector to confirm his findings.” In fact, the Nature paper counts Zhou’s two particles among the total of 18 reported, though they were identified at STAR before the time-of-flight detector was installed.
“You could argue that it was not an unexpected particle, but the implications for its discovery and the amount we found agrees with what we were expecting,” Geurts said. “We can now see an extension of the periodic system of elements into regions of antimatter and strange matter.”

The new observation tops the previous find of an antihydrogen nucleus containing three particles, including an anti-strange quark, by the same team a year ago. The new record will probably stand for a long time, Geurts said.
He suggested even heavier antimatter particles might be found — but probably not on this planet. A statement from Brookhaven noted that antilithium-6, a heavier antimatter nucleus that does not undergo radioactive decay, is predicted to be a million times more rare, and its discovery is well outside the reach of current technology.
More basic discoveries could be made in distant galaxies where antimatter from the Big Bang may still be detected. The Alpha Magnetic Spectrometer (AMS) that will be mounted on the International Space Station will measure cosmic rays for evidence of dark matter and antimatter. The space shuttle Endeavor will carry the instrument to the ISS if it launches April 29 as planned.

AMS will also look for antihelium-4 that, if found, could be evidence of the existence of larger regions of the universe made entirely of antimatter. The STAR measurement will help scientists understand the conditions in the very early universe that would allow such antimatter galaxies to form.
The discovery of the anti-alpha comes on the centennial of Ernest Rutherford’s first modeling of the atom using alpha particles.

The paper’s co-authors include all of STAR’s collaborators, hundreds of researchers from 53 institutions. Six of those institutions are in China; Geurts said they joined the RHIC heavy ion community through their work on the time-of-flight detector.
Additional major contributors to the research at Rice and co-authors of the paper are Pablo Yepes, a senior faculty fellow in physics and astronomy; research scientist Jing Liu; and graduate student Daniel McDonald.
The United States Department of Energy supported the research.

- See more at: http://news.rice.edu/2011/04/25/rice-born-detector-finds-heaviest-antimatter-2/#sthash.EHIKSY3i.dpuf

Grant advances quark-gluon plasma studies

Frank Geurts — 2010-10-07T12:00:00-05:00

Grant advances quark-gluon plasma studies
Rice University’s Bonner Nuclear Lab wins DOE backing for ultrarelativistic heavy-ion research

Rice University’s Bonner Nuclear Lab has won a $1.175 million grant that will support its research on high-density and hot nuclear matter.

Rice physicist Frank Geurts, who has spent his career looking for clues to the basic elements of the universe by smashing the nuclear contents of gold, lead and other heavy atoms, said the Department of Energy grant will facilitate his group’s transition from constructing and commissioning a highly complex detector system to using that machinery to do basic research.

Much of the Bonner Lab’s focus over the past two decades has been on the Solenoidal Tracker at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator for nuclear physics research at Brookhaven National Laboratory in New York.

A device known as STAR (short for Solenoidal Tracker at RHIC) has been taking data at Brookhaven since 1999. Rice designed and built essential components for STAR, which helps detect and study the subatomic particles released when heavy nuclei collide at nearly the speed of light.

In 2005, RHIC announced the breakthrough discovery of a quark-gluon plasma, a dense, high-energy state of matter believed to have existed in the first milliseconds after the Big Bang. Scientists referred to the very hot material created in the lab — 150,000 times hotter than the sun’s core — as a “perfect liquid,” one with practically no viscosity, or as little as quantum physics will allow. Such properties were quite a surprise, Geurts said, because original expectations were that this phase of matter would behave much more like a gas.

The main component of STAR, the time projection chamber (TPC), “gives us a 3-D 80-megapixel picture for every collision, and that allows us to know the charge of the particles, the momentum of the particles and to some degree the identity of those particles,” said Geurts, assistant professor of physics and astronomy.

The roughly 14-foot-long, 13-foot-wide cylinder is a gas-filled chamber surrounded by a powerful magnet that captures images of particles, which look like contrails from a high-flying jet. The particles zoom off in every direction from the collision of heavy nuclei, usually gold. Those collisions happen inside the accelerator that runs through STAR’s center.

In recent years, the team that includes William Llope, a senior faculty fellow in physics and astronomy, and Geary Eppley, a Rice research scientist, has worked to extend STAR’s particle identification abilities by cladding it with a layer of 23,000 sensors collectively known as the time-of-flight (TOF) detector. It will tell researchers how long the most robust particles take to fly through the TPC. “It acts as a fancy — and highly accurate — stopwatch,” Geurts said. “The TPC gives us all the details of the momentum and path traveled by the emerging particles, and the new detector provides us with the time it took them to travel that far. We can then calculate what the mass of that particle is.”

The new detector is accurate to a 10th of a billionth of a second, he said. “People are very excited about this because we will be able to identify about 96 percent of the particles that come out of collisions.” In fact, the new sensors will allow the characterization of subatomic particles out to higher momenta. “This allows us to peek deeper into the hot and dense matter,” said Geurts, who has also worked extensively at the Large Hadron Collider, an even bigger new accelerator in Europe that has started to smash heavy nuclei at even higher energies.

With completion of the 10-year time-of-flight project this fall, Geurts said the Bonner Lab is shifting its priorities from constructing the subdetector for STAR to analyzing the data it produces and reaping the exciting results. While STAR has been upgraded, so will other components at RHIC, including the addition of a new firing mechanism that will give the collider the ability to handle uranium nuclei and perhaps other heavy nuclei.

The DOE grant provides the Bonner Lab the opportunity to analyze all the data these new tools will make available. “The group has invested a lot of effort to develop the detectors and has vast experience in successfully operating such devices. Now we can switch from commissioning this new detector to doing the physics it makes possible,” Geurts said.

“We understand this hardware better than anyone else, so we’re in a good position to use the detector to provide researchers with well-identified particles. On the other hand, we are still committed to improving the detection capabilities of the STAR experiment by researching the addition of new components.” Recently, Geurts’ group took a leadership role in the proposed research, development and construction of a new subdetector that will use techniques similar to those in the TOF detector, but geared toward the detection of muons, electrons’ heavier siblings.

Current experiments at RHIC include efforts to map out the phase diagram of hot and dense matter and to look for its critical point. “With RHIC lowering its beam energies, we are now able to answer questions that Hadron cannot answer,” Geurts said. He is particularly interested in the movement of quarks and gluons inside the liquid, which will provide clues to the early state of the universe before all those particles began to coalesce into matter.

- See more at: http://news.rice.edu/2010/10/07/grant-advances-quark-gluon-plasma-studies/#sthash.JmhgNoVU.dpuf