Ruthenium & Zirconium
March 13, 2018
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.
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.