PAC recommendation 2016

Weekly phone meeting: 
Monday 3-4PM (EDT) 
https://bluejeans.com/333205157

April 4, meeting agenda: 
Drupal Calendar

latest version of current BUR:
Version 12, 05/21/2016

Last-year's BUR and CAD projections

Lambda/Lambdabar polariation at 27GeV

Subsequent meeting with Berndt after the NSAC meeting in March 23 about 
Run17: Berndt said that after discussion with DOE and BNL management,
it is likely that 19 cryo-weeks of RHIC operation should be taken as baseline,
this should include two weeks of CeC commissioning.
That means effectively 17 cryo-weeks for run 17. 

Executive Summary: 

The STAR Collaboration makes the following two-year beam-use proposal, in order to achieve its spin and relativistic heavy ion physics goals on a timescale consistent with intense international interest and competition in these areas, as well as to utilize RHIC beams effectively, taking full advantage of recent improvements in machine and detector capability.

Table  STYLEREF 1 \s 1‑ SEQ Table \* ARABIC \s 1 1: Scenario I: 19 cryoweeks for Run 17 and 13 cryo-weeks for run 18. We assume most of the TPC bandwidth (1800Hz) is for the minbias event rate for isobar data-taking with 90 hours per week of DAQ time. All luminosities requested are actual sampled luminosity. See text for details of HFT and pp510 run conditions and optimizations.

STAR’s highest scientific priority is the first significant measurement of the sign change of the Sivers’ function, when compared to the value measured in SIDIS, and evolution effects in transverse momentum distributions through measurements of single spin asymmetries in W^+/-, Z, direct photon and Drell-Yan production in transversely polarized √s = 500 GeV p+p collisions. The sign change measurement is a fundamental test of QCD and is being pursued by other experiments, making a timely measurement imperative.

STAR’s second scientific priority is to clarify the interpretation of the observed signatures of the chiral magnetic effect, chiral magnetic wave and chiral vortical effect by making measurements that disentangle signal from background v₂ effects.  We request a 3.5 week run each for Ruthenium-96 (Ru+Ru) and Zirconium-96 (Zr+Zr) collisions in run 18.  This choice of nuclei is ideal as it allows for a variation in magnetic field at a maximum of 10%, while keeping nearly all other parameters the same. This decisive measurement of the ratio of charge separation in the isobar reduces the flow background dramatically, and will greatly advance our understanding of the chiral magnetic effect, which has fundamental impact beyond the field of high-temperature QCD.

Table  STYLEREF 1 \s 1‑ SEQ Table \* ARABIC \s 1 2: Scenario 2: 24 cryoweeks for Run 17 and 13 cryo-weeks for run18

Our next scientific priority is to take data at beam energies that are lower than the nominal energies, but are not part of STAR’s proposed Beam-Energy-Scan Phase-II program. There are two programs in our requests in this category:

a)     Au+Au collisions at 62 GeV for measurements of inclusive jets and charm spectrum at low energy. With newly developed analysis techniques, inclusive jet measurements are possible with minimum-bias data in Au+Au collisions. We have recently extended the measurement to Au+Au at 62 GeV with limited statistics from run 10. We request 4 weeks of Au+Au collisions at this energy for an inclusive jet R_CP measurement. This will also provide a measurement of Non-photonic electrons from charm semileptonic decays. In addition, with the significant reduction of material from run 16 to run 17 and run 18, dilepton measurements with good statistics are possible in 4 weeks of data-taking.

b)     STAR has observed an exciting new effect, the global polarization of hyperons in noncentral Au+Au collisions. Theorists are excited and BES-II (2019-2020) will provide opportunities for higher precision explorations of the effect. There is also a possibility of observing a difference in Lambda and anti-Lambda polarization if the global polarization effect connected to the Chiral magnetic effect. We propose to extract important information from this effect at beam energy above the nominal BES-II energies through a high-statistics dataset at 27 GeV. It will be even better if we are able to collect this dataset in run17 with sufficient beam time, which allows us to analyze the effect with high statistics and guide our future direction in this subject ahead of the BES-II program.  

The STAR Collaboration presents in this BUR five compelling and prioritized scientific programs for the 2017 and 2018 RHIC runs, prior to the start of BES-II [[i]]. In this BUR we furthermore discuss the highlights from the scientific publications, on-going analyses and detector performance from recent runs. We also outline the planned upgrades in the next few years in preparation for Run 17 and the Beam Energy Scan II.