SN0648 : The STAR Forward Calorimeter System and Forward Tracking System beyond BES-II

Author(s):the STAR Collaboration
Date:Jan. 19, 2016
File(s): ForwardUpgrade.1p.docx ForwardUpgrade_1pager.long_.docx FCS MRI narrative FINAL.pdf Proposal.ForwardUpgrade.Nov_.2018.Review.pdf Review of the STAR forward upgrade-5.pdf ForwardUpgrade.Nov_.2018.Review.docx
Abstract: STAR proposes measurements of forward photons, electrons from J/y and Drell-Yan processes, inclusive jet, dijet, and hadron/jet correlation probes at both 200 and 500 GeV center of mass energies, and demonstrates measurement capability and sensitivity through simulations. These measurements allow STAR to probe the fundamental structure of nucleons in new kinematic regimes, and where existing data still provide rather poor constraints. One aspect is the composition of nucleon spin in terms of quark and gluon degrees of freedom; the other is to go beyond the one-dimensional picture of nucleons in momentum-space by correlating the information on the individual parton contribution to the spin of the nucleon with its transverse momentum and spatial distribution inside the nucleon. 

In p+A collisions, these measurements will enable STAR to study Cold Nuclear Matter (CNM).  The proposed FCS and FTS provide kinematic access to very small momentum fractions x in nuclei, facilitating investigations into the dynamics and nonlinear evolution effects in the regime of high gluon-density.  The proposed upgrades and RHIC’s extraordinary versatility are integral to these measurements.

In addition to QCD studies with polarized p+p and p+A collisions, the proposed upgrade will facilitate the determination of QGP properties in A+A collisions through improved measurements of the initial density fluctuations as well as the collective flow seeded by these fluctuations. The proposed forward upgrade will further quantify η/s through improved understanding of initial conditions via measurements of longitudinal flow de-correlation, multiple harmonics and event-shape engineering in A+A collisions, and will allow studies of the possible existence of and limits on hydrodynamics and jet-medium interaction in small systems at RHIC energies.

Keywords:forward calorimeter, forward tracking, cold QCD, Drell-Yan, TMD, longitudinal correlations, 3D hydrodynamics