RHIC challenges for low energy operations

Abstract

There is significant interest in RHIC heavy ion coIlisions at , , h =5-50 GeV/u, motivated by a search for the QCD phase transition critical point. The lowest energies are well below the nominal RHIC gold injection fi = 19.6GeVIu. There are several challenges that face RHIC operations in this regime, including longitudinal acceptance, magnet field quality, lattice control, and luminosity monitoring. We report on the status of work to address these challenges, including results from beam tests of low energy RHIC operations with protons and gold.

Low energy program at RHIC

“…The RHIC beam synchronous clock system, used for all single-bunch timing, was modified between 2007 and 2008 to avoid phase problems that plagued earlier runs [2]. Tests in 2008 successfully triggered RHIC instrumentation and experiment DAQ clocks without major problems.…”

“…The required integrated luminosities for this search are challenging since luminosity is expected to scale as γ 2 down to nominal injection energy, and at least γ 3 below [2]. Approximately 5 × 10 6 events are needed at each of 6-7 energies to improve on existing SPS and AGS results by a factor of 2-4 [3,4].…”

“…Main power supply regulation has been tested in RHIC at these currents and shows no problems. Other field quality was experimentally investigated during the 2006 and 2007 test runs [2].…”

Summary of the rhic performance during the FY07 heavy ion run

“…HI collisions at energies below 100 GeVInucleon were also provided during the various runs. This year, 4.6 GeVInucleon beams were collided during a dedicated machine study period within less than 24 hours including setup [6]. This report summarizes the most recent 100 GeVInucleon Au-Au run from 2007.…”

IBS and Potential Luminosity Improvement for RHIC Operation Below Transition Energy

“…Collisions in this energy range, much of which is below nominal RHIC injection energy, will help to answer one of the key questions in the field of QCD about the existence and location of a critical point on the QCD phase diagram [4]. There have been several short test runs during 2006-2008 RHIC operations to evaluate RHIC operational challenges at these low energies [5]. Beam lifetimes observed during the test runs were limited by machine nonlinearities.…”