From: Brendan Fox (fox@drax.Colorado.EDU)
Date: Fri Jun 27 2003 - 05:19:23 EDT
Hi y'all,
Gerry wrote up the following summary of the last week's RHIC Spin Meeting.
- brendan
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Summary from RHIC Spin meeting of June 20, 2003
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The meeting was organized by Brendan Fox, and the focus was on getting
information to develop a spin run plan for Run 4, to bring to collaborations.
Polarized gas jet target: great progress described by Yousef Makdisi
-- expected to be ready for Run 4 (to be installed in summer/fall,
then removed during gold-gold run, to work in lab; installation
then takes 3 days for a pp run)
-- 1 development silicon detector of 4 works from 1st batch (reported by
Sandro Bravar), looking at other existing silicon of similar size from
Hamamatsu (expected 50% to work, also issue of schedule for production
from BNL Instrumentation)
STAR spin (Les Bland): machine development and physics for Run 4
-- this is only from the spin group. STAR has not started discussions on
the beam use proposal yet
-- machine development--toward spin goal of 30 pb^-1/week, P=0.7
-- goal for Run 4 P^4 x LT > 10 nb^-1/week (10x run 3)
-- 3/4 barrel EmCal, 3 pb^-1, P=.4
-- physics for A_LL, jets-==>gluon polarization
-- polarized gas jet ==> commission, Delta P/P to +/-10%
-- STAR multi-year plan in the 02 beam use proposal was:
-- Au-Au 19 weeks (16 weeks at root(s_NN)=200, 1 at 3 lower energies)
-- pp 8 weeks, root(s)=200
-- important to develop credible plan on luminosity and P, leading to
direct photon program
-- root(s)=500 running requires large LT to be useful, reference data
for heavy ions important
PHENIX spin (Yuji Goto): main discussion next week after info. from here
-- Run 3 gave 350 nb^-1, P=.27, P^4 x LT = 1.8 nb^-1
-- expectation on A_LL 2-3 sigma from max. gluon model
-- vs. 3 pb^-1, P=.4 (about 20 sigma from max. gluon pol.) (Run 2 plan)
-- Run 2 plan would give 20K direct photons, p_T>5, 10K J/psi,
1M single e, 4K mu-mu and 7K e-mu charm events.
-- root(s)=500 (discussed for run 6, vs. 200 GeV)
-- compared xdelta(Delta g) for 200, 500 GeV--200 GeV better
BRAHMS spin (Brendan Fox):
-- Run 4 would place spectrometer at 2.3 deg., get interesting measurement
in 20-40 hours.
RHIC summary (Haixin Huang):
-- source problem early in run (ok for Run 4?)
-- pp started March 26
-- yellow snake failure, partial snake solution saved run
-- physics started May 3
-- STAR rotator commissioning May 15
-- switch to 2 IRs May 23
-- run ended May 30 (9 weeks total)
AGS (Leif Ahrens):
-- expected to reach P=.5, reached above .4
-- intensity dependence of P not resolved (but see Mei Bei plot)
-- lower P at end of run--not understood yet
-- plan to use thinner stripping foil (half) into Booster to reduce
emittance for Run 4
-- warm snake for Run 4 (but no plan to correct weak intrinsics--issue of
manpower, and small emittance improves pol. losses for these resonances
-- cold snake for Run 5
Q: why 2 steps?--if cold snake necessary, what do we learn from warm snake?
A: warm snake for spin matching (but then commissioning useful in Run 4?), also
problem seems to be strong intrinsic resonances-->replace rf dipole with
cold snake (Thomas).
RHIC polarization (Mei Bei):
-- Mei shows much lower avg. P than we use--probably not throwing out
low P runs (aborted store for low P)
-- no correlation between P and intensity at 24 GeV in RHIC
-- snake resonance curves--after correction, yellow (with partial snake)
still had larger strength than blue (discussion about optimization for
yellow done at 24 GeV after recovery from snake failure; may have been
off of optimum at 100 GeV)
-- 20% loss in Delta P/P at end of beta squeeze--coupling problem, plan to
squeeze during energy ramp for Run 4, stay on histeresis curve
500 GeV issues--what is possible? (Thomas Roser):
-- spin resonances 2-3x stronger between 100-250 GeV, orbit corrections
imply that we preserve P, but tight tolerances on corrections
-- other issues all same as for 200 GeV--i.e. need to be solved first
Plan (Thomas Roser):
-- considering changing working point (fractional tune, related to both beam
resonance space and spin resonance space)--to improve beam-beam tune
spread and shift issues. Presently about .22 to .23, change to .18?
This was the original plan, but early running had problems at this tune.
-- tune feedback required to be operational--worked in Run 3, but not
operational (delta tune to <.005 with feedback, 10x larger without
(check))
-- introduced letter from Wolfram Fisher and Thomas Roser on expected
performance for Run 4
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