# Summary from RHIC Spin meeting of June 20, 2003

by Gerry Bunce

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