STAR Status/Plan20080215 RHIC Spin Meeting

L.C. Bland

• Local Polarimetry

• Status

• Plan

Effective Analyzing PowerBBC Polarimeter

• Analysis from available run-6 data more complete analysis still to do

• Event data suggests BBC very similar year to year assume same effective analyzing power for run 8

Run-8 Status• Needed to retime bits to “Crawford” scaler due to hardware upgrade

• Timing completed prior to RHIC store 9850 (20080212)

• Run-8 beam polarization using run-6 effective analyzing power

Fill Tstart Tstop PYellow PBlue

9850 0212-0625 0212-0755 51±4% 56±4%

9859 0213-0420 0213-0508 41±3% 51±3%

9866 0214-0250 0214-0444 35±2% 47±2%

9880 0215-0259 0215-0331 47±2% 55±2%

Measurements continuous between Tstart,Tstop only for 9880

Forward Meson Spectrometer

North FMS half before sealing

STAR Plan for Run-8 p+ p

From Gagliardi presentation to 22 January 2008 weekly planning meeting

Physics goals for the 200 GeV p+p run

• Comparison data for FMS CGC search

• Extend xF and pT range for forward single-spin asymmetries

• Study direct photon asymmetries in forward direction

• Electrons from Charm and Bottom, with low material, to resolve STAR/PHENIX discrepancy

What do these need?

FMS Integrated Luminosity Goal = 30 nb-1

0.00

10.00

20.00

30.00

40.00

50.00

60.00

FMS progress during d+Au

• If things don’t break, we will achieve the reduced goal• If things go well, we might end up at ~40 nb-1

• 40 nb-1 is the same nucleon-nucleon luminosity as 16 pb-1 of pp• RdAu reduces somewhat the pp luminosity needed for equal statistics

Original goal

Reduced goal

Red triangles are with final or near-final PMT gains

25 nb-1 as of midnight last night

Forward single-spin asymmetries

Acceptance of FMS and projected RHIC performance will enable…

• Further reach for inclusive and heavy mesons

• Spin-dependent near-side correlations () separation of Sivers and Collins effects

• Spin-dependent away-side correlations (-jet) isolation of Sivers effect

• Embark on spin-dependent inclusive and +jet

Projections for 9 pb-1 recorded with 70% polarization

Transverse spin direct Theory expects repulsive color charge interactions to result in an opposite sign to spin-correlated momentum imbalance for +jet. Magnitude of effect requires >105 events to see significant effect.

Comparison of run-6 data to simulation provides indication that prompt can be extracted. The large acceptance and dynamic range of the FMS is needed to veto daughter from ,… decays.

Expect >0.150K events with E>25 GeV into small fiducial volume in 9 pb-1 sampled.

Bacchetta et al., PRL 99, 212002

What might we expect?

• Anticipate 10 to 24 pb-1 delivered for four weeks of physics production

Goals for the 200 GeV pp run

• FMS reference data– Sample at least 9 pb-1 with fast detectors

• FMS transverse spin asymmetry measurements– Sampled figure of merit (P2L) at least 3.8 pb-1 with fast detectors– Equivalent to 9 pb-1 at 65% polarization

• Slow detector measurements for non-photonic electrons– Sample at least 4.5 pb-1

• This requires:– C-AD deliver at least 18 pb-1 (assumes 50% STAR up time)– STAR operate the slow detectors with at least 50% live time– FMS fast detector data recorded when the slow detectors are

both live and dead• Has not been done during this year’s d+Au run

• Was done during Run 6 p+p