Run8pp and Run9PHENIX Kensuke Okada April 4, 2008 RSC meeting
PHENIX Run8pp It was a hard time for PHENIX. Only MPC is the major detector upgrade since Run6. 500GeV longitudinal ~5 weeks (3 weeks preparation + 2 week physics) New cross section measurement First Ws in the central arm Check muon arm condition for the trigger upgrade 200GeV transverse-radial 6 weeks IFF (at the central arms) Jet kT asymmetry A_N with MPC 200GeV transverse-vertical 6 weeks (after 3 weeks of struggling) IFF (2.3 times less statistical significance compared to with radial) Jet kT asymmetry (forward hadron + central = new trigger) A_N photon, MPC
Integrated luminosity From M.Leitch pp - almost no progress on luminosity & polarization development towards future 5.2 pb-1 200 GeV p+p Transverse Vertical luminosity recorded (1.1 pb-1 FOM) Peak luminosity per day ~0.37 pb-1 (r)adial (t)ransverse Now we have a big sample of transverse data.
Recorded / delivered From M.Leitch Black vertical lines are markers for Maintenance and/or APEX days • 200 GeV p+p • Live Time – 89% • PHENIX up – 69% • Overall (w/o vertex) – 62% • (where 10% correction for loss due to CNI measurements is made) The vertex cut is a big factor. (9MHz Cavity + beta squeeze) will be more effective.
Run9 discussion (It is a very simplified version) • Two goals Direct photon ALL to settle the g program (The original goal was 320/pb. It is reduced to 71/pb recorded.) 500GeV run for W physics • But both can’t be accomplished in a single (or two) run with the current machine • performance. • Options we discussed Low energy (e.g. 62GeV) run to access larger x range? The discriminating power is almost same as 200GeV run, because of the low pT limitation. And there may be a difficulty in the theoretical interpretation. (*) under the GRSV model. Search for non-zero ALL evidence in 0 mode with more statistics. If there is no hint, we would postpone the g program for a while until our detector upgrades. How much FOM do we need to make this decision? Jump into the 500 GeV program directly. Postpone the 200GeV program.
Remarks Search for non-zero ALL evidence in 0 mode with more statistics. If there is no hint, we would postpone the g program for a while. How about 25/pb, 60% polarization? s=200 GeV, 25 pb-1 P=0.6 From the pi0 projection plot, there is no strong reason to set the goal at this FOM…. GRSV-std It is getting closer to the relative luminosity uncertainty derived from the comparison between ZDC and BBC counts. The spin flipper helps to reduce the systematic uncertainty. GRSV-0
Remarks Jump into the 500 GeV program directly. Postpone the 200GeV program. From the RSC meeting on Nov.30 10/pb/week (200GeV) *0.25 (vertex, exp. uptime) *2.5 (500GeV/200GeV) ―Parity violation process (W physics) AL measurement Central arm: W+e+ 140/week for 7.5/pb/week signal asymmetry ~0.25 Requiring 1/P/sqrt(2N)~0.25 /3 leads N~300 with P=0.5 BG contamination reduces the significance. Muon arm: A proto-type will be Installed in Run9 !! Without a trigger and a thick absorber, it’s not useful. We obtain a result with 2 weeks physics period.
Summary PHENIX had a hard time in Run8. In Run9, we can’t finish the g program in a single year. Can we set a reasonable interim goal for 200GeV longitudinal program? Or we go to the 500GeV program ? More materials in the following slides • Inclusive measurements Eta in the central arm : technically similar to pi0 ± ALL : due to RICH threshold, it starts at ~5GeV/c Direct photon ALL : An isolation cut is effective from ~9GeV/c MPC forward pi0 ALL : access to low x gluon. • Model calculation Are we able to distinguish GRSV and GS-C with MPC pi0? Theory scale uncertainty in ALL
astrid Central arm, based on run6 preliminary
Robert Central arm, With an isolation cut. At low pT, suffered by dilution factor.