1 NCC Task Force Richard Seto NCC Task Force Meeting Jan 8, 2007 BNL

2 Agenda Assessment of where we are and time schedule - plans for work over the holiday. I would like to hear reports from everyone as usual. 1) Dave/stefan - pi0's - could I get a plot or something to show (or a slide)to the DC and an update 2) Ken/Paul/Todd - same for spin 3) Takao - plan for the direct photon. (a slide or so for summary to the DC)

3 The Document The goals in simplest terms for the NCC task force is to produce the following figure of merit (FOM) plots from realistic physics simulations. Realistic means a full simulation using PISA with detector response, reconstruction, and data analysis. a) R_AA for pi0 as a function of pt for various centralities in AuAu and dAu collisions b) Direct photons cross sections, and likewise R_AA. c) R_AA for the Chi_C via its decay to J/psi photon as a function of pt for various centralities. Very likely we will limit this to rapidity d) A_LL(pt) for direct photons in 500 GeV polarized pp collisions d') Because we already have jet reconstruction going in pp collisions we should easily be able to use this information to get A_LL(x) giving a greater sensitivity to low-x e) a demonstration that we can we can extract pi0's at various angles in various centrality collisions with a known efficiency - This should answer the projective Geometry question. Schedule To collaboration – Jan 20 To DOE – End of Jan HI spin answer to committee

4 comments from axel What is missing all together are slides addressing b) the direct photons and more specifically e). For e) one more technical slide explaining that the NCC has "tracking capability" and showing reconstruction efficiencies as function of function of impact angle for different pt and maybe vertex positions should be sufficient to address the issue. For the next two the single track pi0 is critical b) you might consider, and I do not know how much work that is, comparing a MC input spectrum for single photons with the reconstructed one plus and R_AA plot. Spin(RKS added this)

5 Status of simulation effort Full GEANT based simulation (PISA) Full reconstruction and PID pattern recognition of showers in PADS (stripixels have not been incorporated into pattern recongnition stage) energy and rapidity dependent calibrations of sampling fraction and energy corrections Particle Identification using longitudinal and transverse shower shapes – also function of energy and rapidity – transverse shower shapes using both pads and stripixels Single track pi0 using stripixels done generation of signal and underlying event – with signal being embedded into underlying event when necessary. Analysis of events. Mixed event technique used to extract backgrounds

6 Critical simulation analysis goals reconstruction pi0’s in pp to AuAu From this projective geometry question can be answered R_AA can be formed From this direct photons can be extracted for heavy ion direct photon analysis for Delta G from direct photon A_LL status: 2 gamma complete – this will take us to pt~4 GeV single gamma is running at RCF reconstruct chic pp to AuAu R_AA for chic status: complete to mid-central AuAu central AuAu running at RCF

7 π 0  2 γ pp to central AuAu 10K events simulated for AuAu (real data ~10 9 events) AuAu 40-50% AuAu 20-30% AuAu 10-20% AuAu 0-10% AuAu 60-80% y=1-1.5 pt=2-2.5 dAu mb dAu cent 20% y=1-1.5 pt=1.5-2 ppmb 200 GeV ppmb 200 GeV y= pt= y=1-1.5 pt=1.5-2 pp mb 500 GeV pp mb 500 GeV y=1.5-2 pt= pp mb y=1-1.5 pt=2-2.5 y=1-1.5 pt=2.5-3 y=1-1.5 pt=2.5-3 y=1-1.5 pt=2.5-3 y=1-1.5 pt=2-2.5 y=1-1.5 pt=2-2.5 y=1-1.5 pt=2-2.5

8 Single track pi0’s Jobs running at RCF

9 R_AA stat error only – 2 gamma y=1-1.5 single track takes over Assumed AuAu – 10B min bias events (since is 10% of cross section) scale error bars by 3 for 1B

10 χ C pp to AuAu 40-50% central Embed χ C and J/  in appropriate ratio where χ C  J/  + γ in pp min bias Dimuon decay of J/  measured in muon arms plot J/  + γ mass – J/  mass Mixed bkg: J/  + γ mass – J/  +γ mass mixed event, normalized above 1.6 MeV mixed bkg foreground All y – (jobs for lower pt, y bins, and most central AuAu running at RCF) pt=5-6 pt=7-8 pt=9-10 pt=5-6 pt=7-8 pt=9-10 pt=5-6 pt=7-8 pt=9-10 pt=5-6 pt=7-8 pt=9-10 ppmb dAu mb dAu 0-20% AuAu 40-50% M(J/  +γ)-M(J/  ) subtracted χCχC

11 Chi_C R_AA should be straightforward once RCF jobs complete latest error on this point (stat) is 8% using pt>3 i.e old prediction is unchanged R_AA of chic present J/psi r_AA data 50-60% central

12 sweet spot note change in scale for GSC pi0 ~ little asymmetry Done Weight scheme to input spin info implemented Prompt photon events generated and made to be consistent with NLO pQCD calculations. A LL vs. p T done for PYTHIA and in agreement with earlier calculations. Error bars assuming no background GRSV models added to weighting scheme Note: for pi0 we find very little asymmetry (consistent with Volgesang)  pi0 background will not contaminate direct photon asymmetry To do Calculate error bars with background using reconstructed direct photons Plot vs reconstructed p T Spin update