NCC Task Force

1. NCC Task Force Richard Seto NCC Task Force Meeting Nov 20, 2007 BNL

2. Updates on • Agenda • Bugs • pi0 folks – goal R_AA, pi0, direct photon, Delta G • chic folks – goal R_AA • Trigger • Dec 4 –asses whether Dec 20 is a reasonable goal for completion. Report from • Dave/Stefan – pi0, dir photon • Carla/Sky - chic • Ken – delta G • Some software docs for my code and cross sections in https://www.phenix.bnl.gov/WWW/p/draft/seto/meet/NCC_taskforce_Nov_20_2007/nccinstruction.pdf

3. Comments • continue to make progress cleaning up bugs – Bug in SF(1) figured out • Need to clear up more bugs – e.g. zebra bank size in pisa • Mickey has a DST ready – I have not tried it yet • Edouard is done optimizing the NCC code • Would like to see for pi0’s • pi0’s single track (Stefan and Dave) • then turned over to takao to make the direct photon spectrum and then to the spin folks to produce delta G • then turn to heavy ion to produce R_AA • For chic – barbara would like to see more manpower on this • T-28 days and counting • FVTX review went well. Need to have HW clearly done – Ed/Barbara tell me I should work on the management plan and not on simulations….

4. Comments on mixed bkgd • I realized out mixed bkg for both the pi0 and chic was being done incorrectly • Steps • we take signal • embed it in bkg • This assumes ALL events have a signal. But most of the time (for pi0) and often (for chic) in a mixed event we are mixing one signal event with a non-signal event, or two non-signal events

5. event with signal event without signal The problem real life what we do mixed pairs mixed pairs events events 1 1 2 assume 4x mix i.e. mix depth=4 3 2 4 5 3 6 skip some 5 6

6. Solution - chic • I believe the group Sky+Carla always mix a j/psi in the main event with photons in previous events • we trigger on the j/psi • mix J/psi and chic into signal in a 6 to 4 ratio (please check this number) • This may be enough if the j/psi signal is very clean – (which I don’t think it will be even with the DCA cuts on the FVTX) • Find the bkg under J/psi, these will be events in which there is neither a J/psi or chic – we will have to find the fraction of these. • then in the mixed events we will (according to the fraction) keep only the bkg in the mix stack, and not the merged event

7. solution – two track pi0 • pi0 • Calculate fraction of events which really have a pi0 of the relevant pt and y • keep bkg in mix stack usually. For the small fraction which does have the relevant pi0, keep the merged event • The question is when we have TWO such events in the range of the mix depth

8. two track pi0’svs pt and y, new code, cuts, a first look at dAu richard seto

9. comparing old and new NCC code • The next few plots compare the old and new NCC code. 1 pi0 at the specified energy is embedded into 1 hijing pp min bias event. I then look for a two track pi0 in that bin. The new NCC code uses SF(0), i.e. just a constant sampling fraction. When Ondrej manages to debug SF(1) it should get better. • No cuts (e.g. chisq/assym/energy etc) have been applied. They will help of course • Plots on the upper left have black – all events, red- mixed bkg using events with embedded pi0, blue-mixed bkg without the embedded pi0 • The statistics here are 10K, pi0’s embedded into 10K hijing • At the higher pt the background (bottom right in blue shows the background in events without the embedded pi0. I am running out of statistics here. I will need to run lots more background events. (perhaps a factor x10)

10. y 1-1.5 pt 1.5-2 similar result – slightly better S/B, much better eff new code (Nov 16) SF(0) old code (oct 11)

11. y 1-1.5 pt 6.5-7 red – bkg with signal in it blue – bkg w/o signal pi0 better eff, better S/B new code (Nov 16) SF(0) old code (oct 11)

12. y 1.5-2 pt 1.5-2 red – bkg with signal in it blue – bkg w/o signal pi0 higher y bins not possible with old code – low pt new code (Nov 16) SF(0) old code (oct 11)

13. y1.5-2 pt5.5-6 red – bkg with signal in it blue – bkg w/o signal pi0 higher y bins not possible with old code – higher pt new code (Nov 16) SF(0) old code (oct 11)

14. y 2-2.5 pt 2-2.5 red – bkg with signal in it blue – bkg w/o signal pi0 higher y bins not possible with old code –low pt new code (Nov 16) SF(0) old code (oct 11)

15. y 2-2.5 pt 5-5.5 red – bkg with signal in it blue – bkg w/o signal pi0 higher y bins not possible with old code – higher pt new code (Nov 16) SF(0) old code (oct 11)

16. extremes • the next few slides are the highest and lowest I could go with the new ncc code. The plots on the left are the lowest (1-1.5 is the lowest I threw) and the ones on the right are the highest. At the higher pt my pisa jobs crashed so I didn’t have any data there, hence I don’t think these plots are really the highest I can go. I did not bother to figure out why they crashed since I didn’t think I could do two track pi0’s that high.

17. y=1-1.5 – new code SF(0) red – bkg with signal in it blue – bkg w/o signal pi0 pt=9.5-10 pt=1-1.5

18. y=1.5-2 new code SF(0) red – bkg with signal in it blue – bkg w/o signal pi0 pt=8.5-9 pt=1-1.5 ran out of simulation data

19. y=2-2.5 new code SF(0) red – bkg with signal in it blue – bkg w/o signal pi0 pt=2-2.5 pt=5.5-6 ran out of simulation data

20. cross section eta = 1-1.5 two track old code new code better error bars (better eff and S/B) pt (GeV)

21. efficiency eta=1-1.5 pp min bias old code new code Nfound/nthrown eff tot eff higher in pt bin thrown pt (GeV) pt (GeV) in 0.5 GeV high bin in 0.5 GeV low bin pt (GeV) pt (GeV)

22. other stuff old code new code signal to back in merged events signal to background S/B looks better now pt (GeV) pt (GeV) pi0 mass low pi0 sigma (GeV) pi0 mass (GeV) pt (GeV) pt (GeV)

23. compare hits in EMC to NCC • this is the cluster energy distribution, d^2N/dE/dy, for one PbSc sector • (W1) in Run-3 p+p: • https://www.phenix.bnl.gov/WWW/p/draft/bathe/ncc/dN_dEdy.gif • This is a physics quantity, fully normalized: • - N_evt, 25e6 • - bin size, 16./320. • - azimuthal acceptance, 22.5/360. • - pseudorapidity acceptance, 0.7 • - dead towers, ~1. • Is this what you were looking for? • Best regards, • Stefan 2 eta E GeV PbSC W1 3.5 E GeV from 1-4 GeV central arms drops 3.5 OM and NCC drops 2.0 OM

24. pp cross section - new code–all rapidities y=2.0-2.5 y=1.5-2.0 y=1.0-1.5 remember I assume the phenix y=0 cross section for this. I need to update that with some hijing-like or brahms data pisa crashes for pi0 signal in pp all rapidities possible - for 500 GeV good, Delta G coverage

25. Eff all y in pt bin thrown tot Nfound/nthrown eff tot in 0.5 GeV low bin in 0.5 GeV high bin y=2.0-2.5 y=1.5-2.0 y=1.0-1.5 eff drops off at low pt at higher eta

26. other all, y signal to back in merged events signal to background pi0 mass (GeV) pi0 sigma (GeV) y=2.0-2.5 y=1.5-2.0 y=1.0-1.5

27. dAu – first look

28. dAu mb y=1.0-1.5 – new code red – bkg with signal in it blue – bkg w/o signal pi0 pt 1.0-1.5 pt 7.5-8.0

29. Now try cuts to increase S/B Come back to question of why S/B gets worse at higher pt Does extra stuff in NCC shown before do this? Answer I think- what I am missing is cuts on assym, which would require TWO showers at relatively high energy jobs are running now to get final answer A first look

30. Cuts pp y=1.0-1.5 pt=1.5-2.0 red – bkg with signal in it blue – bkg w/o signal pi0 small sample – 2K events No cuts Assym>0.8 E_photon>0.3 GeV pt_photon >0.2 GeV Y_photon<2.5 (in good part of NCC) with Cuts : cleaner signal, better S/B

31. My Plans • Next –look cross sections for dAu (have to put data in) • cuts with cross sections for pp, dAu (running) • SF(1) with cuts for pp, dAu • Move on to central dAu, AuAu • running time a problem – my priority has dropped • Adopt DST’s • run at ISU (will transfer bkg and signal files and use disk space) • help the chic folks