Date: Sat Mar 27 2004 - 14:58:05 EST
We have had some reasonable progress since Thursday in collecting data at 63 GeV (or 62.4).The data so far consists of ~500k trigger 3 MRS for 40 deg, MRS was move to 45 last afternoon. at 3 deg we have 2M trigger 6 for B-pol (protons) an ~ 800k for A-Pol. So have well are we doing? I analyzed run11344 and 11333 and got a rough statistics for particles with PID in Rich with a first non-opt matching, geometry etc... The setting is 1/2A,B accepting momenta in range ~8-20 GeV. I attach the mass plots for pos and neg. Recal that most protons (p-bar) are in fact below the rich threshold so most particle with mass=-1 are protons (apart from an effeciency corrections). The two runs have ~175k tr6 an 125 k. Based on this the rough counts are p 192 + 1200 p-bar 5 + 180-60 pi+ 1801 pi- 2907 K+ 718 K- 333. the statistics for protons is ~10* times this i.e. 14k which I guess is quite good. (What did we have in run-2 at 3 deg?? (peter)). Since the p-bar are very much reduced compared to p. it will be impossible to get a comparable spectra for p-bars'. Since the 3 deg is essentially at the peak of the net-p istr, as evaluated from Hijing it seems to me best after the completion of the 3 deg B pol (same # triggers) to measure around y~2.1 since 1/2 units change does not tell us so much. regards Flemming Since I gave you the numbers let me also do the particlae ratios since otherwise someone else in the coll. will do so: Normalise to N(tr) pi+/pi- ~ 0.85 K+/K- ~ 0.33 p-bar/p ~ 0.03-0.07 (which is right on Becatinis curve if you wonder) ---------------------------------------------------------------- Flemming Videbaek Physics Department Brookhaven National Laboratory e-mail: videbaek@bnl.gov phone: 631-344-4106 _______________________________________________ Brahms-l mailing list Brahms-l@lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-l
