Minutes of BRAHMS Analysis meeting 23 Feb 2007 ============================================== Submitted by Michael Murray Slides are at http://indico.cern.ch/conferenceDisplay.py?confId=13148 Present: Michael, Selemon, Dipali, Hong Yan, Ramiro, JH Lee, Flemming Steve Previous Action Items: 1) Please have a final check of Ionut's proceedings which will be submitted in a few hours. http://folk.uio.no/ionutca/ qm06_IA_proceeding_v3.pdf Done I guess 2)Dipali: Look into normalisation of background See this meeting Agenda 09:30 dau PID analysis (40') Ramiro Debbe 10:10 Drift Velocity Calibration for T1 (20') SELEMON BEKELE 10:30 phi->kk analysis (update) (20') Dipali Pal 10:50 plans for analysis meeting (10') ( Paper ) F.Videbaek presentation and discussion of plans for analysis meetings, as distributed before. Action Items from this week: Ramero: Understand the rescaling for group B runs Explain the 20% difference between spectra from productions 3 and 2. Selemon: Select only Trigger 2 and 6 and increase statistics for failing runs. Dipali: Think about how to handle the normalization of events with 3 and 4 kaons. Next week: We should here from Nathalie and also Selemon will present CuCu spectra: This week's minutes: ==================== Ramero: dAu PID: ================ He is using only the RICH and is using the 3rd set of DSTs. This set includes some more troublesome runs which have problems with the Z vertex. Group A) No ADCs for INEL counter sigma = 10cm Group B) cross talk, don't use INEL z vertex Group C) Good vertex, sigma = 5cm. Stratagies a) Normalization INEL and Trig 5, pointing to vertex by tracking only. b) These runs are useful for our negative pion distribution.use BB to get z vertex and normalization done with trig 1. Will correct for lower efficiency of BB detectors. He finds this factor in good runs. FV notes that this correction factor depends slightly on the vertex bin. Note scaling factor for polarity B seems to be different from polarity A. With fudged scaling factor he can get a nice agreement with spectra. When comparing to DSTs from production 2 he find an increase of 20% for both pi+ and pi-. This could be due to tracking efficiencies caused by a difference in maps. A new PRL will To concentrate on measurements performed at 4 degrees. Spectra: min bias 0-30% 30-60% and 60-80% for pion kaons and protons. (Note on a semilog plot one cannot see the difference in centrality between the spectra). RdAu for the most central set. We may be able to highlight the physics behind meson baryon difference, as well as the “standard” discussion about evolution and multiple scattering. We appear to have a decent data sample of p+Au events tagged with a single neutron in the right ZDC. There may be interesting physics in that measurement. Action Items: Understand the rescaling for group B runs Explain the 20% difference between spectra from productions 3 and 2. Then he can make p,pbar spectra and work on a paper draft. Centrality Dependence: Hong Yang will Flemming:Schedule and preserving analysis info ============================================== 3/9 Selemon: CuCu spectra and Nathalia - 3/16 Catalin: AuAu high pt Flemming: pp 62 GeV 3/23 Truls: auau,cucu 62 JH: Spin at 62 and 200 GeV 3/30 Steve: v2 analysis We need to make our results widely available and easily understandable. Data should be saved as simple root historgrams with easily identifable names. Spectrum specification : Each spectrum analysis should deliver spectra (invariant yields as root directories with simple names, and titles) (ptalso mt?), Centrality CuCu (0-10, 10-20, 20-30, 30-40,40-60,60-80) - Selemon Centrality AuAu (0-10, 10-20, 20-50, 40-60) - Catalin Centrality dAu (0-30, 30-60, 60-80) those were used in multiplicity papers. Rapidity bins (dy = 0.2) HY - dA, pp What are the appropriate centrality scales, dy and dpt. In general ones should try to stick to something like dy-0.1, dpt=50 MeV/c, coarser binning at higher rapidities Dipali Mixed event normalization factor. ======================================== Previous scheme Mix K+/-'s from an event with K-/+'s from the next 10 events within same centrality and vertex. Normalize above φ mass range ( 1.1 < M < 1.5 GeV) Normalization factor, R = Σ(Measured) / Σ(Mixed) within above mass range R should be ~0.05, but we found it ~0.03 The weakness of this method is that the mixed events may not all contain two kaons. She now requires two kaons for all events that are used in the background. This gives a much better normalization factor. Action Item: Think about events with 3 and 4 kaons and discuss offline with JH. Selemon: Drift Velocity calibration of T1 ========================================== One horizontal calibration fiber seems to be dead. Many calibrations fail because of "Inconsistent number of fit points" Some runs seem to have low statistics, Selemon only uses 5 sequences but he may need more. Flemming reported that he should select only events with triggers 2 and 6, ie something hitting the spectrometer. In supermon the hit distributions for the calibration fibers seem to be missing but this may be simply that the ADC threshold was wrong. Action Item: Select only Trigger 2 and 6 and increase statistics for failing runs. _______________________________________________ Brahms-l mailing list Brahms-l_at_lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-l
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