Minutes of BRAHMS Analysis meeting Friday 16 March 2007 ======================================================= Submitted by Michael Murray http://indico.cern.ch/conferenceDisplay.py?confId=13684 Present: JH, Flemming, Ramiro, Hongyan, Steve, Selemon, Dipali, Pawel, Catalin and Michael Action Item: 1) Tell Europeans that US has moved to daylight savings time. Until the end of March there is only 5 hour difference between BNL and Europe 2) Calibrate Zdc vertex for dAu runs 3) JH to work with Hongyan on dAu normalization This has already started. JH sent out a procedure that is listed below and Hongyan will try it. 4) Catalin: For AuAu at 200GeV Check efficiency of TPCs. 5) Catalin: Do momentum correction at high Pt. Agenda 09:30 pp at 62 GeV Flemming Videbaek Update on analysis of 62 gev spectra 10:00 STAR dAu paper discussion Ramiro Debbe A couple of figures to get the discussion going 10:20 AuAu 200 GeV analysis Catalin Ristea (NBI) Update on the mrs analysis for this time. 10:40 a few updates on dAu Hongyan Yang normalization method update for runs with cross talk ------------------------------------------------------------------------ - Flemming Update on analysis of pp 62 Gev spectra His Analysis note is now posted as documents in todays agenda, please read and comment. • Data used (detailed list of runs ...) • Analysis Method • Selection and Cuts • PID: TFW2 in MRS, RICH in FS, H2 in FS (4,6 degree low field). • Corrections Histograms • Trigger biases, Data yields • Spectrum generation• Quality Control • Comparison to ISR data For the paper he plans to show minimum bias spectra y~0, y~1 y~2.5, y~3. –Pion, kaon, proton and compare to ISR. There will be figures of K/p, k/pi Pi+/pi- ratios as well as H+,h-spectra. He would like to compare to pythia and pQCD and look at Limiting fragmentation for spectra pi,K.. ======================================================================== =========== Ramiro, d-Au Centrality: STAR Uses TPC for centrality determination, while Phobos using the forward rings, which they claim are less biased. We have to use charged multiplicity for |eta|<2.2 and we should discuss in our paper what effect this causes. ===================================================== Hongyan Yang, dAu update: For 90 degrees half field Hongyan has compared spectra where she uses 3 different detectors for normalization and vertex detection. JH We should not select tracks with ZDC vertex, rather use vertex from tracks. For normalization count min bias events for a given vertex range. For a given vertex window count number of ZDC events with that vertices in that vertex bin and then correct with INEL/ZDC to correct for limited acceptance of ZDC. Steve for events where all 3 detectors have vertices do we have detectors have consistent vertices? Ramiro says yes for INEL and BB. BB/INEL is the same, ~1.5, for all different particles. Action Item: Check ZDC vertex calibration Normalisation 1. For runs outside run range [8076, 8306], using INEL 2. In range [8076, 8306], using BB vertex to select event, and rescaled BB events to do normalization Finally, spectra are constructed by the combination of these two set of data Catylyn and JH: Scaling of spectra should be done from ratio of min- bias vertices, not from spectra. Action Item: JH and Hongyan will work on normalization. This was done a few hours after the meeting. JH suggested the following procedure. 0. Before you tried to use ZDC/Trigger4 for the normalization, check the calibration as Steve suggested. Look at "|ZDC vtx - MRS Vtx| vs. run number". 1. Make ratios of (For a vertex bin 0-5cm for an example) N5 N(Exclusive Trigger5 with 0< INEL vertex <5cm) *scaledown5 R= ---- = ------------------------------------------------------------------------ ----------- N4 N(Exclusive Trigger4 with 0< ZDC vertex < 5cm) *scaledown4 2. Check "R vs run number", and see if it's flat. If not we might have a problem of using ZDC for the normalization. 3. Build spectra using Track Vertex and Spec Trigger 4. Now calculate the final yields - A: using N5 as you normally do - B: using N4*R instead of using N5 5. See if you can get consistent results from A and B 5. If the results are consistent, you can extend the method for the runs where we have a problem with INEL trigger. There will be no loss of statistics since the spectra come from Spec trigger and with vertecies from tracks. However requiring a ZDC (or BB) vertex, would mean the data were not minimum-bias. Hongyan agreed to try this. AuAu 200 GeV analysis Catalin Ristea: Update on the mrs analysis for this time, FS in a couple of weeks. He switched over to the standard BanApp analysis and this cost hims some time. Vertex selection: [-15, 15] cm 4 sigma cuts around the vertex offsets Using banapp Acceptance maps 5 cm vertex bins 0.5 edges cuts slat range 32 – 113 in Tofw slat range 3 – 41 in Tfw2 3 sigma pid in m2p, using dead slat He compares his old method (build spectrum by filling a certain bin in Pt and then doing all corrections) and 2d method (y,pt) and then projecting on to Pt axis. They agree fairly well. He has an issue with acceptance maps and finds he needs a cut on TPM2. Flemming remember that their was some problem with TPC FEE cards in AuAu. Action Item: Check efficiency of TPCs. He finds a PID efficiency of about 98% after he ignores sick slats. He makes the ratio of identified particles to charged particles. He also compares to STAR and finds we are closer to them than PHENIX is Action item: Do momentum correction at high Pt. To be consistent with PHENIX he has to leave off any corrections. He has also compared identified particles to PHENIX and STAR. The agreement is better with STAR and than with PHENIX. Please see his slides. The meeting had to close at 11am BNL time. _______________________________________________ Brahms-l mailing list Brahms-l_at_lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-lReceived on Fri Mar 16 2007 - 14:32:05 EDT
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