Hi Claus, I haven't gotten up to the 5900's yet (I should get there sometime tomorrow), but I suspect this looks much worst than it is. In order to calibrate the centrality I need to start with a min-biased multiplicity spectrum. These essentially don't exist for the later runs with any reasonable statistics. A very small change at the high multiplicity end of the spectrum will be STRONGLY magnified when looking at the centrality histogram. For these runs I would suggest bin sizes of no less than 2% in centrality to avoid nightmares of bad calibrations... Having said this, I am noticing some differences in the centrality behavior when I compare the 0-20% range a centrality spectrum based on min-biased events, and one using trigger 6. Hiro and Flemming have also noted this and the behavior is currently being explored. The effect of concern is a dip in the centrality spectrum for the most central events when using trigger 6. Until this latest replay using the reduced event files I have only been looking at trigger 4 events since these are the ones needed for the calibrations. Regards, Steve Claus O. E. Jorgensen wrote: > Hi Steve > > I've looked at the centrality for the high field runs (5901-5983) and > I found this: > > http://www.nbi.dk/~ekman/centTest.gif > http://www.nbi.dk/~ekman/centTestZoom.gif > > which worries me a bit. I should say that to produce these plots > I've made a vertex cut (+- 15cm) and requiring good zdc-bb correlation. > It looks like the calibrations are not optimal. > > However, I don't think that there's much to do about it now. The reduced > files are produced and I don't think we have time to do more calibrations > and reductions before QM. And I guess that 5% central is more or less the > most central events. > > Cheers, > > Claus > > +-------------------------------------------------------------+ > | Claus Jørgensen | > | Cand. Scient. Phone : (+45) 33 32 49 49 | > | Cell : (+45) 27 28 49 49 | > | Niels Bohr Institute, Ta-2, Office : (+45) 35 32 53 07 | > | Blegdamsvej 17, DK-2100, E-mail : ekman@nbi.dk | > | University of Copenhagen Home : www.nbi.dk/~ekman/ | > +-------------------------------------------------------------+ > > On Thu, 27 Jun 2002, Stephen J. Sanders wrote: > >> This may come across twice...or not at all. I sent it yesterday but it >> never showed up on the server.... >> >> ---------- >> From: "Stephen J. Sanders" <ssanders@ku.edu> >> Date: Wed, 26 Jun 2002 13:41:45 -0500 >> To: <brahms-l@bnl.gov> >> Subject: MA Calibrations update >> >> Hi, >> Now that we have the beautiful reduced event files (thanks Claus, Ian, and >> whoever else helped to produce these files!!!), I've started to replay the >> runs to: a) get all of the MA pedestals correct and b) check that we don't >> have any serious problems with the array calibrations. >> >> To check the MA calibration, I'm calculating dN/dEta (SiMA) for the 0-5% and >> 30-40% centrality cuts, with the centrality calculated using the combined >> TMA and SiMA data as done for our multiplicity papers. The calculations are >> identical to what was done for the 200 GeV paper. >> >> Although I still have a number of runs to complete, I think a fairly >> reasonable picture is started to emerge and I wanted to relate this to the >> Collaboration as people get started on "final" passes. >> >> A figure of the dN/dEta results vs. run number is at >> >> http://kuphsx2.phsx.ukans.edu/~sanders/MACalib/dNdEta.jpg >> >> I've fixed the error bars at +/-4%. >> >> I have some other figures that might be of interest at >> >> http://kuphsx2.phsx.ukans.edu/~sanders/MACalib >> >> In particular, there is pretty clear evidence of a slope to the BB Vertex - >> TPM1 Tracking Vertex vs. Multiplicity plots for most runs. The same is true >> with the ZDC vertex. I've been doing these calculations since Monday and so >> any very recent changes in the DB may not be included in the present >> results. >> >> I hope to have new pedestals for all of the runs where we have reduced event >> files by this weekend. Unfortunately, these will be added to brat as ascii >> calibration files... >> >> Regards, >> Steve >> >> >>
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