Hi Steve, Hiro, Have you guys got a good idea of the error on the centrality? That is, if I select the 5% most central, I really select (5+/-X)%, and I'd like to know, roughly, what is X? I suppose it is around one, since Steve says we cannot bin more finely than 2%. Is this supposition correct? Ian > -----Original Message----- > From: owner-brahms-dev-l@bnl.gov [mailto:owner-brahms-dev-l@bnl.gov]On > Behalf Of Stephen J. Sanders > Sent: 27. juni 2002 19:12 > To: brahms-dev-l@bnl.gov > Subject: Re: FW: MA Calibrations update > > > 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 > >> > >> > >> > > > >
This archive was generated by hypermail 2b30 : Fri Jun 28 2002 - 06:40:53 EDT
