Hi Djamel, I was also puzzled, which is why I looked at the offsets using a narrower range about the peak for a couple of runs-- This tends to look MUCH better. I would not make much of the absolute offset at this time. When I get a few more runs done I'll regenerate the offset figure using the +-6cm range that you show in your figure. I am quoting a mean offset (+-20cm) rather than the offset of the peak of the BBC-TPM1 distribution. Looking at your figure I see the same sort of asymmetry in the tails of the distribution that I think is responsible for the relatively large offsets that I see taking a +-20cm range. One other point that I need to check is whether I would see any significant change in the dNdEta distribution if I used the BB counter rather than the TPM1 vertex for most of the events. After I get the pedestals for all of the runs, I plan to go back and look at these issues. Regards, and thanks for the comments... Steve > From: Djamel Ouerdane <ouerdane@nbi.dk> > Reply-To: brahms-dev-l@bnl.gov > Date: Thu, 27 Jun 2002 17:11:27 +0200 (CEST) > To: brahms-dev-l@bnl.gov > Subject: Re: FW: MA Calibrations update > > Hi Steve, > > I looked at your plots and something really stroke me. On the plot > BBVertexOffset.jpg, which shows BB - TPM1 vs Run number, one can notice a > group of runs at ~ -2cm (5400 to 5450 or so). But I was sure that the > offset calibration was ok for these runs. I checked it and made a plot > (a 1d that merges all runs between 5400 and 5450). You can check it out > here : > > http://www.nbi.dk/~ouerdane/bbVtxOffset.gif > > The mean is -0.01cm and _not_ -2cm. > > I am really puzzled. Or maybe I misunderstood something. > > Djam > > > -- > Djamel Ouerdane ------------------------------------------o > | Niels Bohr Institute | Home: | > | Blegdamsvej 17, DK-2100 Ø | Jagtvej 141 2D, | > | Fax: +45 35 32 50 16 | DK-2200 Copenhagen N | > | Tel: +45 35 32 52 69 | +45 35 86 19 74 | > | http://www.nbi.dk/~ouerdane | > | ouerdane@nbi.dk | > o---------------------------------------------------------o >
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