Hi, I've looked at vertex correlations and it seems that BB vertex z and tracks (intersection with beam plane) are nicely correlated sigma \approx 2 cm, but with an offset around 8 cm. The ZDC vertex is still way off (~50 cm) and the correlation with the other methods does not look very good. I think it's because the old ZDC time calibrations are still hardcoded in the BrZdcRdoModule, or??? You can find some plots at http://www.nbi.dk/~ekman/bbVsZdc.ps.gz http://www.nbi.dk/~ekman/bbVsTrack.ps.gz http://www.nbi.dk/~ekman/bbMinusTrack.ps.gz http://www.nbi.dk/~ekman/bbMinusZdc.ps.gz (these plot are from run 4223, I've also checked run 4169 and it look approximately the same). In my opinion this (getting a good ZDC vertex) has a very high priority, since normalization to minimum bias events in a certain vertex range can only be done with the ZDC vertex. Without this we cannot get a reasonable centrality determination, and that makes it hard to do any useful physics analysis. What is the status of the ZDC 2001 software? - best regards 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 Mon, 20 Aug 2001, Ian Bearden wrote: > Hej dev-iants, > I would like to determine the collision vertex for each event that I > analyze. > I can get a vertex from the ZDC. Averaged over many collisions, this tells > me that the average VTX Z is approx -40 cm. I can do the same for BB, and > find that the > average VTX Z is approx 10 cm. This is, by the way, for run 4265. > Now, I guess that both of the above cannot be right. In fact, the two are > not only different, they are not very well correlated at all. > So...I'd like to try to extract a TPM1 vertex, which should be the easiest > to get "right". Is there a > module which takes local TPM1 tracks and returns Z? Is there another way > one can do this? Say, any module which takes TPM1 data and returns Z? And > can this be used in the context of Christian's bratmain. Rumors from the > north (of Copenhagen!) indicate something in the works, but I could not find > anything in the html documentation on pii3. > > -Ian > >
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