From: Claus O. E. Jorgensen (ekman@nbi.dk)
Date: Wed May 21 2003 - 11:35:37 EDT
Hi Mads, First of all the back part of MRS was moved forward by 50 cm at run 588X, so that explains the first step in your plot. (I hope you are aware of this and use different maps for the different settings). When you make the track to vertex cut, is the sigma then calculated for each run? If not I guess that's where the second step comes from. Try to plot trkVtxZ-bbVtxZ and trkVtxY as function of events (instead of runs) to check if the width or the offset changes. It could of course also come from the matching in the magnet (check the MRS matching histograms) or the TOFW matching. In these cases you can either redo the DST from the new global tracking or just skip the runs where you know the offsets/widths are wrong. Cheers, Claus +------------------------------------------------------------+ | Claus E. Jørgensen Phone : (+45) 33 32 49 49 | | Cand. Scient. (M. Sc.) Cell : (+45) 27 29 49 49 | | Office : (+45) 35 32 54 04 | | Niels Bohr Institute, Ta-2, Fax : (+45) 35 32 50 16 | | Blegdamsvej 17, DK-2100, E-mail : ekman@nbi.dk | | University of Copenhagen Home : www.nbi.dk/~ekman/ | +------------------------------------------------------------+ On Wed, 21 May 2003, Mads Mikelsen wrote: > > Hello! > > I have taken a look at the Au data for the MRS. I have found problems > relating to one spectrometer setting in particular; 90degrees 1000B. (Runs > in aerea 5850 to 5990.) By > plotting the average number of tracks versus run-number I get a stair-case > like distribution. (Three flat plataus with sharp increases separating > them. Each increase is around 20-25%.) -- See attached plot. > > This indicates that something has happened with the detectors between > certain runs. (Tuning, triggers etc.) > > Only trig 6 events with <5% centrality and vertex between -5 and 5cm have > been counted. (And with ok zdc vtx.) And only primary tracks are counted. > (The number of identifiede pions etc. shows the same variation as primary > traks pr event.) > > Has anyone noticed this before? Or is there any explanation? > Shurly someone must have done theese tests before. > > I have not used the data from the latest reductions, since they are not > compatible with BDST. But Claus assured me that the QM data lockaded at > /brahms/data05/data/dst/MRS should be OK. (-- I do not expect that the > latest calibrations will give such a drastic effect.) > > I have cheked the shiftreports from the shifts around the runs where the > sharp increases are located but has not not found anything that can > explain this. > > I hope to get some comments soon as I plan to use the data for my thesis! > :-) > > Best regards > from Mads
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