TPC calibrations: To bring this discussion forward let me add some comments. I think it becomes crucial to minimize the amount of calibrations to be done. It seems from PCs list that at least some of these will come very natural be analyzing the pedestal runs, and with no need to repeat this from with real data. Or maybe one could get away with checking/comparing when doing the calibrations that are needed. /PC 1st loop 1) look at sync triggers to get the noisy pads Her special care should perhaps be taken to not target pads that hav irregularities for low time bins, so maybe just look at time bin 50-80. 2) look at trigger whatever to get the dead/ low performance pads. 2nd loop After removing these pads 3) do clustering on sync events to get a feel for if there is any real clusters/ back ground tracks - I would not expect any. 4) Use the pads not in any real clusters from 3 to get an estimate for the level of white noise in the TPCs somehow I think all of the above comes from the pedestal information. KO has a quite complete program that analyses a given pedestal run and stores this information in output files. I think what is needed is that this gets extracted an put into a data base that contains for each Row and Pad 1. Instrumented 2. OK, W,T,A .. 3. equivalent white noise (for Gaussian assumption or 1/5, 1/10 of max value.) 4. Pedestal and threshold used in front end zero suppression. A) Calibrate ADC gain for each pad row by collecting ADC max (or Sum(ADC)) for all identified e single clusters. (possible requiring clusters from tracks). 5) do tracking on trigger 6 events to find the offset in hits for each row. I am currently looking at this. This is to fine tune the time offsets in each pad (at the level of ~0.1 cm) - this should improve the chi^2 very much. 3rd loop after adding info from 2nd loop to detector parameters 6) test that row offsets are small and that chi^2 or confidence level is reasonable (tests with noise) and eventually that chi^2 of cluster fits are reasonable (long way to go). This is certainly important since T1,T2 and TPM2 has the 1,2 and last row timing offsets. I assume this is done by looking at cluster-track deviations from found (single) tracks not including a given row. I also agree this might wan iterative procedure. I would suggest these offsets should be done in time-bins, not in cm to separate out the issue of drift velocity. Since this is an edge affect it can unfortunately also effect the first/last pads in other rows. Presumably it extends some 4 cm from the edge of the TPC Have anyone seen if tracks that runs along say pad 1-6 show the first/last row attenuation in time? The calibration should be guided by the Garfield calculations that Borge did last year. Experience will determine how often we need to do each of these calibrations. Question : 1) where does the drift velocity fit in ? n I think for this years runs it has to be done by the track matching between T1,T2 (TPM1, and TPM2) and cannot be done for all runs. Checking of matching result ould confirm reasonable values. I do not see any easy way for this years run. Peter also raised questions of special modules for calibrations. Rather than doing the complete coding first maybe PC could write the specifications for such module e.g. by outlining in more details (starting from the idea described) the class description, the principal methods at belongs to such a class, and how it would interact with the calibration DB.
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