Let me add a comment to this. Ramiro has very recently shown there is a correlation between the Vdrift and the TPM1/2 best values (as also indicated in the mail below). Since he has also shown the that output DVM for ALL 4 tpcs correlate it is a safe bet to assume that Vdrift also varies for T1 and T2. It would be very good to get a confirmation of this from the FS data analysis ------------------------------------------------------ Flemming Videbaek Physics Department Brookhaven National Laboratory tlf: 631-344-4106 fax 631-344-1334 > the physics runs since there is a vertical focusing effect due to the > magnetic > field. But one of the possibilities is that we use TPM2 Fiber information > in > zero-field runs, and comapare the measured positions of TPM1 tracks in the > Fibers with the DVM values to get a scale factor (hopefully it's a > constant). > Then it's just drift velocity = DVM value*scale factor. > Here is a y distribution of the TPM1 tracks projected to the Fibers on the > front of TPM2 for the run 5823 (D5=0). The measured distances (integrated > over x) between two Fibers are consistent with the physical separations (2 > cm) > for this run, > > Fiber2-Fiber3 = 2.305-0.315 = 1.99 cm > Fiber3-Fiber4 = 0.315+1.73 = 2.045 cm > Fiber4-Fiber5 = -1.73+3.74 = 2.01 cm, > > which means that the TPM1 drift velocity we used (1.7) is correct for this > particular run. I'm looking at some more Fiber data from zero-field > runs, which we don't have much, with DVM values to see if we can > just scale them with a constant factor. > > JH
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