Hi I got a script from Ramiro that shows how to get the DVMs and included them in my plots. There are not so many for FS. The correlation with T1 looks ok while the correlation for the few points that are there for T2 seems less pronounced. The code used to generate these plots can be found in pc_app/tpc/dvvsrun. There is an example of how to access the DVM data from brat. Cheers Peter P.s : Plots are on : http://www.nbi.dk/~pchristi/BRAHMS/TPC/driftvelocity.html On Fri, 14 Dec 2001, Flemming Videbaek wrote: > 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 > > > > -- :-) --------------------------------- )-: |Peter H L Christiansen aka PAN @ NBI | |EMAIL : pchristi@nbi.dk | |OFFICE : Tb1 @ NBI | |PHONE : 353 25269 | |SNAIL : Hans Tavsensgade 35, 4th | |PHONE : 35 349336 | :-D --------------------------------- \-:
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