Hi I made some plots of the T1 and T2 drift velocities that are in the database and found out I don't know how to access the DVM data, so if someone could explain how to do that I will include those on the plots. The preliminary plots can be viewed on : http://www.nbi.dk/~pchristi/BRAHMS/TPC/driftvelocity.html Cheers Peter 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 --------------------------------- \-:
This archive was generated by hypermail 2b30 : Mon Dec 17 2001 - 07:34:16 EST