Peter H. L. Christiansen wrote: >>4. >>Your time correction as function of row number is very nice, but as has >>been shown earlier it is not the full picture. There is also some pad >>number dependence for the time correction. Do you envision probing this >>dependence also? >> >> > I don't think I will investigate this the next 2 months. There have also > been some talk here, if you could use the time distribution of each pad, > where you should see the "top" and "bottom" of the TPC to map out these > corrections, do you know/think this is a good idea ? Nice of you to call use quotes for "top", as the what you will get as the top from the distributions will most likely correspond to the height when the gating grid is fully open. What's more it will probably be rounded off since the opening is not instantaneous. Typically the gating grid is not open until timebin 20 or so. Therefore I don't think you'll get much out of using the "top". The bottom edge, on the contrary, may be more usefull,at least for TPM1 which is fully illuminated in y. The other TPCs are limited by magnet openings, i.e. if you use tracks. Possibly one could use background comming in from the sides for these TPCs and thus get a time distribution. I think it is a good idea to use the bottom for pad-by-pad time calibration, but it may be tricky for other TPCs than TPM1. Actually, earlier this year T1 was tested with pulsed signal to determine the time for a pulse to go through the readout chain. Possibly, this could be done for the other TPCs as well. Then one could have a wonderful time calibration where one is able to separate the contribution from electronics (using the pulse data) and from the charge drifting through the cage (using the bottom edge). That would be something. Best wishes from Jens Ivar -- Jens Ivar Jřrdre e-mail: JensIvar.Jordre@fi.uib.no usually: Dep. of Phys., Allégt. 55, N-5007 BERGEN, NORWAY currently: Bldg 510D, P.O.Box 5000, Upton, NY 11973-5000, USA phone: +1-631-344-4223
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