We are proceeding with the calibration of the TOF and have developed a procedure
for determining all constants. Unfortunately, these procedures must build one on the
next, so we need your TDC calibrations to start the process. Up to now, we have been
using the constants in the map, but would like to get to the point that we put the best
possible set of constants into the map in preparation for the run in December. Do you
know when your program will be complete?
In order to minimize the correlation between offsets, we suggest the following
constraint on t0: average value of t0 for a given TDC card = 0. That is, the average
value of t0 for a card should be subtracted from the fitted value of t0 for a given
channel. This definition implies that the converted time in ns is (on average for a
FASTBUS card) proportional to the raw TDC value. I believe that this definition will make
the t0 offset relatively insensitive to a change in FASTBUS cards, which you suggested at
an earlier meeting.
Thanks, Elton.