User name R. Michaels
Log entry time 00:53:44 on February10,2002
Entry number 82446
This entry is a followup to: 82428
keyword=T4 time offset ok (but now kine dependent)I took access and repaired the massive time offset of T4. There was a 200 nsec
cable and a delay module with 90 sec intrinsic delay and 90 nsec setting. This was
a setup from the previous experiment and not correct for RCS. The consequence
for earlier RCS data is that although the tracks show up in VDCs (their TDCs have a
big enough time window) and FPP they will not show up in scintillator ADC, TDC.
At first I thought I could leave the delay module in place, so that the time offset of
T4 would not depend on kinematics. But this was not possible, because its intrinsic
offset would knock the tracks out of the scintillator TDCs (the intrinsic delay could be
reduced to maybe 50 nsec by looping less through the module). So, I sent the signal
directly from the MLU to the RCS trigger supervisor, the minimum path. Now the
scint TDCs are in range (typ 80 to 120 nsec). However, the time offset of T4 will
vary with kinematics. The variation is max 40 nsec, so paddles will probably remain
in range (however, note, if a TDC measurement is below ~50 nsec it is inefficient.)
Fig 1. VDCs for T4. Fig 2 Some scintillator TDCs for T4. From run 2374
FIGURE 1
FIGURE 2
