User name R. Michaels
Log entry time 02:03:09 on February24,2001
Entry number 56897
keyword=re: odd mult. peaks in TDCsThere are some wierd multiple peaks in TDCs, especially R-arm.
Observations corresponding to plots below:
fig 1, top left -- hit pattern on R-arm, looks ok except for glitch at (-1,1)
meaning no hit on S1.
fig 1, top right -- VDC hits, showing big peak at zero.
fig 1, bottom left -- A typical TDC spectra for NVDC<20.
fig 1, bottom right -- S2 paddles that got a hit corresponding to the strange
secondary peak in S1 (near 1600). Note, all S2 paddles participate, so
it seems not an acceptance effect. The peak near 1600 might be because
S2 is too early to make retiming, S1 makes trigger timing and retimes itself.
fig 2 -- TDC spectra when we require NVDC>20. Fairly clean.
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It looks like the zero hit VDC events are background from neutrals which
are correlated in time but not space. Note, if the neutrals were uncorrelated
in time, then based on rates we expect ~10% background at present, but
it is much higher. The weak 2nd peak in the cleaned up spectra is probably
due to the ECL delays, it was a problem we found earlier in the run which was
alleviated by increasing the pulse widths, but probably not solved completely.
FIGURE 1
FIGURE 2
