User name choi
Log entry time 15:58:38 on January31,2003
Entry number 94046
Followups:
keyword=Structure in dp spectra with PID cutEarly, it has been reported that there is a structure in delta-p spectra for the right arm with PID cut applied. The problem has been traced back to two sources: bad calibration for shower counters and near-dead block in preshower counter. I did a very quick, crude calibration of shower counters using my eye and half of the problem has been fixed. But one near-dead block in preshower counter can not be fixed online and as last resort, the low limit preshower cut has been removed from the particle ID cut. After this modification, for statistics with one run, it is very hard to see any structure in the delta-p spectra, but if statistics are accumulated over many runs, the dip at arount dp=+0.015 is quite visible as the attached plot shows. Red curve is dp spectrum with acceptance cut only and blue curve is dp spectrum with acceptance cut and PID cut.
FIGURE 1
