User name D.J. Mack
Log entry time 15:16:54 on May 21,1998
Entry number 127
keyword=more vdMeer cuts displays (cut variables)Figure 1: Cut variables shown with all the other cuts. I will enter what I assume is Rob's cuts file ~robvdm/coin_16_4.cuts via fpilogfile in a subsequent entry.
Quick comments:
0. The scer_npe threshold needs more thought. It is currently set to .5. Leave it there for now. However, a few percent pions are passing this cut and showing up in the shower counter. That is a larger fraction than one would expect from delta ray production. I added the study of this issue to the "to do" list.
1. Increase the sshtrk lower cut to .6 for now. The low energy tail may be due to pions above threshold in the sos gas cerenkov. By the way, replay_2 does not make a shower counter fiducial cut in the analysis code. This has to be added to the cuts file. Jochen is documenting that now.
2. The lower missing mass cut can be tightened to 0.85. In terms of excitation energy that is roughly -90 MeV.
3. I assume the "halo" around the hms ytgt reconstruction is indeed due to pi-->mu nu decays. (This has not been proven, but we expect a muon fraction of about 10% at the focal plane.) The beam spot MAY have been moving left-right somewhat. The HMS sitting at very small angles would see this as a drift in ytgt. It is therefore important that the HMS ytgt cut be CENTERED. The present width is okay.
4. The SOS Ytgt cut is set at a bad place because the yield is still dropping off steeply, namely, +- 2 cm. Change it to +- 3 cm for now. The SOS is at larger angles so is less sensitive to left-right beam motion, but it is more sensitive to cryotarget cell misalignment.
5. The HMS beta cut is still conservative. More protons could be rejected without endangering good pions. We will eventually switch to (TOF MASS)**2 for hadron PID but Jochen has to document that.
6. The cointime cut is bizarre, evidently a leftover from replay_1 when the peak was sitting near +1 nsec. (It looks like 6 nsec or 3 beam bursts.) The cut should be [-2.0,+2.0] nsec for replay_2. That means that the randoms subtraction has to be done a little differently.
FIGURE 1
