• Main INDEX
  • Monthly INDEX
  • PREV
  • NEXT

    User name jpchen

    Entry time Tue May 11 10:04:51 EDT 1999

    Entry number 38

    keyword=5/5 analysis meeting minutes

    Minutes of 5/5 analysis meeting: Present: Alexandre Deur, Ioannis Kominis, Marat Rvachev, Zhengwei Cai, Xiaodong Jiang, Mark Jones, Jian-ping Chen. Called Temple U, but did not get answer, so the phone conference did not happen. Ioannis: Showed analysis results on electron shower/preshower. The electron shower blocks #63, 83 and 92 have problems. #63 is one central block, it is a crucial one. The problem for #63 is that it has a lot of events with low ADC pulse height. The high pulse peak is also wider than the normal ones. The low pulse part can be got rid off with a reasonable cut. Showed the effeciency for e and rejection effeciency for pion. Some discussion on the proper way of doing these. Also started to look into the hadron shower. Alexandre:Here a quick summary of my weekly work. With cut on hadron shower only I was not able get ride of the low energy junks and I was finding 3 % of good e- with 2 tracks and 99.7 % efficiency (e arm gives 1 % and 99.97 %). So I did a very tight 2d cut with shower vs cerenkov to make sure I get real-very-good-nice e-. The efficiency is now 99.88 % and 2 tracks events are 1.05 %. We are close to the e-arm numbers but it appears even real-very-good-nice e- cut are not cleaning all these junk events. I looked at the T0 numbers on the database. They stay the same for hadron arm but did change at the end for the e arm. For example T0 for wire number 1 is : for e arm 1888.3 run 1615 1888.0 run 2195 1888.5 run 2647 1839.7 run 3352 <-- for h arm: 1590.6 run 1615 1586.6 run 2195 1587.0 run 2647 1590.1 run 3073 1586.6 run 3352 I looked also at the origin of these low energy events. on e arm x_shower vs y_shower plot shows they are mostly concentrated on a same spot, i.e they are coming from a bad block. If it appears that these events are really junks like it look like they are easy to cut (2D cut on shower vs preshower). For h arm I have also plotted x_s2 and y_s2 but nothing strange show up. (Well it's not Bogdan's opinion but he did not convince me. we can talk about that). I am still working on it while Ioannis is looking at shower block per block. If we have to cut these events it will be difficult to do it for h arm by 2D cut (shower and cerenkov) since as I was saying at the beginning these cuts are not cleaning all these events. But if these events are coming from bad blocks like it seems we can perhaps correct the blocks, avoiding a 2D plot and getting better results. It appears if we try to include the 1 % 2 track events, standard cuts are removing 30 % of these events (0.3 % of the total). As the selection algorithm can mixed good electron from 3He with good e- from glass (bad choice of track) we decide to cut these 1 % events and apply a correction as a VDC efficiency (this rely on assumption that 2 track events vertex is uniformly distributed on the target). With cut on hadron shower only I was not able get ride of the low energy junks and I was finding 3 % of good e- with 2 tracks and 99.7 % efficiency (e arm gives 1 % and 99.97 %). So I did a very tight 2d cut with shower vs cerenkov to make sure I get real-very-good-nice e-. The efficiency is now 99.88 % and 2 tracks events are 1.05 %. We are close to the e-arm numbers but it appears even real-very-good-nice e- cut are not cleaning all these junk events. I looked at the T0 numbers on the database. They stay the same for hadron arm but did change at the end for the e arm. For example T0 for wire number 1 is : for e arm 1888.3 run 1615 1888.0 run 2195 1888.5 run 2647 1839.7 run 3352 <-- for h arm: 1590.6 run 1615 1586.6 run 2195 1587.0 run 2647 1590.1 run 3073 1586.6 run 3352 I looked also at the origin of these low energy events. on e arm x_shower vs y_shower plot shows they are mostly concentrated on a same spot, i.e they are coming from a bad block. If it appears that these events are really junks like it look like they are easy to cut (2D cut on shower vs preshower). For h arm I have also plotted x_s2 and y_s2 but nothing strange show up. (Well it's not Bogdan's opinion but he did not convince me. we can talk about that). I am still working on it while Ioannis is looking at shower block per block. If we have to cut these events it will be difficult to do it for h arm by 2D cut (shower and cerenkov) since as I was saying at the beginning these cuts are not cleaning all these events. But if these events are coming from bad blocks like it seems we can perhaps correct the blocks, avoiding a 2D plot and getting better results. It appears if we try to include the 1 % 2 track events, standard cuts are removing 30 % of these events (0.3 % of the total). As the selection algorithm can mixed good electron from 3He with good e- from glass (bad choice of track) we decide to cut these 1 % events and apply a correction as a VDC efficiency (this rely on assumption that 2 track events vertex is uniformly distributed on the target). Zhengwei: Y_targ optimization without introduing mid-plane symmetry breaking term. But for Phi/Delta optimization, without introduce midplane symmetry breaking terms, the offset term was too large. So used P011 etc. Results are nearly ready. Marat: 2nd round optimization. Xiaodong: Was at E95001 collaboration meeting. They were making good progress (see minutes on E95001 homepage). Next week, we will wrap it up on the first pass analysis of the detectors (scintillators/trigger, shower, VDC, Cherenkov), beam positions and optics study. Then will discuss the plan for next step. Also discussed about the up-coming collaboration meeting at Kentucky. All students will make presentations at the meeting.