Minutes of the E00102 meeting Wednesday, August 22, 2001 BR present: FG Franco Garibaldi WH Wendy Hinton XJ Xiaodong Jiang JLR John Lerose DM Dave Meekins BR Bodo Reitz AS Arun Saha SS Simon Sirca 1.) XJ reported on his ideas about improvements on the timing resolution of the trigger scintillators in the two HRS - draft of the Hall A NIM paper claims a timing resolution of 1.39 ns (FWHM) (for comparison: Hall C reaches a resolution of 500 ps) - a test measurement performed this year gives 2.00 ns (FWHM) (this values was achieved after software corrections for different flight passes in the HRS, walk corrections ...) - XJ said, the reason for the resolution is hardware related, improvements are possible using better PMTs, probably an improvement by a factor of two is possible. He showed results from a test measurement performed by John Calarco. - BW ordered 16 of those PMT for various purposes some time ago, in principle they should be available, but XJ doesn´t know where all of them are at the moment - buying more of those PMTs is not possible in the period left until E00102 is scheduled - there might be another type of PMTs available, which are not as good as the 16 ones, but better than the ones used - XJ already discussed the whole topic with Bogdan Wojtsekhowski. Who mentionned that it might be already to late, to install another set of PMTs, since there is not enough man power available XJ himself offers to spent two weeks in installing if we are interested. But more manpower is needed. At that moment it is not clear, if even machining is necessary. The question arose, if the machine shop of ODU could help in that case. - XJ additionally suggested, to use the S1 plane as the time defining one, instead of S2 (like it is done at the moment) - JLR mentioned, that another possible change to improve timing performance would be to change the discriminator setup, e.g. using two threshold discriminators per channel (with different thresholds). He admited, that the necessary equipment is also not available. - JLR asked, if there would be any software/analysis problems related to change in hardware. XJ points out, that only new calibrations would be necessary - AS points out, that improvements on the timing resolution are not crucial for the experiment. Advantage would be, that at high rates one would decrease the background from random coincidences. - AS asks, if the two MIT are available. SS says that they are both here at the moment, but one might go back to MIT at some time. - XJ again offers to spent some time in this project, and asks if e00102 is interested. - the decision is postphoned, until Larry Weinstein is back. 2.) Waterfall target - the safety review is scheduled for Friday, August 24, 10:00 am - DM reported, that still some preparations have to be done. He was asked to do a pressure test of the whole vessel. The windows have to be finished - DM assures that we have a safety factor of three everywhere. 3.) Runplan issues - what beam energy is needed for the commissioning of the experiment - WH will think about it, and also discuss it with Larry - it was asked to post the runplan for the commissioning on the web. - FG said, that the pump speed scan is important for the waterfall commissioning - DM reported that the allignment of the target will be a big effort, nevertheless the geometry of the target is now very well known - concerning the production runplan, AS presented the results from him, LW and KF for Signal to Noise ratios in the various kinematics and the different suggestions for the time split between (+) and (-) kinematics. (please see the email exchange between those three in the e00102 mailing list for detais. here I just repeat the three results for the left side time fraction) p1/2 | p3/2 | suggestion kinematic| AS LW KF | AS LW KF | AS LW KF ----------------------------------------------------------------- I | .59 .45 .58 | .73 .55 | 94/66 72/88 90/60 H | .71 .65 .50 | .51 .60 | 85/35 70/50 66/54 G | .51 .56 .61 | .45 .60 | 45/35 19/21 48/32 - JLR asked, how much we would suffer, if we do not split ideally. AS pointed out, that it is very difficult to estimate DM suggested to give the RunCoordinators much flexibility, to change between (-) and (+) kinematics, whenever there is an interruption of beam delivery, and to adjust the distribution during the experiment 4.) Shift schedule - Dimitri Margaziotis has prepared the web page for the shift-signup http://curriculum.calstatela.edu/faculty/djm/E00102.html - before opening this webpage to the whole Hall A collaboration, BR will ask the Hall A staff and the people heavily involed in the oxygen experiment, to fill the first five days with at least one person. - AS will then prepare an email to the Hall A collaboration 5.) Date for weekly meetings - discussion postponed, because date should be organized together with Larry, so that he can attend the meetings.