Summary of Tuesday meeting 5/2/00 Present: Gollwitzer, Seo, Rumerio, Garzoglio, Menichetti, Mussa, Baldini, Lasio, Negrini, Obertino, Stancari(G), Stancari(M), Graham, Cester, Kasper, Pordes Last Store: We ended the store at 11 am this morning having taken 0.97 pb-1 at the psi' peak and 2.56 pb-1 at the chi-0 wing point. The stacking rate over the weekend was quite impressive. (A note on the new beamline: the new B-3 magnet replaced two Lambertsons). Marco mentioned at the All Experimenters' Meeting that we really appreciate the effort the pbar source staff made to achieve this. Margherita reported that out of the psi' data, we have 2790 e+e- events for Cerenkov calibration; the CCAL gain looks about 2.5% low. Michelle says that the newest constants are yet to be entered. Out of the chi-0 wing data we have a decent point on the wing. Margherita showed a width of 9.8 MeV +/- 1.8 MeV Keith showed a plot of the j/psi pi-0 rate - the background to the 1P1 search. The level is about 2 events/pb-1 - about what we had in E760 which Stephen finds reassuring. Experiment Status: There was a serious problem with the VLPC cryogenic system which developed over the weekend. The engine started to be unable to keep up with the heat load and by Monday evening the Dewar was losing liquid at a rate of 6 liters /hour. Since we want the experiment in its best shape for the 1P1, we shut off gas to the cryostat to see if a new heat load had appeared or whether the problem was in the engine itself. Tests on the engine on Monday night showed it was making <10 liters of liquid an hour while it is usually capable of making >20 liters/hour. It is probable that the engine was contaminated last wednesday or thursday in the same incident that led to the work on the cryo system in AP-30. The Beams Division Cryo group responded to a request made at 9:45 pm Monday night and this morning an engineer, Arkady Klebaner, and technician appeared at AP-50; the engine was "derimed" and started to produce liquid at a decent rate again this afternoon. With luck, the cassettes will be cold by Wednesday morning. DAQ issues: Paolo has tried to investigate the DYC synchronization issue (not all DYC's report the same event synchronization numbers) with Sten Hanser but could not reproduce the problem without beam. He has replaced the DYC's which seem to offend the most. The hang with the Data IN light set which happens in DYC crates 3 and 5 is still a mystery. This hang is the one that doesn't produce a MURMUR message on the screen (MURMUR - interesting name for an ALARM system (ed)). Trigger: Wander has implemented a requirement in the pbar-p trigger that requires two bundles that both bundles not be in the forward region (ie one bundle at least in the backward region). This reduced the trigger rate by 30% allowing the prescale to go from 50 to 35. Keith asked if a similar requirement could be put on the backward bundles - to eliminate events where both bundles are in the backward region. Wander replied that he did not see a simple way to implement this. (Wander will update the trigger page on the web with a description of the new configuration) HV: It took 15 minutes or so to realize that an HV Mainframe had failed early on Monday morning. Stephen asked if one could implement a hardware alarm to notify shifters promptly. Giovanni L. will look into this. Giovanni added that he is preparing a history page showing which runs have HV problems. CCAL Monitoring Giovanni showed some plots of the run-to-run stability of the CCAL response to the laser - which seems good to 1 or 2% and compared it to the calibrations from pi-0 pi-0 which occasionally suffer from poor statistics. In the latter cases, the laser monitoring is probably the right thing to use. Michelle pointed out that the use of the calorimeter itself to normalize the laser loses any overall gain drift and suggested that the pin-diode may be a better reference. OFFLINE Computing System Gabriele reported that the old (revived) machine we were given by Computing to serve the 200 Gigabyte of new disk now has its system installed and will next be connected to the disk. The new server does not have the fastest ethernet card - it has a 10 MBS card - and we may want to request a change to 100 MBS. (see later Assignment of space item) OFFLINE program Matteo is investigating the theta track fitter. Marco will help - at least in identifying the authors of the existing routines. Some problems might be expected since this is the first time we have more than 2 points on a theta track. Ezio is looking at the tracking in phi. Bombo has written code to recover the events where the data from crate 15 are scrambled by containing the last word of the previous event as the first word and the events where the TDC header is missing the header identifying bit. These patches will be put into the offline rather than rewriting the raw data tapes. Fiber Tracker Studies. Bombo reported studies he is doing using the pbar-p events on the alignment of the fiber trackers. The resolution is what would be expected from 1.1 mm quanta. He will show some plots of the resolution and the vertex distribution (please). Assignment of space in new disks. Keith will send out a request for suggestions on how to organize the space on the new disks. With responses, these could be considered at the Saturday group meeting. pbar-p filter: There was a lively discussion of the virtues of generating a sample of pbar-p events by implementing a pbar-p filter online compared to doing the same offline. Bombo will try to implement a filter. NEXT STACK will be decelerated around 6 am. (as of midnight there are 29 mA and the stacking rate is close to 4mA per hour - thanks to the operators who are watching and correcting for changes in the AP1 line). 1P1 - here we come..