Summary of E835 meeting 4/18/2000

 Present: Kasper, Gollwitzer, Stancari(M), Stancari(G), Pordes,
          Obertino, Baldini, Negrini, Graham, Seo, Garzoglio, Lasio.

 The meeting was held in the shadow of the 10 mA beam loss (1 pb-1) suffered
 at 11:11 am today. Apparently no cause had been found in the pbar source.
 Gabriele and Stephen looked at the gas-jet data logger after the meeting
 and everything seemed very normal there, too. They could see the unclogging
 procedure which was started just after the beam was lost. The people 
 on shift had noticed the counting rates had gone way down and before they 
 noticed the beam loss, they wondered if the reduction was due to the jet.
 So it's a mystery. The only thing Gabriele and Stephen saw was a big rise
 in the temperature of the inlet hydrogen starting around 12:30 pm. (1hr
 20 minutes after the beam loss). This means a problem with the liquid
 nitrogen.

 Stacking had restarted by the time of the meeting and it is planned to go
 to 3411 (not 3409) with a 55 mA (or so) stack.

 There was some discussion about stack sizes and efficiency. Stephen is
 concerned that we recognize the problems of excessive beam loss. We have
 lost several (5-10) mA at the beginning of data taking with larger current
 beams until the beam was brought under control. It is probably less 
 confusing if we simply turn off (or do not start) until the beam is under 
 control. A reasonable measure is a (jet-off) beam lifetime of >or=200 hrs as 
 calculated from the ratio of the beam current and the beam current loss rate 
 (stack rate on ch13). Another measure is the integrated luminosity per mA 
 used up which should be about 100 nb-1. (it will be 10%-30% less at 
 currents above 30 mA)

 We do not know if the day of the 5 day MI shutdown has been changed.

 Michelle gave a summary of the gamma-gamma data. She has about 3 pb-1 on the
 peak and about 4 pb-1 on the background. She asked if May 1 was a hard 
 cut-off date.
 Matteo showed the psi-gamma cross-sections derived from the runs at 3385 MeV
 (1.65 pb-1, 7 events, 4.1pb observed cross section) and 3426 MeV (1,80pb-1,
 16 events, 8.9 pb observed cross section)

 Keith said that the disk which had failed would be replaced wednesday
 morning and that he has instituted a procedure to make an automatic back-up 
 to disk of the run-by-run data files which are written to the disk being 
 replaced. Some procedure for moving the minidst's at the end of stack is
 also being implemented. (Have I written this before?)
 
 Wander announced that two pbar-p triggers have been implemented. One is
 the 90 degree insisting that the appropriate fiber bundle only and the
 2 h logic be set and the other requiring exactly 2 bundles and the 2h logic.
 The former has a rate of 100 Hz and the latter a rate of 5kHz which is
 being prescaled by 50. Wander will confirm this in an e-mail.

 Jason said that he has checked the ETOT hi efficiency using the ETOT lo and
 it is essentially 100% (99.6% or better)

 Seon-Hee asked when the surveyors could get in to check the z of the FCal.
 At the end of the shutdown?

 Stephen