Summary of E-835 Meeting on Thursday, 5/4/2000

 Present: Cester, Borreani, Bettoni, Pallavicini, Menichetti,
          Stancari(G), Stancari(M), Negrini, Seo, Graham, Baldini, Lasio,
          Garzoglio, Hu, Gollwitzer, Kasper, Mandelkern, Schultz, Pordes

 ANNOUNCEMENT:
 The group meeting will start at 9:30 in the conference room on the
 12th floor (West) (The comitium is not available due to some air-conditioning
 work)

 PRESENT STACK:
 The present stack will continue till about noon Friday after which there 
 will be about 12 hrs of studies; stacking to 55 mA will start around
 Friday 24:00. The exact Ecm energy will be discussed on Saturday but will
 probably be around 3528.

 Ecm Energy:
 Giulio showed a plot of the Ecm energy which for some time was oscillating 
 with a 2 hr period and an amplitude of up to 200 keV. (100 keV is probably
 not a problem). The oscillation is driven by the new "baby-sitter" program 
 which tries to keep the beam energy constant by moving the pick-up plates to 
 control any energy error. It presumably needs the proper pid parameters to 
 be calculated and installed. A picture showing how the beam energy follows 
 the pick-up plate position is in our Y2K forum (copied from the pbar E-log).
 (Giulio will put in the more complete plot he showed at the meeting)
 For now, things are being done by hand - as before.

 Beam Energy Spread:
 The beam energy spread is quite big - 550 keV in the center of mass. 
 This is rather large for a potentially narrow resonance like the 1P1 
 and we will ask the source people to reduce it (the beam energy spread - not
 the 1P1) to more like 400 keV Ecm. (1.5 MeV in lab). It was said that there 
 is some concern about doing this with a large (55 mA) stack...

 Luminosity:
 We have taken about 2.3 pb-1 so far and if things go reasonably we should
 collect a total of about 3.5 pb-1 for the stack which will be quite nice.
 
 Beam Loss Incident:
 Martin recounted a period when the beam loss rate increased by about 1 mA/hr
 for some time for no obvious reason. He says that he turned various things
 off and the problem went away; he is trying to identify what actually
 did the trick.

 General beam:
 Gabriele has done the offline calculations for the stack and they seem
 very similar to the online.
 
 DETECTOR
 Fibers: The cryo system seems to be in reasonable shape after some tuning by 
 Wander. A (one-time?) increase in temperature of the cassettes to 8 degK 
 resulted in a large volume of fiber data but things seem stable now.

 CCaL: Michelle reported on her access last time to investigate a block whose 
 gain seems to vary a lot and which has some double pulsing. This channel shows
 a resistance across the input cable at the summers of some kilo-ohms (scribe
 has forgotten how many) instead of 50 ohms. Stephen suggests throwing out
 any events with any signal in that channel since it will hardly hurt the 
 acceptance and we don't want to let background in.

 Rates: Mussa noticed an 8% drop in all neutral rates compared to other rates
 since the beginning of the stack. The cause of this is unknown.

 DAQ: Keith has fixed one of the DAQ problems - the DYC's out of synch.
 This turns out to have been a bug in the software which handles the
 case (a problem in the hardware) when the event synchronization number 
 increments by 2 instead of 1. This leaves the perpetual DATA-IN hang as the 
 current problem. 


 DETAILED RUN PLAN
 Giovanni Borreani's model of a scan (see his previous e-mails) is the only 
 one presently available. There will be informal discussions tomorrow and 
 presumably we will decide on an exact plan on Saturday.