Summary of E835 Meeting, Tuesday: 4/4/2000

 present: Marchetto, Cester, Stancari (M), Pordes, Graham, Seo,
          Kasper, Obertino, Legger, Garzoglio, Negrini, Joffe

 Stacking was in progress (for the first time in three weeks and reached 
 2.5 mA/hr at one stage.)

   This stack is for (re)commissioning and introducing the phi-phi
 filters as per mail from Keith. We are using the psi' as a monitor of the 
 recommissioning (see the end of these minutes). The next stack is planned 
 to be 30 mA and it was decided to go to the peak of the chi-0.

   Federica gave a summary of the phi-phi and phi-phi-gamma rates and filter 
 cuts. The hardware trigger rate was 111 Hz after a prescale of 8 at 
 1.2*10^31 or 0.75 kHz/10^31 raw rate. The filter requirements (to keep an 
 event) are:
    number of ccal tdc's must be < 13 (or < 15)
    - rejects 6563 (5809) out of 10,000 leaving 3437 (4191)
    after this, several requirements looked at independently:
 a) both phi-phi and phi-phi-gamma:
    no (CCaL) tdc's in rings 1 to 3 or 18 to 20 (inclusive)
    1843/3437 (2449/ 4191) events fail this requirement
 b) phi-phi:
    energy in fcal < 50 MeV 
    2820/3437 (3429/4191) events fail this requirement
 c) phi-phi-gamma: 
    energy in fcal < 50 MeV or 1 GeV < energy in fcal < 2GeV
    2074/3437 (2546/4191) events fail this requirement
 d) phi-phi-gamma:
    energy in 1 CCal channel (0.2 GeV < Ecm < 0.5 GeV) (theta dependent)
    2281/3437 (2600/4191) events fail this requirement.
 e) both:
    enough straw hits (4 to 20) (not included in rejection rate below)

   The net efficiency of the phi-phi cuts on a sample of 134 candidate phi-phi 
 events (data) is 0.9 (+/-0.03). It is not known yet for the phi-phi-gamma.
 The rate that is left as either phi-phi-gamma or phi-phi is 680/ 10000 
 (845/ 10000) ie the overall rejection is 15 (12). At a luminosity of
 2.5*10^31, this would correspond to a rate to tape of 130 (160) Hz which is
 quite acceptable.
   The program has been tested on the offline and (I quote) "the initialization
 routines have been debugged (in the online) thanks to Keith". They will
 be installed this run with the beam. (It's happening now, in fact).

 Seon-Hee gave a talk on looking for forward pi0's in the FCAL2000. The
 z-position for the front-face in the offline needs to be checked and
 corrected if it is more than a few cm different from 3.15 meters.

 These minutes are a day late and so I can add that there is already a nice
 plot - thanks to Margherita and Matteo - in the counting room showing ~200 
 events from 45 nb^-1.

 Stephen