Minutes of the 3pi meeting 19.1.94
 
Present: T.Ruf, E.Hubert, A.Ealet, E.Aslanides, P.Fasnacht, M. Tschertok,
         P. Weber, O.Wigger, M.Dejardin, A.Filipcic, R.LeGac, M.Fidecaro,
         A.Schopper, R.Rickenbach
 
- Anne reported on the data production and analysis done in Marseille. She
  looked at the full statistics of P17 to P23 and about 30% of the P24 statics.
  After filtering with m3pip this means 112'000 events corresponding to 10.6%
  of P24 super3pi data and 5.6% of data from previous runs. The two numbers
  can not be compared directly as for P24 we used for the first time stronger
  conditions in the SUPER3PI filter (ie 1c fit).
  Application of the pi0gold cut removes about 20% of of P24 data (at short
  lifetimes) and about 25% of the data from periods 17 to 23. A decay time
  independant cut on the space angle removes 5% of the data. As the same amount
  of events is cut using MC, and a lifetime dependant cut (Patrick) on the
  space angle removes almost nothing, it was decided not to use this cut in
  the future.
  The nn cut removes about 10% of the data flat in lifetime. Here we do not
  have reliable MC info for comparison. It would be nice if M.Dejardin could
  provide us with a clean sample of semileptonic data in minraw format.
  Marc has upgraded the 3C fit. It know removes about 10% of ouer data but
  only 3 % of MC data. This reopens the possibility to use it in the filtering.
  The results on the CP violating parameters are reproduced within the
  expectations. There is some confusion concerning the CP allowed decays.
  The problem is under investigation.
 
- Patrick investicated the influence of the HWP ,NN , pi0gold and space
  angle cut on the ratio of the momentum spectra of the secundary pions,
  and on the CP allowed asymmetry. He finds a slope with opposite sign
  for K0 and K0bar in the momentum spectra ratio. This slope is removed
  by the cut on pi0gold. The cut also causes a shift in the parameters of the
  CP allowed decay.
 
- Background studies using MC (Andrej Francois Rene) are not finished.
  Preliminary studies show that K+K-pi+pi-npi0 seems to be unimportant.
  According to Andrej pi0gold agreas with our data but Francois finds a
  by a factor 4 lower acceptance.
 
- Edwige reported on first results on fake gammas and pipigamma background.
  she finds and neutral shower enhancement near the charged Kaon. (compare
  last NFS minutes). To study cuts she needs to look at MC with full calo
  simulation (HADR flag).
  The pipigamma background where the gamma comes from Bremsstrahlung is
  negligible. The contribution with direct gamma production (harder spectrum)
  still needs to be investigated.
 
- The next 3pi meeting will be Jan 31. at 14.00 during the collaboration
  meeting. I hope to have presentations by Jose and Emmet on their analysis
  (From Jose there is still no response) , by Andrej on the background
  studies, and by Marko on pipigamma. We should also discuss the latest
  developement concerning the analysis with m3pip.
 
                                                    cheers
 
                                                         Rene