Minutes of the NFS-meeting held on 19/4/94:
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In this meeting we had two reports. Only the conclusion of the reports
is given here, since they will be summarized in the NFS-notes to
appear by end of April.
 
* On the significance of phi_00 in data with 4 detected gamma's (O.Behnke):
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  The new loop method brings a gain in significance of approx 12% on
  phi_00 as compared to the old loop method. The limit in improving
  this significance seems to be reached. We expect an error of
  4.5 degrees at the end of 1995. Under ideal conditions, that means
  with ideal resolution and no background, one would reach a statistical
  precision of 2.5 degrees.
 
* On background studies in data with one converted gamma (M.Wolter):
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  The error on phi_00 is dominated by background and not by the
  lifetime resolution (at present level of analysis one expects 6 degrees
  by end of 1995).
  MC studies have shown, that the main background contribution comes
  from 3pi0 and that the decay vertex resolution is lifetime dependent
  (getting worse for higher lifetimes).
 
Following the presentations and some discussion, we agreed on the
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following points:
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* NFS-notes will be written on both analysis, the K0-->pi0pi0-->4gamma
  as well as the K0-->pi0pi0-->1converted photon until end of April/begin
  of May, containing the following conclusions:
 
  - actual statistical precision (incl. data of P24) on phi_00
  - estimation of final precision by end of 1995
  - comparison of final expected precision with the precision reachable
    under ideal conditions (ideal lifetime resolution and no backgrd.)
 
* The changes in the analysis since the collaboration meeting are
  summarized for both subjects in a Tuesday meeting
  (for 4 detected gamma's on 19/4/94, for 1 converted photon on 3/5/94)
 
* The final figures for the summer conferences will arise from these
  reports and will be supplied to the collaboration in a nice form
  (colored transparencies) by end of May
 
* We miss two further documentation (NFS-notes) on the following
  finalized activities:
 
  - definition of a "photon" (around charged K) by M.Wolter
  - new calibration of the shower angle reconstruction by O.Behnke
 
* As mentioned above, from the analysis with 4 detected photons
  it becomes clear, that the new loop method has brought a significant
  improvement in the significance of phi_00 (approx. 12%).
  Also it became clear, that no further significant improvement can be
  reached and that the only way to improve further the statistics
  is to reduce the prescaling of 2 track events in the data taking
  (status quo: 11% of two track events at trigger level)
  by reducing the HWP2.5 cut from 6 to 5 clusters.
  To measure the effect on the 4 track events and the gain in 2 track
  events as well as in signal, we should foresee tests with 50X-trigger
  in P26.
 
 
Next meeting:
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* We agreed to have the next NFS-meeting on Tuesday 3/5/94 at 10.30 h  *
* in the CPLEAR meeting room.                                 =======  *
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