From LEITCH@P2VAX Tue OCT 12 12:44 MDT 1992
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From: LEITCH@P2VAX  (Mike Leitch P-2 MS D456 7-5481) <LEITCH@P2VAX>
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Date: Tue, 12 OCT 92 12:44 MDT
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From:	P2VAX::LEITCH       "Mike Leitch P-2 MS D456 7-5481" 12-OCT-1992 12:44:46.30
To:	@[-]E789ANAL.DIS
CC:	LEITCH
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E789 collaborators:                                10/12/92 12:45

I am scheduled to give a 10 minute talk on the D E789 results at the
Division of Nuclear Physics meeting in Santa Fe later this week. Below
is a summary of the results I have obtained so far. I plan to present
these with lots of VERY PRELIMINARY all over them. They are similar
to what I showed everyone at the South Caroline meeting but are from
a new analysis with wiring corrections and improved alignment.
I am confident in the general A dependence, PiPi/KPi BR ratio,
and the rough absolute cross section. The asymmetry and KK results
depend a lot on the type of fit you use to extract the peak areas.
My latest fits using Q/HPL give no asymmetry within statistics.
Since this week is filled with meetings I may not make much further
progress before the talk but I may manage to improve some things
from here.
                                             Mike

		STATUS OF D ANALYSIS - MJL - 10/12/92

1) All 900A is analyzed; with vertex cuts having about 9% efficiency:
		~600 Be counts and ~430 Au counts (KPi).
2) KPi peaks are clear with about 5 MeV sigma and signal/bkgd of
     ~2/1 for Be and ~1/1 for Au.
   PiPi peaks have ~<40 counts in both Be and Au with signal/bkgd
     of ~1/2 or worse.
   KK only stands out by making harder vertex cuts, i.e. with about
     a factor of 3 lower efficiency.
3) Absolute xsection ( 0<xf<.08 ):
   sigma-KPi ~= 17 microb/nucleon (with eff-trg=.8, and 10e6 protons/sem)
   compare to, e743: 22+9/-7+/-5 or e653: 38+/-3+/-13
   * see trigger efficiency below
4) BR-PiPi/BR-KPi = 3.6+/-.6%; compare to WA82: .048+/-.013+/-.008.
     Also nKK ~= nPiPi as expected.
5) A-dependence (statistical error only)
       Branch     R(Au/Be)     Alpha
       -------    --------    ---------
       K- Pi+    .61+/-.11    .84+/-.06
       K+ Pi-    .60+/-.09    .84+/-.05
       K Pi      .60+/-.04    .84+/-.02
       Pi Pi     .89+/-.70    .96+/-.26
       K K        -------      -------
    * see monte carlo acceptance problem below
6) Asymmetry:
                               Be           Au
                          ----------    ----------
       R(K-Pi+/K+Pi-)     .90+/-.07     .91+/-.09
       (e.g. D0/D0-bar)
    * see monte carlo acceptance problems below
7) Monte Carlo acceptance
   BMX0 problem:
              data    data    monte carlo
     target fraction  BMX0    accept.*eff
     ------  ------   ----   ----------------
       Be     2/3     .24"    2.74+/-.13 e-4
       "      1/3     .32"    2.51+/-.12 e-4
       Au     7/24   -.29"    2.81+/-.13 e-4
       "     17/24   -.09"    3.29+/-.15 e-4
      (the effect is from BMX0; Be and Au have the same
       acceptance for the same BMX0)
   * need to check absolute Xtgt calibration (e.g. wrt sm12 aperture);
     maybe use flag tgt data.
   Also the slight asymmetry in y of the target w.r.t. the dump causes
   no appreciable asymmetry in the acceptance of K-Pi+ vrs K+Pi-.
8) Pi and K decay ( used 2000" and 25 GeV)
             Branch  Survival
             ------  --------
              KK      ~.53
              KPi     ~.69
              PiPi    ~.93
   * need to put into monte carlo
9) Trigger efficiency, e.g. hodo and calorimeter.
   Need enough prescale-3/4 triggers to check hodo efficiency.
   Calorimeter threshold efficiency?
10) 1000A D's: starting analysis now,
    expect:  ~< 300 Be and ~<2k Au.