[BLAST_SHIFTS] T20 projection

From: Genya (evgeni@mit.edu)
Date: Fri Jul 23 2004 - 16:35:46 EDT


  Since there was a descripancy between the proposal and projected error
bars (by Chi),
I tried to do the projection separately.
   Please note, that Chi and me have somewhat different theoretical
models and it may
affect the projected errors, but not very much, IMO.
   Using my model, I measure Pzz of abou 80 %. In order to be
conservative, I took Pzz=70%
in my estimations.
    Calibrated by data from unpol runs, the target flux F=3*10**16
at/sec, total thickness in the
area +- 2 cm from the center is about t=8*10**13 at/cm**2, and the
luminosity at 100 mA is
about 5*10**31. We expect to collect 300kC of data.
    My results with these asumptions differ drastically from Chi's:
                         Chi mine
q, f-1 T20 dT20/T20, % dT20/T20, %
2.28 -0.83+-.03 3.6 1.4
2.66 -1.12+-.06 5.4 1.8
3.10 -1.25+-.11 8.8 2.6
3.62 -1.12+-.14 12.5 4.1
4.20 -0.68+-.17 25.0 10.2

  One can see that the difference in error bars projections is around
factor of 3, which corresponds to almost
factor of 10 in statistics !
   Two additional remarks. In all our data taken after shutdown I
observe that we don't have enough elastic events.
In pol and unpol runs, with D2 and H2. The difference is almost factor
of 2. Possible explanations:
   a) another hole in the cell
   b) inefficiency in detection/tracking/cuts.
   c) I've made a mistake somewhere.
    At least point c) must be checked by someone other than me (Chi?)
    And we need to sit with Chi and work out our differencies in error
bars projection.

    Genya
 



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