Re: [BLAST_ANAWARE] k-factor, theta correction and resolution

From: Eugene J. Geis (Eugene.Geis@asu.edu)
Date: Mon Aug 30 2004 - 14:46:33 EDT


In some of the calibrations that Chris and I are doing, the k-factors have
proven to be slightly <1 on one side of the cell and >1 on the other side
of the cell (due to B-field)... Is this proving to be the case with you too?

Also, you mentioned severe difficulties with the front of the chambers last we
talked. Is this still the case? Since you mentioned a number for dP_e I'm
assuming you've had more success in the front of the chambers than previously
described.

eugene

Quoting Chi Zhang <zhangchi@MIT.EDU>:

>
> Not yet.
>
> On Fri, 27 Aug 2004, Wang Xu wrote:
>
> > Hi Chi,
> > Did we recrunch all data with these new k-factor & theta
> > correction?
> > Wang
> >
> > On Thu, 26 Aug 2004, Chi Zhang wrote:
> >
> > >
> > > Hi,
> > >
> > > I found the following interesting thing about wire chamber
> calibration
> > > and resolution.
> > >
> > > With k-factors revived, AND theta correction activated. We in fact
> are
> > > looking at improved resolutions. The comparison with current setup
> for
> > > online crunching is:
> > >
> > > current improved
> > > k-factor only for tracks with beta<0.9 for all
> > > theta correction not used used
> > >
> > > I believe the "improved" calibration has also the advantage of
> being
> > > easier to retionalize than the current approach which treats slow
> and fast
> > > tracks differently.
> > >
> > > Some more details including the fact that k-factors calibrated in
> Feburary
> > > do not really fit data since May. I have made a new set of
> k-factor
> > > calibration based on a score of July runs and they seem to improve
> > > resolution for June/July/Aug H2 runs.
> > >
> > > I list results here for some H2 runs I can find:
> > > dP_e dtheta dphi dz dP_p dE_beam
> > > 6451-6452 (Apr 10): 21 0.50 0.63 1.0cm 22 28
> > > 21 0.53 22 27
> > >
> > > 6992( Apr 23): 24 0.51 0.59 1.0cm 20 28
> > > 19 0.48 23 29
> > >
> > > 8372-8375 (Jun 20): 27 0.54 0.64 1.2cm 24 33
> > > 24 0.56 23 29
> > >
> > > 8868-8870 (Jul 23): 30 0.63 0.65 1.5cm 29 41
> > > 28 0.61 28 38
> > >
> > > 9854-9864 (Aug 08): 28 0.58 0.65 1.3cm 28 34
> > > 27 0.57 21 35
> > >
> > > For these runs, the April ones are crunched with k-factors
> calibrated in
> > > Feb (Wire.Cal v1.6). The rest are crunched with k-factors newly
> calibrated
> > > off July runs.
> > >
> > > angular resolutions are improved from the >~1 degree level we
> currently
> > > have. electron momentum resolution is also improved and is
> comparable to
> > > the best we have ever seen in past. vertex resolution is also
> improved to
> > > 1cm level from the 1.5-2cm we had. Proton resolution is still a bit
> worse
> > > than the 15MeV we had according to Chris. I believe these figures
> overall
> > > are an improvement.
> > >
> > > I believe with more work devoted into calibrations(Eugine, Chris,
> > > Taylan and me) it is very likely the resolutions would improve on
> top of
> > > this level.
> > >
> > > I also want to point out that we did not have ANY H2 runs for the
> entire
> > > May. So it is a little hard to determine how the calibration worked
> for
> > > that period of time.
> > >
> > > I would like to repeat the observation made in one of the "big"
> analysis
> > > meeting last summer, when I presented the change in time of WC
> resolution,
> > > periodically running H2 is necessary. Unfortunately, we were very
> deep in
> > > the deuterium data rush.
> > >
> > > In the end, recrunch from DST using this new set of "calibration"
> will
> > > give us the improved resolution.
> > >
> > > Chi
> > >
> >
> >
>

--------------------------------------------------------------------------
Eugene Geis
PhD Student, Physics Department, ASU
Research Affiliate, MIT-Bates Laboratory of Nuclear Science
eugene.geis@asu.edu
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