Hi Richard,
If not already done I would like to propose that we implement an inclusive
trigger that uses the Cerenkov detectors. We should do this in the present
running with hydrogen. This should be a simple matter and the only issue is
event rate which can be dealt through pre-scaling.
I have two students who can start right away evaluating the quality of the
data and performing preliminary analysis.
With this trigger we can get another measurement of the elatic scattering
asymmetry and get very good statistics in the Delta region. Radiative
corrections are going to be very important so the sooner we start the
better.
Thanks,
Ricardo
-----Original Message-----
From: richard milner [mailto:milner@mitlns.mit.edu]
Sent: Sun 8/31/2003 5:50 PM
To: Electronic Log Book
Cc: Blast_shifts@rocko.mit.edu
Subject: Re: [BLAST_SHIFTS] Shift summary 08/31/2003 E (16-20)
This is interesting. We should continue to take data with decreasing
atomic fraction (AF) for a couple of days. We should look for a
correlation of the measured asymmetry with the measured AF. Each day we
should also measure the AF and its dependence on the MFT being ON or OFF.
Does this track with lower sextupole pressure? How muc ep data do we have
to take to see a 10-15% chnage in the target polarization?
Richard
On Sun, 31 Aug 2003, Electronic Log Book wrote:
> Operators: ajmasch vziskin tavi
>
> Running beam untill 18:30. Stopped to measure the atomic fraction.
> The atomic fraction in the cell with MFT 2-3 off was measure 43 to 45
(current dependance)%. I found a MFT 2-3 resonace @ -5 Amp with the BLAST
field off. With this MFT2-3 on the mass1 signal drops by about a half
(current correction needed) however mass2 dropped by significantly less(less
than 1/3). The atomic fraction with MFT2-3 is 39.3 % which is more
consistant with the data (on that later). This indicates that there is a
significant number of H2 that does not come from the recombination
(otherwise H2 would also drop by a half).
>
> The data definately shows an assssymetry, with dilution factor of about
0.18 (60 and 30% beam and target respectively), with the asymmetry from
latter data showing slightly lower dilution. However, the bigger issue is
the left/right inconsistancy. Electron on the left asymmetry look very
dissent. Electron on the right looks a lot worse. I looked into the issue
further and found that my making even tighter cuts on the vertex this
discrepancy seems to reduce. Upon further investigation I found the
negative overall electron-right asymmetry gets diluted by mostly "positive
asymmetry" comming from downstream (????). More statistics need for
investigation. By comparison, electron-left asymmetry vs. vertex looks
exactly like you would expect it.
>
>
>
>
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