Attending VZ,TA,DH,AM,BF,MK.
-LDCCT calibration:
+new calibration implemented in BlastLib v3.4.7
+effective since run 15214
+2005 runs before 15214 need to be recrunched
+beam-related raw scalers are written to DST, so lrd-recrunch should be
sufficient
+reduced normalized coincidence rate had been observed at high currents
before LDCCT was recalibrated, needs to be checked now after.
-Wire chamber veto for neutral tracks:
Eugene showed at the collaboration meeting that the candidate (e,e'n)
yield (trig2 or at least noTOF with good electron) are reduced by 50%
when turning on the wch veto (no-track requirement) (from the height of
the quasielastic peak in the W spectrum). It is the question if those are
mostly misidentified protons that go through the gaps and inefficiencies
of the TOFs (=e,e'p). In this case the situation should be the same with
hydrogen target ... However, if these events are real (e,e'n) with
randomly another charged particle or hit pattern in the chamber, the veto
would be overefficient and throw good data away. In this case,
constraining the veto geometrically to the region in front of the neutron
counter (the wire chamber veto track should be swum to the neutron wall)
could help to salvage many of these events. Could be as much as a
factor 2 in neutron yield! And with the higher luminosity in 2005 with
enhanced rates the cut could be even deeper ...
On the other hand, VZ argues that the observed (e,e'n) yields are in good
agreement with (e,e'p) assuming a neutron efficiency of 30%.
-Radiative BLASTMC: Could not be discussed due to lack of attendance
-Attendance: The analysis meeting was only poorly attended. It is
understandable that people are overloaded these days and perhaps somewhat
tired. We had very good analysis sessions during the collaboration
meeting on 4/6 and 4/8. However, also our weekly meeting is important,
and we should *not* reduce our meetings to bare deliveries. The weekly
meeting provides the possibility of real discussion, about issues, ideas,
even physics. I can only repeat my recommendation to you to attend the
weekly meeting as often as you can. Hopefully, with the end of the
classes approaching, we could have more lively weekly meetings in the
near future and over the course of the summer.
Regards,
Michael
--
+-------------------------------------+--------------------------+
| Office: | Home: |
|-------------------------------------|--------------------------|
| Dr. Michael Kohl | Michael Kohl |
| Laboratory for Nuclear Science | 5 Ibbetson Street |
| MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
| Middleton, MA 01949 | U.S.A. |
| U.S.A. | |
| - - - - - - - - - - - - | - - - - - - - - -|
| Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
| Work: +1-617-253-9207 | Home: +1-617-629-3147 |
| Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
| http://blast.lns.mit.edu | |
+-------------------------------------+--------------------------+
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