Attending CZ, NM, RF, BF, BT, DH, MK.
VZ:
-plots of quasielastic d(e,e'n) tensor asymmetry show nonzero values at
low pmiss (see webpage). E-left data (spin-perpendicular) shows negative
asymmetry of about 6%, E-right data (spin-parallel) shows positive
asymmetry of same magnitude. Theory (convoluted with BLASTMC) wants
A_d^T to be zero.
VZ checked all false asymmetries but they are zero. If 2*Pzz(T+) is
unequal Pzz(T-), false asymmetries would arise, and a sign change with
as a function of the spin angle would not be explained.
Data is for 2004 only. Need to see how 2005 data looks like.
FSI can be large for e,e'n at low Q2. Question is if H.A.'s FSI
calculation is correct for this case. Question is also how this evolves
over time.
EG:
-we went through EG's pdf-file he sent out recently (see webpage) to
compare old and new crunch for ep elastic from December. Difference of
the library is mainly the magnetic field map for BLAST. New recrunch
seems to have shifted angles slightly, momenta are mostly not affected.
All in all reconstruction looks a bit worse with the new field map.
It was emphasized the importance of the wire positions. We discussed
about the role of the geometry. The wire chamber in a sector
consists of three chambers, each consisting of an pair of superlayers.
A whole chamber can be shifted versus the other two, and CC had shown in
the collaboration meeting of 08/30 that 1 mm shift of the middle chamber
could account to first order for both the corrections for the electron
and the proton in the right sector simultaneously.
This needs to be supported by straight tracks. Straight tracks are
available in plenty as cosmics events even in regular production runs.
However, not the entire wch volume would be covered by these events
because of constraints by the second level trigger. There are
nevertheless also dedicated cosmics runs without the second level trigger
but with the wire chamber turned on. It is needed to identify these runs
and to produce event lists in order to do the straight track analysis to
determine individual wire calibrations.
Finally, with a new wire calib the entire data will have to be recrunched
(lrd would be sufficient if we are happy with the number of tracks found
with the current calibration).
Renee:
-is looking at raw ADC spectra for 2004 versus 2005 for good quasielastic
events. Goal is to understand wether the TOFs 4-6 in the left sector have
been indeed inefficient.
Nik/Chi:
-new Montecarlo generator for d(e,e') is working now, accounting for both
ed elastic and for quasielastic processes accoerding to H.A.'s inclusive
structure functions. New MC has advantage of enhanced statistics. Next
task is to extract GMn again with the new MC.
There will be no meeting on 11/16. Next analysis meeting will be on
Wednesday 11/23 at 13:30. Doug will run the meeting. I will try to call in
to report on how the BLAST@ELSA presentation will have been received.
Find these minutes along with the plots at
http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/ANALYSIS_MEETINGS/meeting_051109/
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 | |
+-------------------------------------+--------------------------+
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:32 EST