Hi,
below are the minutes of today's analysis meeting. Read and enjoy.
Regards
Michael
Attending JC,BT,YX,CZ,TA,VZ,RF,KD,DH,MK,CC(phone),AD(phone)
-Recrunch preparation, bugfixes, workarounds
+TOF pedestals added for 7002-12143
+2004 deuterium recrunch started, no new tag (v3_4_18 is actual)
+Found also timing issues with 2004 hydrogen runs (see ppt):
TOF entries in database were modified, will fix it
+Pathlength fix: ltwl,r instead of Lwl,r.
This also matters for Tnn, because of Twl,r=Lwl,r/30 for electrons.
Hence, Tnn(corr) = Tnn + (ltwl,r-Lwl,r)/30
Correction is on the order of 1ns, mostly at backward electron angles
+working on 2004-H2 and 2005-D2 calibration fixes while crunching
2004-D2
-Mascarad handling
+Mascarad channel "666" only produces tail, starting from low energy
cutoff. Default is 10 MeV
+Use channel "266" (mixes Epel and Mascarad) for realistic MC
Sum of unradiated and radiated yield should reproduce total elastic
cross section (important to normalize radtail for inelastic
channels).
+The smaller the low-energy cutoff, the more the Mascarad part is
weighted (automatically in "266", however renormalization of total
cross section required). The cutoff can be chosen in the input
file.
+Cutoff should be smaller than the resolution, but large enough to
not cause numerical instabilities. Present default is 10 MeV, resolution
is ~30 MeV.
+To-do-list for Mascarad users (Eugene, Adrian,...):
Run Epel+Mascarad ("266") for different low-energy cutoff values and
compare MC yield with data (W spectrum). Find range of cutoff values
for which MC/data doesn't vary, assuming realistic resolution (!)
+Tune the resolution such that MC best reproduces data. Tip: look at
ratio MC/data versus W for all adjustments of cutoff and resolution
+Goal: By how much does the location of the W peak maximum bin shift
compared to the unradiated peak position depending on the resolution?
This result should be parametrized and separately accounted for along
with energy loss of the proton when "residual kinematic corrections" are
determined.
-Shifted acceptance
+Acceptance has not shifted in data reconstruction
+Discrepancy between data and MC at forward angles for d(e,e'p)n and
d(e,e'n)p, see Eugene's and Adam's plots (meeting_060412)
+Tossing volume starts at 24 degrees which is too large, should be 22
degrees or smaller
+VZ attributes discrepancy to the way the white generator distributes
events in phase space, giving poor yield at small angles but I don't
buy this
+Tossing volume should be at least as large as necessary to cover all
resolution smearing.
+Unclear how hPz at smallest Q2bin is affected
+-------------------------------------+--------------------------+
| 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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