Minutes of the Blast analysis meeting on Wednesday 8/09/2006

From: Michael Kohl (kohlm@mit.edu)
Date: Wed Aug 09 2006 - 17:00:13 EDT


Hi,

below are the minutes of today's analysis meeting.
There is a new directory on the Blast website where paper drafts are
collected: http://blast.lns.mit.edu/PRIVATE_RESULTS/DRAFTS/

Minutes:

-Discussed status of the GEp/GMp paper.
  +Chris still working on implementing corrections. Largest effort is to
   update the figures.
  +Issue of what exactly is plotted as "world data" for GE and GM
  +Even if figures take more time, there should be a new draft of the text
   in order to wrap up that part.

-Status timing calib/recrunch
  +Mark has updated the mysql database for the 2005 time calib, with
   significant changes compared to the previous version
  +2005 deuterium recrunch (v3_4_21) now being started
  +Mark redid time calib for both 2004+2005:
   -Stabilized peak finding for flasher signals in TDCs (this had caused
    noisy peak location and "sidebands"
   -Interpolation of periods with missing flasher
   -Discontinuities: Sometimes real, sometimes fake, spent quite some
    effort to understand this
   -Evaluated as many cosmics runs as possible to "calibrate" the flasher
    monitor
  +quality needs to be evaluated after recrunch by looking at
   pathlength-corrected time correlation of coincidence events (e,e'n),
   (e,e'gamma), (e,e'p), all as function of run number and broken down
   into detector channels. If quality still not good enough when utilizing
   the flasher monitor, we may revert to pure cosmics calib of offsets and
   linear interpolation between cosmics runs.
  +Will show more details next week

-hPz analysis:
  +Adam showing vector asymmetry pm<0.1 versus target-z
  +strong variation of d(e,e'p) vector asymmetry near the edges of the
   target cell reproducing what Chris had seen in ep elastic
   (see meeting_060426)
  +Asymmetry deviates from average by more than 10% near the edges,
   getting closer to zero. Chris' MC from 060426 still used flat (=no) spin
   angle profile
  +Need to compare with MC with and without spin profile, both ep elastic
   and d(e,e'p) quasielastic
  +Remaining variation of extracted hPz along z can then be attributed to a
   polarization profile
  +As the spin angle parameter correlates with the polarization parameter
   in the asymmetry, it is not unlikely that the seen effect is mostly due
   to the spin angle variation.
  +Polarization profiles are not necessarily equal for hydrogen and
   deuterium due to different spin depolarizing effects, however, spin
   profile is the same for both targets

-Aki showing plots from new Montecarlo "pionmc"
  +Generator for radiative elastic events to quantify elastic radiative
   background in inelastic region in p(e,e'p)pi0 and p(e,e')
  +Generator combined with Geant3 / reconstructed variables
  +Comparison of W measured and simulated: peak slightly shifted (no
   kinematic corrections applied); overall shape of the W-yield reproduced
   by MC modulo locally varying efficiencies
  +Asymmetries very well produced; radiative tail asymmetry quite constant
   with W confirming the "soft-photon apprximation" meaning that the
   radiative process is helicity-independent (proportional to cross
   section) to first order
  +Expected photon "peaks" along incoming and outgoing electron directions
   reproduced in generator, but quite smeared out in reconstruction
  +Benchmark for dgen/mascarad and elradgen
  +pionmc can use optional pion production models (Maid, Sato-Lee,
   Dubna-Mainz-Taipei)
  +Should also include other models (SAID, EFT) for completeness

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 | |
+-------------------------------------+--------------------------+

---------- Forwarded message ----------
Date: Fri, 7 Jul 2006 11:57:49 -0400 (EDT)
From: Michael Kohl <kohlm@mit.edu>
To: "[BLAST_ANAWARE]" <Blast_anaware@rocko.lns.mit.edu>
Subject: Special Blast analysis meeting on Wednesday 7/12/2006

Hi,

though I had announced earlier to cancel next week's meeting, we decided to
still have one on Wednesday 7/12/2006 at !! 10:00 !! at Bates.
Note that 10am was chosen as there is a STAR collaboration meeting ongoing at
MIT with a session on spin physics in the afternoon.

By the time Sasha Ilyichev will be at Bates. The meeting will be about
radiative corrections at Blast:

-Summarize status quo of treating radiative effects in Blast
-Define task list, priorities, estimate of effort

Sasha will also give us a presentation on details of the procedure of handling
radiative effects in elastic and inelastic scattering at the collaboration
meeting on Friday 7/14.

Best 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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