Minutes of the Blast analysis meeting on Wednesday 7/19/2006

From: Michael Kohl (kohlm@mit.edu)
Date: Thu Jul 20 2006 - 18:20:54 EDT


Hi,

here are the minutes of yesterday's analysis meeting.

-Update on hPz for deuterium and d(e,e'p) (Adam, see ppt)
  +Showing measured minus calculated electron momentum assuming elastic
   kinematics, now after correcting the angle used to calculate the
   momentum, using EG's corrections for electron momentum and angle from ep
   elastic.
  +For pm<0.1, remaining momentum offset is on the order of -(2-4) MeV,
   almost in agreement with the binding energy of the deuteron (i.e.
   scattered electron momentum is smaller by the binding than in free case.
  +Extracted hPz for 2005 from the super ratio method, both for the spin
   angle map applied and for assuming a constant yield-weighted average
   spin angle (which value??). Difference with and without spin angle map
   is quite small.
  +Compared to Renee's analysis, hPz has become larger which is understood
   by the change of the average spin nangle assumed now and then.
  +hPz still shows quite a Q2 dependence which remains not understood.
   Need to work on event selection. Relax Cerenkov cut, instead use missing
   mass and time-of-flight information to identify d(e,e'p) event sample.
  +Thinking offline about it, another recommendation is to vary the
   azimuthal acceptance. Choose phi=+-15,12,10 degrees and extract hPz vs.
   Q2 for each one. Chris had seen some effects at the edge of the
   azimuthal acceptance in ep elastic.
  +Need to extract polarization dependent on z: Compare to Chris' plots of
   hPz vs. z from 060429. There was a strong dependence of the polarization
   product on z with a falloff outside of +-15cm. One should evaluate which
   figure of merit is larger FOM=N*(hPz)^2, for +-20cm or +-15cm and adjust
   the cut for z such that FOM is maximized.
  +EG suggests to determine hPz with super ratio method from Montecarlo
   data as a crude check, which should yield hPz=1.

-MC of quasielastic deuteron electrodisintegration (Eugene, Vitaliy)
  +VZ produced new Montecarlo files with his version
  +EG now able to compile his version.
  +Put branches into cvs
  +Pursue tests of results, comparison with data. Need to be done for both
   d(e,e'p) and d(e,e'n).
  +Energy threshold for neutron detection in MC improves agreement at large
   time of flight / low neutron momentum.
  +MC relative yield in Ohio walls seems to be higher than in real data.

-MC of radiative corrections (Tavi, Sasha, Yuan, Aki)
  +Collaboration with Sasha to be continued after his return to Belarus.
  +RadGen, ElRadGen should determine all four-vectors in radiative events,
   which will enable simulation of radiative effects of exclusive processes
   (e,e'pi+), (e,e'p)pi0. Some work needs to be done here.

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

---------- 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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