Dear colleagues,
please find below the minutes of the BLAST collaboration meeting on Monday
9/10, 2007 at LNS.
Best regards
Michael
Minutes BLAST collaboration meeting on Monday 9/10, 2007
==========================================================
Attending: Douglas Hasell, Adam DeGrush, Robert Redwine,
Richard Milner, Aki Shinozaki, Bill Turchinetz,
Ricardo Alarcon, June Matthews
Videoconference: Renee Fatemi, Chris Crawford
Special guests: Bill Donnelly and Aron Bernstein
Discussion on GEn - Kohl
========================
In June it was decided to split the tasks of presenting the results for GEn,
and of extracting the charge distribution of the nucleon (then based on
published GEp/GMp and GEn/GMn results, into two separate papers (letters).
MK worked on draft paper for GEn
-Improved introduction
-Sent draft to shortlist of people on August 17
-Copied files to DRAFTS folder on BLAST website
(http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/DRAFTS/GEn)
-New plots for Fig.1 (Asymmetry), Fig. 2 (Yield), Fig. 3 (GEn)
-Introduced discussion about FSI validation with tensor asymmetries
-GEn: BLAST fit = 2 dipoles, confront with Mainz parameterization
-Used the same GMn parameterization for all experiments
-Include hPz from A_par in (e,e'n)
To do list
Shortening by half a page (experiment description, discussion of
backgrounds)
Finalize plots/values:
Eugene:
+will generate root file for 47 degree MC, shift GEn=0 curve
+will produce hPz from (e,e'n) for 47 degree data
+will check final numbers for GEn
+will provide numbers for charge, current etc.
Chris:
+generate MC with free neutron, to be added to AedV plot
Adam:
+to specify values, stat. and system. errors on hPz from 2004 and 2005
Michael:
+control/manage files
+summarize systematics quantitatively: hPz and theta*
+envision revised draft within two weeks to be circulated within
collaboration, submittable early October(?)
+pending on hPz
Discussion on charge densities - Crawford
==========================================
Chris presenting overview of literature on nucleon charge distributions
Transformation from Breit to rest frame matters mostly for high-Q2
Parametrizing GEp, GMp,GMn with Fourier-Bessel, Laguerre-Gaussian,
quantitatively with error bands (GEn yet to be done)
Discussing oscillations
Sum of Gaussians: Error band difficult to be determined
-Restrict to GEp/n only
-Restrict to expansions in coordinate space
Quasi-elastic d(e,e'p), hPz, systematics - DeGrush
===================================================
Adam presenting current status of systematic error progression in hPz.
Effects of residual kinematic offsets on systematics are negligible,
dependence of hPz on target angle is dominant; hPz dependence on potential
model very small.
Q2 dependence of hPz (order of 15% over entire range) remains not
understood. Getting left-right consistency, and consistency with
spin-parallel (e,e'n) result for lowest Q2 bin.
Elastic d(e,e'd) - Kohl
=======================
Showed current status of ed elastic analysis
Goal to have results and two letters for tensor and vector finalized this
year
Radiative effects - Shinozaki
=============================
Presented exact calculations of radiative effect on cross section and
asymmetry for low-energy elastic scattering, by not neglecting the
electron mass.
Motivation: The usual assumption of ERL (extreme relativistic limit) has
an unphysical consequence of a negative cross section for soft photons.
It is often argued that radiative corrections to the asymmetries are below
one percent. The actual finding is that the effect on the asymmetry is
much smaller than one percent, ~2e-5.
Inclusive pion production from hydrogen - no report
Exclusive pion production from hydrogen - no report
Exclusive pion production from deuterium - no report
AOB
===
BLAST@DORIS:
-No news since submission of LOI in June 2007
-PRC meeting scheduled for November 8-9, 2007
Next BLAST collaboration meeting:
-One more before X-mas, date to be set pending on items to be discussed.
+-------------------------------------+--------------------------+
| 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. | |
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| Work: +1-617-253-9207 | Home: +1-617-629-3147 |
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