Agenda:
1)Renee: news about hPz
2)Pion production: Review of N-Delta analysis, inclusive p(e,e'), and
exclusive p(e,e'pi+), p(e,e'p)pi0, p(e,e'n)pi+. Runlist, event
selection, yields vs W,Q2,thcms;time and experimental asymmetries.
Status of MC: MAID + ep elastic, radiative effects (YX,AS,TF)
3)On the meeting structure
Attending RF,DH,KD,JC,PK,VZ,CG,YX,CZ,AS,MS,MK.
1) Renee's update on hPz extraction for 2005
R. verified (and demonstrated!) that the used cuts are valid for the 2005
data. Fitting hPz at lowest 0.1<Q2<0.2 for pm<0.15 yields left-right
consistent result around 0.47. Still, hPz exhibits Q2 dependence. If
attributed to a deviation of the proton form factors from the
dipole, question is how much the form factor ratio should be changed in MC
in order to agree with the measured asymmetries.
2) Yuan showed us again the event selection for (e,e'pi+)n, (e,e'n)pi+ and
(e,e'p)pi0 and corresponding asymmetries. There is a discrepancy between
MAID-MC based on DGen and MAID-MC from Aki which agrees better with
the data. Aki suspects a phi->phi+180-type error in DGen which may cause
sign changes of one or more response functions. YX is working on MAID
implementation.
On the validity of MAID in BlastLib, there should be references available
by Shalev Gilad (Hall C experiment) and also from A. Bernstein or Sean Stave
to compare with. The MAID version in DGen evaluates pion production cross
sections from first principles, so there is in principle the danger that
it disagrees with what the website would predict. Sean earlier created big
tables with MAID results covering the phase space of his experiment at
Mainz. We should have something similar for BLAST and interpolate (like we
do with Arenhoevel's electrodisintegration). This is faster and more
reliable, I guess. I will meet Lothar Tiator in September.
Tavi is working on implementing POLRAD into generator. POLRAD, originally
for DIS, accounts for polarization-dependent radiative effects, also of
the produced pions. It needs MAID cross sections (or transition form
factors) for input. Effect on asymmetries can be large, as much as 40% (!)
compared to the very small effects in elastic scattering (~1%).
3) It was raised wether and if so, how the structure of the analysis
meeting should be changed in order to be attractive and useful.
-The analysis meeting shall provide a forum for discussion and scientific
discourse
-The analysis meeting differs from the three-monthly collaboration
meeting in the sense that the latter is pure collection of results
without discourse while the former has focus on discussion, too. The
analysis meeting prepares for the collaboration meetings.
-The BLAST experiment is more than the sum of its proposals. The meeting
shall locate and make available synergistic effects. One's result can be
very useful for another one's analysis. Examples are manifold like hPz,
Pzz, spin angle, kinematic corrections, etc. etc.
-The meeting offers practise for the student in presentations
-It is feedback to everyone's analysis - one should not only notice at the
time of a collaboration meeting if one is on a wrong track
-We shall have topical meetings, once per week
-The agenda of the next meeting should be determined at the end of each
meeting.
-People should come prepared, especially when they are supposed to report.
This means a few slides are in order to make things easier to understand.
HOWEVER, presentations at the analysis meeting are no conference talks
and are thus far more informal. Also recycled slides from earlier
meetings may be useful for this. Renee's presentation of her progress was
a very nice example on how it could be.
-It was pointed out that the minutes could be rotated, but for the time
being I'm fine with doing it.
-I will try to keep the length of the meeting below 90 minutes.
Proposed agenda for meeting on Wednesday 2005/08/17:
-Radiative effects in the BLASTMC generator (Mascarad)
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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