Dear all,
below are the minutes of today's BLAST meeting. Find them also, along with
the presentation in
http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/ANALYSIS_MEETINGS/meeting_071128/
Minutes:
Attending Bill Turchinetz, Bob Redwine, Doug Hasell, Tim Smith, Michael
Kohl, and John Calarco, Haiyan Gao via speakerphone.
MK reporting on status of GEn paper
===================================
-latest draft in
http://blast.lns.mit.edu/PRIVATE_RESULTS/DRAFTS/GEn/paperGEn_071128.pdf
-final numbers still worked on by EG and MK, accounting for change of hPz
-evaluated systematic errors and propagation accounting for covariances
-how to combine 2004 and 2005 datasets
-hPz from d(e,e'p) has increased. From Adam's investigations, the most
convincing explanation for the Q2 dependence of hPz is pion contamination
from d(e,e'p)pi0n. With tighter Mmiss cut and evaluation of hPz at the
lowest Q2 bin gives consistent results with two methods of 1) treating
data like e-p elastic (super ratio method) and 2) comparison of
asymmetries with Arenhoevel-MC for both sectors. As a result, hPz is
~8-10% larger than the previously circulated values. A separate email
will be sent out with a summary of BLAST calibration parameters
(hPz, Pzz, thd)
-Asymmetry plot updated: added curve for free neutron target evaluated for
pointlike kinematics for e-n elastic scattering and standard form factor
parameterization GEn = Galster and GMn/mun = Dipole. Result is close to
PWIA-Montecarlo as expected.
-Yield plot unchanged
-Plot of GEn results: GEn data points from EG's thesis reduced by ~5% due
to an error when converting from the fit parameter to the actual GEn
value assuming the parameterization by Friedrich and Walcher. However,
this is still subject to change
-"BLAST fit" is based on 2 dipoles with one of the four params fixed due
to GEn(0)=0. The neutron charge radius is now treated as a constraint
(e.g. as a datapoint in the chi2 minimization, rather than a fixed param)
-Discussed values of neutron charge radii in theories and experiment.
Impact of BLAST data on extracted <rn^2> with 2-dipole fit studied with
and without constraint from neutron-atom scattering. Without constraint,
BLAST data improve error on <rn^2> from ~50% to ~30%. With the
constraint, <rn^2> is known to ~3%, while the BLAST data is very
consistent with the radius from neutron scattering.
-GEn plot now with 1-sigma error band. In the fit, all data points were
weighted with their total=sqrt(stat^2+sys^2) errors. Result very close to
dispersion analysis. Miller's (LFRCQM) prediction slightly lower.
-evaluation of systematic errors by source, identified correlations,
propagated errors into GEn and combined two datasets.
-correlation between hPz and thd:
+statistical error on thd leads to a systematic error on hPz that is
UNCORRELATED between 2004 and 2005
+systematic error on thd leads to a systematic error on hPz that is
CORRELATED between 2004 and 2005
-cov(hPz,thd) = 0.0079*dthd^2(2004) or 0.0120*dthd^2(2005)
-partial derivative dGEndhPz for each Q2 bin from Eugene's Montecarlo
investigation: 2004: very small; 2005: ~ -2%(GEn) / %(hPz)
-partial derivative dGEndthd for each Q2 bin from MK's analytical
calculation for e-n elastic scattering using GEn=Galster and
GMn=Friedrich-Walcher, confirming VZ's previous result of ~10-12% per
degree
-Resulting uncertainties:
+dhPzstat and dhPzsys both ~<1%
+dGEn(thd) ~5%, dGEn(hPz) ~2% for 2005 but only ~0.2% for 2004. Reason is
that asymmetries in 2004 are closer to zero than in 2005
-combining two datasets (2004+2005) accounting for correlations:
+2004 weight ~2/3, 2005 ~1/3
+2004 uncorrelated syserr smaller than 2005 -> higher weight
+total GEn staterr ~12-16% in each bin, total syserr ~5-6%
-to-do-list:
+Shortening: reduce by one page (not too difficult)
+include other uncertainties, finalize numbers (machinery exists)
-envision final draft within 2 weeks, to be circulated within
collaboration
-envision submission to PRL before Christmas!
Nucleon charge distribution paper
=================================
-first draft prepared by Bill Donnelly
-regular meetings held between Chris, Bill, Richard, Doug & MK
-model-independent parameterization of proton and neutron charge
distribution in momentum space (form factor) and coordinated space (Breit
frame). Proper determination of error bands
-Distributions of isoscalar and isovector charge
-Using charge symmetry (rho_p,up = rho_n,down), extract up and down quark
distributions in proton and neutron
-envision finalized draft ready for submission before Christmas,
simultaneously with the GEn paper
Relocation of BLAST farm
========================
There will be enough time to carefully plan the relocation of the BLAST
farm from the counting bay to the room next to the accelerator control
room in the administration building to minimize any downtime.
BLAST collaboration meeting
===========================
The next BLAST collaboration meeting will be scheduled early in 2008,
possibly end of January or early February. Stay tuned.
Best regards
Michael
On Mon, 26 Nov 2007, Michael Kohl wrote:
> Dear all,
> the conference room 26-502 has been reserved for the BLAST meeting on
> Wednesday 11/28 at 10:30am.
> People calling in from outside can use the number 617-324-7520.
>
> Best regards
> Michael
>
>
> RE: Audio Bridge Request from Michael Kohl, Wednesday 11/28/2007
>
> ---------- Forwarded message ----------
> Date: Mon, 26 Nov 2007 13:18:52 -0500
> From: Nancy Harney <nanch@MIT.EDU>
> To: kohlm@mit.edu, tele-info@mit.edu
> Subject: RE: Audio Bridge Request from Michael Kohl, Wednesday 11/28/2007
>
> Audio Bridge Confirmation
>
>
>
> To: Michael Kohl
>
>
>
> Date: November 28, 2007
>
>
>
> Day: Wednesday
>
>
>
> Time: 10:30 AM to 12:30 AM
>
>
>
> Participants: 12
>
>
>
> Telephone Number Assigned: 617-324-7520
>
>
>
> Thanks,
>
>
>
> Nancy
>
>
>
> Nancy Harney
>
> Telephony Information Center
>
> Team Leader
>
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>
> Information Services & Technology
>
> Massachusetts Institute of Technology
>
> E19-741
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> nanch@mit.edu
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>
>
>
>
> -----Original Message-----
> From: kohlm@MIT.EDU [mailto:kohlm@MIT.EDU]
> Sent: Monday, November 26, 2007 1:07 PM
> To: tele-info@MIT.EDU
> Cc: kohlm@MIT.EDU
> Subject: Audio Bridge Request from Michael Kohl, Wednesday 11/28/2007
>
>
>
> Errors to: tele-info@mit.edu
>
> --------
>
>
>
> Reservation requested by: Michael Kohl
>
>
>
> Requestor's e-mail: kohlm@mit.edu
>
>
>
> Requestor's telephone number: 617-253-2367
>
>
>
> Name of Audio Bridge host: BLAST
>
>
>
> Host's e-mail address:
>
>
>
> Requested date: Wednesday 11/28/2007
>
>
>
> Requested start time: 10:30am
>
>
>
> Requested end time: 12:30am
>
>
>
> Number of participants: 12
>
>
>
> Comments: The meeting's agenda is to report on the status of paper writing
> -GEn -Nucleon charge distribution
>
>
>
> This form will be submitted to the MIT Telephone Information Center
>
> at tele-info@mit.edu, with a confirming copy to the requestor.
>
> Tele-info will respond with a confirmation e-mail,
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> including the phone number to be used for the conference call.
>
>
>
>
+-------------------------------------+--------------------------+
| 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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