Hi Michael et al,
My talk at SPIN2006 on nucleon form factors was held Thursday morning.
I think it went smoothly and was well received. There was a lot of
interest in the GeN measurement, particularly in the BLAST fit and the
implications for the pion cloud. Several people who had not seen the
data asked me for more information and it's clear that the final
results are eagerly awaited. Hal Jackson, who chaired the last Bates
PAC, was pleased to see the impact that the data will have. I wound up
not showing the elastic deuteron data (which I probably would have had
time to weave in after all), but during coffee break conversation it
was clear that people will be interested in these data too.
Overall the conference has been very interesting. In one relevant note
for BLAST, it is good that the proton paper has been submitted. There
was an e-p recoil polarimetry measurement done last week at JLab where
they lowered the machine energy to 680 MeV to allow them to get data at
several values of Q2 down to 0.1 (GeV/c)2. The primary purpose of
running at this low energy was polarimeter calibration, but Xiaodong
Jiang from Rutgers, who was on the measurement, claims that the data
will eclipse the BLAST statistical error bars by a factor of about 3
due to the high luminosity. It's too early to tell whether they see
the same structure we see in GEP and GMP.
I am uploading the final slides from my talk to the BLAST web site
private results in the SPIN2006 directory. The talk was significantly
rewritten since last week, although not so much in overall content as
in organization and presentation. Thanks to those who suffered through
the dry run last week and to Ricardo for such a cohesive presentation
at the Bates symposium last week which really helped me put this
together. I learned a great deal in the process.
Bill
***********************************************************************
Wilbur A. Franklin * Research Scientist
Bates Linear Accelerator Center * E-mail: wafrankl@mit.edu
P.O. Box 846 * Phone: 617-253-9518
Middleton, MA 01949 * FAX: 617-253-9599
***********************************************************************
On Oct 2, 2006, at 3:16 PM, Michael Kohl wrote:
> Hi,
>
> we're meeting on Thursday 2006/10/05 at 09:00am at Bates.
> Note the new time for the meeting. We will meet every other Thursday
> starting this coming one. If necessary we can schedule extra meetings
> on the free Thursdays.
>
> I'd like to use this opportunity to introduce another slight change.
> Since there is always two weeks of time between two meetings, I will
> expect brief updates of everyone doing analysis. If you cannot attend
> to present the status yourself, I will expect an email with a brief
> report (Tavi, Yuan, Adam, Eugene for the grads; others (Tim, Kevin,
> Vitaliy, Chris, Adrian, Peter, ....) are encouraged, too.). This can
> be a few lines, some plot, anything. As before, any plots or other
> information will be collected in the respective meeting directory at
> http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/ANALYSIS_MEETINGS/
>
> It is important that any progress or activity is reported to keep the
> Blast analysis on a straight and efficient track.
>
> Always find the minutes of the last meeting at the end of the meeting
> announcement, and you should read it before we meet.
> Use the Bates conference call +1-866-867-8301, passcode 4073393 if you
> cannot come to Bates.
>
> Preliminary Agenda:
> -Status and quality of recrunch v3_4_21 (MK)
> -d(e,e'p) follow-up (AD)
> -d(e,e'n) status (EG,VZ)
> -Brief reports
>
> Best regards,
>
> Michael
>
>
>
>> -Status v3_4_21 recrunch (MK)
>> +See ppt
>> +Recrunch of runs 7002-16506 complete using run-by-run time
>> calibration generated by Mark
>> +Presently evaluating quality, see ppt
>> +Looking at three time correlations, for (e,e'p), (e,e'gamma) and
>> (e,e'n) events: if calib is correct, all measured time diffs should
>> agree with the time diff calculated from tracking, for all detector
>> pairings (16x16 TOFsxTOFs and 16x72 TOFxNeutron bars)
>> +Results are complete for hydrogen runs 12144-13278 and look very
>> good,
>> (mean,sigma) for deltaT(e'p) without any further cuts except vertex
>> and track charge gives (-2.4ns/1.8ns) in v20, becoming (0.2ns/0.9ns)
>> in
>> v21!!!
>> +Will announce victory (and update th links in RECRUNCHDIR) after
>> having
>> completed the quality checks on the entire dataset
>> -Comparison data/Montecarlo for d(e,e'p) (AD)
>> +See files in folder DEGRUSH
>> +Montecarlo vs data for several variables for 2005 deuterium
>> +Normalized MC to maximum bin in each panel
>> -> Better uses only one global normalization, this gives a better
>> feeling for local inefficiencies
>> +Data with Cerenkov cut, inefficient (nonexistent) for rear angles,
>> ->relax this cut for this investigation
>> +Considered MC uses Geant only for acceptance test but tossed
>> variables otherwise. Therefore, resolution (convolution with
>> estimated resolution function) has to be adjusted manually
>> +vs electron momentum: quite some disagreement in higher Q2 bins,
>> could be due to cerenkov cut
>> +vs. phi: disagreement at forward angles already present in AM's
>> thesis
>> +This MC choice was made to facilitate the variation of input
>> parameters (GEn,GMn,GEp,GMp) that affect event weights. This way
>> only one common event list needs to be generated
>> ->event-weighted versus reconstructed MC
>> +As the event-weighted MC has no energy loss, data yield should be
>> energy-loss corrected (in average) before comparing with MC, all the
>> multiple scattering and Landau broadening then needs to be modeled
>> manually to give a realistic response (Gaussian smearing).
>> +EG has used Geant-MC to determine a parameterization of the energy
>> loss effect as a function of particle's energy, will send the result
>> in a separate email
>> +At least one detailed MC including reconstruction of propagated
>> events for one parameter choice of G_E,M^p,n with all multiple
>> scattering and eloss effects turned on in propagation and average
>> Eloss corrections applied in reconstruction is necessary to evaluate
>> the quality of the event-weighted MC (->EG)
>> +need to look at variables such as theta_e, theta_p, TOFnum, CERnum,
>> missing momentum components longitudinal, sideways within the
>> scattering plane and out-of scattering plane (in the physics
>> coordinate frame) for data/MC comparison
>> +When Eloss is applied to data and resolution modeled in MC, the
>> remaining shifts between MC and and data can be used to parameterize
>> kinematic corrections for the d(e,e'p) channel
>> -(e,e'n) analysis (EG)
>> +Showing asymmetries and MC for v3_4_21 2005-deuterium (see ppt)
>> +v21 data doesn't look drastically different from v17 except at
>> certain locations. However, both do not look "satisfactory".
>> +There are regions of disagreement between MC and data regardless of
>> what is assumed for GEn, resulting in a chi^2/d.o.f. at the minimum
>> much larger than 1, also the chi2 distributions do not look
>> parabolic in those cases (1st and 2nd bin)
>> +There is a technical problem in regard of activation of the proton
>> veto from the wire chamber hit multiplicity. Since the
>> lrd-recrunches (v17-21) are done from the DST which only contains
>> track
>> information, multiplicity variables are unavailable unless the
>> ntuples were generated with lrn from raw data. Therefore,
>> lrn-generated ntuples (v14,=ANALDIR) need to be accessed to process
>> the
>> multiplicities in parallel with the events from the lrd-generated
>> ntuples.
>> +Earlier on the phone we discussed a number of steps and detailed
>> checks that need to be done regarding:
>> +Data/MC yield comparisons in various variables, such as z,
>> theta(e,n), phi(e,n), mom(e,n), pmiss (also components);
>> +(e,e'n) rate monitor (after good cuts) vs run number and
>> vs. detector channels;
>> +Not mix things when doing comparisons between version
>> (e.g. different runlists)
>> +On time correction for neutron: Tnn is based on tdcdiff
>> measurement and pathlengths for electron and neutron. The
>> corrected electron track along with the neutron angles allow to
>> calculate Tnncalc. Comparison of Tnncalc with Tnn should be
>> used for event selection instead of missingmass (this way
>> negative Tnn's or shorter than photon-Tnn in case of a
>> miscalibration would not be rejected through the Mmiss evaluation)
>> +In the previous version of correcting Tnn, the difference
>> Tnn-Tnncalc was first parameterized as a function of Q2 and then
>> this function was used to correct Tnn event-by-event (i.e. the
>> correction itself was averaged)
>> +Plan: use Tnncalc for further processing of quantities that
>> depend on neutron momentum (this way the correction is
>> event-by-event and not averaged). Hope is that the uncertainty
>> of Tnncalc is less than for Tnn from the time measurement.
>> +A way to verify that Tnncalc has a better resolution than Tnn
>> would be to compare reconstructed vs. tossed MC values of these
>> two variables (if there wasn't the pathlength problem in MC).
>> +Also, the MC for the first and second bin look suspicious,
>> contracting to zero at pmiss ~=0.16-0.20, but not in the third and
>> fourth bin. VZ tried to convince me that this is real (or at least
>> in Arenhoevels calculations), but a zero-sensitivity to a variation
>> of GEn is hard to understand. Anyway it is important to also compare
>> the MC yields with data yields for the same bins/plots!
>> -aob
>> +status prl: confirmed receipt; 4 lines too long
>> +collaboration meeting on Friday 2006/11/17
>> +new meeting schedule: proposed every other Thursday 13:30
>> with occasional Bates Lunch seminars with 3pm limit to commute to
>> campus for departmental colloquium. HOWEVER: Adam may have classes
>> from noon on, and there may be senior campus lunch meetings.
>> Therefore we consider every other Thursday at 9am.
>> LET ME KNOW IF YOU HAVE OBJECTIONS!
>> 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 | |
>> +-------------------------------------+--------------------------+
>>
>
>
> +-------------------------------------+--------------------------+
> | 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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