Hi,
below are the minutes of yesterday's analysis meeting. The next meeting
will be on Thursday 10/19/2006 09:00am at Bates.
Find the presentations in
http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/ANALYSIS_MEETINGS/meeting_061005/
Regards,
Michael
Minutes:
-Status and quality of v3_4_21 calib and recrunch (MK)
+See ppt
+Quality of recrunch and calib is very good, the time-dependency of
the offsets is generally well under control. Few spots with "problems"
remain. TOF calib is good <1ns (absolute) for entire BLAST dataset.
+Recrunch v3_4_21/lrd complete for 2004 deuterium (7002-12143), 2005
deuterium (13278-16506) and 2004 hydrogen (12144-13278)
+Looking at three time correlations, for (e,e'p), (e,e'n) and
(e,e'gamma) events. If the calibration is correct, the quantities
dT=T-Tcalc are expected to peak at zero, where T is the
time-of-flight for the proton, neutron, gamma, respectively, and
Tcalc the expected time-of-flight from tracking information. The
widths of dT result from convolution of uncertainties in T, Tcalc.
+Proton peaks for 16x16=256 TOF paddle combinations
+Neutron, photon peaks for 2x(8+14+14)=72 neutron detector channels
+Proton peaks used to check TOF-TOF calib, neutron+photon peaks to check
TOF-NeutronDet calib
+e'p peaks very good and consistent for entire dataset,
broken down into channels, deviations of peak positions up to
1-2 ns, total mean of ~0.4ns, sigma<1ns.
+Photonpeaks:
L15_L,NC_L jumps in certain channels: at certain run numbers related to
validity ranges of cosmics calib for flasher monitor. Effect on total
yield rather small, not clear wether it is worth to spend the effort and
fix it. Rather, the affected detector channels/run numbers should be cut
out. I will send a list of runs and detector channels who have this
problem.
L20,NC_R: have double peaks, not correlated with time, cercut, adc
->could be misidentified e,e'n events in e,e'gamma channel
+Neutronpeaks:
Time dependence of tdc offsets well under control; however peak
positions generally 3-5ns off zero. Could be due to wrong absolute
offsets, wrongly assumed tdc slopes (ch/ps), slightly wrong
pathlength (different pathlength of cosmics tracks and real neutral
tracks in production runs; detector thickness: n-interaction inside
detector material, whereas cosmic ray produces signal right at the
surface after entering the detector.
-> It's necessary to determine time peak position bar-by-bar for the
clean e,e'n event sample. Apply shift as time correction for
neutron time of flight, and/or length correction of the neutral
track (as a scale-factor correction). This shift is then valid for a
full dataset, not time-dependent; consider 2004 and 2005 separately.
-d(e,e'p):
+See ppt
+Comparison v19 data with MC: Cerenkov cut on/off, plot p_e for
various Q2 bins. Good agreement at lowest Q2, but then increasing
disagreement towards higher Q2 or theta_e. This is a potential
candidate to explain the Q2 dependence of hPz. Remember hPz was
left-right consistent only at the lowest Q2 bin.
+Data-MC discrepancy in pe vs. Q2 has substructure (->nonlinear t2d?)
+Agreement for proton momentum much better than for electron momentum
+Discrepancy largest in third Q2 bin 0.3-0.4: Data has low-momentum
excess tail for electrons and high-momentumn excess tail for protons
which is not seen in MC and which is not explained by the Cerenkov
acceptance
+Apply EG's kinematic corrections and energy loss and compare again
+Use same normalization factor for MC in each plot
+Vary acceptance cut for phi (+-12deg) and/or z (+-15cm)
+Look at location of Mmiss peak (supposed to be delta-function like)
instead of maximum of p_e (is continuous)
+Break down into tof bars and cerenkov boxes
+comparison data-MC for pmiss components ->crucial for asymmetry
evaluation
-d(e,e'n):
+See ppt
+Comparison data-MC for 2004 (v18)(!) and 2005 (v21)
-> need to update 2004 part, then compare 2004 v18/v21 and for
v21 2004/2005
+Excess of electron momenta around 0.6GeV/c in MC, not in data
+pmiss tail in 2005 longer than in 2004 -> =more efficiency for
high-pmiss neutron tracking in 2005 with converters and better calib?
+neutron solid angle acceptance data-MC agrees well, some edge effects
+pmiss components: discrepancy in pmiss_par and pmiss_perp,
good agreement in pmiss_oop; theta_cms wider in data than in MC
+third Q2bin: yield in 2005 much lower compared to 2004
->inefficiency in left-sector electron-TOF ("dip")??
+L15 hits with angle >46deg -> Problem with neutral track assignment?
+timecorr: wrong offset(additive) or wrong Lnn (multiplicative)
-> time correction to be done bar-by-bar, not as a function of Q2
+MC: Geant-based+recon?
+Adt,AedV vs reaction effects and vs. pot., vs. pm,thcms
Status of the proton PRL:
=========================
CURRENT STATUS OF MANUSCRIPT: With referee(s)
CORRESPONDENCE:
SENT RECEIVED DESCRIPTION
22Sep06 Review request to referee; response not yet received
22Sep06 Review request to referee; response not yet received
15Sep06 Acknowledgment sent to author via email
15Sep06 Corr. to author (paper long; short version NOT required now)
08Sep06 Correspondence (miscellaneous) sent to author via email
> -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. | |
| - - - - - - - - - - - - | - - - - - - - - -|
| 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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