Hi,
we're meeting this coming Thursday 10/19/2006 at 9am at Bates.
See the previous minutes of last time below.
If you can't attend, call in at
Bates conference call +1-866-867-8301, passcode 4073393
Preliminary agenda:
-p(e,e') inclusive analysis (Tavi)
-d(e,e'n) followup (Eugene, Vitaliy)
-aob.
Meeting minutes of 10/05/2006:
==============================
-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
+-------------------------------------+--------------------------+
| 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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