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Nov 30/23 PionLT/KaonLT Analysis Meeting Notes
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----------------------------------------------
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(Notes by GH & AH)
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Today: PionLT will be discussed first
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Please remember to post your slides at:
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https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings
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Present
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-------
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Regina - Muhammad Junaid, Garth Huber, Ali Usman, Alicia Postuma,
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Nathan Heinrich, Vijay Kumar, Nacer Hamdi
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JLab - Dave Gaskell
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CUA - Richard Trotta
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CSULA - Konrad Aniol
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Nathan
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------
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TCoin Reference time cuts to improve event selection before feeding into HCANA.
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- Showed ElReal coincidence time for trigger TRIG1 ROC1 and ROC2, with lower
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edge cut on the time
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RED: multiplicity=1 cut applied (signal peak)
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BLUE: no multiplicity cut (flat bkg)
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- only 2 sets of cuts needed:
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pTRIG5 = (ELREAL_hms X 3/4_shms)
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pTRIG6 = (3/4_hms X 3/4 shms)
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- looked at ~20 runs taken at various times to check cut stability, which
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appeared to be good
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- Nacer: what would be the effect of having a wider window?
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NH: hcana takes the first time after the cut. If an event had two hits, a
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good one in the peak, but a bad hit coming earlier before the peak, a wider
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cut would allow the bad hit to be used instead of the good hit. This means
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we would actually lose the event if we had a wider cut
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- the point is that a wider cut does not necessarily mean more events. We
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need the optimal cut to get as many good events as possible.
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Plan for next 2 weeks:
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- by next Tuesday: will have new TCoin reference time cuts implemented
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- then will run a full replay of PionLT data
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- will do a quick comparo of Heep vs SIMC distributions so GH can work on
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PionLT offsets and compare them to KaonLT offsets
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- GH: it will be worthwhile to see if any report file changes are needed before
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doing the full replay
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- NH will discuss this w/Ali
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- also need to be sure helicity info is enabled in the reply
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- DG: and also enable EPICS trees so that magnet set points can be checked
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Junaid
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Recheck of drift chamber calibration after hodoscope calibs
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- all LD- data needed to be recalibrated, changes particularly large for 2022
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- no changes needed for positive SHMS polarity runs
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Plan for next 2 weeks:
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- as Nathan, full replay of PionLT data
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- then will work on tracking effs
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- meeting w/Ali next Monday
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- it would be good if Ali/Richard could find some old slides for Junaid to
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review
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Richard
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Heep offsets
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- presented final results for all 5 KaonLT energies
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- Ali found that 8.2 GeV Heep polarities were not inverted after all
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HMS=electrons, SHMS=protons, as usual
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- Richard's analysis only had them flipped for dummy target data, but it
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affects how the 8.2 Heep data were interpreted for the offsets
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- final offsets (units of 0.1%, 1mrad)
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in-plane: dthe=1.0 dthp=1.1 oop: dphe=2.51 dphp=-0.11
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dpp=-2.0
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dpe=-1.0 (3.8, 4.9, 6.2 GeV), -2.0 (8.2), -2.8 (10.6)
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de varies for beam energies, but generally small
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- Improved variables after offsets, except Emiss (trade off between E_miss and
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W)
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BLUE=SIMC, Red=Data
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- 10.6 GeV: W gets worse, EM better
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- offset chosen to get both to be similar, not prioritize one over the
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other
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- DG and GH agree this seems a sensible approach
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Next steps:
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- goal is to rerun Heep analysis to double check all is okay after Ali's
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analysis script changes (to incorporate offsets)
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- then do full KaonLT replay
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- will meet w/Ali to discuss uncertainties and efficiencies
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Ali
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---
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Updating a lot of stuff in LT replay in last 2 weeks
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- while updating energy offsets in standard.kinematics, the 8.2 GeV Heep
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setting caught his eye, and he found the polarity discrepancy
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- the run sheets were wrong in that they had negative polarity for SHMS and
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positive for HMS, while the reality was the normal configuration
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- Dave: all magnet set points are recorded in EPICS, one could have compared
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the set momentum values and look for outliers
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- in SIDIS analysis, a script was written to do this
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- please enable EPICS trees in next replay, and he will do a check
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- 10.6 param files were updated for new TOF tolerance value, to fix beta-CT
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correlation seen in recent weeks
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- made sure other KaonLT energies had correct tolerance values
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- Implemented the Heep offsets in the LT software framework.
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Plan for next 2 weeks:
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- Working on DeltaPi beam spin asymmetry analysis
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- started looking at L,C,R SHMS settings
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- PhD committee meeting is on Dec 13
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Vijay
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-----
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No report, busy on PhD committee report
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Alicia
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------
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No report, busy with classes
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- Once offsets are implemented, will replay 10.6 GeV pion data w/helicity
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- discussing DeltaPi beam spin asymmetry w/Ali
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- need to understand how to handle L,R settings where (t,phi) bins have poor
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statistics
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- GH happy to discuss this offline. Bill had the same issue in his omega
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analysis, and included in his scripts some various criteria for whether to
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exclude a (t,phi) bin or not
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- Dave: asks if L,C,R will be combined before doing background fitting
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- GH: No, in that case one is too sensitive to whether the MC properly
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handles the kinematic variation of the background across the acceptance
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- much more reliable, but also more tedious, to make MM plots for each
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(t,phi) bin and fit each one separately, as Bill did in omega analysis
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- Need discussion on the how to treat the background, especially the
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sensitivity to phi angle
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Nacer
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-----
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3.8 GeV KaonLT, fixing shift in beta_SHMS
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- looked at hodo time walk correction, looks good, no new calib needed
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- Re-calibration of Vp signal propagation velocity vs time of walk difference
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(PMT+, PMT-) for each paddle
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- SHMS Beta shift is now corrected for one dataset, which is great news
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- beta dist is noticeably narrower and with peak just below 1
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Next steps:
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- check SHMS Beta for different settings at 3.8GeV, and for 4.9 GeV data as
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well
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- issue is first to see whether new 3.8GeV calib works properly for them,
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without doing more recalibrations
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- when these are confirmed to be good, then need to recheck DC calibs, will
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discuss w/ Junaid when he gets there
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Next Meeting
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------------
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- Thur Dec 7 @ 15:00 Eastern/14:00 Regina
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- KaonLT will go first
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