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Kaon LT Meetings » mtg_24mar28.txt

Garth Huber, 03/28/2024 06:25 PM

 
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                 Mar 28/24 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                                (Notes by GH)
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                     Today: KaonLT 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 - Garth Huber, Ali Usman, Alicia Postuma, Muhammad Junaid,
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   Nathan Heinrich, Nacer Hamdi
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York - Stephen Kay
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JLab - Dave Gaskell
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CUA - Richard Trotta, Tanja Horn
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CSULA - Konrad Aniol
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Richard
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-------
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RF TOF correction
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- discovered an issue in xptar, xptar distributions for physics data
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  - Heep data had good similarity between data and MC xptar, yptar
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    distributions
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  - p(e,e'K+)L had similar MC xptar, yptar dists than Heep, but physics data
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    dists were different than expected
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  - investigated whether this was optics issue, etc. and finally tracked the
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    problem to originate from the RF cut
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  - the issue is that there is no TOF pathlength correction to the RF time,
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    giving a correlation between xptar, yptar and RF time
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  - the RF cut (for low epsilon K+ data) was too tight, and removed events at
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    edges of TOF distribution
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  - the RF distributions for K+ and pi+ overlap strongly for higher Q2 data, so
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    the RF cut is not all that effective for these events
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  - relying on pion subtraction anyways, so probably will not use RF cut for
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    these data
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Nacer
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-----
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Low Q2 KaonLT PID analysis, Q2=0.5, W=2.40 THshms=9.79(left)
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- for these data, the RF time cut is remarkably effective
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- plot of RFtime vs MMk shows a large separation between K+Lambda, K+Sigma and
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  pi+Delta events
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- plots of K+Lambda yield and K+Lambda/\sqrt(sig+bkd) vs (>RF cut) show a
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  stable plateau for some ranges of cuts, ~1.05-1.2
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- plot of MMk for various types of cuts:
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  - using all other PID cuts but no RF cut, still lots of pi+ bkd underneath
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    K+Lambda and K+Sigma peaks
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  - using only RF cut, no other PID, pi+ are highly suppressed
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- comparison of K+Lambda yields for various cuts indicates that we can get rid
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  of all SHMS PID cuts and keep only RF cut, reduction in K+Lambda peak counts
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  is minimized in comparison to bkd, with additional SHMS PID cuts the K+Lambda
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  peak yield also is decreased
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- Dave: is the SHMS momentum low enough to rely only on SHMS_beta?
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  - NH shows beta distribution plot, and MMk using beta cut, clearly not
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    effective for distinguishing pi+ from K+
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- Clearly for Nacer's analysis we need to deal with the RF TOF correction
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  identified by Richard 
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  - Stephen had tried implementing the TOF correction from the CoinTime,
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    unfortunately it was not successful (the TOF correction seemed to go the
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    wrong direction, made the RF worse instead of better), and not pursued
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    further
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- Stephen has two blocks of code where he was trying various things:
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  One block is at:
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https://github.com/sjdkay/hcana/blob/d4c646ecc46b99bfd610669f57047c4e8a83e457/src/THcRFTime.cxx#L348
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  Another big block of stuff in THcCoinTime - CT corrected RF values:
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https://github.com/sjdkay/hcana/blob/d4c646ecc46b99bfd610669f57047c4e8a83e457/src/THcCoinTime.cxx#L170
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Nacer can access some of Stephen's RF testing work on lark at:
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/d8tb3/sjdkay/JLab/RF_Class_Update_21_10_22_Tests
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- might be some pdfs with testing there. Unfortunately his notebooks are
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  in York. will check when he gets back next week and forward anything on
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Ali
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---
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pi+n Radiative Tail contribs in piDelta BSA Region
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- pi+n normalizing SIMC to data peak vs data integral
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  Option 1: match pi+n peaks - use for systematics studies
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  Option 2: match pi+n radiative tails - too extreme, won't be used
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  Option 3: match pi+n integral - chosen default for analysis
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  - integral range is 0.92-0.96, seems to approximately balance overheight at
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    peak with underwidth lower down
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- Other fits planned for systematic studies:
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  - integrate Bkd subtracted data
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  - integrate piDelta MC fit to data
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  - MM-cut dependence
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Alicia
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------
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pi+n BSA results w/ delta_SHMS correction now implemented
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- Q2=3.0, W=3.14, 7 t-bins, data looks very nice, maybe a bit smoother than
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  before (did not yet do a detailed comparison)
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- Q2=5.5, W=3.02, 5 t-bins
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- Q2=4.4, W=2.74, 2nd t-bin still has some phi-oscillation as before
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- hopes to have rest of BSA results ready by early next week
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PARTONS GPD model update
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- previously found weird statistical fluctuations in PARTONS output
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  - uses a MC module, needed to increase MC calls by 10x to remove fluctuations
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- PARTONS now gives roughly the same shape as LT' data vs t, but ~3x too high
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  - will rerun PARTONS again with GPD H_Tx2, as Stefan Diehl did, to improve
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    agreement
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BSA uncertainty discussion
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- for systematics studies, will have 2 BSA fits, and cut adjustments to CT, MM
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- separate discussion needed to incorporate all this into errors
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- Tues Apr 2 @ 15:00 Eastern/13:00 Regina/12:00 Calif
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  Zoom ID:  991 7509 1967
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  Passcode: 225211
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Nathan
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------
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PionLT Lumi analysis
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- modified RT's scripts to get them working for PionLT 
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  - added some dummy=-1 flags for HMS when doing SHMS only
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- getting some weird results:
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  TLT~4000% for Carbon Runs 16738-16746
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  - running times are very nearly zero
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  - most events apparently are excluded by beam current cut
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  - BCM not calibrated for these runs yet
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    - Dave Mack can do BCM calib for this one run next week
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    - NH can do other BCM calibs if DM gives instructions
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- other aspects do look good:
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  - CPULT looks reasonable
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  - SHMS track-eff ~99.88%, seems suspiciously too good
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- Richard: there are some hard coded corrections and cuts in the script you
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  need to watch for
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Junaid
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------
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PionLT Heep Coin study (9 settings)
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- applied same cuts to Data & SIMC
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  - BCM calibs not yet done, as noted by Nathan
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- made plots of PMX,Y,Z,EM,W for in-plane offsets
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  - all beam energies show same trends, unlike KaonLT
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  - hopefully this means that all 9 settings can use the same offsets, will see
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  - GH asks for some plots to have finer binning so that peak centroids are
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    more accurately defined
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- next steps:
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  - HMS Calorimeter and Cherenkov efficiency studies
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Stephen
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-------
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Reminder to send comments for York NSTAR* conference abstract
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Next Meeting
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------------
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- Thur April 4 @ 15:00 Eastern/13:00 Regina
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  - PionLT will go first
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- Also don't forget about the dedicated BSA uncertainties discussion
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  - Tue April 2 @ 15:00 Eastern/13:00 Regina
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