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Kaon LT Meetings » mtg_24apr11.txt

Garth Huber, 04/11/2024 06:43 PM

 
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                 Apr 11/24 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, Nathan Heinrich, Muhammad Junaid, Alicia Postuma,
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   Nacer Hamdi, Ali Usman, Vijay Kumar
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CSULA - Konrad Aniol
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York - Stephen Kay
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UVa - Richard Trotta
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JLab - Dave Gaskell
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CUA - Tanja Horn
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FIU - Pete Markowitz
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Richard
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-------
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Resolving various issues in KaonLT LT-separation
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- RF time cut now removed
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- -t distribution offset between data and SIMC
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  - found that proton mass was used for detected particle instead of K+
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- SIMC recon script did not use the updated kinematics to recalculate the
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  weight
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  wt'= wt*(sig/sigcm_sim)
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- weights were not properly recalculated when doing an iteration
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  - ROOT was always using the first iteration weights
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  - an over-writing issue in ROOT script now fixed
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- with these corrections, there is a significant improvement in the
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  phi-distributions at high and low epsilon for the kinematic setting shown,
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  Q2=3.0, W=3.14
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Outstanding issues
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- some mismatches remain between SIMC and data distributions
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  - PMISS shape is off
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  - Dave: this could be due to the SIMC model not yet being optimized, wait for
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    more iterations to be completed before checking this again
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- pion subtraction needs improvement
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  - "clean" pion sample used for Q2=3.0, W=3.14 leakage subtraction clearly
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    shows some K+Lambda events
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  - Garth: need to be very careful with the pion subtraction, as it has a
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    different epsilon-dependence than the true K+ events, and you don't want to
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    induce an artificial epsilon-dependence to the data
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    - also very important that both K+ and pi+ samples populate the same focal
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      plane limits, i.e. can't have an HGC hole cut on one but not the other
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Vijay
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-----
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Low Q2 pi+ LT-sep update
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- unseparated cross sections shown for 3 epsilons
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  - some weird issues remain with phi-distribution of lowest -t bin, although
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    not as bad as last time this was shown
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- preliminary separated cross sections for L,T
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- no ratios or kinematic comparison plots shown, so it's impossible to provide
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  helpful suggestion on what to look at
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  - it's *VERY IMPORTANT* to also show diagnostic plots
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Ali
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---
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piDelta BSA analysis
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- last week, showed some preliminary BSA results at Q2=3.0, W=3.14
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- since then, the t-bin limits have changed
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  - the issue is that the background in the Delta region grows immensely with
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    -t
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- HGC cuts are applied to remove K+Lambda contamination in piDelta region
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  - *IMPORTANT* any SIMC plots need to have the same cut
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- MM plots shown for new -t bins, 0-0.37, 0.37-0.60, 0.60-1.0 and total 0-1.0 
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  - will exclude the 0.60-1.0 region since there are too few piDelta events
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    there for a reliable fit
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  - in process of doing MM fits for new t-bins
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  - an issue with 0.37-0.60 region is that some phi bins (center setting) have
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    very strong background, so getting a good piDelta fit is tricky
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    - the SIDIS background grows much faster with -t than the piDelta does
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Alicia
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------
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pi+n BSA Q2-scan
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- delta(FIT) error will be treated separately from delta(CUTS) error, since
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  they're not of comparable size
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  - doing RMS of both together results in under-estimate of total uncertainties
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- LT'/sig0 data shown vs. Regge model curves from B-G Yu
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  - much larger x-dependence than Q2-dependence
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  - LT' at fixed t vs Q2 is mostly flat, but different for each x-bin
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- overlay of LT' at xB=0.25, 0.40
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  - xB=0.25 data sets at Q2=3.0,W=3.14 and Q2=2.1,W=2.95 overlap very well
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  - xB=0.40 overlay has more scatter, but still small Q2 dependence
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  - Dave: how different are the -t_min for the two xB=0.25 data sets?
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    - the difference is quite small, about 0.01
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  - Dave: since the Q2-dep is small, how about overlaying all Q2 and look at
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    the x-dependence
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    - Alicia will make a plot for next week
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Nacer
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-----
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Low Q2 K+ PID studies
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- using runs=6921-6978, Q2=0.5, TH_shms=9.79(left) for comparison
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- Main cuts:
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  - H.cal.eTotTrackNorm>0.5
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  - H.cer.npeSum>2.0
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  - 0.15>RFtime(corrected)>0.95
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- RF time correction
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  - applied an adhoc correction to remove xptar dependence
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- Signal/Bkd study via a Gaussian fit + polynomial bkd
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  - does fit vs RF time cut
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  - apply both Low and High RF cuts, vary each one independently
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  - optimum values: Low=0.15, High=0.95
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    - throw away events between these limits, correponding to pions
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- Best K+Lambda yield appears to be with only RF cut, RF+HMS cuts is similar
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  - applying SHMS cuts greatly reduce the K+Lambda yield due to various
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    inefficiencies, the extra clean-up of the MM spectrum is not worth it
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  - Ali: there appears to be a small amount of piDelta contamination underneath
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    the K+Sigma events
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    - suggests to do a pi+ leakage subtraction, similar to what Richard is dong
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    - Garth: since the RFtime is so effective, can use a tight RF cut to easily
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      generate a clean pi+ spectrum for subtraction
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- Next steps
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  - RF cut efficiency, Lumi checks
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Nathan
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------
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PionLT lumi scans
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- figured out a reasonable BCM offset for the runs in this scan
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  - offset=-0.17uA
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  - make scaler(ELREAL) normalized yield flat vs rate
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- RelYield-NoTrack has a rate dependence (anti-boiling) indicating a LiveTime
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  issue
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  - TotalLiveTime(TLT) is too low at high rate
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  - Dave: as an intermediate step, try using CPULT instead of TLT, the
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    Electronic DeadTime should be very small
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  - Richard: can use the CPULT to fine tune your cuts, then re-introduce EDTM
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  - Nathan will add EDTM timing plots to investigate cuts
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- Dave Mack sent a new BCM calib, but had difficulty w/replay, investigating
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  - has a meeting with DM next Monday re. learning how to do BCM calib
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  - Dave: do we know how complicated the BCM calib is?
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    - the UNSER is very noisy, DM throws away UNSER points that are outliers,
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      requires some judgement
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    - Nathan: expecting to generate plots and have DM identify outliers to be
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      removed, will still take less time than DM having to do all parts from
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      scratch
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Junaid
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------
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- arriving at JLab on Tuesday night
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  - Dave: beam studies on Wednesday, so a Hall C walk through is possible
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PionLT Heep analysis
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- Ali had pointed out that BPM calibs were wrong
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  - slope values were right, but offsets wrong.  All updated now
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  - raster config files were also wrong
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  - there was an issue for two run ranges where only one pair of raster coils
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    were operational, so the other had to be run at double current
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    - this is also fixed
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- Heep Effective Charge, corrected for TrkEff, but not Calor or Cer Eff
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  - wrong BCM still used
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  - for setting shown, the data normalized yield is ~2x SIMC yield, which is
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    surprising
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  - for a different run, the yield ratio is much closer to 1
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- Richard: you need to use the kinematics recon script on SIMC data
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  - unfortunately, this means the PM, etc. plots have to be redone again
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- Dave: make sure you have the correct_eloss flag turned off in the SIMC input
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  file
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  - by default, SIMC both does energy loss, and corrects for it in the event
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    reconstruction, but hcana does not correct for eloss, so you need to turn
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    it off
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Next Meeting
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- Thur April 18 @ 15:00 Eastern/13:00 Regina
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  - PionLT will go first
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