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Kaon LT Meetings » mtg_24mar07.txt

Garth Huber, 03/08/2024 02:26 PM

 
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                 Mar  7/24 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                                (Notes by GH)
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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 - Garth Huber, Nathan Heinrich, Muhammad Junaid, Nacer Hamdi, 
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   Alicia Postuma, Ali Usman, Vijay Kumar
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FIU - Pete Markowitz
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CSULA - Konrad Aniol
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CUA - Richard Trotta, Casey Morean, Tanja Horn
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JLab - Dave Gaskell
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Nathan
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------
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PID plots for SHMS NIM paper
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- HGC efficiency was found to be low, ~80%
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  - removed zero bin entries as Vijay had found in his PID study, then ~99%
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    outside of hole region
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  - indicates this is still a problem during PionLT data taking
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    - DG: are you sure these aren't otherwise bad events?
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    - GH: Vijay had shown that bad HGC events corresponded to good MMK, not due
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      to other expt backgrouns
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  - believed to be due to either a bad reference time or bad pedestal caused by
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    high rates per PMT due to low HGC granularity (only 4 channels covering
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    focal plane)
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  - will eventually need to use fADC mode-10 data to determine an apporpriate
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    correction
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  - *IMPORTANT NOTE* Richard uses HGC NPE<1.5 cut, so maybe a correction is not
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    needed for his data, but he will have to confirm, for example if a good HGC
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    time is required to calculate the NPE, then a correction would still be
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    needed
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- shows efficiency plots vs X,Y and vs delta for Aerogel, NGC, HGC
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- shows NPE correlations between detectors for PID
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Next steps:
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- will look through Lumi scripts and try to understand recent changes
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Junaid
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------
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DC efficiency plots for SHMS NIM paper
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- removed outliers
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- finalizing calorimeter plots for paper
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Next steps:
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- setting up scripts for Heep COIN data analysis
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Richard
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-------
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Fixes to xsect uncertainty calcs
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- met w/GH on Monday afternoon and found the problem
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- errors were not propagated correctly
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- uncertainties now stable vs iteration
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Pion contamination subtraction
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- Ali provided clean pi+ samples for Q2=2.115 and both Q2=3.0 settings
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- a sample subtraction is shown
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  - pi+ subtraction is red curve, stops at MM=1.24 for some reason
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  - DeltaPi contribution seems surprisingly small
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  - some rechecks should be done
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Xsect comparo w/ and w/o pion subtraction
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- Q2=3.0, W=3.14 shows ~20-25% reduction in sigL at low -t, no MM cut applied
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  - makes sense that low -t region is most affected, as pi+ cross section
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    should have much steeper t-depenence than K+
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- comparison with 1.10<MM<1.18 cut applied
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  - about 50% reduction in lowest -t bin, less in other bins
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Continuing separated Xsect issues
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- Q2=3.0, W=2.32 still shows epsLO>epsHi yields
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  - sigL works out negative, sigT unrealistically small
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- Q2=2.115, sigL consistent w/zero for lowest -t bin
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- compare to Marco's K+ data for Q2=3.0, W=2.32
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  - his epsLO value is close to our epsHI value
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- having difficulty getting things to converge sensibly for different
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  iterations
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- Vijay: what do your Ratio plots look like?
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  - RT shows Q2=3.0, W=2.32 ratios vs phi
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  - sees strong epsilon-dependence to Ratios
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  - Ratios at epsLO larger than Ratios at epsHI
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  - GH: it is *very important* to look at the Ratios plots for each iteration
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    - the goal is to get the Ratios having similar values for both epsLO and
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      epsHI, otherwise any separated cross sections are not reliable
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  - look more closely at the parameterization
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    - GH: suggests to start with only P1 for sigL and P5 for sigT, setting
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      others to zero initially
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Ali
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---
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Quick updates
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- iFarm is very slow, but finished replays for two higher Q2 settings
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  - will get these pi+ spectra to RT soon
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- working on hodoscope efficiency plots for SHMS NIM paper
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SIMC resolution study
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- no HMS delta-corr needed for 3 of 5 kinematics, so can finalize SIMC
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  resolution tuning
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  - Q2=5.5, W=3.02 comparison of MM vs t-bin between new and Feb analysis
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  - Feb had overall good agreement, but poor agreement vs t-bin, SIMC was wider
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    than data at low -t
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  - now doing tuning for all t-bins, to make sure SIMC is not wider than data
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    anywhere
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- DC resolution factor is now 4x instead of 9x
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  - Q2=3.0, W=3.14 center: now 5 t-bins instead of 4
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  - Q2=4.4, W=2.74 center
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  - reasonable agreement of MM shape w/data
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- now running MC for all DeltaPi BSA kinematics w/new resolution correction
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  - will start MM shape study for 3 of 5 settings
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- Dave: still don't understand why the correction factor is so large, but at
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  least it's no longer 9x
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- Vijay: suggests to look at xptar, yptar comparison, to make sure this is not
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  adversely affected by the MC resolution tuning
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  - definitely a *GOOD IDEA* to check this
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Vijay
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-----
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Summer 2019 LT-sep analysis, Q2=0.38
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- shows Yield Ratios vs phi-bin at epsLO w/o iterations
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  - sees some unusual phi-dependence in the Ratios that doesn't make sense
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  - GH: suggest to turn of LT, TT in initial parameter fit
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  - Dave: notices a weird Left-Right asymmetry in the Ratio error bars, one
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    side has dramatically smaller errors than the others, if there is
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    reasonably uniform phi-coverage these errors should be more uniform
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  - Tanja: suggests to look at Ratios separately for each SHMS setting to see
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    if things make sense, will be helpful diagnostic for debugging
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Alicia
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------
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BSA update: looking at the 3 Q2-settings that don't need HMS delta-corr
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- MM cut study
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  - compare MM from data and SIMC, more zoomed in than Ali's plots
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  - Q2=3.0, W=3.14, center Data is wider than MC
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  - Data-SIMC agreement is best at Q2=5.5, but still wider than SIMC
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  - what MM cut values to use?
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    - Dave: prefers no lower limit cut at all, unless the lack of a cut
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      introduces a problem (e.g. extra background)
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    - Dave: upper cut 0.98 is too tight, likes 1.0 better
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      - suggest to look at Data/MC vs MM and look where the Ratio plateaus for
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        deciding your cut values
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    - Tanja: the Ratio plateau will occur somewhere around 5-10 sigma from pi+n
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      peak
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- CoinTime windows for Random subtraction
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  - CT spectra are now flat after earlier error fixed
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  - can use 6 peaks Left and Right of main peak without issues
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  - PID cuts are applied to the plot, but no HGC, and loose MM cut applied
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  - Dave: suggests to look at yield of each bucket and stay away from that
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    region where yield/bucket starts to decrease
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    - GH: the roll off in the yeild will in principle occur at different CT for
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      different settings, as the coincidence signal timing is TOF dependent
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  - Nacer: where is there a region where peaks are merged together next to the
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    first random peak?
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    - Dave: it's just due to finite timing resolution and the fact that the
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      prompt peak is so large
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Nacer
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-----
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Resuming KaonLT Q2=0.50 analysis after calibrations
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- H.gtr.beta plot is now centered at 1.0 after new calib
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- SHMS P.gtr.beta vs P.gtr.dp shows a wiggle
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  - Nathan: this is due to a minor fault in the Hodo calib but you can ignore
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    it
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- P.aero.npeSum vs P.hger.npeSum for K+ identification
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  - HGC<3, Aero>3 NPE cuts used so far
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  - will have to tune the cuts according to the data distributions
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- CTime.eKcointime_ROC1 vs P.kin.secondary.MMK
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  - can see small K+Lambda and K+Sigma dots amid large pi+ background
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  - GH: can apply a MMK>1.05 cut to remove the big pi+n CoinTime peak and make
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    it easier to select K+ CT cuts
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- Ali: for these kinematics, you will find the RF cut to be very effective
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  - Vijay: agrees, looked at these data earlier, with RF cut, you can get the
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    pi+ CT peak to be smaller than K+ peak
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- Nathan: eK cointime is not quite centered at 1
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  - Stephen may have not set the CT offset quite correctly, you can tune it
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- testing some Real/Random cuts to apply
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  - MMK after random subtraction shows negative counts in DeltaPi region
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  - needs more optimization as part of PID studies
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Next Meeting
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------------
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- Thur Mar 14 @ 15:00 Eastern/13:00 Regina
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  - KaonLT will go first
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  - note the change in time for Regina people, because of USA daylight savings
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    switch 
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