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Kaon LT Meetings » mtg_24mar14.txt

Garth Huber, 03/14/2024 06:49 PM

 
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                 Mar 14/24 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, Nacer Hamdi, Ali Usman, Muhammad Junaid, Nathan Heinrich,
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   Vijay Kumar, Alicia Postuma
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CUA - Richard Trotta
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York - Stephen Kay
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CSULA - Konrad Aniol
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JLab - Dave Gaskell
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Ali
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---
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MM shape study for DeltaPi BSA
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- reran MC's with new resolution parameter
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- starting on settings with lower P_HMS, where delta correction is not needed
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- shows Q2=3.0, W=3.14, high stats setting, positive helicity
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  - initial fit of MCs to data
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  - new 10 MeV/bin instead of previous 4 MeV/bin (lower statistical errors/bin)
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  - with new MM binning, it is now more clear that strength of DeltaPi peak is
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    underestimated for some phi-bins
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  - since SIDIS and rho bkds are so similar, using a fixed ratio of 90%
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    SIDIS/10% rho for now
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  - cyan=sum of bkds, pi+n tail+SIDIS+rho
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  - optimistic that 2 t-bins can eventually be used for this setting (data
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    shown is over full t-range)
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- GH: since they are so similar, why don't you try fitting just one of rho or
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  SIDIS to see which one is better, and just use that one?
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  - DG: this would be an unphysical choice, but it probably makes no difference
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    to your analysis
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- Nacer: why are you fitting each phi bin separately?
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  - we have confidence that SIMC can properly describe the shapes for the
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    different processes, but not their amplitudes, so we need to fit each phi
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    bin separately
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Alicia
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------
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MM cut study after resolution correction implemented in SIMC
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- Dave suggested calculating Data/SIMC ratio for different MM cut values
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  - UofR group meeting also suggested to compare w/ w/o HGC cut
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    - HGC gets rid of KLambda leakthrough but not the shape of the region
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      between pi+n and KLambda
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  - ratios do not in general have a plateau vs MM cut
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    - Q2=3, W=3.14 data shown
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      - t-bins 1,2 show a decrease in ratio vs MM
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      - t-bin 3 shows a plateau
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      - t-bins 4-6 show an increase vs MM
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    - behavior is similar for Q2=4.5, 5.5
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- since the ratio is not flat, will instead try placing MM cut in region where
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  expt yield is flat
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  - Q2=5.5, flat region is MM=0.99-1.03, so will try MM cuts 1.01+/-0.02
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  - Q2=4.4, Q2=3.0 W=3.14, flat region looks similar, so same MM cut
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  - GH: can't think of anything better to try, given the situation
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- Dave: have you looked at BSA vs MM cut?
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  - a preliminary study was done last year, the final study will be done with
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   these MM cuts
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- Dave: if SIMC handles the radiative corrections properly, any cut below 2pi
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  threshold should give the same answer
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  - GH: not sure about this, the pion scattering in the collimator also
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    populates this region, in Fpi-1,2 we had to use a cut well below 2pi
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    threshold to avoid being too sensitive to this region
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- Dave: there is no SHMS collimator routine in SIMC
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  - GH: wasn't aware of no routine was included at all.
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    *TASK for GH:* find the HMS collimator code used in Fpi-2 analysis, and get
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    instructions on how to modify it for SHMS collimator geometry
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- Nacer: can an RF cut be applied to help clean up this MM region?
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  - no, only a small subset of 10.6 GeV data has the RF information available,
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    unfortunately
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HMS Delta-correction
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- P_HMS=6.59, Q2=3, W=2.32 data
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  - hcana uncorrected MMpi vs hsxpfp shows line with tilt on top half
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  - using reconstructed MMpi script to determine correction
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    - applying if hsxpfp>0: hsdelta+=3.0*hsxpfp
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  - resulting MM distribution is narrowed
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- P_HMS=5.292, Q2=2.1, W=2.95 data
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  - hcana uncorrected MMpi vs hsxpfp shows line with tilt on bottom half
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  - correction: if hsxpfp<0: hsdelta-=4.0*hsxpfp
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- having difficulty implementing this correction in hcana
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  - recompiling hcana on iFarm gives complaint about missing PODD variables
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  - Stephen: please *send* the PODD error and he will look at his notes to see
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    if he can fix
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  - Nathan: thinks it might be better to implement correction in the kinematics
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    file
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CKY Regge model
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- received LT' predictions from BG Yu for the BSA paper
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Richard
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-------
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Subtracting pion leakthrough
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- last week's results had HGC hole cut inverted, taking only events in the hole
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- now the pi+ dist comes all the way across the MM acceptance
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- Q2=2.1 setting, high epsilon
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  - pi+ subtraction does not clean up region left of KLambda peak
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  - planning to re-optimize PID cuts after graduation
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Unsep and Separated Q2=3.0, W=2.32 xsect
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- shows ratios vs phi,t at high, low epsilon
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  - looking at what's responsible for Data/SIMC ratios being much larger at
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    high eps than low eps
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  - trying various initial values of model parameters
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    sigL=g(W)*(p1+p2*logQ2)exp(p3+p4*logQ2)*(-t+0.2) 
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    -- changed last part to just -t to get better t-dependence
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    sigT=g(W)*p5/(1+p6*Q2)
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  - Dave: maybe remove the Q2-dependence and only have a simple t-dependence
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- Dave: the *real issue*, however, is that if you have sigL<0 from the
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  beginning, there's a problem with the data itself, not the iteration
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  - GH: exactly what MM region is integrated for these yields?
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  - MM cut is applied after pi-subtraction
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    - GH: if we can't clean up the region left of KLambda with cuts or pion
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      subtraction, then we will have to consider fitting a polynomial and
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      subtracting it
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    - Dave: yes, we will need to sort this out
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- Richard shows MM plots for same setting at high and low epsilon
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  - RF cut can be used only at low epsilon, region left of KLambda is
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    noticeably cleaner than high epsilon
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  - GH notices that pion subtraction peak is much narrower than the pi+n MM
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    leakthrough peak
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  - Ali's pion sample was analyzed as if pions, not K, hence the peak is narrow
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    - normalizing to the height of the pi+n peak will result in too little pion
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      leakthrough being subtracted, as the integrals won't match
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  - *Ali* will give Richard his cuts and RT will make a branch of his analysis
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    for the pion subtraction
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Vijay
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-----
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PionLT low Q2 lt-analysis
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- found bug in script, error bars vs phi now more reasonable
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- shows results after 1 iteration for Q2=0.38, all 3 epsilons
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  - some discussion about phi-dependence of lowest t-bin
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  - the low epsilon setting seems to have a different phi-dependence than mid
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    and high eps, which is weird
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    - Dave: this could indicate a residual offset issue, lowest t-bin is always
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      more sensitive to the offsets
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    - Vijay will investigate further
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  - t-bins 2-7 have more consistent phi-dependence at low, mid, high epsilon
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  - 8th t-bin has poor statistics, might have to be removed from analysis
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- shows separated cross sections after 1st iteration, and model fits for
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  iteration #2
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  - t-bins 1,8 look like outliers for sigT,L after iteration #1
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  - if only t-bins 2-7 included in fit, things are more consistent
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  - will have to see what this looks like after more study
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Nacer
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-----
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KaonLT low Q2 event selection
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- won't show any plots, since the meeting is getting long
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- tweaking some cuts, changing the RF windows
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  - RF cut is very effective, needs fine tuning
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  - GH: since the RF cut is so effective, you can probably get by with a
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    combination of slightly looser PID cuts, to avoid cut-dependence to the
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    result
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Nathan
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------
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Setting up PionLT Luminosity analysis
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- in contact with Dave Mack regarding BCM calibrations
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  - DM did our first calibs from 2021 run, NH will follow up with him on run#'s
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  - Dave: if you can generate ROOT trees for him to analyze, it would be even
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    better
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Weird hcana issue
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- hcana suddenly did not know what replay variables were
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  - spent a day debugging
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  - restored things, but no idea what happened, as could not find any
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    difference from how things were set up before
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Going through Richard's python scripts and finding what's missing
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- will plan on meeting RT in early April, after his defense
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Junaid
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------
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Setting up PionLT Heep study
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- had some issues with lt-sep package
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- merged cut files for 2021,22
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- added ngcer
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- updated RF time offsets
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PID cuts
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- HMS cal-etot-track-norm>0.7
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- HMS cer NPE>1.5
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- CoinTime, extremely clean, practically no randoms
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  - should be able to just place a cut around prompt peak, no random
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    subtraction
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Next Meeting
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------------
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- Thur Mar 21 @ 15:00 Eastern/13:00 Regina
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  - PionLT will go first
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