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Kaon LT Meetings » mtg_24apr18.txt

Garth Huber, 04/18/2024 06:14 PM

 
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                 Apr 18/24 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, Ali Usman, Vijay Kumar, Nacer Hamdi,
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   Alicia Postuma
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CUA - Tanja Horn, Casey Morean
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UVa - Richard Trotta
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York - Stephen Kay
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CSULA - Konrad Aniol
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Nathan
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------
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PionLT BCM calibrations
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- met with Dave Mack on Monday to learn how to do the calibrations
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- things going very well, made some improvements to Dave's scripts
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- waiting for feedback from Dave Mack on results NH analysis
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The steps:
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- do a scaler replay of BCM calib runs
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- pick beam on/off times
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- do a fit of BCM frequency vs Unser current
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- look at fit residuals, and exclude outliers
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Initial results:
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- it looks likely that BCM slopes and intercepts can be combined for periods
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  where the physical configuration (PreAmp setup, tune) did not change
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- BCM2 intercept and slope looks pretty stable
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- DaveM thinks BCM4A is most reliable, as it generally has less non-linearity
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  at high current
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  - KaonLT used BCM4A and BCM1
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- BCM4B is optimized for low current, saturates above 40uA, so calib will be
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  done only for lower current portion of scans
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- Nathan will make a write-up on changes to code and instructions
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Richard
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-------
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mc_recon script changes
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- as shown last week, there was an offset to some kinematic distributions
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  because the recon script was using proton mass (left over from Heep) rather
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  than K+ mass
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  - after the fix, MM VS yptar correlations look similar for data + MC
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  - some odd looking correlation between MM and xptar shown(!)
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pi+ leakthrough subtraction
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- now using an HGC cut, K+Lambda peak in pi+ sample is eliminated
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- investigated variations to pi+ spectrum when varying HGC cut
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  - no significant changes seen for NPE>1.5 to 3.0
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  - also looked at variations in Aerogel cut
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initial iteration results (Q2=3.0, W=3.14 only)
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- sigL seems to have a fairly small Q2-dependence within the diamond
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- t-dependence still not right yet
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  - using exp(-t+0.2), will need to adjust the +0.2 offset in the exponent
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- GH: the MMk spectrum after pi+ leakthrough subtraction looks nicely clean
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  now, suggest that you try fitting the SIMC K+Lambda and K+Sigma peaks to the
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  pi+ subtracted MMk data
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  - the K+Sigma peak sits on top of K+Lambda radiative tail, it would be good
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    to see what the comparison looks like
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Alicia
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------
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- making plots for the BSA paper
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  - CoinTime, MM data vs SIMC w/cuts shown
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  - sample asymmetries vs phi for Q2=3.0, W=3.14 (2nd highest stats setting)
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BSA xB dependence
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- last week we saw there is nearly no Q2-dep to LT', so it was suggested to
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  explore the xB dependence by fixing -t (but not Q2)
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- plots of LT' vs xB shown at -t=0.17, 0.27, 0.31, 0.36
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  - 0.17: shows an interesting trend, all of these points are in similar
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    Q2-range
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  - 0.27, 0.31, 0.36: xB dependence is flatter, generally good agreement
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    between Hall C and CLAS results
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    - some discrepancy between Hall C and CLAS results at 0.27, which cannot be
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      traced to Q2-dependence, as both sets bracket similar Q2-ranges
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- don't yet know whether will include in paper or not
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  - if we do, we probably won't compare to any theory curves
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  - since the Q2-dependence of the data is ignored when making these plots, and
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    the Q2-dep of the models differs from the data, this would be a messy
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    comparison
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Ali
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---
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- last week saw that Q2=3.0, W=3.14 data at high -t had few piDelta events
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  - proposed to exclude highest -t region which had many fewer piDelta events
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    than background events
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- similar study extended to other settings:
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  - Q2=3.0, W=2.32, one t-bin
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    - exclude events for -t>0.9, based on t-coverage of events in piDelta MM
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      cut
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  - Q2=4.4, W=2.74, one t-bin, exclude -t>1.0, region is tuned separately for
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    each setting, based on how the MM plot looks at high -t
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  - Q2=5.5, W=3.02, one t-bin, exclude -t>1.05
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- Q2=5.5 phi-coverage
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  - found that the piDelta MC somehow changed phi-range to 0-2pi instead of -pi
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    to +pi
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  - fixes underway, but source of the problem is not yet understood
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    - one possibility is an issue with mc_recon
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  - Richard: the phi range in hcana is different than SIMC
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    - Ali: this is not the issue, that was already taken into account in the
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      code, this is a kinematics-dependent change
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  - Ali is still testing mc_recon script if it is using correct Mpi instead of Mp
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Vijay
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-----
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- planning to show diagnostic plots next week on LT-separation
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  - full set of plots not ready yet
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Nacer
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KaonLT Low Q2 Cut Efficiency studies
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- RFtime vs MMk
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  - will use data to determine the fraction of excluded KLambda, KSigma events
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    excluded due to the RFtime cut
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  - since the pi+n MM region is clean, will select these events for the study,
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    under the assumption (seems reasonable) that the RFtime distribution is the
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    same for pi+ and K+, just shifted in phase
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  - apply same cuts (but shifted) to pi+n events as used for K+ selection
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  - get an efficiency of 0.987, high epsilon 4.9GeV data
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  - will have to repeat study for low epsilon data
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HMS electron selection efficiency studies
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- quick check using physics data, rather than Heep data
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  - For the Cherenkov, get an efficiency of 0.981, which still contains some
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    pi- contamination
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    - Ali: for higher Q2 KaonLT, the sample was not as clean, got efficiencies
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      as low as 0.75, even after using tight Calorimeter cuts to clean up the
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      event sample
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    - looks like it's good to use Ali's electron efficiencies
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pi+ subtraction sample
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- the idea is the same as Richard's, except that a very clean pi+ sample can be
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  obtained just by using a tight RFtime cut
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  - still need to normalize the pi+ sample to the leakthrough
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    - Richard: takes MMk region 0.89-0.93, scales to equalize integrals
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Next Meeting
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- Thur April 25 @ 15:00 Eastern/13:00 Regina
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  - KaonLT will go first
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