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Kaon LT Meetings » mtg_24jun13.txt

Garth Huber, 06/14/2024 12:50 PM

 
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                 Jun 13/24 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, Vijay Kumar, Ali Usman, Muhammad Junaid, Zach Sullivan
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JLab - Dave Gaskell
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FIU - Pete Markowitz
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Virginia - Richard Trotta
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CUA - Tanja Horn
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Vijay
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-----
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MM cut study for low Q2 PionLT data
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- scanned MM cuts from 0.972 to 0.988 GeV
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- reanalyzed both data and SIMC with these cuts
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- reran LTsep script, but did no iterations with model
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- computed variation in sigL and sigT compared to standard MM cut at 0.980
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- results show nearly zero variation in lowest -t bin, rising to ~5% for
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  highest -t bin
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  - calculated RMS of deviations (in absolute units) for all 8 cuts
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- Dave: if the deviation is systematic between different MM cuts, cannot
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  use the RMS to determine the uncertainty
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  - however, the deviation seems somewhat random, signs flip too, so maybe RMS
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    is okay
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- no one else has any other suggestions
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- Vijay will also look at deviations for sigLT and sigTT
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Next steps
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- computing RadFlag On/Off systematic
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- investigate variations in XPtar YPtar cuts
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Ali
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---
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- spent a lot of time this week making plots for thesis, calibs, efficiencies,
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  PID
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- completed MM shape study for piDelta BSA, to show results next week
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  - extracted BSA for all settings
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  - will extract LT'
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- in parallel with this, computing some systematic uncertainties related to MM
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  fitting
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  - variation in neutron fit
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  - MC to data normalization
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  - still has to look at MM cut dep to BSA result
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- worked w/Nacer last week on Heep analysis, will show some plots next week
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  - at last meeting, Nacer's low Q2 analysis agreed well w/ Richard
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  - worked on 6.2 GeV Heep, also compares well w/ Richard
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  - still looking at Cherenkov efficiency
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     - Junaid's Cherenkov eff (~99.8% vs 97%) helps the discrepancy compared to
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       Ali's eff, but the discrepancy still reamins at 6.2 GeV
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- Dicussion on things that might address the discrepancy
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  - *NB* Alternate Heep cross section parameterizations are available,
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    e.g. Bill checked multiple Heep parameterizations in his thesis, since the
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    Heep cross sections are less reliable at higher Q2, it would be a god idea
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    to switch parameterization in SIMC and see what the effect is
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  - Dave: is proton absorption included in the Heep analysis?
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     - SIMC does not correct for absorption, only scattering
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     - *NB* need to apply the correction to the Exp data
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     - it could be a 4-5% correction, depending on kinematics
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     - *NB* we had discussed this before, but it was forgotten, Richard and
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       Vijay need to also determine a correction for pi/K absorption and apply
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       it to physics data prior to doing LT-separations
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  - Junaid: Zach applied 3 different Cherenov cuts in his PionLT analysis, gets
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    efficiencies similar to Junaid
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     - need to check if Cherenkov gas pressure changed between KaonLT and
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       PionLT, this could explain the reason why the inefficiency is 10x less
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       for PionLT
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     - Dave: the same gas was used, but the pressure was changed
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       - Burcu identified a light leak in the J/psi data, which caused a large
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         inefficiency issue
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       - the light leak wouldn't have been fixed until much later
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     - *NB* Ali/Zach(?) should search hclog for info on on when the leak was
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       fixed and what gas pressures were set
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     - if we can't explain the discrepancy, we might have to take the
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       difference between them as a systematic, which would be undesirable
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     - if we can explain the discrepancy, then we have a good reason to apply
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       different efficiencies to KaonLT and PionLT data, and the assigned
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       systematic is much lower
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 Richard
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--------
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KaonLT LT-sep iterations
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- 1st iteration w/ new functional form for Q2=5.5
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  - 2nd t-bin has highest statistics
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  - has 4 t-bins now, probably should reduce to 3 t-bins
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- some discussion on what minimum #phi-bins is acceptable
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  - too few phi-bins makes it impossible to separate LT from TT
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  - has 6 phi-bins now, which is also the minimum number that Marco had
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  - Garth: a good way to find out what is the true minimum #phi-bins is to do
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    an MC study similar to what Alicia did, and see what results in a reliable
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    separation of LT, TT for different #bins
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  - *NB* Richard will look into revising #bins, will contact Alicia as well
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Junaid
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------
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PionLT Heep coin analysis, 9 settings
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- rechecked all files, found there was a momentum offset applied to the data
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  prior to determining offsets
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  - renalyzed data w/o offsets, GH generated new offsets
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    - new offsets very similar values to before
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- checking what sign of offset to apply, tried +/- sign momentum offsets
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  - wrong sign offset gives results nearly identical to correct sign offset,
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    presumably because the applied momentum offset is very small
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  - Garth: the beam energy offset and the momentum offsets should be applied
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    the same way, so you probably should check changing all 3 in the same way
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Zach
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----
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Working on PionLT efficiencies for Lumi analysis
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- will discuss results w/ Nathan before showing
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 Next Meeting
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-------------
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*NOTE THE SPECIAL TIME*
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- Next meet: Wed June 19 @ 15:00 Eastern/13:00 Regina
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  - PionLT will go first
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