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Kaon LT Meetings » mtg_23nov16.txt

Garth Huber, 11/17/2023 12:39 PM

 
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                 Nov 16/23 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                            (Notes by GH & AH)
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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, Ali Usman, Alicia Postuma, Muhammad Junaid, 
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   Nathan Heinrich, Vijay Kumar, Nacer Hamdi
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CUA - Richard Trotta, Tanja Horn, Casey Morean
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JLab - Dave Gaskell
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CSULA - Konrad Aniol
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Richard
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-------
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Optimization of offsets for high beam energy datasets
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- new study based off GH's older 5_recon offsets, adjusting dPe offset, keeping
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  dPp=-0.1%
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 - dPe has a greater effect on W
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- then try GH's new offsets, determined with dPp constrained
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  - these work fairly well, but RT adjusts dPe to optimize W, EM overlap
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  - Displayed different variables after including offsets. It seems that some
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    variables get better with some extra variation.
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- Garth: concerned about optimizing offsets for Heep, which may not work for
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  other data.  Better to determine global offsets, for multiple beam energies,
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  so we have some confidence they can be applied to physics data.
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  - RT will try to get 3 sets of offsets:
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    a) 3.8, 4.9, 6.2 GeV
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    b) 8.2 GeV, where the SHMS - HMS spectrometer roles are reversed
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       - fortunately, the SHMS, HMS momentum offsets are similar
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    c) 10.6 GeV, where there may be HMS saturation
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- Dave: are the optics fine for HMS=6.6 GeV/c setting @ 10.6 GeV?
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  - yes, using Jacob's Matrix Elements, sieve spots look okay
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  - RT is actually using smaller offsets than GH provided for energies other
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    than 10.6
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Ali
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---
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Coin Time vs. Beta leakage in 10.6 GeV data
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- completed the cut-dependence study requested by Tanja/Dave
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  - ~96% efficiency @ 10.6 GeV, >99% for 6.2, 8.2 GeV
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- Mark sent a write-up on Improved Hodoscope timing and Hit reconstruction
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  algorithm
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  - initial test of ptof_tolerance from 100ns to 2.0ns had no effect
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    - the problem was traced to AU adjusting the wrong cut file
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    - a set of dedicated cut files were used for certain sets of run #
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  - now the smaller tolerance works, the cointime vs beta tails gone, no events
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    lost
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- the problem seems coming from too loose time window on the hodoscope, our
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  earlier hypothesis that it was related to inverted signal cable was a red
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  herring
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  - Nacer: what is the meaning of this tolerance?
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    RG/Casey: times from all hodoscope hits are propagated to the focal plane,
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    ptof_tolerance is the time window to accept different hits from the
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    hodoscopes when reconstructing an event
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  - 100 ns clearly far too loose, 2ns (a beam bunch spacing) should be good
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    since TOF variations to the hodoscope planes is taken into account in the
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    focal plane projection
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  - fortunately, the ptof_tolerance was already set correctly for the 6.2, 8.2
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    data, it's a mystery that only the 10.6 GeV data had such a wide window
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    - Garth: we've had repeated issues with things set wrongly in the 10.6 GeV
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      replay.  Really hope we have caught them all now.
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  - Ali will update the cut files and make a pull request.  A full replay will
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    be submitted after RT has finalized the offsets.
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Vijay
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---
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OOP offsets
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- applied 0.99 mrad HMS offset, obtained from GH's fit to just 2.7,3.6,4.6 GeV
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  data
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- PMY variable is improved for all 3 beam energies
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- Dave: investigated change in beam angle in different beam periods.  The
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  changes were of order ~0.1 mrad, not 1 mrad, so not enough to explain why we
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  need different OOP offsets for different beam periods
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Alicia
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------
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No report, was looking into CoinTime issue reported by Ali, and corresponded
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w/M.Jones
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- will do a 10.6 GeV pion replay (including helicity info) after RT has
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  finalized offsets
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Nacer
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-----
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Checking 3.8 GeV hodoscope calibrations after finding shifted beta distribution
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Nathan
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------
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CoinTime reference times
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- Checked multiple T.coin.pTRIG.ROC variables, and looked at different
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  multiplicity cuts
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  - Plot of T.coin.pTRIG1_ROC1_tdcTimeRaw
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    Blue: No cuts, Red: MULTIPLICITY=1
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- MarkJ indicated need to separate SINGLES and COIN events, to avoid multiple
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  peaks and allow cut windows to be tightened
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  - will need separate cuts for SINGLES and COIN, different PTRIG
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  - For most variables the timing window cuts are clear
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- T.coin.pT2_tdcTimeRaw has all events at zero, needs further investigation
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Junaid
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------
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- Finished hodoscope calibration, changes pushed today
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  - will post documentation slides on RedMine
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- Moved to drift chambers calibration. Started with with 2021 data for both HMS
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  and SHMS
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  - Drift distances for different drift chamber planes look better before
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    re-calibration, so it seems the calibration is okay
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  - submitted 40 more jobs for more thorough check
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Next Meeting
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------------
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- No meeting next week due to US Thanksgiving
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- Thur Nov 30 @ 15:00 Eastern/14:00 Regina
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  - PionLT will go first
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