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Kaon LT Meetings » mtg_23aug31.txt

Garth Huber, 09/01/2023 01:32 PM

 
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                 Aug 31/23 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                              (Notes by GH & AH)
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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, Vijay Kumar,
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   Nacer Hamdi, Alicia Postuma
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FIU - Pete Markowitz
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CSULA - Konrad Aniol
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CUA - Richard Trotta, Tanja Horn, Casey Morean
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JLab - Dave Gaskell
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Nathan Updates
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--------------
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Corrections to standard.kinematics went well.  Finished!
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- pushed changes to GitHub yesterday
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- no huge errors, only small corrections
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- a few notable issues:
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  - Target Mass: Corrected entries to use free proton mass rather than hydrogen
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    atomic mass (in AMU). 
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  - LD- runs, same for deuteron (use free neutron mass)
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Next steps:
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- will meet soon with Junaid to coordinate strategy
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- need to double check Jacob's Hodoscope calibration, to be sure its set up in
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  the database correctly 
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  - if it was not entered correctly, it would affect Drift Chamber calibs, and
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    some work would unfortunately need to be redone
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- started writing batch scripts for full replay, which will be done after
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  Junaid finishes calorimeter calibs
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- Garth: are the report files ready for the new replay? 
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  Nathan: need to add in NGC info
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  - may want to add PID efficiency info
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  - can probably do a full replay, then do 1st pass studies and optimize cuts
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    for 2nd pass replay
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- Richard: will clean up his Lumi scripts, particularly the EDTM calcs, so
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  they're ready for Nathan and Junaid's analysis
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Junaid Updates
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--------------
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Calorimeter calibs
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- HMS 2021,22 calibs done
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- now working on SHMS calorimeter calibs (negative polarity runs), should be
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  done in a few days
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- Cuts used for HMS CAL calibration:
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  H.cent.npeSum > 7
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  -8 < H.gtr.dp < +8
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- Cuts used for SHMS CAL calibration:
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  H.cent.npeSum > 7
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  -10 < H.gtr.dp < 20
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- the high SHMS npe cut is needed to select electrons (neg polarity runs only)
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Nest steps:
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- checking the hodoscope calibs (mentioned above) is the most important thing
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  - will probably do a few DC calibs and compare, as a check
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- Found Jacobs's hodoscope calib slides. He sent them to Garth and Nathan, and
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  will post them on RedMine
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Richard Updates
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---------------
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Luminosity analysis
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- looked more carefully at getting a clean electron sample
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  - Solved software bug which allowed bad events not passing cut to still get
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    included in the analysis
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  - fixing this helped a lot, much less scatter in the data
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- Carbon HMS relative yield vs current: looks good
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  - compare to Carlos Yero's Carbon and LH2 boiling factors vs current
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- Carbon HMS Boil factor vs. ELREAL rate: looks flat without correction
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  - (unweighed fit)
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- Obtained corrections (error-weighted fits):
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  Carbon: 1.85% +/- 2.1%/100uA (slight boiling)
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  LH2: 4.86% +/- 2.8%/100uA
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  - results are nicely consistent with Carlos'
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- DG: the correlation for Carbon vs Current is tighter than the flat
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  correlation vs Rate, this suggests a correction to the BCM calibration is
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  needed, based on the Carbon vs Current correlation of 1.85%/100uA
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  - then re-check Carbon vs Rate to see if the BCM correction introduces a
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    residual rate dependence that needs to be removed (there might not be one,
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    as the points get re-ordered on the rate plot)
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  - finally, check the corrected LH2 correlation vs Current to get the final
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    cryotarget boiling correction
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Next steps:
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- update SIMC for LT-sep analysis, needs to update the function in
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  physics_iterate.f
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  - was planning to start with the function in Marco's thesis
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  - GH suggests to instead use the same function that Vijay has already tried,
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    as it has more free parameters and is more flexible
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  - Marco's analysis had many fewer statistics, and so could only use a simple
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    function with fewer free parameters
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  - GH suggests to get the subroutine from Vijay, as he already has it working
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    - the only change that should be needed is to replace mpi with mK in the
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      pole term part
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Vijay Updates
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-------------
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- DaveG asked for hodoscope efficiencies per plane, needed to add to report
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  file, still waiting for replay
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Next steps:
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- working on Luminosity Summer-2019 data
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Alicia Updates
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--------------
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BSA Binning MC requested by DaveG
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- the question to be answered is "how much difference does phi-binning make to
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  the BSA fit results?"
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  - Since some sets have limited number of bins, trying to find the adequate
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    number in bins for beam asymmetry fits
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  - generate random pseudodata with known inputs: A=3; B=0.8; C=0.3
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- Fit breaks at: 5 phi bins, and at <= 100 entries 
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- 9 phi bins fit OK w/ good statistics
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- 11,13 phi bins OK except when stats poor
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- second study with A=6; B=0.2; C=0.1
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  - similar results
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  - Deltapi data have poor statistics, study shows probably fitting only A is
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    best
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- real data Q2=5.5, W=3.02:
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  - vary # phi bins and compare Full Fit to Approximated Fit
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  - Number of bins do not change the beam asymmetry outcome up to 1 sigma
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- recommended binning:
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  Q2=5.5:         4 t-bins, 13 phi-bins
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  Q2=4.4:         5 t,      13 phi 
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  Q2=3.3, W=3.14: 7 t,      15 phi
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  Q2=3.3, W=2.3:  7 t,      15 phi
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  Q2=2.1, W=2.95: 8 t,      15 phi
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  - Dave: Use same number of phi bins for all the plots, study suggests that
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    the minimum number of bins, maintaining good fit in beam asymmetry, is 13
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    bins.  Makes it a lot easier to explain in the paper
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Discussion of new CLAS BSA paper:
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  S. Diehl, et al., Phys Lett B 839 (2023) 137761 1-7
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  - analysis of sigma_LT'/sigma_0 for similar kinematics to ours
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- Our results are still important: expecting higher precision than CLAS-12
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  - combining our data with theirs, we can do Q2-scans of LT' at fixed
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    x=0.255+/-0.01, 0.415+/-0.01
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  - Diehl's conclusion: JML Regge better at low Q2, GK GPD better at high Q2
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    - however, Regge comparison to their data is actually never very good,
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      while GK is equally good at low Q2
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  - our Q2 scan at fixed x,t should provide a more definitive conclusion
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  - Dave: Hall C should have significantly better t-resolution than CLAS-12, so
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    t-bin migration will be much less of an issue
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    - can do finer t-binning to better see rise in LT' at low -t
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- considered whether we can reliably extract LT, TT from BSA A,B,C fits
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  - used binning MC w/ known inputs and plot outputs to see how well we can
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    accurately measure B->LT, C->TT
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  - A=3; B=C=0, Nevts=1000: full fit does give a slight non-zero B,C and slight
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    shift to A
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  - leaning to not extract B,C values, as they are too uncertain
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  - leaning to quoting weighted average for A fits as most reliable
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  - the MC study has been very useful, definitely we can make use of these
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  - results in the paper
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- Diehl's paper used approximate fit and assign 3% systematic error from full
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  fit
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  - Alicia's MC study suggests that their errors largely underestimated
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Garth Updates
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-------------
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In plane global offsets
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- wrote a simple Fortran code to do a global analysis, took only a few days
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  - code includes the Heepcheck derivatives and Vijay/Ali's input data, with
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    global minimization
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- unconstrained fit gives unrealistically large offsets to the beam energy, and
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  this then drives unrealistically large HMS, SHMS momentum offsets
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- then tried a constrained fit, keeping the beam energy offsets to not larger
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  than +/-0.7E-3, based on the arc energy measurement uncertainties
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  - Constrained fit works much better
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  - Dave: obtained global offsets look plausible
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    - SHMS momentum offset: MarkJ put in ad-hoc 2% correction, another 0.18%
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      correction to this is reasonable
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- GH can do a further study, including the three higher beam energy Heep data,
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  will ask Richard/Ali for the shift data
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  - it's not obvious whether the same set of offsets will work for the higher
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    energy data, or not, as the HMS momentum gets quite high for some of them
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  - will decide what to do after seeing initial fit results
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Out of plane global offsets
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- Vijay provided xptar info for three Heep coin settings from Summer-2019 data
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- with these data included, offsets follow linear trend, with one exception of
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  one data (3.8 GeV)
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- Can Richard/Ali take another look at the replay of the 3.8GeV Heep data,
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  there is clearly something wrong with it, maybe a wrong BPM calibration, or
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  an error in standard.kinematics?
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- to extract the final offsets from the linear fit:
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  - need to locate the first order SHMS expansion coefficient in Matrix Element
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    file
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  - need plots of BPM data for several Heep coin settings
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    - will differ from online results, due to newer calibration
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    - offsets of up to several mm are reasonable
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    - in principle, only 1 setting is needed, but best to do at least several,
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      to check for consistency
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Next Meeting
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------------
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- Thur Sept 7 @ 16:00 Eastern/14:00 Regina/13:00 Pacific
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- KaonLT will go first
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- Poll to see if this meeting time will continue to work for the fall
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  https://www.when2meet.com/?21121667-zMYFn
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  - so far, the best time appears to be Tuesdays at 16:00 Eastern/14:00 Regina
(281-281/443)