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Kaon LT Meetings » mtg_22nov16.txt

Garth Huber, 11/16/2022 01:08 PM

 
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                 Nov 16/22 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                           (Notes by GH and SJDK)
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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, Stephen Kay, Ali Usman, Alicia Postuma, Nathan Heinrich,
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   Love Preet
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CSULA - Konrad Aniol, Johnathan Conrad
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CUA - Richard Trotta, Tanja Horn
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JLab - Dave Gaskell
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Stephen Updates
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---------------
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- RF time correction updates
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   - the idea is to implement a path length correction similar to how the
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     coincidence time is corrected
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        CT-CT_raw +/- (eCorr-hadCorr)-Offset
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     where
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        eCorr/hadCorr are the time corrections for path length
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        Corr=Length/Beta*c
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        L_HMS=2200+(0.12*xptar*1000)+(0.17*delta)/100
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        L_SHMS=1810+(0.11*xptar*1000)+(0.0575*delta)/100
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   - first tried the method similar to Shuo's
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        RF=mod_4.008(RF_raw-FPtime+Corr_cent-Corr_delta+Offset)
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     Shuo applied the correction outside the modulus, which spreads the data
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     outside the 4.008ns time range.  Stephen applied the correction inside the
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     modulus, but also checked it outside the modulus to see if any difference
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     (none).
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   - this correction did not improve the RF time dists, if anything they
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     because broader instead of sharper, K/pi separation degraded
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   - the correction was only about 0.1ns, which is too small to improve things
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   - testing two new methods, results shown for method #1
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     1) add on TOF for path, use delta and calculated beta
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     2) determine difference between TOF w/golden track beta and calculated
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        beta and correct for this
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   - analyzed Q2=3.0, W=2.32, E=6.19GeV
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   - Looks like new RF time corrections depending upon particle type actually
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     helps flatten RFTime vs delta correlation
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   - RF peaks for each particle type are notably sharper, K/pi separation is
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     improved
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   - can apply a secondary correction to remove remaining tilt on K_CTime vs
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     K_RFtime plot, and further improve K/pi separation
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   - TO DO: add a separate RF offset for each particle type, so they're all
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     centered at zero
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Richard Updates
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---------------
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- Luminosity updates
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   - Started testing the beam current offset
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      - Clear rate dependence when offset applied, but applied offset was up to
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        2.5uA, which is an order of magnitude too large
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      - Mentioned would like to try adding offset in replay itself, due to some
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        weird issue with how current cuts are applied in the analysis script
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- Discussion of beam on/off cut being done by hcana
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   - DG: need to *remove* this cut!  it removes all flexibility in the hcana
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     analysis
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   - BCM offset should be applied directly to the yields, as a ratio between
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   - old and new Q
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     Dave method to apply correction:
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       cor = (Inom+offset)/Inom
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- Bill's LT-separation code
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   - Getting yields, but they don't make sense, some cut in the script, not in
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     the cut section
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      - Missed something small? Will check with Bill?
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   - Checking HeeP data
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      - Test runs
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      - Want same yields as Bill
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   - once the yields are fixed, each setting will need a separate script
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      - Some scripts (t_phi as an example) have hardcoded file names
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      - Will need to edit this
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      - GH: yes, some script-dependent scripts will be needed, since the
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        t-binning will be different for each (Q2,W) setting
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   - TH - *Prioritise* getting the scripts to work and getting to the cross
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          sections over the efficiency updates and making the code more elegant
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        - once you have everything working and have done one LT-sep iteration,
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          then you will have a better idea of what is important to optimize, or
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          not
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- Raster centroid moving in some runs
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   - DG - Only reason this would change is if beam trajectory is changing
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      - Should have fixed beam positions
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      - GH/TH/RT - We did have intentional beam position changes between some
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         KaonLT beam energies, had to redo carbon hole etc
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   - DG: in 6 GeV era, we would put beam offset into SIMC to reproduce beam
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     position in data
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   - hcana is "smarter" than the old 6 GeV analysis code, tries to correct
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     delta, etc. for the beam position
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   - TH/DG: try to find a way to *turn off* this hcana "improvement", since we
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     don't know exactly what it does.  Better to use old 6 GeV method, which is
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     robust, and not try to correct beam spot for actual position change
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   - DG does not know how to turn this off, consult w/MJ
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Ali Updates
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-----------
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- Trying to apply Peter B's offsets to the Heep data
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   - Global offset to HMS momentum
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   - Improves things marginally
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   - Makes one beam energy worse (this energy already looked OK)
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- Peter also applies a vertical angle offset in the HMS
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   - Assumed vertical angle is theta
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   - In hcana, which angle is xptar is a bit mixed up
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   - Found a bug: they are mislabled in hcana
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      - Offset in "theta" is actually on yptar
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      - To apply to xptar, need to apply on phi in hcana
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   - With offset applied, don't actually see any difference
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     Plots shown: W, Emiss, Pmiss components
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   - When applied to the wrong variable, it did actually have an impact
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   - Going to meet with Peter, when he applies these corrections to our data it
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     works
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- GH - hcana/SIMC variable calculations not exactly the same, should correct
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  this *first* before diving into this?
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   - Yes, will discuss with Richard and try to implement
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   - Other groups (e.g. SIDIS) just calculating variables themselves
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      - Some (e.g. Bircu) only looked at HeeP singles data
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   - DG suggests RT to talk to Carlos about the SIMC code modifications
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- Lumi discrepancies between Tracked & Untracked Yields
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   - trying to test different combos of tracking parameters, but ifarm jobs not
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     done yet
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- Error propagation for efficiencies
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   - Still need to go look at this
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   - Should use poissonian/binomial statistics?
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      - DG - Binomial more appropriate than Gaussian
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      - Effs are more like "flipping a coin" situation
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      - should be applied on most efficiencies
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Alicia Updates
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--------------
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- Making progress on helicity analysis
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   - Checking same data Steve Wood was looking at
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      - Steve had preliminary results, will compare results with his
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      - Q2=3.0, W=2.32, high epsilon
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- Updating analysis scripts
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   - Processing replays via the farm
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   - Should have asymmetry plots for these data fairly soon
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Vijay Updates (Presented by Garth)
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----------------------------------
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- In previous scaler luminosity plots, saw BCM offset related issue at low
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  current and a slow trend at higher current
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   - Vijay was taking a look at the ELT trend to fix the higher current
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   - Some TLTs over 100%, up to 105%
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   - Richard had most of these resolved?
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   - ELT taken as ratio of TLT to CPULT
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      - Due to TLT issue, see some strange outliers
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- When Vijay was applying ELT originally, was using 6 GeV method, which is
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  based on different gate widths for a scaler
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   - Numbers weren't crazy, but too low
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   - GH surprised these numbers existed, though that system no longer exists
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   - RT - Still in the script, but doesn't actually use them
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   - DG - Eric Pooser had this setup, but had to physically go and plug in the
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     relevant cable that you want for the scalers
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      - doesn't know what scaler was plugged in during KaonLT/PionLT runs,
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        probably ELREAL
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      - Values still read out, but probably not be useful
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   - RT suggests to use CPULT if TLT doesn't make sense
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      - for scaler analysis, this would mean applying NO correction
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Other Updates
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-------------
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- Richard has a picture of how the beam positions are calculated from the BPMs
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   - Will post photo on Redmine
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Next Meeting
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------------
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Wed Nov 23 @ 8:15 Eastern/7:15 Regina/5:15 Pacific
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- PionLT will go first
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