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Kaon LT Meetings » mtg_23may25.txt

Garth Huber, 05/26/2023 12:16 PM

 
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                 May 25/23 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, Ali Usman, Muhammad Junaid, Nathan Heinrich, 
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   Portia Switzer, Alicia Postuma, Love Preet, Vijay Kumar
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FIU - Pete Markowitz
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Ohio - Mark Mathison, Julie Roche
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CUA - Richard Trotta
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JLab - Dave Gaskell
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CSULA - Konrad Aniol, Jonathan Conrad
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Richard Updates
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---------------
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Spend most of last week on thesis writing, so only a short update
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- tried fixing UpRoot script issues
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   - converting lists to NumPy arrays, these should be faster and more compact
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     and address some memory issues
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- working on Lumi scans with Coin physics data, needed to modify some scripts,
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  still waiting for jobs to finish running
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Ali Updates
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-----------
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OOP offset studies
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- since SIMC xptar are non-zero, now subtracting Data-SIMC xptar values
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   - Left: same as last week, Right: Data-MC
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   - only slight movement of points, clustering slightly tighter
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- include 3 Heep points from Summer 2019 run
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   - these have Pp/Pe ratio near 1
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   - fortunately, the 3 new points continue the main linear trend as the others
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   - now it's much more clear that is one outlier at highest Pp/Pe~1.3
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   - this point is Heep with 4.9 GeV beam
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   - the other low Q2 KaonLT run at 3.8 GeV is on the correlation, with
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     Pp/Pe=0.83
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   - actually the two points have nearly the same xptar computed y-axis values,
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     but they are at very different Pp/Pe ratios, so one point is on the
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     correlation and the other is far off it
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   - curious to see if *BPM* will explain the outlier
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- some discussion about the fact that the linear trend is with a positive
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  slope, while the plot in Tanja's thesis is with a negative slope
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   - DG: need to keep in mind the role of the HMS has switched from Fpi-2.
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     There, HMS was the proton arm, here it's the electron arm
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     This means you need to compare the slope of HMS in TH plot to offset of
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     HMS in AU plot, since the spectrometer roles are reversed
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- some discussion about how to check the BPM value to see if the outlier can be
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  discarded or not
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   - DG: hcana already corrects for the beam position in the optics, so you
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     just need to be sure BPM position is held constant
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      - if the BPM value (extrapolated to target) is much different, then can't
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        use this run for OOP offset study
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   - VK: found a variable in hcana, is it the correct one?
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     H.rb.raster.fr_ybpm.tar
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      - DG: yes, it sounds like the right variable, would need to look at the
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        hcana to be 100% sure
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         - this is in BPM coordinates: y-vertical, x-beam left
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      - NH: even better, simply compare the variable values with a hand
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        calculation of the beam position at target, extrapolated from BPMs
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        3H07Ay, 3H07By, 3H07Cy
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- started looking at in-plane offsets using Heep-Check program, will present
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  results next week
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Vijay Updates
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-------------
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HMS Calorimeter Efficiency studies
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- physics data with new cuts, ~99%
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- Heep data, ~99.9%
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- DG: please re-check if using Binomial Errors on the Eff Calc, as the errors
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  seem a bit large
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- DG: need to be careful with the Calorimeter Efficiency at low HMS momentum
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   - at very low P, the shower peak is broader
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   - for a constant Calorimeter cut, expect the efficiency to drop off at low
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     momentum
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   - VK: lowest momentum for Heep runs is P_HMS=1.73 GeV/c
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     lowest momentum for physics runs is P_HMS=0.544 GeV/c
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     So clearly this will be an issue, and we can't use only the high momentum
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     Heep runs to determine the efficiencies for low momentum physics settigns
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   - KaonLT should also check, there is probably a physics setting with P_HMS<1
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     GeV/c
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- Suggestions:
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   - for next week, please show a HMS Calorimeter distribution at low
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     momentum, it is probably broader
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   - VK comments that yes this is an issue, he's using a much lower
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     calorimeter cut for these low momentum runs (>0.2)
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   - DG: please pick a fixed cut and plot all efficiencies versus P_HMS, you
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     should get a smooth curve showing the drop off at low momentum
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   - also, confirm that Binomial errors are being used
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Alicia Updates
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--------------
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BSA analysis
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- looking for a newer version of VGG code, ours doesn't calculate LT'
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   - JR: DVCS no longer uses VGG as it doesn't fit our data very well
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     there is a new model from CEA called PARTON3D, I'll send information on it
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   - RT: suggests that GH send an email to Meson WG
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- simluated pi+Delta0 channel, to see if it contributes the tail seen in high
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  -t MM spectra
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   - pi+Delta0 contributes significantly to bins 4,5 but at higher missing
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     mass, does not contribute to the pi+n tail
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   - there is clearly also room for 2pi-n phase-space before the pi+Delta0, but
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     this has a threshold of MM~1.08, and also should not contribute
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     significantly to the tail
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   - DG: agrees this is not the cause of the tail
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      - suggests to make a *plot* of MM vs delta for the high -t data, to see if
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        there are any weird *correlations*
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   - GH: thinks the issue is that there is an aspect in the radiative
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     corrections model that doesn't work so well for the higher -t data.  This
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     deficiency was probably not visible at 6 GeV, where the momentum transfer
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     was lower
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   - at any rate, AP will proceed with the cut-dependence studies, clearly the
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     higher -t bins will have a larger systematic due to the tail and we will
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     just have to live with it
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- coming tasks:
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   - Ali and Alicia need to meet to discuss t-binning
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   - re-extract sig_LT' for all settings
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   - MM and CT cut dependence studies
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   - need to go through the info on Beam Polarizations from Steve Wood
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Nathan Updates
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--------------
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HMS Cherenov calibrations
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- did more calibs on runs around the strange behavior periods, so that each
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  calibration goes up to the end of a given kinematic setting.  It's probably
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  not a good idea to change calibrations part-way through a setting
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- 4 regions chosen, giving 4 different calibrations
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   - error-weighted averages used to determine the calib for each one
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- updated standard.database and pushed to GitHub
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- looked at effect of new calibration for various runs, compared to online
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   - 2D plot of HMS Cherenkov vs Calorimeter doesn't show much difference
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   - probably not surprising, since many of the selected runs have online
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     calibrations that are close to the new ones
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   - will look for a run where the calibration difference is larger, as a check
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   - JR: the #events seems lower for offline than online
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      - NH: yes, the cuts are a bit different now, tighter
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Working on NGC calibrations
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- found a bug in code, alerted Cameron Cotton, NH already fixed it
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- looking to implement Petr Stepanov's multi-Gaussian peak fit that was used in
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  Aerogel calibs
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   - for the Aerogel, we found that this gave a better calibration than a fit
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     with a simple Poisson distribution
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Junaid Updates
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--------------
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- no report, working on reports for Proton Structure class
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- next week: SHMS DC calibs
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Next Meeting
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------------
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- Thur June 1 @ 16:00 Eastern/14:00 Regina/13:00 Pacific
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- PionLT will go first
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- DG has agreed to take notes on June 1,8 as GH will be unavailable in Europe
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