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Kaon LT Meetings » mtg_23may04.txt

Garth Huber, 05/05/2023 03:39 PM

 
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                 May 4/23 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                                 (Notes by GH)
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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 - Nathan Heinrich, Ali Usman, Alicia Postuma, Love Preet, 
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   Muhammad Junaid, Portia Switzer, Garth Huber, Vijay Kumar
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Ohio - Jacob Murphy, Julie Roche
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CUA - Richard Trotta, Tanja Horn
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CSULA - Konrad Aniol
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FIU - Pete Markowitz
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JLab - Dave Gaskell
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Nathan Updates
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--------------
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HMS Cherenkov Calibrations
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- sees two peaks in PE spectrum, behavior is puzzling
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   - selects low calorimeter energy, low peak doesn't change
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   - selects electrons with calorimeter, only low peak present
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   - both peaks are at very small amplitude <20, most of the histogram up to
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     100 is empty
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- electrons appear to be in lower peak and pi- in upper peak, but this makes no
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  sense
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   - we are confident that the detector is working properly, because the 50k
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     detector replays during the experiment made sense, something else must be
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     wrong with the analysis
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- GH had earlier suggested looking into timing cuts
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   - cuts are a little wide, could be tighter
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- HMS Cherenkov detector time cuts
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   - PMT#1: 3 peaks
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   - PMT#2: 2 peaks
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- DG: could Cermode-0 be causing issues?
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   - NH: hasn't looked yet at mode-10 data, but could
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- DG would like to look at the data
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   - root trees are in Nathan's volatile directory
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Later in the meeting, we return to this topic
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- DG makes a plot of H.cer.goodAdcPulseInt with 
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  H.cal.Etotnorm>0.7 & abs(H.gtr.dp<8) cut
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   - sees a more sensible distributino where pi- have 1PE peak ~25 and e-
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     distribution is ~60-160
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   - DG: please look at run interactively first, not a fan of running a sript
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     until you know what the script needs to do
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   - somehow NH is not selecting the electrons
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Junaid Updates
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--------------
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- Nathan, Jacob and Junaid had a discussion earlier this week on PionLT
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  analysis timeline
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   - the updated schedule is posted on the Wiki at:
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     https://redmine.jlab.org/projects/hall-c/wiki/Analysis_Tasks
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HMS DC Calibrations
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- looking now at LH+, LD+ runs.  For LD- runs, is it better to use pi- or e-?
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   - DG: e- are probably easier to calibrate, drift maps should be equally
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     valid for both
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   - GH: also probably more e- than pi- for many LD- runs
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- HMS Drift Distance distribution for different Planes
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   - new calibrations are a significant improvement, residuals looking much
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     better
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   - sharp peaks at both ends of drift distance spectra
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   - DG: Cameron Cotton needed to place Multiplicity Cut=1 to avoid extraneous
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     peaks at end
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      - the calibration algorithm needs clean single track events so this makes
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        sense, and should probably also improve the calibration result
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- still working on SHMS DC calibrations, will need same Multiplicity Cut
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Jacob Updates
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-------------
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Results of delta-optimizations from 2022 run
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- 6.8 GeV/c HMS delta-scan
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    - delta_true-delta_recon sees improvement
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    - W_calc vs X_fp, after corrections the slope is largely gone, centered on
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      right W value
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    - still have a correlation for X_fp>35
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    - GH: since these are a small portion of the events, maybe try placing a
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      cut and fitting only the large X_fp separately
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- 5.9 GeV/c HMS delta-scan
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   - delta_true-delta_recon still not quite lined up at zero
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   - W_new vs X_fp, boomerang shape near X_fp~0 after calibration, but overall
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     W peak is narrower than before
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- working on optics work chapter of his thesis
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   - Nathan asked for an operation manual on the optics, will base one on his
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     thesis chapter
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- Next Plans
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   - once done writing chapter, then help with Calorimeter calibrations, since
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     there are a lot of them to do
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Richard Updates
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---------------
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Proton leakthrough issue that we discussed last week
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   - some cuts were probably not applied correctly, a cut-and-paste issue
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   - no new results yet
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Luminosity studies
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- met with Jacob on PreScale Calc to be sure it's calculated correctly
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   - TLT calculation look fine
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   - scaler read code, discrepancies noted by CarlosY at Hall C software
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     meeting last week, couldn't find anything wrong
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   - Jacob noticed that Carlos' T3-scaler rates and BCM currents nearly
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     identical, which seemed suspicious
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      - T3 = ELREAL
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      - meeting with CarlosY tomorrow about this
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Small update on carbon 10.6 Lumi Run #1 w/ SHMS positive polarity
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- HMS carbon, LH2 scans
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   - restored some previously "bad runs", current cuts were too tight, only 6
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     sec data in some cases
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   - +2% carbon anti-boiling @ 65uA
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   - same value for LH2
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   - still investigating a few issues
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   - DG: the highest current/rate point is driving the fit, probably a flat
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     line would work, in which case no significant rate dependence
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   - GH: the fit doesn't look like it corresponds to minimum chi-square, is
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     this an error-weighted fit?
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      - RT: no.  Error bars are plotted, but not used in the fit
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      - it's important to ALWAYS do error-weighted fits, otherwise you get
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        artifacts like this, where the high rate point with larger error bars
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	drives the fit
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   - GH: to improve the statistical significance of the high rate region,
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     suggests to combine both sets of data
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      - if the rate/current effect is real, both will behave consistently
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      - first for each set of data extrapolate the fit to R=1 at zero
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        rate/current
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      - then use the extrapolated point to separately normalize both sets of
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        data
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      - then do a combined fit using both sets of normalized data
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      - that should give 2 high rate points instead of one
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      - if you truly see "carbon anti-boiling" then it indicates a rate
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        dependence that needs to be applied to all the data
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      - only after that step can the cryo boiling vs current be determined
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Ali Updates
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-----------
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BPM calibration issues
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- was using only one file for all KaonLT runs
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- there was BPM girder work in Feb 2019, so different calibs are needed for
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  10.6,3.8,4.9 GeV compared to 6.2,8.2 GeV and Summer 2019 data
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- DG provided a different calib file for 2019 data
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Comparison with no offsets - 8.2 GeV data
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- Left=Old, Right=New
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- PMdata has shifted significantly
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   - PMZ: shift larger, PMY: shift closer to SIMC, PMX: shift away from SIMC
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- Target variables
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   - xptar: HMS almost exact overlap w/SIMC now while there was a shift before
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   - SHMS also looks pretty good
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- HMS delta almost unchanged
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- 6.2 GeV data are similar, W distribution now worse
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DG: follow up on Vijay's email
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- DG's file assumes use of EPICS xpos variable from survey
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- Discussed with MJ, hcana uses the RAW variables, not the survey offset
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  corrected variables
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   - either set of variables will probably give a good result, but 
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     MarkJ says it's better to use the RAW variables if you want to compare
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     your results with those from other experiments
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   - GH: it's important to have the ability to cross-compare our offsets to
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     those from other experiments, so we can have greater confidence in our
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     result
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- DG: will generate new files early next week
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   - both the fall 2018 and spring 2019 files need to change, all data will
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     have to be replayed with the new calibs
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- summer 2019 data has a dedicated calibration by MarkJ
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   - in principle that calib should be the same as for spring 2019, will be a
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     useful cross check
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- DG will also look again at the 2021 BPM calibs
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   - slopes should not change in 2022, but offsets will, these can be
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     determined from the harp scans
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Plot of Raster_Y vs W
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- looks like a slight left pointing slope
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- DG: change sign on RasterY gain and see if it improves, hopefully it gets
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  more straight
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DaveG has to leave at this point.  He has agreed to take notes at next week's
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meeting in GH's absence
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Discussion on determination of OutOfPlane offsets in Tanja's thesis
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- what is beam offset D?
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   - the offset needs to be projected to the target, in a manner similar to
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     what was done in the counting house GUI used in PionLT
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   - use the closest BPM (x,y) values, and the (x',y') slopes between the last
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     two BPMs, then extrapolate to z=0
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- Ali shows plot of xptar_SOS vs formula from Tanja's thesis
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   - numbers are from means of xptar from both spectrometers, and errors on
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     means
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   - one offset comes from slope, the other from the offset
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- Ali will endeavor to make a similar plot from KaonLT data, using both the
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  3.8,4.8 GeV data to get more range
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Vijay Updates
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-------------
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Verbal update
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- working on HMS calorimeter and Cherenkov efficiency studies, and setting up
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  LT-sep software for second Q2
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- will also be starting low Q2 Lumi study
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Alicia Updates
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--------------
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BSA progress
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- 5 (Q^2,W) settings with full phi-coverage @ 10.6GeV
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   - submitting jobs for 2 (Q^2,W) that were not analyzed yet
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Systematic study on MM cut
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- looking at HGC and how it affects MM dist vs t
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   - magenta=data w/o HGC cut, K+ leak through
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   - blue=data w/ HGC
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   - grey=SIMC (weighted and scaled to data w/HGC cut)
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   - lowest 2 t-bins have good agreement between blue and grey, but significant
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     difference seen for highest 2 t-bins
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   - data much wider than SIMC at high -t
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   - for full data, without t-binning, the agreement fairly good, looks like
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     MM cut ~0.96 okay
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   - Julie: is this due to bad description of radiative tail at high -t?
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   - Tanja: gives link to 2010 document on the radiative corrections in SIMC
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     https://hallaweb.jlab.org/data_reduc/AnaWork2010/mkj_simc_mceep_radcor.pdf 
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      - radiative corrections not updated since then, probably not sufficient
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        for some regions of 12GeV data
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   - Ali: Alicia's data of course have no diamond cuts, since there is no
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     LT-separation
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      - hopefully the discrepancy between data and SIMC will be less at high -t
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        when the diamond cuts are applied
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- the good news is that no significant BSA variations are seen with HGC cut
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   - fluctuations are consistent with BSA error bars
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   - w/HGC Asin(phi) error bars ~60% larger than without
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   - preferring to not apply an HGC cut to the BSA data since the K+
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     leakthrough can be removed entirely with MM cut and then keep full pi+
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     statistics
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Next Meeting
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------------
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- Thur May 11 @ 16:00 Eastern/14:00 Regina/13:00 Pacific
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- KaonLT will go first
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