Kaon_LT Experiment

                 Octt 3/23 PionLT/KaonLT Analysis Meeting Notes

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                            (Notes by GH, AH & RT)

                     Today: KaonLT will be discussed first

Please remember to post your slides at:

https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings

Present

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Regina - Alicia Postuma, Muhammad Junaid, Nacer Hamdi, Nathan Heinrich,

   Vijay Kumar, Garth Huber

CUA - Richard Trotta

FIU - Pete Markowitz

Richard

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Q2=2.1 R=Data/SIMC plots vs phi for t-bins at low, high epsilon

- Sync the range of angles between SIMC [0, 2Pi] and hcana [-Pi, Pi]

  - added pi to hcana phi

- high ratios at phi=240,280 deg consistently for all 3 t-bins, SIMC events go

  to zero for these bins

  - unweighted distributions show events in these bins, so it is presumably a

    weighting issue

  - sigTT is calculated way too large for some bins as well

- using starting parameters from LD+ Fpi-2 analysis

  - no changes to t-average calculation yet

  - m_pi pole factor not yet modified for m_K

  - no (Q2,W) scaling appiled yet to leading parameters

    - this may solve the issue, the important thing is to estimate a set of

      initial starting parameters that behave reasonably, Richard will need to

      do a by-hand calculation to find them

Some high epsilon data have two slightly different TH_shms, e.g. some right

setting data were taken initially and came back to take more statistics later,

the TH_shms differ slightly between the two sets

- Garth: for the experimental data, need to select the right angle for each run

  number in standard.kinematics

  - for SIMC, if the difference is small (typically 0.005deg), run SIMC using

    the mean angle of the data (weighted by the accumulated beam charge)

Still running Heep for offset check

- getting ifarm replay errors: SLURM FAIL

- Nathan also has ifarm issues since Friday

- will follow up with IT tomorrow

Vijay

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Sent Heep plots for new offsets to GH yesterday

- looking at comparison of tar and spectrometer variables between data and SIMC

  after reconstruction script

Lumi studies will start son

- low current BCM calibs are very important to the low Q2 data!

Nathan

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Hodscope calibration ongoing (V_prop 2021 data)

- met w/Junaid to explain the calibration process

- batch errors lead to slowing calibration jobs

Junaid

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Helping Nathan with Hosdoscope calibration (V_prop 2022 data)

- was using Stephen's old scripts, now switched to new scripts

- one of the points of NH and MJ work is that we don't know how many different

  sets of V_prop will be needed, so need to calibrate a selection of all data

  to study parameter stability

  - V_prop is a whole matrix, so many more parameters than time offsets

- using interactive so far for script testing, so not yet delayed by ifarm

  issues

Alicia

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HGC vs. Aerogel Cherenkov NPE (10.6 GeV data)

- Noticed negative NPE in the HGC! 

  - 2D plot of HGC vs Aero

    - events w/ HGC npe<0 but Aero having 5-20 npe

  - needs some investigation of the HGC calibration for these runs

- Vijay quickly confirms that HGC calibrations for 10.6 GeV data were done for

  runs 4875-5325

  - first step is for Alicia to confirm that she is using the correct

    calibration files

Nacer

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- going through event selection & variables for low Q2 KaonLT data

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Post-Meeting on CoinTime leakage in 10.6GeV KaonLT data

- Dave, Richard, Alicia, Junaid, Nacer, Vijay, GH

Alicia shows plot of CT (range -30,30+log z) vs MM (pi+n PID)

- mmpi_10p6.pdf

- see a band with good pi+ MM over a wide range of CT

- the behavior is atypical, but could be due to poor CT timing resolution

  during 10.6GeV run, which was fortunately fixed before rest of KaonLT run

- Nacer confirmed at Regina group meeting that this behavior is absent in 3.8

  GeV data, no CT band at pi+n mass

- Dave: Why is the band not through whole region?

   - Should be at other MM peaks (ie K+lambda)

   - Is it just because pi+n is so large, and harder to see in lambda?

     - this is most likely the case, Alicia changes some cuts to select

       pi+Delta region and the problem seems to be there too, although more

       washed out in MM

- Dave: can have singles within cointime window and steal the good time

  (making it show up at bad time) although the tracking algorithm still picks

  up the correct MM

  - In general, this should have a very small probability, unless timing

    window cuts are wide open

    - need to treat CoinTime like any other detector and place time windows on

      both legs into CoinTime module

Richard confirms that Timing windows for KaonLT hallc_replay are set:

github.com/JeffersonLab/hallc_replay_lt/blob/LTSep_Analysis_2022/PARAM/

  TRIG/KaonLT/PARAM/tcoin.param

- *Alicia* will double check that this is set the same way in hallc_helicity

  analysis

*Richard* needs to add CT vs MM for lambda analysis (log scale CT, no CT cuts)

to confirm whether he sees the same behavior

- we have to deal with the issue either way, but how we approach it would be

  different, whether or not he sees it

Dave: Maybe non-Gaussian behavior caused by the reversed signal to CoinTime

module causes it to broaden in the CT spectrum so we're seeing long

non-Gaussian tails

- Dave suggests: Check Heep 10p6, since no randoms shouldn't be seen for clean

  elastics.  This would allow us to estimate the size of non-Gaussian tails

This suggests two possible ways to correct for the issue:

- Dave's way: use Heep CoinTime distribution to estimate size of Non-Gaussian

  CT tails

- Garth's way: subtract "far randoms" from "close randoms" in physics data to

  get size of Non-Gaussian tails

- best to check both methods.  If consistent within errors, then can apply

  easier-to-determine Heep correction to 10.6GeV KaonLT physics data

Richard finds a Heep-COIN 10p6 replay that we can look at

- CT looks very asymmetric even here, non-Gaussian tails -25 -> -5 and +5 ->

  +20 ns (plot posted on RedMine)

  - heep_coin_time_10p6.pdf

  - Cuts applied:

    tv__tree->Draw("CTime_epCoinTime_ROC1","abs(CTime_epCoinTime_ROC1)<50 &&

    abs(hsdelta)<8 && H_cer_npeSum>2 && ssdelta>-10 && ssdelta<20 &&

    P_aero_npeSum<2","", 86385, 0);

Dave: Beta cut may be hiding the issue, a comparison may be useful

- Plot of P_gtr_beta vs CoinTime for Heep-COIN replay

  - ctime_vs_beta.pdf

- beta has a bifurcation that occurs outside usual cut abs(beta)<0.3

  - Richard and Stephen saw this effect with beta much earlier, but didn't

    investigate further

- Alicia coinfirms that 10.6GeV physics data have the same issue

  - cointime_beta_10p6.pdf

  - *Alicia* will explore CT vs beta to see if cutting it makes much difference

  - seems likely that we should remove beta cut as it complicates the

    correction for non-Gaussian tails, particularly since beta provides limited

    PID information at high momentum

  - Alicia and Richard will ask Stephen about this, but this CT asymmetric

    peak generally might be a good thing to bring up for the next Quarterly

    Analysis meeting

Homework:

- Alicia: confirm that tcoin.param cuts are applied correctly

- Alicia: explore CT vs beta to see if cutting it makes much difference

- Richard: confirm that get same behavior of CT vs MM (although Heep-Coin seems

  already to show this)

- Richard: compute Non-Gaussian correction both ways, and we will have to

  decide which method is more reliable to apply to data

GH checks logbook, and thinks the CT timing error was fixed by Brad on

2018-Nov-15

- https://logbooks.jlab.org/entry/3626796

- https://logbooks.jlab.org/entry/3626194

- This is during the SIDIS-CSV run between the 10.6 and 3.8 GeV KaonLT data

  taking

Next Meeting

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- Tues Oct 10 @ 15:00 Eastern/13:00 Regina/12:00 Pacific

- PionLT will go first

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