Kaon_LT Experiment

                 Aug 22/24 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                     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 - Garth Huber, Ali Usman, Alicia Postuma, Muhammad Junaid, 

   Nathan Heinrich, Vijay Kumar, Nacer Hamdi

Virginia - Richard Trotta

JLab - Dave Gaskell

Ohio - Julie Roche

CSULA - Konrad Aniol

Richard

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KaonLT Q2=3.0, W=2.32 setting

- HMS-delta shows lots of discrepancies between Data and MC distributions, they

  peak in different spots and have markedly different shapes

- HMS-delta vs XPtar, unweighted MC dist fills the same phasespace as the data,

  but distribution is much different

  - the fact that the filled phasespace has the same shape is good news, so

    it's a weighting issue, not something more fundamental

  - the MC functional form must be completely inappropriate for these

    kinematics

- SHMS-delta vs XPtar, data have a weird banana region at delta~0 that is not

  shown in the MC

  - data are not pion subtracted, so maybe it's a pi+ leakage issue?

- *NB* it's important to be sure the data dists are clean from pi+ leakage when

  making comparo to MC.  Next time, please also show a MM plot of the data used

  for the distributions, so we can see how much contamination there is.

Nacer

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KaonLT Heep Studies

- concentrate on 8.2GeV data, where Exp/MC=1.12

- MM dist shows a small bump at pi0 threshold that needs to be removed

  - it would be best if this could be removed with some cut with less

    cut-dependence than MM, but that might not be possible

  - Ali: *NB* select just the pi0 events with a MM cut and see where they end

    up in the other distributions

- the Heep MM distribution is much narrower in MC than Data

  - *NB* need to use Ali's resolution tuning result in the MC, so that the MM

    distribution gets closer to the data

  - probably will eventually need to use a MM>0.10 cut, so it will be important

    that the MC more closely resembles the data, to reduce the cut dependence

    - *NB* a MM cut dependence study would be required as well

- closer look at the Exp Yield ingredients for this setting

  - two notable low effs are EDTM_LT ~89.5% and SHMS_Hodo-3/4 ~97.3%

  - concentrate on the EDTM for now

  - extracts ElecLT from two methods:

    1) ElecLT=EDTM/CPULT  2) calculated from 55ns Hodoscope discriminator width

    - method 1:

      Run 7974  ElecLT=95.6%, 7975=99.4%, 7976=99.6%

    - method 2: some discussion on how to correctly calculate this

      - need the total trigger rate from both arms

        HMS: ELREAL rate  SHMS: 3/4-trigger rate

        The total of these two is about 4kHz

    - Dave: the Hodoscope discriminator width should always be 55ns, so Method

      2 should work the same way for all beam periods, even when the trigger

      timing changes

  - Dave: *NB* please compare the beam current for these 3 runs and the %time

    that the beam current is over threshold, so we can better understand the

    variation between run 7974 and the others

- plots shown of HMS-delta and SHMS-delta vs MM

  - the Heep data distribution has a blob on one end while the MC distribution

    is more uniform

  - this blob can't be due to pi0 contamination, since it occurs at elastic MM

  - *NB* also need to investigate use of different HMS-Matrix Element for

    intermediate momenta, as suggested last week

    - *NB* setting up an offline meeting on this w/ Dave would be a good idea

Junaid

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PionLT Heep study

- 2022 data had a broader EM distribution than others

  - fixed raster correction, dists now sharper, more similar to 2021 data

  - extracted new mean values and gave to GH for Offset Fitting

- looking at efficiencies to better understand non-unity Exp/MC ratios

  - SHMS_Hodo-3/4 effis are low ~89%

    - Plane-by-Plane efficiencies show a decreasing efficiency with plane

      number

    - Plane 4 (the quartz bars) has an eff of only ~61%

  - *NB* suggest to look at efficiencies vs rate, if it is real there will be

    correlation, if it is something else, it will be more random

- also looking at pi0 contamination study, given Nacer's findings

Ali, Alicia, Vijay

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- no reports

- congratulations to Vijay on the successful PhD defense!

Future Meetings

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- the current time will not be good for both Julie and Nacer due to conflict

  with teaching

  - Julie will be available at 4pm and 11am Eastern

- GH will set up a poll to find a new time, starting in September

 Next Meeting

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- Thur Aug 29 @ 15:00 Eastern/13:00 Regina

  - PionLT will go first