Kaon_LT Experiment

                Oct 10/25 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, Alicia Postuma, Nathan Heinrich, Nermin Sadoun,

   Vijay Kumar, Nacer Hamdi, Muhammad Junaid

FIU - Pete Markowitz

CUA - Chi Kin Tam, BC Manoj, Tanja Horn, Sameer Jain

Virginia - Richard Trotta

Ohio - Julie Roche

CSULA - Konrad Aniol

JMU - Ioana Niculescu, Gabriel Niculescu

Vijay

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Summer 2019 PionLT data analysis

- CoinBlocking correction

  - made plots of CTime.CoinTime_RAW_ROC1,2

    - ROC1 plot is cleaner than ROC2, will use this one

  - found oscilloscope traces of trigger timing at logentry #3655655

    - based on oscilloscope tracs, the timing cut window should be ~140ns wide

- pion absoprtion correction

  - will apply correction previously determined with Alicia's Geant4 simulation

Sameer

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KaonLT high Q2 CoinBlocking correction

- looking at Q2=2.115 data taken on 2018.10.02

Chi Kin

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KaonLT Q2=3.0, W=3.14 data analysis

- MissingMass checks

  - applying cut 1.10<MM<1.14 to select K+Lambda region for both data and MC

  - pion subtraction applied to data

  - previous error needing large MM shift to data was fixed, the shift is only

    a few MeV now.  However, correcting both data and MC, as neither are at PDG

    mass

    - *NB* Tanja: you need to remove the MM shift from the MC, the Lambda peak

      will be at a mass slightly higher than PDG value due to energy loss in

      the target and other materials.  Just shift the data to the MC peak

      position

- Data & SIMC plot comparisons

  - various differences in the distributions, particularly for right SHMS

    setting

  - Gabriel: pion leakthrough subtraction has a different delta-distribution

    than K+Lambda data, how do you correct for this?

    - Richard: shows Q2=4.4 pion subtraction

      - needs to add an empirical fit underneath the Lambda, Sigma peaks that

        is not removed by the pion leakthrough subtraction

      - RF timing information was added mid-way through Q2=3.0, W=3.14 setting.

        The Q2=5.5 setting has it, so these data have much less pion

        leakthrough than the other settings.

  - Tanja: Chi Kin is intentionally treating the background different than

    Richard, so we can better understand how reproducible the results are

- LT-sep iterations with 10 phi-bins

  - after 4 iterations, Data/MC ratios are much closer to unity

  - L/T/LT/TT functional forms are the same as Richard's, but parameters are

    different

  - separated cross section ratios are fairly stable from IT=0,4,8

  - Julie: the Data/MC ratios have phi-dependence, but the sig_uns are flatter.

    Does this mean the model has a larger (and wrong) phi-dependence compared

    to the data?

    - Tanja, Garth: yes this is what it means.  The LT/TT cross sections are

      determined directly from the Rosenbluth fits of sig_uns.  It will be

      important to confirm the model dependence in the result is small.

Alicia

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Difficulties re-submitting the pi+n BSA paper to PhysLettB

- editorial manager portal has changed completely since initial submission

  - need to upload XML info for all authors via undefined "standard procedure"

    - no guidelines given, following INSPIRE-HEP instructions for now

    - using ror.org Research Organization Registration for institution

      addresses, which is helpful

  - need to include ORCiD numbers for all authors included in MetaData.  Did a

    lot of work to find ORCiD for most people, but a few have left the field and

    don't have one

 - Tanja: please contact Haiyan Gao directly, including screenshots of where

   you're encountering problems

Richard

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Computer Physics Communications paper on LT-function fitting algorithm

- combined Fpi-2 data for both Q2=1.6, 2.45 into one dataset (t-dep only) and

  put it through the fitting algorithm

  - algorithm improves the Chi-squared compared to earlier results

- got CSV files from Vijay(pi+n) and Nacer(K+L) on their separated

  low Q2 cross-sections

  - next step will be to include these in the fits

Q2=4.4 LT-separations

- data has pion subtraction and empirical fit underneath Lambda

  - no Sigma fit is included

  - equations slightly different than what Chi Kin is using

- Data & SIMC plot comparisons

  - center SHMS setting, SIMC has narrower Q2,W-distributions than data

  - acceptance plots look good for both SHMS settings

- Data/MC ratios between 0.75 and 1.5

  - surprisingly, the lower -t bins have worse ratios than high -t bins

    - might be a pion leakage issue at low -t, Richard will have to look into

      it

    - *NB* Tanja: please make a comparison of Richard and Chi Kin's

      background subtractions for this setting

- made a weighted verage of phi-bins at each epsilon similar to what Vijay

  showed last week

  - it shows that high epsilon>low epsilon, which is good news

  - sigL<<sigT for all bins

  - Garth and Tanja willing to compare separated results with VGL model when

    things are ready

Nacer

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KaonLT Q2=0.50 LT-separations

- rechecking Data & SIMC MM distributions to be sure pion leakthrough is not an

  issue

  - to recap, sigL has a surprisingly large peak at low -t that is suspicious

  - RF timing cut is available for these data, so pion contamination is small

  - Data/MC ratios are fairly flat 0.8-1.2 at low epsilon, some phi-oscillations

    at high epsilon, particularly for higher -t bins

  - shows MM plots for 7 t-bins for center SHMS low epsilon, then shows for

    t-phi bins (i.e. dividing each t-bin into phi bins)

    - pion subtraction looks very good, no evidence that background is the

      cause of the weird sigL at low -t

    - *NB* Garth: SIMC normalization seems off for t-phi bins, compared to

      t-bins, plotting script needs to be rechecked

- will go back to model optimization

  - had LT=TT=0 functional forms in model

  - earlier, had tried Fpi-2 parameterization, but this gave bad ratios, so

    stopped

  - then tried changing LT,TT functional forms to same as L,T forms in

    sig_factorized_2007.  This looks more promising, so will do more iterations

Nathan

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PionLT Coin Lumi analysis

- calculating systematic uncertainties on Coin Blocking correction

  - will move timing cuts by 5 ns in and out

  - *NB* Vijay: suggest to take 1 beam bucket (4ns) left and right instead

  - will take symmetric cuts around main distribution for systematic

    uncertainties

    - Garth: unless there is a good reason for asymmetric cuts in the error

      analysis, suggest to keep the cuts as symmetric

- calculating LiveTime systematic errors

  - compared CPU*ELLT to EDTM values

  - the difference gave a ~4% difference at high coin rate, which is

    suspiciously similar to the AdHoc correction discussed earlier

    - Garth had suggested to recalculate the normalized coin yields (after Coin

      Blocking) with EDTM instead of CPU*ELLT

      ** the resulting distribution is flat, which means no AdHoc correction

      ** would be needed

    - clearly this means the EDTM is capturing some element of deadtime that

      CPU*ELLT misses

      ** will use EDTM for all coin data, and no AdHoc correction!

      - EDTM is still unreliable for singled data though

- will need to evaluate a systematic uncertainty in the EDTM

  - suggests to fit each TLT vs Rate for each CoinLumi setting and look at the

    spread of points from the fit curve

  - concerned that simply combining the variations between the settings, as the

    TLT differences them (at same CoinRate) are probably real

  - *NB* Gabriel: suggests to make a histogram of the residuals between the

    data and fit function and see if this gives a Gaussian distribution

  - *NB* Julie: the used logarithmic fit diverges at zero rate.  It's important

    to switch to an exponential fit that goes to 1 at zero rate

Junaid

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PionLT Q2=3.85 LT-separations

- working on LT,TT functional forms to reduce oscillations in Data/MC ratios

  - ratios are 0.8 to 1.2, but with 2-bump oscillations coming from TT

  - Rosenbluth fits give sigL>sigT at low -t and fairly small LT,TT

  - will need to modify the sigTT functional form

  - sigLT functional form seems fine, based on much smaller 1-bump oscillation

    in ratios

Nermin

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PionLT data analysis

- met w/ Junaid on hcana software setup

- reading up on Hall C detector systems

Next Meeting

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We will try our new 2-meeting/week structure

- Thurs: Oct 16 @ 16:00 Eastern/14:00 Regina

  - PionLT will go first

- Fri: Oct 17 @ 11:00 Eastern/9:00 Regina

  - KaonLT will go first