Kaon_LT Experiment

                 Feb 22/24 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                     Today: PionLT 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 - Nathan Heinrich, Garth Huber, Ali Usman, Alicia Postuma,

   Muhammad Junaid, Nacer Hamdi

CSULA - Konrad Aniol

CUA - Richard Trotta, Tanja Horn

York - Stephen Kay

FIU - Pete Markowitz

Nathan

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Writing Lumi analysis script for PionLT

- modifying script from Richard, which always assumed an active HMS and SHMS

  trigger for each run, as some PionLT Lumi scans were single arm only

- had to make similar edits earlier for CoinLumi script, so confident of the

  needed changes

- edits made, still testing

Script for plots for SHMS NIM paper

- started to modify old plotting script

- looked briefly so far at the draft NIM paper text

- once the plotting code has been run, will look up needed details for the

  paper

Junaid

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PionLT efficiency studies

- investigating outlier runs identified last week, about 30 runs in total

- will make some decisions soon on which runs to discard

- then will post efficiency slides on RedMine

Ali

---

SIMC resolution study

- on hold until Alicia finishes HMS delta-correction study

Setting up for pi+n LT-analysis

- replayed 3 of 5 settings so far (both epsilons)

  - of these, analysis completed for 2 of 3 settings

  - will give Richard clean pi+n data for subtraction

- updated SIMC w/ physics_iterate.f model

  - compared to Vijay's code, almost identical except for different Q2-settings

- looking at Richard's LT-sep scripts, hoping to have some initial ratios soon

Info re HGC cut issue

- no HGC cut intended to be used for pi+n analysis, get a small K+L leakage,

  but in MM region well above pi+n

  - this means pi+n analysis will also not need an HGC efficiency to be applied

  - on the other hand, pi+Delta0 region is affected by K+L leakage, and will

    need an HGC cut as well as an HGC efficiency to be applied

- the pi+ sample for Richard will not have an HGC cut applied

  - will give skimmed ROOT files w/o HGC cut to RT, he will have to apply the

    HGC cut before subtracting pi+ leakage sample from K+ data

Richard

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Comparing SIMC model to preliminary data

- looked at 4 of 6 settings (including Q2=0.5)

  - Q2=0.5 has lots of issues that he will flag for Nacer to eventually look at

  - standard.kinematics issues:

    - need to confirm that CoinTime offset is set correctly for EVERY run

    - SHMS_RF_Offset was also not set for some low Q2 runs

Initial look at Q2=2.115, W=2.95

- all LT, TT terms set to zero for now in model

- sigL model: adjusted exp(|t|-0.2) factor to exp(|t|+0.2), seems to give more

  stable ratios vs t

- sigT model: compared p5+p6*log(Q2) with alternative p5*log(Q2)+p6/Q4

- also compared to Tanja's global K+ analysis in PRC 85, 018202 (2012)

  - checked W-factor and sigT models in this paper

  - W dependence: tried changing W-factor=1/(W2-Mp2)^2 to 1/(W2-Mp2)^3

    - Tanja's paper has the power as 2.5

  - when changing the W-factor, found that the sig_UNS expt error bars changed

    a lot, which should have not happened

    - this indicates a coding error that needs fixing

- then tried sigT=p5/(1+p6*Q2) and old W-factor

  - manually changing p5 from 120 to 25 gave better ratios

  - doing things by hand right now, instead of using MINUIT to get new params

Initial look at Q2=3.0, W=3.4

- same procedure, changing sigT and sigL factors

- lowering sigT p5 param improves ratios, just as at Q2=2.115

- *WARNING* data have NO MM-cut applied at all, not only do the exp yields

  contain pi+ and proton leakthrough, they also include all K+ contributions

  from inclusive spectrum above Lambda peak

  - right, now sees a weird phi Left-Right asymmetry in the data

  - the experimental yields will CHANGE SIGNIFICANTLY once Richard has a clean

    sample

- Ali offers to generate for Richard also a clean proton sample for subtraction

Initial look at Q2=3.0, W=2.32

- looked at using W-factor with ^3 exponent

- getting negative sigL for lowest -t bin, CAVEATS in data as above

Compared initial results vs x_B

- early indications that a systematic change in the model vs x_B will be

  needed, will be interesting if this holds up in more thorough analysis

GH: as a reminder, we will eventually have to look again at the residual

  Q2-dependence of the Heep-Coin ratios, and resolve this issue before we can

  finalize the data and publish

  - this should happen after Richard graduates

Alicia

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Implementing HMS delta-correction, hsdelta_NEW=hsdelta-p0*hsxpfp

- took MM calc from Richard's reconstruction script and implemented calc for

  data

- as a check, compared new MM calc w/p0=0 to old MM calc

  - overall very similar, but a slight difference between them

  - plot difference in #events vs Mx, most pi+n events within +/-2 MeV compared

    to old MM calc

- best guess is that there is some rounding error difference in the HMS

  momentum calc compared to hcana when applying offsets

  - GH: as a coding check, can try comparing old and new MM w/o offset

- then applied Dave's p0 values and compared the old-new data

  - MM gets wider instead of narrower, something still seems wrong

  - GH: suggest to make a plot of hsdelta_NEW vs hsxpfp to see what kind of

    correlation you get, should be a straight vertical band if applied

    correctly

  - Alicia will send her script to Richard for review

Nacer

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Low Q2 KaonLT calibs

- finished DC and Hodo timewalk calcs

  - pull request to GitHub was accepted

- did a full replay, including all of Ali and Richard's improvements

- plot of EDTM vs Coin_trig_rate

  - sees sharp drop off above 2.7kHz trig rate, as expected, due to buffered

    mode data acquisition (good news)

- plot of COIN_CPULT vs COIN_trig_rate

  - similar behavior, looks good

- plots of HMS(e), SHMS(pi) SING_TRK_Eff vs S1X hodo rate

  - no HMS outliers

  - a few SHMS outliers that need investigation

To Do:

- check other plots

- move to K+ PID

- also should get Lumi scripts from Richard and look at Low-Q2 Lumi scans

Next Meeting

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- Thur Feb 29 @ 15:00 Eastern/14:00 Regina

  - KaonLT will go first