Kaon_LT Experiment

                 May 18/23 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 - Garth Huber, Ali Usman, Muhammad Junaid, Alicia Postuma, Nathan

   Heinrich, Love Preet, Vijay Kumar

CUA - Richard Trotta

Ohio - Jacob Murphy, Julie Roche

JLab - Dave Gaskell

CSULA - Konrad Aniol

Nathan Updates

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HMS Cherenkov Calibrations

- Last week, DG asked to tighten up the fit range, new results shown

- peculiarly, PMT1,2 gain parameters are anti-correlated for some run periods,

  runs where PMT1 is high, PMT2 is low

   - NH looked more carefully at Adc plots, everything seems okay, so the

     effect appears real

   - NH looked in logbook at time of outliers near run ~16250, nothing unusual

     was noted

   - DG: inclusive meeting on Wednesday (Cameron Cotton) sees something

     similar, depends on what background is underneath the 1pe peak

      - are all these at the same kinematics?  are different ranges of the

        focal plane illuminated?

      - NH: no, a variety of settings

      - the inclusive group decided to choose the run with the cleanest

        spectrum and go with it for those runs

      - NH brings up a pulse integral plot, much less bkd than what inclusive

        sees, DG agrees it looks pretty clean

- Discussion on picking run ranges for parameters

   - GH: try dividing runs into 3 groups:

      - for PMT2, all runs with gain >9, two groups with gain <9

   - error weighted means for the PMTS:

      - PMT1: 10.2 (looks reasonable), PMT2: 8.8 (definitely too low)

Next week: will also show initial results of NGC calibrations

Junaid Updates

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- no report, busy on Proton Structure class reports

Jacob Updates

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- no report, writing thesis

   - hopes to have a draft of the optics chapter ready soon

   - then will help Junaid with calorimeter calibrations

Richard Updates

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Carbon Lumi studies

- plot of HMS relative Tracked Yield vs ELREAL rate for all Carbon runs

   - used method suggested by GH to combine different settings by normalizing

     each one to zero rate

   - curve with combined settings is nicely consistent

   - error-weighted fit:

     get a slope of (2.1+/-0.995%)/100 kHz

- plot for SHMS is similar, except that rate is up to 250 kHz

   - slope is nicely similar (1.9%+/-1.0%)/100 kHz

- *Next* RT should move to doing same with Physics Lumi study to see if results

   are consistent

   - analysis by PeterB indicates that this will be definitive in deciding

     whether to apply a correction to the data

Problem processing large ROOT files

- met yesterday to discuss problem

- RT will make changes to the python code

   - inefficient memory usage caused by error in upRoot

   - everythng now uses List data structure, can change to NumPy arrays

   - if this doesn't work, then RT will try cache-ing

Ali Updates

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OOP offsets from Heep Coin, now that BPMs are fixed

- using method from Tanja thesis Fig 3.11

- Heep settings at 3.8, 4.9, 6.2, 8.2, 10.6 GeV are used

   - data mean and errors from HMS, SHMS xptar plots

   - at 10.6 GeV, the P_HMS=6.59 GeV/c, so deep into saturation region

- DO NOT get a nice correlation like in TH thesis

   - outlier at Pp/Pe=1.3 is low Q2 data, far from saturation

  - DG: survey data indicate a fixed survey offset should work for both

    spectrometers, so we need to understand this

- GH notes that SIMC distributions also do not have xptar mean=0, so should

  the difference between MC and data be used, instead of trying to move the

  data mean to 0?

   - DG: Yes, MC predicts a non-zero xptar, so this should be taken into

     account

   - subtract data-MC xptar

   - SHMS xptar has a weird OOP acceptance, due to HB and other effects

   - nonetheless, DG expects the method in Tanja's thesis should be totally

     applicable here

- AU: should he include the Summer 2019 data too?  Yes

- DG: other effects.  If the beam position is changing, then would have to

  throw away the data from that run.  i.e. that run would be good for all

  purposes EXCEPT determining OOP offsets

   - would need to enable EPICS variable tree in hcana

   - make a histo of vertical beam position at target from BPMS 3H07A, 3H07C

   - then extrapolate from these to the target

- Summary of Suggestions:

   - use data-MC xptar means

   - look at BPMs to see if beam position is changing

   - include two Summer 2019 settings to get more points

- To avoid waiting for others, can look at PMx,PMz,EM from HeepCheck in

  parallel, as these should be independent of OOP offset

Vijay Updates

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Raster for Summer 2019 data

- checked raster correlations for all 3 beam energies

- very small left slope is observed, consistent with what Ali found

- DG will talk to MarkJ about this

   - the Matrix Element fit is from single arm MC, so not surprising if a

     little bit off

   - the question is whether we should ignore the small slope or make a

     correction to further improve things

- working on HMS calorimeter efficiency study, will give results next week

- then will do Lumi study on Carbon, similar to what RT showed today

Alicia Updates

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BSA status update

- looking at CoinTime to investigate effect of K+ contamination on pi+ BSA

   - magenta: HGC cut, Red: MM cut, cyan: MM+HGC cuts

   - HGC cut gets rid of most K+ but causes larger BSA errors (undesirable)

   - MM cut gets rid of randoms

   - MM+CT cut looks cleanest

   - proposing a cut of ~2.25ns, and do a cut study +/-0.5ns to check cut

     dependence on BSA result

      - would quote the variation relative to 2.25ns cut as a systematic error

   - CT, aerogel, calorimeter, MM cuts will be used

      - HGC >2pe cut makes little difference

- initial look at two new settings 

  Q2=3, W=3.4  and  Q2=5.5, W=3.02

   - tentative t-binning

   - generally looks OK, but some t-bins need adjustment, so that statistics

     are more equalized

   - will co-ordinate with AU for common t-binning over kinematic range between

    AU's diamond cut and AP's no-diamond cut

- some further discussion about SIMC not properly reproducing the neutron peak

  width at higher -t we observed 2 weeks ago

   - DG says radiative model in SIMC has no free parameters that can be tweaked

   - rather, sugggests that the wider peak width is due to piDelta final state

     coming underneath the n peak at higher -t

   - AP will look into simulating piDelta with SIMC to see if this is a good

     explanation

   - DG: PeterB's piDelta model is implemented in SIMC, will send the

     appropriate flags by email

   > To simulate the Delta in the final state in simc, the input file flags

     should be set as usual for exclusive pion production, but there are

     additional options for "which_pion":

     which_pion = 2 ;  (0=p->pi+,1=n->pi-,10/11 for pi+/pi- coherent, 2/3 for pi+/pi- Delta final state)

     For pi+ production, which pion should be set to 2. 

Next Meeting

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- Thur May 25 @ 16:00 Eastern/14:00 Regina/13:00 Pacific

- KaonLT will go first