Kaon_LT Experiment

                 Apr 27/23 PionLT/KaonLT Analysis Meeting Notes

                 -----------------------------------------------

                           (Notes by GH and SJDK)

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

   Nathan Heinrich, Vijay Kumar, Love Preet

CUA - Tanja Horn, Richard Trotta

Ohio - Julie Roche, Jacob Murphy

FIU - Pete Markowitz

JLab - Dave Gaskell, Peter Bosted

CSULA - Konrad Aniol

Richard Updates

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Tracking/lumi updates

   - Recap from 6/4/23 meeting, some runs were outside of the general trend

      - Bad TLT?

      - Will discuss with Jacob tomorrow about TLT calculation

      - if the TLT calc is fine, then will need to look more closely at the

        running conditions, and try to figure out what's wrong with these runs

Pion/proton subtraction, normalized to pi+n p+omega peaks

- Pion subtraction looking pretty good

- Proton subtraction dosn't look so good

   - somehow the proton distribution is missing the omega peak, but it 

     does show substantial pi+n leakthrough, and also a small K+Lambda peak

      - GH: it's essential that the pion and proton spectra used for background

        subtraction are clean, as otherwise you will subtract K+ too

      - No hole cut on HGC 

         - Just <= 1.5 on HGC for proton sample, which allows pi,K near hole

      - SK: Apply proton PID cuts, keep -5 to 5 in CT, then plot MM vs

        CT, see where 0.8 GeV peak is popping up

   - No Ref time cuts for pion/proton spectra

   - also need to re-check proton CT cuts

   - PeterB: What is the momentum here?

      - 10.6 GeV data, SHMS ~ 6 GeV/c

      - Pion/Proton are 0.5~ns separated in CT at 6 GeV/c

- Meeting with Ali on HGC next week

   - HGC is the top priority going forward

- To Do: Want to look at BPM calibrations too

Vijay Updates

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Ratio of SIMC/Experimental yields

   - 8 t bins

   - 16 phi bins

   - plots at high, mid, low epsilon to show the code is working

- Experimental yields not finalized, so shouldn't expect much yet

- Ratios generally sensible for high, mid, low and low epsilon given the lack

  of iterations, but the phi distribution has a weird dip

   - thinks it's a SIMC model issue

   - DaveG: Could be an artifact of not having offsets, they aren't finalised

     yet

   - Peter B: is the 2.7-3 mrad Out of plane offset in?

         - Typical offset used for coincidence experiments

         - No, net yet

- Need to move back to yields, experimental data will move bin to bin

   - GH: Do not have SIMC model issues, you have experimental issues

      - Need to finalise offsets, rate dependencies etc then can come back to

        this

      - the data will migrate between different phi-bins, depending on the

        offset, so don't worry about the model or LT-sep until this is

        finalized and applied

Nathan Updates

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Finished aerogel calibrations

   - Updated slides from last week, on redmine already

- Added new calibrations files and updated databases to git

- GH: Will have to check Redmine, do we have an area for calibrations?

   - If not, maybe a new area for this would be nice

   - otherwise, your final slides on the calibration will be difficult to locate

First look at the HMS cherenkov calibration

   - Got the existing code going

   - Ran for 15-20 runs or so

- GH: Selecting pi- to do the calibration?

   - Dave G - No, don't need pions to be high momentum, better to use delta

     knock-on electrons as source of low PE events

- PeterB: Use a run with a lower momentum setting for two reasons

   1) Higher pi- to e- ratio at low P

   2) Lack of pi- Cherenkov radiation

      - Threshold set to 4.5 GeV/c?

      - Dave G - Sounds about right

- Picked a random set of runs between 12000-16000, just ran them to check what

  they look like

   - Will do a more systematic pass now, looking more carefully at the pi-/e-

     ratio (see runplan spreadsheets) and the pi- Cherenkov threshold

Junaid Updates

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HMS DC calibrations

   - 9.2 GeV beam energy, 2021 run

   - Applied electron cuts (HMS Cer NPE Sum > 1.5, HMS ETotNorm > 0.7)

     RED=before calib, BLUE=after calib

   - Residuals mostly improved, but still get double-peaked distributions for

     some planes

   - changed a few parameters and still waiting on second replay

   - DaveG: Does the code work by doing groups of 16 wires or individual wires?

      - Not sure, will need to check.  Not sure whether groups of 8 or 16 wires

        are used

   - Dave G: Time window cuts are applied?

      - Yes

   - GH: Who has the HMS calorimeter on their list?

      - Junaid

         - Working on calorimeter already too, modifying batch script

      - SK: Reminder to be a bit more selective with SHMS calorimeter

        calibrations, only want -ve polarity runs

Ali Updates

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Heep Coin Analysis, offset studies

- Richard talked about the new SIMC kinematic variable calculations in the

  Quarterly Analysis Meeting

   - Using these when comparing with data

- Last week reported a constant 13 MeV shift in out of plane offset (Pmy)

  in all kinematics

- Juanid: What is the physical origin of the OOP offset?

   - AU: Correspondence to difference between two reaction/scattering planes

     compared to what we actually think

      - HeeP reaction is inherently coplanar

      - Physically, comes from spectrometer misalignment?

   - Dave G: Could be something in carriage that isn't flat, not pointing

     correctly

   - PeterB: Mark Jones believes it's a property of the magnets, magnetic axis

     of one spectrometer is a little bit offset

      - changes ThetaE (xptar) and adds 0.0027 to it

      - seems to be a property of the spectrometer, also had similar offset in

        6 GeV era

         - Add 2.7 mrad to -xptar (theta_e angle)

         - Lots of ways to check it, HeeP, asymmetries

      - TH: Yes, had two offsets in this era too

      - DG: Look at Fig 3.11 in TH thesis

- First look at Out of plane offset

   - Constant 13 MeV PMy shift

      - An angle offset works out into a momentum offset when you calculate

        momentum quantities, as a percentage of the spectrometer central

        momentum

   - Tried applying offset to SHMS first, smaller range of central momenta

   - found the angle offset needed to put PMy near zero

   - Plotted Pmy offset vs SHMS momentum

      - 6.2 beam: 0.0038

      - 8.2, 10.2 beam: both are 0.0030

      - projecting to higher P_SHMS would give significantly smaller offsets

        for physics settings 

   - Dave G/Tanja: How can you do this for Physics settings? Not kinematically

     constrained?

      - Could just use 0.003 everywhere

   - Tanja - Can't just use an offset/make one up to fix the data

      - These are just projections/expectations for physics offsets

   - GH: Should get error bars for three HeeP points, based on the widths of

     the PMy distributions, then I expect you will find a flat fit will be

     sufficient

   - Vijay: How can you get OOP offset without getting other offsets

      - Garth - OOP offset is independent of the others, since Heep reaction is

        coplanar

         - the HeepCheck program only gives the in-plane offsets

         - Can set/fix OOP offset, then use the HeepCheck program to get the

           rest, OOP offset is separate

         - Need to determine OOP first before determining the others

            - Didn't really fully appreciate this until last week

   - Vijay: Even after adjustment from Richard, plots still don't match

      - Ali: Yes but this is a limitation of the data

   - PeterB: What does Pmy correspond to?

      - xptar

   - PeterB: Actually looked at asymmetries of exclusive pions to determine

     this offset, didn't really have enough HeeP runs

      - Should take the events, calculate angle between two planes for HeeP

        settings you have

      - also looked at the azimuthal asymmetry of the exclusive pi+ events,

        although this is tricky because of the interference terms

   - PeterB: Previously found that it was more consistent to apply the offset to

     the HMS

      - Offset was consistent in 6 GeV era, only spectrometer in common is the

        HMS, implies it's an HMS issue

      - please try an HMS offset and see how well it works

      - DaveG: Figure 3.11 in Tanja’s thesis has a nice description of how to

        separate HMS and SHMS out of plane offsets

   - Peter is applying offset directly to xptar

      - GH: How do you do this?

         - recall that PB recalculates all variables from scratch via a script

         - xptar += 0.0027, manually reconstruct whatever is shifted

            - Recalculate all Physics variables from xptar etc

            - Only read in non-offset data from the replay

      - Plot coplanarity delta

      - Do it for all settings, see if coplanarity offset is independent of

        momentum

      - CYero found a slight dependence in the offset, but basically the same

        as PB

   - TH: it's important for everyone to be familiar with what was done in her

     thesis, Peter and Carlos work, etc.

      - try to learn from everyone's experience and not lose time working out

        the procedure

Very useful offsets discussion.  Summary to things for Ali:

- review TH, CY theses offsets discussions

- try an HMS OOP offset

- try estimating errors in each OOP offset as this affects what conclusions to

  draw when extrapolating to physics settings

Alicia Updates

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- Finished exams on Tuesday

   - Hopefully something to show next meeting

- Experimenting with HGC cuts to see if it makes any difference in BSA data

- Getting SIMC running

   - MM changed significantly as a function of t

   - would like to see that pi+n peak looks like versus t

- Hopefully some of this to show for next week

Jacob Updates

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- Welcome back Jacob :)

   - will meet with Junaid and Nathan next week

- PeterB asks about the status of optics

   - can show some delta-optimizations next week

Next Meeting

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- Thur May 4 @ 16:00 Eastern/14:00 Regina/13:00 Pacific

- PionLT will go first