Kaon_LT Experiment

                 May 22/25 PionLT/KaonLT Analysis Meeting Notes

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

                                (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

-------

Regina - Garth Huber, Muhammad Junaid, Ivan Zhenchuk, Alicia Postuma,

   Ali Usman, Nacer Hamdi, Nathan Heinrich, Vijay Kumar

Ohio - Julie Roche

JMU - Ioana Niculescu

FIU - Pete Markowitz

JLab - Dave Gaskell

Virginia - Richard Trotta

Alicia

------

u-channel simulations

- as previously reported, Pythia seems encouraging as a way to simulate

  background processes underneath the omega peak

- the plan is to output Pythia events to a file and then read these into SIMC

- struggling with reading Pythia events, will meet separately with GH

Nacer

-----

KaonLT Q2=0.50 LT-sep

- all kinematic tables and yield files now generated for all t-phi bins

- plots of Data/MC ratios vs phi for each t-bin show some anomalous zero

  entries

  - investigating the outliers, about half of them have been addressed so far

  - making plots of MM for each t-phi bin to investigate further (as suggested

    by Richard last week)

- calc_xsect.f - the routine used to calculate unseparated cross sections from

  the model and Data/MC ratios for each t-phi bin

  - has version from GH, still trying to understand the code

Vijay

-----

pion absorption factor for Low Q2 PionLT

- working with Alicia's Geant4 code, making comparison plots for pions at 2,3

  GeV/c momentum to check against her reference plots

  - plots of calorimeter output look good

  - HGC NPE and Aerogel NPE plots are empty, asked Alicia for some suggestions

Richard

-------

KaonLT high Q2 LT-sep

- Q2=5.5 still running on ifarm

- in the meantime, looking at Q2=3.0, W=3.14

  - high epsilon Data/MC ratios near 1, but with oscillations of +/- 0.5

  - low epsilon ratios good for lowest t-bin, but trend quite a bit higher (~2)

    to highest t-bin

    - GH: this indicates the t-dependence of sigT (primarily) is not correct

  - comparison of Focal Plane variables between Data and MC shows that the

    model is quite far off from the data, shapes not in agreement

  - expects that some change in functional form will be needed (particularly

   for sigT)

- Next steps:

  - will concentrate first on Q2=3,W=2.32, Q2=4.4, Q2=5.5 so we have a good

    Q2-scan at fixed xB before tackling Q2=2.115, Q2=3,W=3.14

Ali

---

pi+Delta0 BSA finer t-bins

- MM shape study for rebinned data is complete

  - has extracted yields for finer binned data

  - has recalculated kinematics for rebinned data

  - in the process of making asymmetry plots

- thesis defense is on May 30

Nathan

------

PionLT anomalous deadtime investigations

- still looking into hodoscope timing issue identified by Dave on May 8

  - looking to rerun calibration script to see if it fixes the time shift issue

  - ran into problems with the calibration script

    - when the OS was updated, a C++ operator was deprecated, which broke

      fit_hoco_calib.c

    - problem has been fixed and will push soon to GitHub

  - the two shifted runs identified on May 8 are from different run periods, it

    seems odd that both broke the same way

    - the most likely explanation is that a timing offset has changed

- rate dependent yield checks

  - removed weird Python integral function identified last week

  - Carbon Lumi scan generally looks good, but there is an outlier that will be

    investigated

  - the next step after that will be the LH2 boiling scan

Junaid

------

PionLT Q2=3.85, W=2.62 LT-sep

- kinematic variables have been calculated for each t-bin

- Data/MC ratios per t-phi bin have been tabulated

  - SHMS settings are combined via error weighted average of ratios

  - doing some by-hand checks to make sure everything is working correctly

- also has Garth's calc_xsect.f and trying to understand the code

Ivan

----

KaonLT Low Q2 BSA analysis

- trying to replicate Nacer's PID and pion leakage subtraction studies

  - for now, using Cherenkov PID cuts

  - will switch to RF cuts, the same as Nacer

- Nacer: suggests to make a CoinTime plot with cut on Lambda/Sigma MM, to make

  the K+ CT peak more clear, otherwise it's buried by the pi+ coincidence

- MM plot pi+ leakthrough and randoms subtracted

  - pi+n peak from clean sample and physics sample have slightly different

    shape, which gives a small number of negative counts on one side of

    difference and a positve number on the other, with the two parts hopefully

    canceling (this is not checked yet)

    - Nacer did not see this, so hopefully the effect will go away when

      switching to RF cuts

- HGC cuts

  - interestingly, when applying NPE cut, the pi+Delta0 peak is removed but not

    the pi+n in the MM spectrum

    - Garth recalls that we saw this in the online data, not all of the SHMS

      focal plane has pions above Cherenkov threshold, the +delta part was

      above threshold and the -delta part was below threshold

      - this can be verified by plotting HGC_NPE vs SHMS_delta

      - since pi+Delta events have larger MM, they will be preferentially at

        lower delta than pi+n events

Next Meeting

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

- Thur May 29 @ 15:30 Eastern/13:30 Regina

  - PionLT will go first

  - Alicia will plan to show her draft CAP Congress slides