Kaon_LT Experiment

                 Feb 6/25 PionLT/KaonLT Analysis Meeting Notes

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

                                (Notes by GH)

                     Today: PionLT will be discussed first

Present

-------

Regina - Garth Huber, Alicia Postuma, Muhammad Junaid, Ali Usman, Nacer Hamdi,

   Vijay Kumar, Nathan Heinrich

CSULA - Konrad Aniol

FIU - Pete Markowitz

Virginia - Richard Trotta

CUA - Tanja Horn

JLab - Dave Gaskell

Short discussion on status of High Q^2 p(e,e'K+)Sigma0 analysis

- Richard and Tanja had a discussion

- There are 2 main parts to this analysis

  a) Sigma0 L/T-separated cross sections (where statistics allow)

  b) g_pKLambda and g_pKSigma coupling constant comparison

- Richard would appreciate Gabi and Ioana's help on the cross section analaysis

- GH will put Gabi and Ioana in contact with Richard

Junaid

------

PionLT data analysis - HMS magnetic optics

- currently using phi offsets=0 for both spectrometers

  - looked at some old files (Stephen's online analysis) and found non-zero

    offsets, SHMS: -8E-4 rad, HMS: 4.9E-3 rad

  - Richard: we discussed this before

    See Nov 21/24 meeting notes at:

      https://redmine.jlab.org/attachments/2673

  - agreement that the offsets are set during the ME fitting and should not

    change

  - Dave: low momentum HMS ME should come from 6 GeV era

  - Ali: thought Holly made a newer set of low momentum HMS ME in the 2017

    commissioning period

  - Tanja: take a look at

    https://hallcweb.jlab.org/wiki/index.php?title=12_GeV_HMS_Optics_Data

    this page lists ME only for >5 GeV/c from the commissioning period,

    nothing listed for low momentum region which must come from 6 GeV

- for higher energy ME, using NPS offsets, for lower energy using zero offset

  - Dave: *NB* will check, has seen various offset values floating around

- implemented NPS ME for 5.8, 6.1, 6.7 GeV/c, work still in progress for 5.6

  GeV/c

Next steps:

- setting up for Pass 2 Physics replay

  - implemented Nathan's boiling correction to Qeff script

Nathan

------

- no report, please send comments on WNPPC slides by email

Richard

-------

KaonLT Q2=4.4, W=2.74 analysis

- adjusted and simplified parameterization

  sigT=p5*exp(-|p6 t|)*QdepT

    where QdepT=exp*(-Q^4)/Q^2

  sigTT=(p13*QdepTT)*ft*sin^2(theta)

    where QdepTT=Q^2*exp(-Q^2)

  both use Wfac=1/(W^2-m^2)^2

- putting absolute values in the exponentials helped keep things well behaved

- obtain nice agreement in focal plane and physics distribution shapes between

  data and MC

- the only issue is that the ratios are 0.2-0.4

  - will have to adjust Wfac, we know from Q2=3.0 analysis that this made a big

    difference in the Data/MC ratios

Alicia

------

Geant4 proton absorption correction

- gave an overview of the PA classes defined

- added an option to turn/off NGC in detectors.dat

  - SHMS exit window is moved forward when NGC not in place

  - only the most dense aerogel is implemented so far

  - target and SHMS entrance windows are included

- had to add Cherenkov NPE to custom stepping action class

- event generation:

  - printed out focal plane variables for a data run into a txt file and reads

    into Geant4, so actual focal plane distribution is simulated

    - events are generated at center of LH2 target, where for the target

      variables

       Xtar=xfp + xpfp*Ztar

       Ytar=yfp + ypfp*Ztar

- S1X, S1Y, S2X, S2Y energy spectra are generated

  - energy deposit is >1 MeV, shape looks reasonable

  - applies an energy threshold per plane based on this distribution, to mimic

    the effect of the discriminator in the trigger

- very preliminary result: 6.4% proton absorption for 5 GeV/c

  - tried 1-10 GeV/c, get similar absorption for all proton momenta

  - Ali points out this is consistent with statement in John Matter's thesis

- starting to try different particle types

  - Pete: you will have to turn off pi/K decay in Geant4, since SIMC already

    takes the decay into account and we don't want to double correct for this

    - i.e. we want missing triggers due to absorption, not decay

- list is made of where different particles stop

  - can do a cross check between absorption fraction of total in spreadsheet

  - aerogel tray is about 15% of total absorption

    - *NB* indicates a need to do different calculations for different aerogel

      densities

  - NGC is about 20% of total, which imples a proton absorption correction for

    KaonLT closer to 5%

- Geant4 outputs the nuclear interaction length lambdaL per material

  - Geant4 numbers a bit lower than PDG except for LH2

  - presumably this difference is due to different temperature/pressure than

    Hall C cryotarget

    - Garth: *NB* suggests to cross check LH2 density with what is in SIMC

      input file

- some detector configuration checks that were done:

  - detector positions pulled from SHMS focal plane blueprint

  - had to convert NGC gas from CO2 to 70% Ar/30% Ne in spreadsheet

  - *NB* need to check what type of material is used for NGC exit window

  - HGC gas changed from CO2 to C4F10 in spreadsheet

    - *NB* Vijay will get Alicia the exact gas pressure used during KaonLT

- arranged with Stephen to present at Quarterly Analysis Meeting

- everything looks very nice!  Thanks Alicia for working on this

Nacer

-----

KaonLT 3.8 GeV data analysis

- fixed problem with SIMC normalization, MC much closer to data now, applied an

  ad-hoc normalization factor to more easily compare distribution shapes

  - Lambda data 2x higher than model

  - Sigma data 9x higher than model

- focal plane and physics distribution comparison looks good

  - now applying a MM cut to select Lambda region

  - also did a Sigma window and compared Data to MC

- Ali: is the MC smearing factor applied?

  - confirmed mc_shms_hut.f resmult=3.5 so the factor is IN

Next steps:

- more checks to confirm cuts are OK on some representative files before

  submitting full data job

  - will check RF cut and RF cut efficiencies

  - should add Nathan's LH2 target boiling factor to Qeff

  - should also add Nathan's ELLT calculation and compare to EDTM to confirm

    reliability of EDTM before proceeding

  - Nathan: here is the raw python code, let me know if it is not clear:

#calculate the ELLT via individual Hodoplane rates per Dave Mack technique

    #For details see: https://hallcweb.jlab.org/doc-private/ShowDocument?docid=1063

    HODOGATEWIDTH = 50/(10**9) #ns - gate width is PionLT

    SHMS_HodoRate = [0]*NRATEHODO

    SHMSTrueRate = [0]*NRATEHODO

    SHMSDT = [0]*NRATEHODO

    SHMSLT = [0]*NRATEHODO

    #HMS_HodoRate = [0]*NRATEHODO

    for iRATE in range(0, NRATEHODO): #iRATE is the number is the hodoscope plane

        SHMS_HodoRate[iRATE] =  SHMS_Hodo_rate_sum[iRATE]/time_sum[bcm_ix]

        #HMS_HodoRate[iRATE] =  HMS_Hodo_rate_sum[iRATE]/time_sum[bcm_ix]

        SHMSTrueRate[iRATE] = SHMS_HodoRate[iRATE]/(1 - HODOGATEWIDTH*SHMS_HodoRate[iRATE]) 

        #HMSTrueRate[iRATE] = HMS_HodoRate[iRATE]*(1 - HODOGATEWIDTH*HMS_HodoRate[iRATE])

        SHMSDT[iRATE] = SHMSTrueRate[iRATE]*HODOGATEWIDTH

        #HMSDT[iRATE] = HMSTrueRate[iRATE]*HODOGATEWIDTH

        SHMSLT[iRATE] = 1 - SHMSDT[iRATE]

        #HMSLT[iRATE] = 1 - HMSDT

    SHMS3of4ELT = SHMSLT[0]*SHMSLT[1]*SHMSLT[2]*SHMSLT[3] + SHMSDT[0]*SHMSLT[1]*SHMSLT[2]*SHMSLT[3] + SHMSLT[0]*SHMSDT[1]*SHMSLT[2]*SHMSLT[3] + SHMSLT[0]*SHMSLT[1]*SHMSDT[2]*SHMSLT[3] + SHMSLT[0]*SHMSLT[1]*SHMSLT[2]*SHMSDT[3]

    #HMS3of4ELT = HMSLT[0]*HMSLT[1]*HMSLT[2]*HMSLT[3] + HMSDT[0]*HMSLT[1]*HMSLT[2]*HMSLT[3] + HMSLT[0]*HMSDT[1]*HMSLT[2]*HMSLT[3] + HMSLT[0]*HMSLT[1]*HMSDT[2]*HMSLT[3] + HMSLT[0]*HMSLT[1]*HMSLT[2]*HMSDT[3]

 P_S1X_scaler = s_tree["P.S1X.scaler"].array()

        P_S1Y_scaler = s_tree["P.S1Y.scaler"].array()

        P_S2X_scaler = s_tree["P.S2X.scaler"].array()

        P_S2Y_scaler = s_tree["P.S2Y.scaler"].array()

        #H_S1X_scaler = s_tree["H.S1X.scaler"].array()

        #H_S1Y_scaler = s_tree["H.S1Y.scaler"].array()

        #H_S2X_scaler = s_tree["H.S2X.scaler"].array()

        #H_S2Y_scaler = s_tree["H.S2Y.scaler"].array()

Next Meeting

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

- Thur Feb 13 @ 15:30 Eastern/14:30 Regina

  - KaonLT will go first

  - Nathan and Alicia will be at WNPPC in Banff then, please remember to send

    your comments on their slides by email