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Kaon LT Meetings » mtg_24sep05.txt

Garth Huber, 09/05/2024 07:55 PM

 
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                 Sept 5/24 PionLT/KaonLT Analysis Meeting Notes
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                 ----------------------------------------------
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                                (Notes by GH)
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                     Today: PionLT will be discussed first
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Please remember to post your slides at:
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https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings
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Present
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-------
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Regina - Garth Huber, Alicia Postuma, Muhammad Junaid, Nathan Heinrich,
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   Ali Usman, Nacer Hamdi
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Virginia - Richard Trotta
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JLab - Dave Gaskell
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CUA - Tanja Horn
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Ohio - Julie Roche
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CSULA - Konrad Aniol
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Junaid
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------
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PionLT Heep Coin Hodo-3/4 effs
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- new plot of 3/4 effs vs SHMS momentum
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  - planes 1,2,3 show a linear drop of eff with increasing momentum
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  - plane 4 shows a low eff, but very large variation (50-75%) at P~2.4 GeV/c
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  - GH: the drop off at low momentum is expected, but the linear drop at
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    high momentum is puzzling
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  - Dave: *NB* confident that there is an issue in the PID selection cuts used
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    to calculate these efficiencies, that needs to be sorted out first, and
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    then we can come back to this
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-  finds the 3/4 effs are sensitive to the ptof_tolerance value
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   - PionLT value=10, apparently set by C. Yero at start of PionLT run
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     - changing to 15 results in slightly LARGER efficiencies
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   - Ali: please recall the beta vs. cointime issue KaonLT encountered last
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     year, this was because the tolerance variable was set wrong (was 100, it
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     was supposed to be 2)
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   - a value of 2 should be applied to ALL data
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     - Junaid had tried this as well, results in even LOWER effs
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More discussion about that to do about the 3/4 effs:
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- Dave: NCER cut needs to be removed entirely, makes sense for negative
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  polarity SHMS, but no sense at all for positive polarity
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  - Junaid tried varying the CERCUT parameter, all the way down to zero
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    (default is 2pe) and it made NO difference to the efficiencies
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    - note Nathan did calibrate the NGC, so the pedestals should have a
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      reasonable value when applying npe=0 cut that Junaid tried
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  - Nathan thinks the CERCUT is legacy code that is not called, since for
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    example no NGC was installed for KaonLT.  What did the code do then?
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  - we spend some time looking at the code, it seems that the HGC is being
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    called here instead of the NGC
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    - however, protons also never Cherenkov in the HGC either, so this cut also
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      should not be applied to Heep data effs
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  - Dave suggests to remove this code completely from hcana and see what
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    happens
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  - Dave looks a bit more at the code, and sees that in THcHodoEff.cxx both
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    Cherenkov and Calorimeter cuts are used
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  - *NB* Junaid will investigate the code more thoroughly
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Nathan
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------
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PionLT Lumi studies
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- new plots using Zach's code applied to 2021 data
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  - SHMS Carbon 12143-12154
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    - Scaler analysis shows a small linear rate dep
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      - ElLT not yet applied
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    - will look at fixing slopes on Carbon Scaler/NoTrack/Track analyses
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- Mild antiboiling seen for LH2 12192-12198
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  - Dave and Tanja expect Coin data are not as reliable for determining
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    boiling corr than the 2022 dedicated singles runs
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- One issue is what to use for TLT
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  - right now, Nathan picks the higher TLT from either EDTM or CPU*ElLT
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    methods
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  - GH: *NB* this is "cherry picking", much better to decide which method is
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    more reliable for a given run period, and then use it consistently for
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    both Heep and physics data
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Richard
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-------
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KaonLT Ratio debugging for Q2=4.4, W=2.74
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- everything is looking pretty good, except that Ratios converge around 1/3
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  instead of 1
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  - ratios much flatter than before
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  - comparisons of data and MC distribution shapes are reasonable
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  - Richard reports that this factor is consistent across all settings, not
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    just the Q2=4.4 shown today
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  - GH and Tanja agree there seems to be a missing factor of ~pi somewhere in
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    one section of the code that is consistent with the others.  When this is
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    identified, things should look fairly good
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- various studies to try to find the missing factor
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  - reran SIMC from scratch instead of recalculating weights -- ratio unchanged
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  - looking at histo binning in Exp Yield calc
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  - also will check SIMC w/o recon_hcana
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    - should change the distribution shapes, but not the normalization
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  - Tanja suggested to run for only a small t range (~0.1) to check if it's a
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    functional issue w/t-parameteriation
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  - Nacer: try applying your code to Vijay's data and hunt for the difference
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    between your plots and his
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    - Vijay should be back and available for a meeting with Richard next week
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Nacer
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-----
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KaonLT Heep studies
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- proton absorption correction
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  - reviewed John Matter's thesis and spreadsheet
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    - they compared calculated and experimentally determined proton absorption
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      results:
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        A_pred=8.56% spreadsheet
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        A_exp=9.03+/-0.07% by looking for missing protons other spectrometer in
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	Heep singles data
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- modified their table, removed NGC, need to adjust aerogel density for actual
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  values used during KaonLT
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  - 0.2 density should correspond to n=1.03 aerogel
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  - Tanja: 1.015 density=0.08,  1.011 density=0.04
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    all trays should have the same thickness aerogel.  The area will be
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    different though
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  - the correction factor ~7.5%, applying this factor changes the ratio from
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    near 1.0 to ~1.08, except for 10.6GeV data where R=1.00 after factor
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- tried different MM cuts to exclude pi0
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  - ratios get a bit smaller for MM<0.10, 0.09, 0.08 cuts, but all above 1.0
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    except 10.6GeV
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- HMS matrix element check, hcana default vs old 6 GeV matrix
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  - data vs MC shape difference gets a bit worse (8.2 GeV data)
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  - ratios also get a few % worse, which is a bit surprising, only expected
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    events to move around but not get lost
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  - clearly the default matrix elements are better, this issue closed
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More discussion about that to do about the ratios with absorption corr included:
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- Ali: asks about the momentum dependence to the interaction length in
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  spreadsheet
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  - Matter's thesis: cross section indep of momentum >1 GeV/c
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    - confirmed with their data for 4-10 GeV/c
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    - our data are 2-8 GeV/c should be fine
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  - Dave: the proton absorption correction is applied by other analyses, it is
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    not optional as there are no proton absorption effects in SIMC
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- Ali: there is a cut applied on aero tray in the replay, irrespective of
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    whether an aero NPE cut is applied to the data
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  - *NB* need to be 100% sure the same cut is applied also to SIMC
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- GH: *NB* the MM distribution clearly has a much larger tail in data compared
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  to MC, independent of the pi0 contamination.  This tail is ~5%, so seems to
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  be the cause of the Ratio problem
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  - Dave: *NB* please try looking at Emiss, W for Data & MC, not so used to
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    looking at MM for Heep data, maybe it will show something
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  - Dave: *NB* it is important to look at some Single Arm Heep to see if there
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    are similar issues
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    - GH agrees this is an excellent idea.  Since no protons are detected, no
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      absorption corr is needed to be applied, so it will give important
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      information
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- *NB* GH's suspicion of what's wrong (added after meeting):
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    - the spreadsheet assumes that interacting protons are completely lost and
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      no trigger is made
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    - if the protons scatter but still give a trigger, they end up in the
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      Heep tail, and the spreadsheet correction is an over-estimate
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    - if so, we would need to apply a much tigher MM cut to remove the
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      interacting protons not included in the SIMC tail
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      - hopefully the W and EM plots will shed light on what cut to apply
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      - the Heep singles Data/MC ratios will also be critical to this
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    - Henk came up with a modified method to evaluate the absorption
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      correction, looking at the proportions of events in peak and tail, to
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      accont for this
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    - *NB* GH will review this info and see how to apply it here
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Alicia
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------
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Update from PRL:
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- referee reports received Aug 12,14,31
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- queries sent to 2 referees after receiving 3rd referee report, 1 response
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  received so far
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- we infer that one referee gives a report disagreeing with the other 2, and
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  they have been asked to comment on it
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Garth
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-----
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Hall C Winter Workshop  Jan 13-14/25
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- at last meeting, discussed a session on "nearly final results" and what
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  KaonLT might have ready by then
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  - 3 talks seem likely:
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    - Vijay, Richard, Ali
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    - Richard and Vijay should coordinate e.g. on how best to show the various
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      systematic studies
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- Tanja: what about general experiment updates?
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  - GH: this was not explicitly discussed.  Since there are starting to be lots
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    of results nearing publication (unlike a few year ago), priority will be
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    given first them.
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    - once that part of the program is fleshed out, we will likely go back and
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      ask for more general updates
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 Next Meeting
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-------------
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- Thur Sept 12 @ 16:30 Eastern/14:30 Regina
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  - KaonLT will go first
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  - *NB* Please note the new time and new Zoom ID!
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