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Kaon LT Meetings » mtg_25sep19.txt

Garth Huber, 09/19/2025 06:10 PM

 
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                 Sep 19/25 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, Nathan Heinrich, Muhammad Junaid, Alicia Postuma,
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   Nacer Hamdi, Vijay Kumar, Nermin Sadoun
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JLab - Dave Gaskell
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CUA - BC Manoj, Tanja Horn, Sameer Jain, Chi Kin Tam, Carlos Yero
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Virginia - Richard Trotta
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York - Stephen Kay
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Nathan
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------
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PionLT Coin Blocking Studies
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- Trigger timing was different in 2021 and 2022 runs
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  See Brad's Trigger Setup Documentation
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  https://hallcweb.jlab.org/wiki/index.php/Trigger_History
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- SHMS-3/4XHMS-ELREAL was used as the CoinTrigger, so remmade CoinTime plots
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  using that info
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  - get a long distribution of times to the right of the main peak
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  - Dave: SHMS-3/4XHMS-3/4 is the highest resolution version of the CoinTime,
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    HMS-ELREAL has extra jitter in it caused by the other elements in the
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    ELREAL trigger, need to keep using 3/4X3/4
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    - it is not the CoinTrigger that is lost (that's already taken into account
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      in the deadtime) but rather that the CoinTime is wrong for some events
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    - the problem is that the TDC looks for signals in the lookback window and
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      some events can sneak in and give a bogus CoinTime that is removed by
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      cuts.  In that sense it's not really a Coin blocking, but a CoinTime
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      blocking
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    - for the blocking correction, need to use a window based on the 3/4X3/4
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      signals
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- tried two cuts, wide (110ns) and narrow (80ns)
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  - the narrow cut gives a flat NormYield vs Rate, but the BlockingCorr is 0.8
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    (i.e. 20%) even at low rate, this is very difficult to justify
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  - the wider cut gives a 6% reduction of NormYield @ 2kHz CoinRate
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    - some discussion comparing to the BlockingCorr that Peter Bosted's
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      correction, which is proportional to Total SHMS+HMS rate
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    - plots made of the BlockingCorr vs Total SHMS+HMS rate and CoinRate
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      - the CoinRate gives a much better correlation, vs Total SHMS+HMS rate
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        the scatter is significantly larger
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      - the BlockingCorr uses loose PID cuts of:
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        HMS: Hcal_EtotNorm>0.7, Hcer>2
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	SHMS: HGC,Aero,NGC,Cal to loosely select pi+
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- Dave, Tanja, Garth agree that applying Nathan's correction makes the most
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  sense for the PionLT data
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  - the correction will be calculated Run-by-Run based on the #events
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    outside and inside the window for each setting, rather than from the
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    fit vs rate
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  - the fits vs rate will be used to estimate the systematic uncertainty in
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    the BlockingCorr, Nathan will fit each CoinLumi setting separately,
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    determine the scatter in the slopes vs CoinRate and from that calculate
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    an uncertainty for a given CoinRate
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  - the uncertainty in the CoinRate for each setting will have to be
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    propagated separately in the errors for each run
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  - *NB* Nathan will make a presentation on this at next Wednesday's Quarterly
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    Analysis Meeting
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- we also need to determine an equivalent correction for KaonLT data
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  - Sameer Jain will look into this, following instructions from Nathan
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    - KaonLT high Q2: using Chi-Kin and Richard's ROOT files
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      - CoinTime plot will be a bit different than for PionLT
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        - the used RO1,2C may be different
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	- the cut windows and offsets need to be checked and changed
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    - it also makes the most sense that he also look at the low Q2 KaonLT and
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      PionLT data, since the setup will be nearly identical
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      - *NB* Vijay and Nacer needs to point Sameer similarly to the location of
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        these data: run list and location of calibrated data
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  - Alma9 Setup on ifarm - Pion-LT (E12-19-006) - Redmine for virtual envir
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    https://redmine.jlab.org/projects/hall-c/wiki/Alma9_Setup_on_ifarm
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Junaid
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------
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PionLT Q2=3.85 LT-sep functions
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- tried fiferent fits, with different LT,TT params floated
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  - obtained Data/MC ratios centered at 1, but with phi-oscillations
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- Latest version:
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  - added Q2-dep to LT,TT: both have param/Q^2 dependence
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  - in addition: LT has p12/t^2 and TT has p15/t^3 dependence
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  - all LT,TT params can float
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  - this gives Data/MC ratios with much reduced phi-dependence at high epsilon
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  - feels on the right track, now that fatios are fairly flat
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Vijay
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-----
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PionLT Q2=0.375, 0.425 LT-sep
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- modified LT,TT functions
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  - removed ft=t/(|t|+m_pi^2)^2 from LT equation
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  - LT now has 1/t^2 and TT has 1/t^3 dependence, similar to Junaid
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  - W-factor unchanged
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- added offsets to all SIMC input files
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- rechecked Diamond cuts, SIMC diamond was slightly off, one edge of diamond
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  needed a small adjustment
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- Q2=0.375 Data/MC yield ratios
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  - high eps: fairly flat at low -t, slightly bigger osc at higher -t
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  - mid eps: similar
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  - low eps: oscillations a bit bigger for higher -t bins
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- Q2=0.425 ratios have had less work, general trend is similar, so promising
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- sig_UNS
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  - Q2=0.375 now has sigL bigger than sigT for all except the highest -t bin,
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    which is closer to expectations
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    - also sigTT is now much smaller at low -t, also closer to expectations
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  - Q2=0.425 sigL has more fluctuations, will need more work
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  - *NB* Garth: notes that none of the functions have any Q2-dependence.  This
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    was fine for earlier (more approximate) work, but now that we're getting
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    closer to final results, we should add in a small Q2-dependence, to take
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    into account the variation of the cross section across the diamond
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Alicia
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------
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pi+ BSA paper modifications
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- summarized changes to the paper and the draft Response to Referees
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  - *NB* please send comments within a week.  Goal is to resubmit the paper by
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    the end of September
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Chi-Kin
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-------
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KaonLT high Q2 LT-sep
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- checked Diamond Cut for Data and SIMC for his Q2=2.1, W=2.95 and Q2=3.0,
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  W=3.14 replays
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  - huge difference between Data and SIMC diamonds, with the Data diamonds
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    being significantly smaller than the SIMC diamonds at both Q2
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    - *NB* clearly there is something wrong, Chi-Kin and Richard will discuss
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      and recheck
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- for now, just using the Data low epsilon diamond
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  - formed NormYields for Data and MC per t-phi bin
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  - for the MC yields, tried both Richard's latest work and CK's corrected
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    parameterization (with positive weight, discussed last week)
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Richard
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-------
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KaonLT high Q2 plans
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- looking at Q2-scan at fixed xB:
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  Q2=3.0, W=2.32; Q2=4.4, W=2.74; Q2=5.5, W=3.02
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- until mid-Oct: looking at refinements to LTsep model
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- November: preliminary systematics
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- by Thanksgiving: final data replay
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- then CK and RT will look at the Q2-dependence study, depending on how much
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  time RT has (due to A1n analysis)
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- also working on a Fitting Algorithm paper, likely for Comp.Phys.Communic.
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Nacer
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-----
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Low Q2 KaonLT LT-sep model optimizations
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- how using a model inspired by Tanja's sig_factorized_2007 report
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- before any iterations: Data/MC ratios ~7 for both low and high epsilon,
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  reasonably flat vs phi
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  - sigUNS eseentially has low eps=high eps, i.e. sigL nearly zero
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  - keeping LT=TT=0 in parameterization, although of course the Rosenbluth fit
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    gives some non-zero values from the phi-dependence
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- 1st iteration: Data/MC ratios ~1, except at low -t, where sigL diverges
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  - later iterations: ratios change only a little
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- one issue is the diverging sigL at low -t
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  - *NB* Richard had the same issuesuggests to double pion contamination, which
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    is particularly a problem at low -t
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  - will also set p5=9 in the exponential vs t in sigL and let LT,TT params to
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    float
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    Richard's parameterization
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    https://redmine.jlab.org/attachments/2819
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  Next Meeting
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-------------
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- Fri Sept 26 @ 11:00 Eastern/9:00 Regina
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  - KaonLT will go first
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** NOTE THE NEW TIME **
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- this time will be in effect until USA daylight savings time change, after
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  which it will switch to 10:30 Eastern/9:30 Regina
(732-732/745)