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Mar 7/24 PionLT/KaonLT Analysis Meeting Notes

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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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Regina  Garth Huber, Nathan Heinrich, Muhammad Junaid, Nacer Hamdi,

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Alicia Postuma, Ali Usman, Vijay Kumar

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FIU  Pete Markowitz

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CSULA  Konrad Aniol

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CUA  Richard Trotta, Casey Morean, Tanja Horn

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JLab  Dave Gaskell

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Nathan

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PID plots for SHMS NIM paper

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 HGC efficiency was found to be low, ~80%

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 removed zero bin entries as Vijay had found in his PID study, then ~99%

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outside of hole region

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 indicates this is still a problem during PionLT data taking

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 DG: are you sure these aren't otherwise bad events?

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 GH: Vijay had shown that bad HGC events corresponded to good MMK, not due

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to other expt backgrouns

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 believed to be due to either a bad reference time or bad pedestal caused by

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high rates per PMT due to low HGC granularity (only 4 channels covering

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focal plane)

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 will eventually need to use fADC mode10 data to determine an apporpriate

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correction

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 *IMPORTANT NOTE* Richard uses HGC NPE<1.5 cut, so maybe a correction is not

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needed for his data, but he will have to confirm, for example if a good HGC

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time is required to calculate the NPE, then a correction would still be

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needed

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 shows efficiency plots vs X,Y and vs delta for Aerogel, NGC, HGC

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 shows NPE correlations between detectors for PID

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Next steps:

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 will look through Lumi scripts and try to understand recent changes

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Junaid

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DC efficiency plots for SHMS NIM paper

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 removed outliers

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 finalizing calorimeter plots for paper

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Next steps:

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 setting up scripts for Heep COIN data analysis

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Richard

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Fixes to xsect uncertainty calcs

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 met w/GH on Monday afternoon and found the problem

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 errors were not propagated correctly

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 uncertainties now stable vs iteration

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Pion contamination subtraction

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 Ali provided clean pi+ samples for Q2=2.115 and both Q2=3.0 settings

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 a sample subtraction is shown

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 pi+ subtraction is red curve, stops at MM=1.24 for some reason

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 DeltaPi contribution seems surprisingly small

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 some rechecks should be done

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Xsect comparo w/ and w/o pion subtraction

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 Q2=3.0, W=3.14 shows ~2025% reduction in sigL at low t, no MM cut applied

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 makes sense that low t region is most affected, as pi+ cross section

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should have much steeper tdepenence than K+

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 comparison with 1.10<MM<1.18 cut applied

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 about 50% reduction in lowest t bin, less in other bins

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Continuing separated Xsect issues

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 Q2=3.0, W=2.32 still shows epsLO>epsHi yields

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 sigL works out negative, sigT unrealistically small

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 Q2=2.115, sigL consistent w/zero for lowest t bin

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 compare to Marco's K+ data for Q2=3.0, W=2.32

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 his epsLO value is close to our epsHI value

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 having difficulty getting things to converge sensibly for different

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iterations

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 Vijay: what do your Ratio plots look like?

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 RT shows Q2=3.0, W=2.32 ratios vs phi

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 sees strong epsilondependence to Ratios

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 Ratios at epsLO larger than Ratios at epsHI

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 GH: it is *very important* to look at the Ratios plots for each iteration

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 the goal is to get the Ratios having similar values for both epsLO and

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epsHI, otherwise any separated cross sections are not reliable

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 look more closely at the parameterization

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 GH: suggests to start with only P1 for sigL and P5 for sigT, setting

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others to zero initially

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Ali

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Quick updates

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 iFarm is very slow, but finished replays for two higher Q2 settings

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 will get these pi+ spectra to RT soon

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 working on hodoscope efficiency plots for SHMS NIM paper

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SIMC resolution study

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 no HMS deltacorr needed for 3 of 5 kinematics, so can finalize SIMC

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resolution tuning

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 Q2=5.5, W=3.02 comparison of MM vs tbin between new and Feb analysis

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 Feb had overall good agreement, but poor agreement vs tbin, SIMC was wider

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than data at low t

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 now doing tuning for all tbins, to make sure SIMC is not wider than data

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anywhere

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 DC resolution factor is now 4x instead of 9x

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 Q2=3.0, W=3.14 center: now 5 tbins instead of 4

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 Q2=4.4, W=2.74 center

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 reasonable agreement of MM shape w/data

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 now running MC for all DeltaPi BSA kinematics w/new resolution correction

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 will start MM shape study for 3 of 5 settings

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 Dave: still don't understand why the correction factor is so large, but at

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least it's no longer 9x

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 Vijay: suggests to look at xptar, yptar comparison, to make sure this is not

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adversely affected by the MC resolution tuning

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 definitely a *GOOD IDEA* to check this

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Vijay

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Summer 2019 LTsep analysis, Q2=0.38

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 shows Yield Ratios vs phibin at epsLO w/o iterations

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 sees some unusual phidependence in the Ratios that doesn't make sense

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 GH: suggest to turn of LT, TT in initial parameter fit

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 Dave: notices a weird LeftRight asymmetry in the Ratio error bars, one

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side has dramatically smaller errors than the others, if there is

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reasonably uniform phicoverage these errors should be more uniform

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 Tanja: suggests to look at Ratios separately for each SHMS setting to see

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if things make sense, will be helpful diagnostic for debugging

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Alicia

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BSA update: looking at the 3 Q2settings that don't need HMS deltacorr

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 MM cut study

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 compare MM from data and SIMC, more zoomed in than Ali's plots

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 Q2=3.0, W=3.14, center Data is wider than MC

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 DataSIMC agreement is best at Q2=5.5, but still wider than SIMC

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 what MM cut values to use?

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 Dave: prefers no lower limit cut at all, unless the lack of a cut

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introduces a problem (e.g. extra background)

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 Dave: upper cut 0.98 is too tight, likes 1.0 better

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 suggest to look at Data/MC vs MM and look where the Ratio plateaus for

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deciding your cut values

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 Tanja: the Ratio plateau will occur somewhere around 510 sigma from pi+n

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peak

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 CoinTime windows for Random subtraction

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 CT spectra are now flat after earlier error fixed

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 can use 6 peaks Left and Right of main peak without issues

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 PID cuts are applied to the plot, but no HGC, and loose MM cut applied

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 Dave: suggests to look at yield of each bucket and stay away from that

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region where yield/bucket starts to decrease

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 GH: the roll off in the yeild will in principle occur at different CT for

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different settings, as the coincidence signal timing is TOF dependent

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 Nacer: where is there a region where peaks are merged together next to the

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first random peak?

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 Dave: it's just due to finite timing resolution and the fact that the

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prompt peak is so large

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Nacer

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Resuming KaonLT Q2=0.50 analysis after calibrations

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 H.gtr.beta plot is now centered at 1.0 after new calib

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 SHMS P.gtr.beta vs P.gtr.dp shows a wiggle

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 Nathan: this is due to a minor fault in the Hodo calib but you can ignore

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it

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 P.aero.npeSum vs P.hger.npeSum for K+ identification

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 HGC<3, Aero>3 NPE cuts used so far

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 will have to tune the cuts according to the data distributions

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 CTime.eKcointime_ROC1 vs P.kin.secondary.MMK

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 can see small K+Lambda and K+Sigma dots amid large pi+ background

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 GH: can apply a MMK>1.05 cut to remove the big pi+n CoinTime peak and make

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it easier to select K+ CT cuts

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 Ali: for these kinematics, you will find the RF cut to be very effective

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 Vijay: agrees, looked at these data earlier, with RF cut, you can get the

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pi+ CT peak to be smaller than K+ peak

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 Nathan: eK cointime is not quite centered at 1

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 Stephen may have not set the CT offset quite correctly, you can tune it

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 testing some Real/Random cuts to apply

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 MMK after random subtraction shows negative counts in DeltaPi region

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 needs more optimization as part of PID studies

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Next Meeting

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 Thur Mar 14 @ 15:00 Eastern/13:00 Regina

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 KaonLT will go first

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 note the change in time for Regina people, because of USA daylight savings

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switch

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