July 24/25 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, Nathan Heinrich, Ivan Zhenchuk, Alicia Postuma, Muhammad Junaid, Nacer Hamdi Virginia - Richard Trotta FIU - Pete Markowitz JMU - Gabriel Niculescu CUA - Tanja Horn JLab - Dave Gaskell Ohio - Julie Roche Gabriel ------- Sigma/Lambda analysis - fitting Sigma0 yield, high epsilon KaonLT data - subtracts Randoms, MT, pion leakthrough - use MC templates to fit Lambda, Sigma0 peaks - allows to shift data by a few MeV to make peaks match - reran SIMC w/ resmult=3.5 factor from Ali - modification in shms_mchut.f - compare data and MC, for pions due to greater statistics - fit MM peak w/ simple Gaussian + bkd function, extract pi+n center and width - increase in MC peak width agrees well with Ali's values, but still much narrower than data - even a factor of 3.5 implies a tracking resolution >0.5mm, definitely unreasonable to increase it further to better describe the data - Junaid: it's important to remove NGC from SIMC since it was not there for KaonLT running - haven't done this yet, yes it's important but it will make the resolution discrepancy even worse, not better - shows plot of pi+n center vs p_SHMS, a correlation is seen, peak shifts from ~0.95 at low momentum to ~0.935 at high momentum - Dave: we've been looking more closely recently at 2022 SHMS data, getting some weird effects starting as low as p_SHMS=4 GeV/c - spoke with Mark about it, apparently there are some saturation effects start as low as 4 GeV/c, which is a surprise - *NB* suggest to keep looking for correlations of MM peak with focal plane and target variables, see if we can find a way to correct it - it may be clearer to start first looking at the KaonLT Heep data Richard ------- Q2=4.4 KaonLT analysis - looking in more detail at cut differences between high and low epsilon, both to better understand where sig_lo>sig_hi is coming from and for systematics study - sig_lo ~10% larger than sig_hi for many bins - the main differences between high and low epsilon are: - no right SHMS for low epsilon - HGC hole cut larger for high epsilon - asked GH about HGC hole cuts - Vijay's study was for the low epsilon data with smaller HGC hole - had done a quick set of HGC cuts for thesis, now need to do a more careful study - looking at lambda peak, clearly there is an extra bkd not included in the pion subtraction - Garth: *NB* the difference between data and pion leakthrough curve to left of Lambda peak is nonzero but nearly flat, could try fitting a flat bkd fit to 1.025.4 GeV/c - fortunately theta_proton is centered on SHMS acceptance - Henry Klest had modified pythia6_eic.f to define program inputs and outputs - added ePmin - event not saved if proton momentum too low - skipping the generation of exclusive events, since these are already in SIMC - 1M evts run in ~5 min, produce 1k evts after cuts - an annoyance is that the Pythia script doesn't allow it to run in bkd, need a terminal prompt every few minutes to keep iFarm connection from dying - have to keep jobs <1M evts - result: 5M evts in Pythia give 5k evts after cuts, of these 311 make it through SIMC - mostly not making the proton arm, investigating - checking Pythia acceptance variables - SHMS_ypfp looks like an issue - HMS_ypfp not centered at zero, most events are rejected - result: 20M Pythia evnts, 19k output, 1233 SIMC events - the MM shape looks reasonable, still need to do detailed comparo w/data Junaid ------ PionLT LT-sep preparations - using Tanja's functional form - in sigL, p7 in exponential and p8,p9 in denominator are all fixed for now - fitting all other parameters - weight recalc script, appplying to SIMC file output by recon_hcana - Dave: it's important to use Ratio method to recalculate the weight, to retain radiative correction, virtual flux factor, Jacobian - Weight=sigCM*Jacobian*GammaFlux*RadCorr - Weight_new=sigCM_new/sigCM_old*Weight_old - tried one iteration, ratios jumped from ~1 to ~40, clearly an error in the weight recalculation script - *NB* recon_hcana does not touch the weight or cross section, no other corrections are necessary that are not in the above equations Nathan ------ PionLT coin deadtime investigations - still debugging weird CT issues - finally has a straight CT line vs xfp_HMS - now using pTRIG4(HMS-ELREAL) instead of pTRIG3(HMS-3/4) - changed time window cuts slightly execpt for HT2, PT2 - now using a cut on HT2, no cut on PT2 - still needs to check that PT2 did not screw up SHMS - Dave: only need cuts on quantities used to calculate CoinTime - should use 1 and 3, ELREAL should have same timing as 3/4, the difference is only on extra PID info - *NB* will try PT3 cuts intead of PT4, and check SHMS - once has a set of runs with no CT anomalies, will start CoinBlocking study - will do a write up for RedMine Next Meeting ------------- - Thur July 31 @ 15:30 Eastern/13:30 Regina - PionLT will go first