Mar 19-20/26 PionLT/KaonLT Analysis Meeting Notes ------------------------------------------------- (Notes by GH) Today: PionLT will be discussed first Thursday: Present ----------------- Regina - Garth Huber, Alicia Postuma, Nermin Sadoun, Muhammad Junaid, Nacer Hamdi CUA - Chi Kin tam, Sameer Jain Virginia - Richard Trotta JLab - Dave Gaskell Junaid ------ PionLT Q2=3.85 W=2.62 LT-sep - added t-shifts calculated by GH - needed to adjust first 4 t-bins to keep ~2500 counts/bin old 3 bins: 0.16-0.208 0.208-0.226 0.226-0.264 new 3 bins: 0.16-0.206 0.206-0.226 0.226-0.262 - had MM offsets with both signs so not all data shifted in same way - average effect is data shifted to slightly smaller -t - Data/MC ratios very similar to before - some oscillations in 5th t-bin at low epsilon, was there before too - Vijay also had some low epsilon high -t oscillations - Rosenbluth "money plots" - before: d2sig/dtdphi for bins 2-4 had big dip at phi=180 where sig_hiepssig_loeps overall - now: the sig_hieps has shifted up by enough that at dip sig_hieps=sig_loeps - separated cross-sect: sigL increased by ~1sigma at low -t, changes smaller at high -t - met with Nathan yesterday to discuss comparison analysis, meeting again tomorrow Nacer ----- KaonLT Q2=0.5 LT-sep - added t-shifts calculated by GH - MM shift is always to the left (i.e. needed to shift data to lower MM), so data need to shift to lower -t as well - biggest t-shift=0.00375, which is comparable to the width of a t-bin - no changes made to binning, 1 iteration only - sigL changes shape a lot, goes strongy negative for first bin - lowest t-bin Data/MC ratio is very bad - yields unchanged to 7-sig-figs, something is claerly wrong - will look carefully at scripts - Garth: *NB* probably the t-binning had to be adjusted as well, take a look at yields/bin, as Junaid did Alicia ------ KaonLT u-channel LT-sep - more u-binning studies for Q2=3.0 W=3.14 - u-bin limits - previously, showed bkd-subtracted omega yields vs u-bin for Left,Center,Right - to get a cleaner sample, tightened cut 0.750 events - investigated at what value of u we lose total phi coverage - investigated u reconstruction resolution - compared u vs u_true in SIMC - sigma of (u-u_true) is 0.008 GeV2, which is much smaller than the u-binning - checking which u-phi bins are dominated by omega radiative tail events - will eventually do a Rad-Off vs Rad-On study in SIMC - for a quick check, looked at peak to tail ratio tail: 0.8550% for -u>0.6, which is higher than where full phi-coverage ends - try 2 u-bins vs 3 u-bins, due to statistics 0<-u<0.12 - many fewer backgrounds contribute than higher -u 0.12<-u<0.40 - center SHMS: harder to pick out omega by eye left SHMS: RF time is not available right SHMS: has RF time - binned shape study 0<-u<0.12 center SHMS: rho fit fails for some cases due to narrower 0.650.2NPE -2.05 cut on HGC - Junaid: don't worry about the exact NPE value to use in the cut, as long as it's sufficiently high to exclude protons, NPE>3 is probably okay too Next steps: - will look at LD- detector efficiencies, same Q2-W setting - after that, will start LD2 Lumi study - *NB* Junaid will send Kathleen and Julie his Efficiencies Report Nathan ------ PionLT Q2=3.85 W=2.62 analysis cross-checks - made a spreadsheet of Yield Comparisons between NH and MJ - Low Epsilon Center yields are different ~5%, other settings are exactly the same - cuts could be different, still checking - Garth: a possible explanation is that a run replay failed and you're comparing a different number of runs - Nacer: an explanation alternate to run fail could be symlinks pointing to the wrong place, remove symlinks to be sure you're using the same file - using ROC2, found an error in Junaid's code that ROC1 was used by mistake - different MM offsets could lead to small yield variations - NH and MJ are both fitting SIMC MM, expecting the same result, but obtaining small differences - Garth: you need to be sure both SIMC files have exactly the same statistical sample, if even 1 event is different, all subsequent events will have a different random number sample Sameer ------ KaonLT CoinTime blocking - instead of a dynaminc timing window, went to a fixed window for each run period - all windows are 140ns wide: Oct/18 - multiple timing windows, each time the DAQ configuration changed Dec/18 - 1 window: -11 to +129ns Mar/19 - 1 window: -25 to +115ns - showed plots of blocking correction vs CoinRate - plots looked good, studies are nearly completed - Richard will send his blocking corr for Q2=3.0 W=3.14 for cross checks - Questions for Nathan: did you calculate the cable length delays? - No, looked at photos of oscilloscope traces and added a bit extra to account for jitter - the way Sammer did it looks good - Q: how did you calculate the systematic uncertainty w/5ns window variation? - Nathan: don't want the cut too tight, want to remain in the shoulders of - good randoms - will try to make a plot of corrected yields after CoinCorr vs Rate, like Nathan did, to confirm everything is correct - Nacer: will the CoinTime blocking correction be calculated in the Report Files? - Yes, still waiting on last checks, will update the files soon Chi Kin ------- KaonLT systematic studies - SIMC systematic Rad On/Off - get 2x difference in yield after applying Diamond Cut - Garth: this indicates the MM cut is too narrow, it excludes all of the radiative tail *NB* the MM cut needs to be broadened - Gabriel: the data looks a lot more like the RadOn dist than RadOff - maybe tweaking one of the RadCorr params in SIMC is better than RadOn/RadOff, which is an extreme change - *NB* CKT will contact Dave for a meeting on how to proceed - acceptance systematics - will vary target cuts - ssxptar cut looks a bit wide - delta cut: can narrow down the delta cut, but not make wider - Tanja: our knowledge of the magnetic optics is not perfect, there are discrepancies between data and MC even within the well understood region. We want to quantify that Richard ------- KaonLT LT-sep - made a write-up on statistical uncertainty calculations that will be posted - will consult GH offline on the exact input values used in his t-shift calc - comparison of thetaCM dists for data and MC - sees a spike at thetaCM=0 in data but not SIMC - Gabriel: what happens in the code when cos(thetaCM)>1 due to resolution effects? This can lead to a spike at thetaCM=0 when taking the ArcCos when calculating thetaCM - *NB* to avoid this effect, don't convert to thetaCM - Tanja: we need to understand this issue, does it lead to the spike in sigL at low -t? Next Meetings ------------------ - Thurs: Mar 26 @ 16:00 Eastern/14:00 Regina - KaonLT will go first - Fri: Mar 27 @ 11:00 Eastern/9:00 Regina - we will continue where we left off