Feb 26-27/26 PionLT/KaonLT Analysis Meeting Notes ------------------------------------------------- (Notes by GH) Today: KaonLT will be discussed first Thursday: Present ----------------- Regina - Garth Huber, Alicia Postuma, Nacer Hamdi, Muhammad Junaid, Nermin Sadoun FIU - Pete Markowitz Ohio - Julie Roche Virginia - Richard Trotta JLab - Dave Gaskell CUA - Sameer Jain, Chi Kin Tam, Tanja Horn CSULA - Konrad Aniol Nacer ----- KaonLT Q2=0.5 LT-sep - Lambda: changed t-binning to fill in gap between lowest 2 t-bins - divided 1st t-bin in half, now 9 bins: -t=0.075, 0.082, 0.087, 0.093, 0.099, 0.105, 0.112, 0.122, 0.140 - Data/MC ratios look good after 7 iterations - 2nd t-bin sigL slightly higher than 1st bin by ~1 sigma, first t-bin went down a bit - Richard: notes that sigT has pole term formula in it, while sigL does not - Nacer will try with the pole term in sigL - Sigma0: results not shown last week, Data/MC ratios look good - kinematic plot comparisons look good too - sigL essentially zero over whole t-range - will also rerun w/o MM shift to see how big of a difference it makes - Garth will look into kinematics equation, to find implied t-shift when MM is shifted Junaid ------ PionLT Q2=3.85, W=2.62 - also added another low t-bin, divided first 2 bins into 3 bins - the new point is mid-way between bins 1,3 - Garth: the gap between the 2 highest t-bins is quite large, suggests to also divide last 2 t-bins into 3 bins, so all bins have roughly equal spacing - Data/MC ratios look better for high epsilon than low epsilon - planning to start systematic studies next week Richard ------- KaonLT high Q2 yield comparisons with Chi Kin - CKT and RT met at JLab and figured out the SIMC discrepancy, yields now match - 2 issues were found: - cut mismatch, CKT hadn't implemented an Aerogel tray geometry cut - miscommunication on which files were used - effect of various cuts on SIMC yields: - MM + t: ~20% decrease from no cut + acceptance: ~50% + HGC hole cut: ~65% + diamond cut (low epsilon): ~80% - plans for full replay of KaonLT data - will start w/ best setting (Q2=3.0, W=3.14) and work down - adding a new branch w/ only CoinTime cuts (no PID) for detector syst studies - will explicitly add PID cuts in analysis and vary them for studies - plans for KaonLT systematic studies - also will start with Q2=3.0, W=3.14 and work down - Phase 1: check now data yields change - compare data yield results due to different bkd subtraction procedures (RT vs CKT) - vary MM, acceptance, HGC hole cuts, and check variation across t-bins, SHMS-settings, and epsilon-settings - Phase 2: Radiative corrections ON/OFF, check how SIMC yields change Chi Kin ------- KaonLT drafting paper: intro, iterations procedure, text not yet on OverLeaf - systematics study: Q2=3.0 W=3.14 - Dave: should not widen acceptance cuts into regions of poorly understood ME, only narrow them - Garth: similarly don't make diamond wider, as then parts of the low epsilon diamond will be empty, only narrow - also does not see the point of varying t-binning, this will change the t-central of the bin and of course the cross section will change Alicia ------ Slides for Phi-007 Expt Readiness Review - did MM resolution studies, demonstrating we understand the expected Phi-007 MM resolution, based on KaonLT p(e,e'p)omega data - proton arm momentum much lower in Phi-007 than KaonLT, TOF separation will be beter, so K+ leakthrough will be less - Phi-007 MM resolution expected to be 1.8x worse than KaonLT, based on magnetic optics properties omega LT-sep - ssypfp big spike at zero resolved - issue was a few runs when reprocessing data - did not have to replay data, only redo python processing after replay - the issue was that not all variables were enabled for some runs - the omega MC of ssyptar dist is somewhat narrower than Bkd subtracted data - Dave: a possible issue is that SIMC does not incorporate collimator punchthrough for protons, only for pions - will try to locate Mark Jones' old proton punchthrough code for us - in general, the Sum-MC kinematic distributions are in reasonable agreement with data - need 2-4x more Pythia MC statistics Friday: Present --------------- Regina - Garth Huber, Nathan Heinrich, Vijay Kumar, Muhammad Junaid, Nacer Hamdi, Nermin Sadoun, Alicia Postuma FIU - Pete Markowitz JMU - Ioana Niculescu, Gabriel Niculescu Glasgow - Kathleen Ramage, Rachel Montgomery Virginia - Richard Trotta CUA - Tanja Horn Nermin ------ PionLT LD2- PID study - last week showed that NGC had very low NPE, looked into recalibrating - went through Cameron's NGC calib script - Run 12035 - placed Pcal cut to select electron sample - cuts placed on approximate boundaries of 4 NGC mirrors - apply SHMS cut: -10% < delta < +22% - optained new NGC gain factors via Poisson fit of fADC spectra - statistics looked a bit low, so tried script on Runs 12026, 29, 35 Gain Parameters: PMT1: 3.38 PMT2: 1.735 PMT3: 6.37 PMT4: 4.91 - Nathan: these are much smaller gain values than he had (about 10) so it explains the observed low NPE - Garth: surprised how poorly these PMTs were gain matched - Nacer comments about PCAL spectrum: - 2 peaks around 1, 1.2 - Nathan: these are most likely an electron and a pi- in the calorimeter at the same time. The other option could be a miscalibration for some data - peak around 2 - Nathan: this is 2 electrons in the calorimeter at same time - after calibration, now gets a more reasonable NGC distribution from 2-6 NPE, more similar to what Das had in his setting (~4 NPE) Next steps: - NS will try to get a NGC calibration using even more runs to get better statistics for the Poisson fit - will also do a NGC efficiency calculation for electrons Kathleen -------- PionLT LD+ PID study - looking at Q2=1.6, W=3.08, Ebeam=6 GeV, theta_SHMS=5.50deg - CoinTime study - with no PID cuts, hard to see prompt CoinTime peak, due to the very high rate with SHMS at small angle - then applied PID cuts, prompt peak is clear, shifted prompt peak to zero - did random subtraction using 3 peaks to left and right of prompt peak - RFtime study - selected main peak for pi+nn events Next step: - refining HMS and HMS cuts Vijay ----- PionLT Low Q2 systematics studies - completed model systematics for Q2=0.375 - this week, varied sigLT and sigTT models by 1 error bar and looked at variation in sigL,T - 1st t-bin is more sensitive than the others, results only in a drop in the cross section - for the other t-bins, sigL,T goes up or down, depending on the model change - this means a 1-sided systematic error (from model dep) will be applied for the 1st bin Next step: - compute the combined uncertainties to apply to the data - it would be good if the model syst could be studied also for Q2=0.425 Nathan ------ PionLT Q2=3.85, W=2.62 cross checks with Junaid's analysis - showed plots from the analysis scripts - next step is to compare yield totals, and kinematic plots with Junaid - Nathan and Sameer had a 3 hour meeting on Wednesday on Lumi analysis Gabriel ------- Alternative PID and channel ID for KaonLT - leaky pi+ has a different distribution than Lambda,Sigma0, so a subtraction pi+n data might not be ideal - first showed a fit of 2 skewed Gaussians to MM data - did 10,000 fits and found the Lambda,Sigma0 yield for each fit - made a frequency plot of yields obtained from the 10k fits, found this led to a 10-15% variation in yield - Nacer: many of the skewed Gaussian fits produce a small peak near MM=1.11 that seems unphysical - then explained Quality-factor fitting (Q-fit) based on recent paper by Williams, Bellis and Meyer: arXiv:0809.2548v3 [nucl-ex] - it is a generalization of the SideBand subtraction method - compute the "Distance" between 1 event and another, using 7 variables: Ebeam, (delta, xptar, yptar)_SHMS, (delta, xptar, yptar)_HMS - select 1000 nearest neighbors to each event, do a MM fit of Gaussian peak and linear background for Lambda and Sigma0 regions, and find fitted signal fractions of Signal and Background - use the signal fraction to calculate the Quality-factor for the event - instead of incrementing data histogram by 1, increment it by the Quality-factor - the idea is to get a MM plot of just the Lambda, Sigma0 peaks with no background underneath - compared Q-fit Lambda, Sigma0 yields to standard fit of MM histogram, they agree nicely, much smaller errors than 2 skewed Gaussian fit Next steps: - plans to adapt Q-fit method to excited hyperon identification, and write a paper on the method - also preparing the analysis framework for general release Next Meetings ------------------ - Thurs: Mar 5 @ 16:00 Eastern/15:00 Regina - PionLT will go first - Fri: Mar 6 @ 11:00 Eastern/10:00 Regina - we will continue where we left off - NOTE: this will be the last week at these times. After this, we move to the summer schedule Thurs: 16:00 Eastern/14:00 Regina Fri: 11:00 Eastern/ 9:00 Regina