Apr 18/24 PionLT/KaonLT Analysis Meeting Notes ---------------------------------------------- (Notes by GH) Today: PionLT 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, Ali Usman, Vijay Kumar, Nacer Hamdi, Alicia Postuma CUA - Tanja Horn, Casey Morean UVa - Richard Trotta York - Stephen Kay CSULA - Konrad Aniol Nathan ------ PionLT BCM calibrations - met with Dave Mack on Monday to learn how to do the calibrations - things going very well, made some improvements to Dave's scripts - waiting for feedback from Dave Mack on results NH analysis The steps: - do a scaler replay of BCM calib runs - pick beam on/off times - do a fit of BCM frequency vs Unser current - look at fit residuals, and exclude outliers Initial results: - it looks likely that BCM slopes and intercepts can be combined for periods where the physical configuration (PreAmp setup, tune) did not change - BCM2 intercept and slope looks pretty stable - DaveM thinks BCM4A is most reliable, as it generally has less non-linearity at high current - KaonLT used BCM4A and BCM1 - BCM4B is optimized for low current, saturates above 40uA, so calib will be done only for lower current portion of scans - Nathan will make a write-up on changes to code and instructions Richard ------- mc_recon script changes - as shown last week, there was an offset to some kinematic distributions because the recon script was using proton mass (left over from Heep) rather than K+ mass - after the fix, MM VS yptar correlations look similar for data + MC - some odd looking correlation between MM and xptar shown(!) pi+ leakthrough subtraction - now using an HGC cut, K+Lambda peak in pi+ sample is eliminated - investigated variations to pi+ spectrum when varying HGC cut - no significant changes seen for NPE>1.5 to 3.0 - also looked at variations in Aerogel cut initial iteration results (Q2=3.0, W=3.14 only) - sigL seems to have a fairly small Q2-dependence within the diamond - t-dependence still not right yet - using exp(-t+0.2), will need to adjust the +0.2 offset in the exponent - GH: the MMk spectrum after pi+ leakthrough subtraction looks nicely clean now, suggest that you try fitting the SIMC K+Lambda and K+Sigma peaks to the pi+ subtracted MMk data - the K+Sigma peak sits on top of K+Lambda radiative tail, it would be good to see what the comparison looks like Alicia ------ - making plots for the BSA paper - CoinTime, MM data vs SIMC w/cuts shown - sample asymmetries vs phi for Q2=3.0, W=3.14 (2nd highest stats setting) BSA xB dependence - last week we saw there is nearly no Q2-dep to LT', so it was suggested to explore the xB dependence by fixing -t (but not Q2) - plots of LT' vs xB shown at -t=0.17, 0.27, 0.31, 0.36 - 0.17: shows an interesting trend, all of these points are in similar Q2-range - 0.27, 0.31, 0.36: xB dependence is flatter, generally good agreement between Hall C and CLAS results - some discrepancy between Hall C and CLAS results at 0.27, which cannot be traced to Q2-dependence, as both sets bracket similar Q2-ranges - don't yet know whether will include in paper or not - if we do, we probably won't compare to any theory curves - since the Q2-dependence of the data is ignored when making these plots, and the Q2-dep of the models differs from the data, this would be a messy comparison Ali --- - last week saw that Q2=3.0, W=3.14 data at high -t had few piDelta events - proposed to exclude highest -t region which had many fewer piDelta events than background events - similar study extended to other settings: - Q2=3.0, W=2.32, one t-bin - exclude events for -t>0.9, based on t-coverage of events in piDelta MM cut - Q2=4.4, W=2.74, one t-bin, exclude -t>1.0, region is tuned separately for each setting, based on how the MM plot looks at high -t - Q2=5.5, W=3.02, one t-bin, exclude -t>1.05 - Q2=5.5 phi-coverage - found that the piDelta MC somehow changed phi-range to 0-2pi instead of -pi to +pi - fixes underway, but source of the problem is not yet understood - one possibility is an issue with mc_recon - Richard: the phi range in hcana is different than SIMC - Ali: this is not the issue, that was already taken into account in the code, this is a kinematics-dependent change - Ali is still testing mc_recon script if it is using correct Mpi instead of Mp Vijay ----- - planning to show diagnostic plots next week on LT-separation - full set of plots not ready yet Nacer ----- KaonLT Low Q2 Cut Efficiency studies - RFtime vs MMk - will use data to determine the fraction of excluded KLambda, KSigma events excluded due to the RFtime cut - since the pi+n MM region is clean, will select these events for the study, under the assumption (seems reasonable) that the RFtime distribution is the same for pi+ and K+, just shifted in phase - apply same cuts (but shifted) to pi+n events as used for K+ selection - get an efficiency of 0.987, high epsilon 4.9GeV data - will have to repeat study for low epsilon data HMS electron selection efficiency studies - quick check using physics data, rather than Heep data - For the Cherenkov, get an efficiency of 0.981, which still contains some pi- contamination - Ali: for higher Q2 KaonLT, the sample was not as clean, got efficiencies as low as 0.75, even after using tight Calorimeter cuts to clean up the event sample - looks like it's good to use Ali's electron efficiencies pi+ subtraction sample - the idea is the same as Richard's, except that a very clean pi+ sample can be obtained just by using a tight RFtime cut - still need to normalize the pi+ sample to the leakthrough - Richard: takes MMk region 0.89-0.93, scales to equalize integrals Next Meeting ------------ - Thur April 25 @ 15:00 Eastern/13:00 Regina - KaonLT will go first