Oct 5/22 PionLT/KaonLT Analysis Meeting Notes --------------------------------------------- (Notes by GH and SJDK) 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, Stephen Kay, Ali Usman, Love Preet, Alicia Postuma, Vijay Kumar CSULA - Konrad Aniol, Erika Gwin, Johnathan Conrad Ohio - Jacob Murphy, Julie Roche CUA - Richard Trotta, Tanja Horm JLab - Dave Gaskell FIU - Pete Markowitz Richard Updates --------------- - Bill's LT-separation code - Two bugs to deal with, going to contact Bill soon - C++ compiling issue - Luminosity Updates - Low beam on time runs - Previously used BCM4A, used BCM1 - One variable index was set to 4A rather than 1 - Current cut applied on BCM4A - which was reading 0 - BCMs can be very different, 1 seems to work best - I think this is the one Dave M recommended? - Should use GoodStartTime in addition to GoodScinHit - Tracking and PID cuts improved - separate pi, p cuts for SHMS +polarity - GH: could take all valid positive particles instead - Things starting to look a lot better, particularly with the relative yield without tracking - Possibly correlated with weird behaviour of tracked yield? - Finds that a discrepancy between EDTM-LT and CPU-LT is often due to bad current cut - 10.6GeV Lumi scan: - SHMS relative scaler yield still looks odd Carbon +14% slope @ 60uA LH2 +30% slope - SHMS untracked carbon looks very good except for 1 outlier - SHMS tracked carbon still has 25% slope @ 70uA - overall HMS scans looking good - 8.2GeV Lumi scan (both spectrometers negative): - change to BCM1 dramatically improves things, as most runs were completely cut out when using BCM4A - LH2: might actually see real -5% boiling, as trend is consistent across scaler, untracked and tracked analyses, on both HMS, SHMS - 6.2GeV Lumi scan: - only 3 runs that look good (so far), up to 30uA - this needs to be rechecked - -ve polarity luminosities looking OK, converging - HeeP Uncertainties - Included uncertainties - Stat uncertainty on Cherenkov? - DG: Should be a global efficiency that doesn't vary run to run - determine this via a dedicated Cherenkov efficiency study (HMS) - Dave G - Uncertainties probably should not just be sqrt(n) - This is an overestimate - Binomial errors instead https://en.wikipedia.org/wiki/Binomial_distribution - Cherenkov efficiency is like a Yes/no question each time - To do - Bill's cross section code - Lumi Analysis - Fast Raster Correction from FPi2 - *Might* already be done in hcana? - In Fpi2 the calibration was off, can take a look - Beam/target positions - confirm dimensions compared to Dave Meekins write-up - DG old document (2007) from XEM experiment - DG: F2 people looked at this in Spring-18 data, need to locate this in the hclog - Calorimeter calibrations - HGC efficiency calculation (Ali has write-up, need to add to code) - Aerogel efficiency too Discussion ---------- - SOS spectrometer acceptance cut in Data - Mentioned in Blok paper - Finds the boundaries of the acceptance - Measured DIS scattering from deuterium, detailed comparison with SIMC - SOS suffered significant saturation effects, which why it was needed - this was not needed for HMS, should also not be needed for SHMS - Richard mentions a tool to port in papers to a bibliography quickly - https://www.zotero.org/ Vijay Update ------------ - Mainly writing committee report - Updated shell script for lumi analysis, processed relevant lumi runs for low energy data - Need to process data through yield scripts - Yield vs Current study is next after the report is done Discussion ---------- - Error bars on the momentum offests - Figure 4.7 (page 61) in Jochen Volmer's thesis - https://misportal.jlab.org/ul/publications/view_pub.cfm?pub_id=5412 - How were the error bars here determined? - From examining width of W peak? - Yes, based on sensitivity from kinematics (Delta-W)*(dp/dW) - seems to be a fixed +/-0.1% uncertainty for 5 highest points - One point has very large error bar - Vijay notes that this point also has an angle offset - Magnets should really behave in a smooth and consistent way - Expect a trend on both spectrometer momenta, not neccessarily a trend for the angle (should be reproducible at the same angle) - Generally have a single in-plane angle offset - What about the vertical angle offset? - Dave G doesn't recall seeing this for Hall C in the past - Could SHMS have affected this? Heavier than the SOS, and Walter says the hall floor has sagged - Expect small point-to-point variation in the angle offset - Start with one angle offset and one momentum offset in each spectrometer, and see if you can get a global solution, allowing only a small point-to-point variation Ali Updates ----------- - Also working on committee report - BCM "calibrations" (the one that checks the beam on/off periods) for Lumi - Double check whether this was done for the HeeP analysis - Wasn't, added scaler replay and this determination back in - Will check the uncertainty in the efficiencies, as per our discussion Jacob Updates ------------- - Chatting to Peter Bosted - Posted something to SIDIS log - He applied 6.2 GeV HMS matrix, sharpened peak and reduced MM tail - should have beter agreement with MC peak shape now Stephen Updates --------------- - Discussion of John Matter's proton absorption spreadsheet - Lots of the legwork is done, a few things we'll need to adjust - probability of proton coming in, that gets through for trigger - material thicknesses in g/cm2 - uses average of nuclear collision length (Lambda_T) and nuclear interaction length (Lambda_I) - probability goes as p(x)=exp(-Sum(x/Lambda)) for total absorption - this is based on the idea that won't lose elastic scatt (forward) in trigger, but can lose multiple elastic scatterings - calculation is for 2.25 hodo planes, corresponding to minimal 3/4 trigger - Switch proton Lambda values to pion/kaon as appropriate - Kaon values not directly available - Scale pion values by difference in cross section at sqrt(s) for our reaction? - Need to make some reasonable assumption that we can justify and use this - plots of pi/K cross sections p.782 of current version of PDG - Need to switch HGC gas from CO2 to C4F10 as actually used in our expt - Remove NGC and replace with scattering chamber as needed - Adjust aerogel based upon refractive index used, i.e. density scales as (n-1) - Adjust LH2 thickness depending upon spectrometer angle Next meeting: Wed Oct 12 @ 9:00 Eastern/7:00 Regina/6:00 Calif - PionLT will start first