Feb 2/23 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 - Stephen Kay, Garth Huber, Ali Usman, Alicia Postuma, Nathan Heinrich, Vijay Kumar JLab - Dave Gaskell Ohio - Jacob Murphy CSULA - Yeranuhi Ghandilyan, Konrad Aniol CUA - Richard Trotta, Tanja Horn FIU - Pete Markowitz Vijay Updates ------------- Update on Q2=0.38 low epsilon Analysis - CT peak, one peak either side of prompt peak looks very different (more counts), one is 2 left of Prompt, other is 3 right of Prompt for LEFT-2 SHMS setting only - Possibly a different particle leaking in, but then why does this give peaks on both sides? - Should create 2D distributions to check this - Plot CT vs MM - CT vs Beta too - TH: some weird random peaks were seen in Fpi-2 as well, but only on one side, it is weird here to have weird peaks on both sides of prompt peak - DG: yes, we can place cuts to avoid these weird peaks in the random subtraction, but we should spend some effort to understand why they're weird first - -ve events in MM distribution after Dummy and Random subtraction, to right of neutron peak - Green - central - Red - left1 - Black - left2 - After dummy + random subtraction - over subtraction? - Wrong charge assumed in dummy subtraction or similar? *Check* - MM peak is also very off, wrong MM used? - neutron peak is at 0.89, this is off a lot! - Vijay thinks it is MMpi, could easily be MMK if using Richard's analysis though *Check* - Diamond cut on low epsilon data - Cut shown for central setting - DG: How was this done? - Script maybe overcomplicating it? - It should be a relatively straightforward set of cuts - TH: Often it is nearly impossible to be sure exactly what you're doing if a complicated script is used - Each plot you make, you should be able to *understand* exactly what is done to the data - Some ragged blue region, it looks like SHMS+HMS acceptance cuts not applied - important to set the diamond cut after applying other physics analysis cuts, apply to ALL three epsilon data, including low epsilon, for consistency - RefTime cuts for this data? - Originally said not set but then said it was, not 100% clear - Think it's set ok? *Verify* - t-binning - Need same t bins for all three epsilon settings - Lowest t bin will have nothing from left2 - Similarly highest bin will be only left2! - Look at all statistics for three epsilons to determine t binning - Apply diamond cut to mid/high epsilon, and other physics cuts too, such as MM, etc. Want the t-coverage and statistics to correspond reasonably well to what will be seen in the final physics analysis - Data/SIMC comparison - No scaling applied to SIMC, and normalization comparison looks reasurringly good, as pion model should work very well at these low Q2 - Pion model should be much better than kaon model to begin with - SIMC distribution broader than data in xptar - implies on some aperture in the simulation is "off" - Which though? Very hard to determine - This is a mystery - Dave G has already updated target geometry in SIMC so it isn't that - DG has no other suggestions, but notes that the same is seen in SIDIS - SHMS yptar distributions SIMC, Data have same width, but a slight shift indicating a small offset issue? Richard Updates --------------- - Diamond cuts - Q2=5.5 looks good - Acceptance cut is applied, less ragged edges than what Vijay showed - script crashes for Q2=2.11, investigating - t binning - Apply all cuts - PID - CT - Only one epsilon shown, will have to show both epsilons after diamond cuts to determine optimal binning - t-distribution goes through zero (not allowed), lots of events at t>0 - Centre/left look OK - Right PID looks bad - Still clearly getting pi/p leakthrough - Large delta background under lambdas that needs to be removed - Try to get a clean pion sample, normalise this to residual neutron peak with kaon PID - Subtract it off - Basically infer the shape of the pion background from selecting out clean pions - Likely have to similarly get a clean proton sample, and normalize to residual omega peak, to remove proton leakthrough - Something seems to have gone very wrong for the right setting *Investigate* - DG: maybe its an error pointing to a wrong calibration file? - On plots, don't supress -ve counts - Want to see where y=0 actually is, preferably by drawing a line there, then can clearly see what's y<0 - SIMC rotation matrix differs from what Carlos has - Missing conversion from cartesian to spherical co-ords - Definition of what theta/phi for central spectrometer mean differ too - DG: Would it be easier to take output of SIMC and pass it through a converter/script to adjust the values - Copy what Carlos did and run this on the SIMC data - Some modifications needed - Should probably take values, convert them and save them to a new variable - Could just be added to repository as a standard tool - In Bill's LT-sep code, definitely seem to be missing a script still - Vijay noticed that there seems to be this missing link - Should be called "average_ratios.f", or something similar, which combines the different SHMS settings together to get full phi coverage - Average the ratios or sum the yields? - Either way should work, see notes from 2 weeks ago (23/01/19) Alicia Updates -------------- BSA pi+n Analysis from KaonLT - Fixed dummy target subtraction with correct thickness factor - widened MM window and NPE threshold in SHMS Aerogel - Q2=3.0, W=2.32, 5 t-bin results - Asymmetry fits look a bit better now - Bin 2 (0.21<-t<0.29) still has a different phi-dependence than the rest - simple fit (A) vs full fit (A,B,C) differs by 2 sigma for Bin 2 - The last t bin is very wide, please *remove* high t tail - comparison of preliminary LT' with VR Regge model - VR model has a known issue that is acknowledged in their paper - Does particularly bad at high -t (> 0.5) - VR curve does not extend to as low -t as the data - GH: this is because the curve is calculated with central kinematics only - need to compare VR to data at actual , for each t-bin - lowest -t bin will have a lower -t_min than the central kinematics, and the VR curve will then extend as low as the data - even with these issues, the VR comparo to data looks reasonable up to -t=0.5 - Q2=3.0, W=2.32 AL data - asymmetry with dummy target data is consistent with zero to 1 sigma - Q2 = 4.4, W=2.74 first results - again see the second bin doing its own thing - difference between simple and full fits is only 1 sigma though - AL BSA is consistent with zero within errors - Q2 = 2.115 results - *need* finer t-binning, lots of stats - full and partial fits different by <1 sigma, bin 2 issue seems largely absent here - Looking at t-bin #2 more carefully - starting to get K+ leakthrough in bins 4,5. Bin 2 looks fairly clean - background between pi+N and K+Lambda peaks also grows in Bins 3,4,5 - DG: Delta contribution seems to have a very different -t dependence to the neutron contribution, see a kink at MM=1.05 - GH: piDelta has different t_min than pi+n, so that's why its absent in Bins 1,2 - GH: wonders how big the pi+n radiative effects are for the higher t bins, and whether this explains the extra counts left of piDelta - we *need* to run SIMC for these settings and look at the growth of the MM radiative tail with t-bin to better understand this - will make a nice plot for the paper too - DG -For weird second tbin, have you looked at asymmetry before combining settings? - AP: Yes, overlayed, hard to interpret as statistics poorer - Nothing strange immediately jumping out - Can *try* at low Q2, where there are more stats, but the weird effect seems smaller there Jacob Updates ------------- new HMS saturation curve including higher momentum data - Saturation correction in B sets in above 5.1 GeV/c - shows 12% effect at P=6.8 GeV/c - DG: Isn't this removed in the magnet setting program? - checks, the program is unchanged since 2018-Aug-26 - JM: using B/I from readback, so this is the real effect - Looking at Q1,Q2,Q3 saturation, expect to have more to show next week Nathan Updates -------------- Detector time cuts update - Made an "open" cuts file - Wide enough that whole distribution can be seen - Summing over PMTs since the're stable - Doesn't change much between PMTs - Plots shown from run 13090, but other runs look the same - Dashed lines with suggested cuts - HMS Cherenkov looks odd - All events at zero for H.cer.goodAdcTdcDiffTime_PMT2 - similarly variables for SHMS calorimeter all zero - GH: unfortunately, hcana initializes all variables to zero, instead of an error code of -9999, so it's not possible to distinguish a "true zero" from an "error code zero". Suspects this means the variable is actually not present, which is not the same as being present but zero - Maybe variable has been renamed to something else? *Investigate* - HMS Cherenkov distributions otherwise look fine - HMS Calorimeter double peaks are seen - most detectors have the right peak larger - some detectors have both peaks - others have left peak larger - making cut wide enough to include both peaks for now - GH: the bkd is down by 100X from the peak, so there is a bit more noise leaking in with wider cut, but probably okay - RT: yes, thinks so too Next Meeting ------------ Thur Feb 9 @ 17:00 Eastern/16:00 Regina/14:00 Pacific - PionLT will go first