## Kaon LT Meetings » mtg_24mar14.txt

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Mar 14/24 PionLT/KaonLT Analysis Meeting Notes |
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---------------------------------------------- |

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(Notes by GH) |

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Today: KaonLT will be discussed first |

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Please remember to post your slides at: |

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https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings |

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Present |

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------- |

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Regina - Garth Huber, Nacer Hamdi, Ali Usman, Muhammad Junaid, Nathan Heinrich, |

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Vijay Kumar, Alicia Postuma |

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CUA - Richard Trotta |

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York - Stephen Kay |

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CSULA - Konrad Aniol |

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JLab - Dave Gaskell |

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Ali |

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--- |

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MM shape study for DeltaPi BSA |

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- reran MC's with new resolution parameter |

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- starting on settings with lower P_HMS, where delta correction is not needed |

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- shows Q2=3.0, W=3.14, high stats setting, positive helicity |

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- initial fit of MCs to data |

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- new 10 MeV/bin instead of previous 4 MeV/bin (lower statistical errors/bin) |

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- with new MM binning, it is now more clear that strength of DeltaPi peak is |

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underestimated for some phi-bins |

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- since SIDIS and rho bkds are so similar, using a fixed ratio of 90% |

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SIDIS/10% rho for now |

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- cyan=sum of bkds, pi+n tail+SIDIS+rho |

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- optimistic that 2 t-bins can eventually be used for this setting (data |

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shown is over full t-range) |

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- GH: since they are so similar, why don't you try fitting just one of rho or |

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SIDIS to see which one is better, and just use that one? |

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- DG: this would be an unphysical choice, but it probably makes no difference |

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to your analysis |

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- Nacer: why are you fitting each phi bin separately? |

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- we have confidence that SIMC can properly describe the shapes for the |

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different processes, but not their amplitudes, so we need to fit each phi |

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bin separately |

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Alicia |

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------ |

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MM cut study after resolution correction implemented in SIMC |

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- Dave suggested calculating Data/SIMC ratio for different MM cut values |

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- UofR group meeting also suggested to compare w/ w/o HGC cut |

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- HGC gets rid of KLambda leakthrough but not the shape of the region |

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between pi+n and KLambda |

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- ratios do not in general have a plateau vs MM cut |

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- Q2=3, W=3.14 data shown |

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- t-bins 1,2 show a decrease in ratio vs MM |

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- t-bin 3 shows a plateau |

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- t-bins 4-6 show an increase vs MM |

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- behavior is similar for Q2=4.5, 5.5 |

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- since the ratio is not flat, will instead try placing MM cut in region where |

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expt yield is flat |

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- Q2=5.5, flat region is MM=0.99-1.03, so will try MM cuts 1.01+/-0.02 |

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- Q2=4.4, Q2=3.0 W=3.14, flat region looks similar, so same MM cut |

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- GH: can't think of anything better to try, given the situation |

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- Dave: have you looked at BSA vs MM cut? |

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- a preliminary study was done last year, the final study will be done with |

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these MM cuts |

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- Dave: if SIMC handles the radiative corrections properly, any cut below 2pi |

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threshold should give the same answer |

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- GH: not sure about this, the pion scattering in the collimator also |

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populates this region, in Fpi-1,2 we had to use a cut well below 2pi |

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threshold to avoid being too sensitive to this region |

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- Dave: there is no SHMS collimator routine in SIMC |

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- GH: wasn't aware of no routine was included at all. |

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*TASK for GH:* find the HMS collimator code used in Fpi-2 analysis, and get |

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instructions on how to modify it for SHMS collimator geometry |

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- Nacer: can an RF cut be applied to help clean up this MM region? |

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- no, only a small subset of 10.6 GeV data has the RF information available, |

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unfortunately |

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HMS Delta-correction |

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- P_HMS=6.59, Q2=3, W=2.32 data |

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- hcana uncorrected MMpi vs hsxpfp shows line with tilt on top half |

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- using reconstructed MMpi script to determine correction |

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- applying if hsxpfp>0: hsdelta+=3.0*hsxpfp |

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- resulting MM distribution is narrowed |

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- P_HMS=5.292, Q2=2.1, W=2.95 data |

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- hcana uncorrected MMpi vs hsxpfp shows line with tilt on bottom half |

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- correction: if hsxpfp<0: hsdelta-=4.0*hsxpfp |

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- having difficulty implementing this correction in hcana |

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- recompiling hcana on iFarm gives complaint about missing PODD variables |

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- Stephen: please *send* the PODD error and he will look at his notes to see |

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if he can fix |

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- Nathan: thinks it might be better to implement correction in the kinematics |

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file |

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CKY Regge model |

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- received LT' predictions from BG Yu for the BSA paper |

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Richard |

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Subtracting pion leakthrough |

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- last week's results had HGC hole cut inverted, taking only events in the hole |

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- now the pi+ dist comes all the way across the MM acceptance |

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- Q2=2.1 setting, high epsilon |

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- pi+ subtraction does not clean up region left of KLambda peak |

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- planning to re-optimize PID cuts after graduation |

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Unsep and Separated Q2=3.0, W=2.32 xsect |

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- shows ratios vs phi,t at high, low epsilon |

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- looking at what's responsible for Data/SIMC ratios being much larger at |

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high eps than low eps |

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- trying various initial values of model parameters |

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sigL=g(W)*(p1+p2*logQ2)exp(p3+p4*logQ2)*(-t+0.2) |

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-- changed last part to just -t to get better t-dependence |

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sigT=g(W)*p5/(1+p6*Q2) |

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- Dave: maybe remove the Q2-dependence and only have a simple t-dependence |

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- Dave: the *real issue*, however, is that if you have sigL<0 from the |

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beginning, there's a problem with the data itself, not the iteration |

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- GH: exactly what MM region is integrated for these yields? |

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- MM cut is applied after pi-subtraction |

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- GH: if we can't clean up the region left of KLambda with cuts or pion |

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subtraction, then we will have to consider fitting a polynomial and |

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subtracting it |

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- Dave: yes, we will need to sort this out |

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- Richard shows MM plots for same setting at high and low epsilon |

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- RF cut can be used only at low epsilon, region left of KLambda is |

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noticeably cleaner than high epsilon |

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- GH notices that pion subtraction peak is much narrower than the pi+n MM |

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leakthrough peak |

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- Ali's pion sample was analyzed as if pions, not K, hence the peak is narrow |

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- normalizing to the height of the pi+n peak will result in too little pion |

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leakthrough being subtracted, as the integrals won't match |

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- *Ali* will give Richard his cuts and RT will make a branch of his analysis |

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for the pion subtraction |

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Vijay |

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PionLT low Q2 lt-analysis |

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- found bug in script, error bars vs phi now more reasonable |

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- shows results after 1 iteration for Q2=0.38, all 3 epsilons |

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- some discussion about phi-dependence of lowest t-bin |

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- the low epsilon setting seems to have a different phi-dependence than mid |

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and high eps, which is weird |

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- Dave: this could indicate a residual offset issue, lowest t-bin is always |

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more sensitive to the offsets |

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- Vijay will investigate further |

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- t-bins 2-7 have more consistent phi-dependence at low, mid, high epsilon |

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- 8th t-bin has poor statistics, might have to be removed from analysis |

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- shows separated cross sections after 1st iteration, and model fits for |

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iteration #2 |

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- t-bins 1,8 look like outliers for sigT,L after iteration #1 |

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- if only t-bins 2-7 included in fit, things are more consistent |

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- will have to see what this looks like after more study |

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Nacer |

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KaonLT low Q2 event selection |

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- won't show any plots, since the meeting is getting long |

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- tweaking some cuts, changing the RF windows |

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- RF cut is very effective, needs fine tuning |

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- GH: since the RF cut is so effective, you can probably get by with a |

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combination of slightly looser PID cuts, to avoid cut-dependence to the |

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result |

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Nathan |

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Setting up PionLT Luminosity analysis |

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- in contact with Dave Mack regarding BCM calibrations |

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- DM did our first calibs from 2021 run, NH will follow up with him on run#'s |

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- Dave: if you can generate ROOT trees for him to analyze, it would be even |

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better |

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Weird hcana issue |

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- hcana suddenly did not know what replay variables were |

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- spent a day debugging |

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- restored things, but no idea what happened, as could not find any |

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difference from how things were set up before |

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Going through Richard's python scripts and finding what's missing |

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- will plan on meeting RT in early April, after his defense |

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Junaid |

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Setting up PionLT Heep study |

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- had some issues with lt-sep package |

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- merged cut files for 2021,22 |

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- added ngcer |

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- updated RF time offsets |

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PID cuts |

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- HMS cal-etot-track-norm>0.7 |

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- HMS cer NPE>1.5 |

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- CoinTime, extremely clean, practically no randoms |

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- should be able to just place a cut around prompt peak, no random |

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subtraction |

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Next Meeting |

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- Thur Mar 21 @ 15:00 Eastern/13:00 Regina |

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- PionLT will go first |

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