## Kaon LT Meetings » mtg_24jul31.txt

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Jul 31/24 PionLT/KaonLT Analysis Meeting Notes |
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(Notes by GH) |

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Today: PionLT 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, Alicia Postuma, Nathan Heinrich, |

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Muhammad Junaid, Vijay Kumar, Zach Sullivan |

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Virginia - Richard Trotta |

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Ohio - Julie Roche |

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CUA - Tanja Horn |

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JLab - Dave Gaskell (last half) |

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Nathan & Zach |

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------------- |

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- Zach had a problem w/ python script in ALMA9. Nathan and Junaid have not |

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been able to fix it |

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- Junaid thinks there has been a change in python syntax, but can't figure it |

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out, stuck for now |

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- *NB* Richard will take a look, probably an incompatibility between versions |

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of python and pyroot that needs to be fixed |

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- the same problem is likely to also affect Richard's analysis, so this is a |

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high priority for fixiing |

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Junaid |

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PionLT Heep Study - 9 beam energies |

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- investigating two issues |

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1) some EM distributions are broad |

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- for all 2021 data, EM peak is sharp |

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- for all 2022 data, EM peak is broader |

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- checked raster parameters, there are multiple raster calibs for 2021, but |

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only one for 2022 that Mark Jones posted, based on run 14809 @ 7.950 GeV |

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- no raster issues were noted for 2022 run, so presumably a single raster |

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calib is sufficient |

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- GH and Richard: *NB* try looking at EM versus raster_x, raster_y |

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- if there is a problem, EM will be correlated (tilted line) with respect |

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to these variables |

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- the plots that Richard recommends are: |

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2D: (S)HMS EM vs delta |

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(S)HMS PM vs delta |

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SHMS delta vs HMS delta |

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raster_x/y vs PM/EM |

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raster_x vs raster_y |

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1D: BPM target x/y |

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2) calculation of Heep COIN error |

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- checked error calculations, was using weighted SIMC yield instead of raw |

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SIMC counts in the error calculation |

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- this makes a huge difference, MC errors now much smaller |

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Nacer |

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----- |

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Heep error checks |

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- worked with Junaid, found the problem by checking numbers step-by-step |

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Comparing Heep models in progress, to establish uncertainty in the MC |

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prediction |

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Comparison of Nacer and Richard Heep yield ratios |

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- it is important that we understand why the Heep ratios deviate from unity, |

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and perhaps understanding the difference between Nacer and Richard's ratios |

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will shed some light on this |

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- *NB* Richard will re-run some scripts to recheck and understand the |

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discrepancy |

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Alicia |

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------ |

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BSA paper update |

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- B-G Yu happy with latest changes, paper is ready for submission |

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- filled out fields on PRL server, will be submitted later today |

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Ali |

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--- |

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piDelta BSA analysis |

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- Garth asked to show BSA plots for all settings |

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Q2=2.1, W=2.95 |

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- 2 t-bins, data very smoothly follow sine-curve fits |

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- BSA amplitude ~0.12, small errors |

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Julie: *NB* can you please make residual plots of data-fit? The fit actually |

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looks too good, Chi-square<1 |

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Q2=3.0, W=3.14, 2 t-bins |

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- errors a bit lager, fluctuation about sine curve gives Chi-square<1 |

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Q2=3.0, W=2.32, 1 t-bin |

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- right SHMS setting had mroe stats than left, so errors vary with phi-bin |

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Q2=4.4, W=2.74, 1 t-bin |

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- errors a bit bigger, BSA amplitude ~0.15 |

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Q2=5.5, W=3.02, 1 t-bin |

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- errors bigger, Chi-square clearly <1 for ALL plots |

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- errors are statistical only, systematics not yet included |

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Julie: *NB* can you please send me exactly how you calculate your error bars? |

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- maybe your errors are over-estimated, do not follow 2/3-rule |

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Next steps |

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- work on systematic uncertainties in progress |

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- syst unc due to 2 types of fits, 2 studies |

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- syst unc due to cut-dependence, 2 studies |

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Richard |

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------- |

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KaonLT LT-iteration fitting |

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- updated sigT functional form |

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- added t-dependence, t-trend of Ratios more uniform now, but more iterations |

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needed as Ratios ~0.4 |

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- Tanja found an old Fpi-1 log entry by Jochen Volmer, dated Mar 16/2000: |

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- he tried a functional form for sigT of the type: |

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a+b*(W-Wc)+c*(Q2-Q2c)+d*(W-Wc)*(Q2-Q2c) |

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- this seems like a very nice function that could describe the variation of |

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the cross section across the diamond, where the diamond center is at |

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(Q2c,Wc) |

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- tried fitting it as sig_UNS at high,low epsilon, just to see what results |

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- b & c terms have significant t-dependence, d more constant |

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- curiously, b & c have opposite t-dependences, but they're in orthogonal |

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directions on the diamond, so not sure if this results in cancellation or not |

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- looks promising, GH suggests to try this form for sigL and sigT, perhaps |

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could use a linear t-dependence for b & c, given their strong t-dependence |

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Vijay |

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Low Q2 PionLT volume cut systematic uncertainties for L,T,LT,TT |

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- varied delta, xptar, yptar by +/-10%, 6 cut changes in total per spectrometer |

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- SHMS-delta |

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- no variation in sigL,sigT |

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- SHMS-xptar,yptar |

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- sigL varies 0.1-0.8%, depending on t-bin |

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- sigT varies 0.1-1.2% |

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- HMS-xptar,yptar |

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- variations are similarly small |

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- HMS-delta |

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- variations are much larger, sigL 28-90%, sigT 40-90% |

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- *NB* we need to better understand what is going on here, unexpected |

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sensitivity |

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Dave: *NB* you might need to increase the SIMC event generation limits |

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- plot delta,xptar,yptar for +10% limits and check |

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- another thing to keep in mid is that the HMS delta matrix elements are less |

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understood past 8%, so the +10% cut is past the well-understood acceptance |

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- 7.2% (-10%) cut is more reasonable, but your results look similar for |

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8.8% |

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- *NB* suggest to look at Vladis Tvaskis' PhD thesis: |

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- Vladis and Henk found that a small correction to HMS-delta was |

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necessary, affected things at the few percent level |

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- if this correction is not implemented in the analysis, then we should |

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look at adding it |

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- *NB* please make plots of focal plane and physics variables for delta-10% |

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cut, so we can see if there are any large discrepancies between them that |

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could explain the unexpected variation |

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Next Meetings |

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-------------- |

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- Note the special time: |

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Wed Aug 7 @ 15:00 Eastern/13:00 Regina |

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- KaonLT will go first |

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- Dave and Julie can't attend then |

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- Garth will be at Exclusive Reactions meeting @ Trento, will connect from |

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hotel room |

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- Thur Aug 15 @ 15:00 Eastern/13:00 Regina |

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- Dave will take notes |

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- PionLT will go first |

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