# 20200720-Optics-Mtg

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## Logistic information

Toll-Free Number (U.S.& Canada): 888-240-2560 PARTICIPANT CODE: # 585 129 220 Room IRL: <none> https://bluejeans.com/585129220

## Agenda

**Please post slides in haplog or docdb, before the meeting**

- Last weeks issues:
- Non-symmetric azimuthal angle acceptance distributions
- instability in Q2 measurements over the PREX-2 run Ryan
- catalog of relevant parameters for Q2 runs (beam E, beam position, spectrometer dp, trigger hole?... others?)
- Lead uniformity measurement vs. target lifetime (expected failure at end only)

- Longstanding topics
- progress on MC simulation of acceptance function
- Carbon fraction
- ultimate precision of angle measurement
- evaluation of optics db reconstruction uncertainty to q2 / acceptance function systematic error
- inelastic contamination Devi

## Minutes

- (Chandan) Acceptance function Chandan
- Started MC simulation of acceptance function
- shows lower Q2 than data, but still work to be done to match scattering angles, etc.
- reasonable looking reconstruction distribution, but very confusing dp from "target" vs "fp". Will talk to ryan about definitions for these variables.

- (Devi) Inelastic study -
- fit of CREX spectrum leads to estimate of inelastic strengths
- estimate of acceptance function.
- can be improved by convoluting acceptance and inelastic distributions
- Asymmetry estimates for inelastic states needed to complete this analysis.
- PREX-1 showed 3- excitation in thin lead target spectrum, looking for thi

s data to try to improve estimate of inelastic cross-section

- (Ryan) Q2 consistency
- After the first Q2 runs on natural lead (June 27) the other runs look more similar.
- reconstructed variables look similar, though dp for the 2nd natural lead run are narrower than other runs, and sometimes with small shifts.
- will need to accumulate the database of info for each run, on beam position, energy, spectrometer dp, etc.

[ https://docs.google.com/spreadsheets/d/1KpI4E1YjqStms2q5VfgF-9d2sTuG7s-OcBEuBSGxnyU/edit?usp=sharing Q2 run summary]

- (Siyu) Looking at non-uniformity for estimate of changes in lead density
- sees "average density" rise and fall - proabably not sufficient to normalize to one corner as in PREX-1
- Stabilty of width suggests limits on time variation of density. (Devi has a plot on this, should be remade with Tao's newest analysis of respin-2).
- Unusual difference between target uniformity distribution when cut on detector his vs detector not hit. maybe thickening of target in some areas causing radiative losses?

## Attendence

Dustin, chandan, bob, cameron, devi, hanjie, ryan, siyu, nilanga , cip, kent