# Optics Meeting Jul 18 2023 200PM ET

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# Agenda

- Fitting with sieve hole centers (Tyler) [1]

# Attendance

Ryan, David, Ruben, Paul S., Ciprian, Andrew, Mike D., Bill, Sayak, Vassu, Zuhal

# Minutes

- (David for Tyler) Removed Hole 71 from pass 1 results, and cut on GEM r,phi location to reduce/eliminate radiative tails. Results look more promising, but there are still puzzles for pass 1 fit. Questions: which hole diameter is being used? Suspect it may be the 9 mm diameter holes rather than 5 mm (no gaps in GEM r seen). Theta residual distribution still looks very broad for pass 1, and phi residuals are double-peaked (even for fit using Monte Carlo truth values) - this is not something we have seen before. However, for pass2, pass3, the residuals have similar RMS using the hole centers compared to using the Monte Carlo truth values, which is good. There is a bias to the mean values of the Theta, but that may be simply reflection of cross-section variation with theta biasing the fits - that would not be unexpected, and can be presumably corrected using simulation. Would also be interesting to see of the fit parameters are similar between hole center and Monte Carlo truth versions.
- (Vassu) Present results don't have the fit parameters (a_i) varying in smooth ways with beam energy. Suggested next steps: try to divide a given simulation in half (or smaller sections), do fits independently, and see what the actual variation in the fit parameters is compared to their error bars. Perhaps try simulations with even smaller steps in theta. Are we over-fitting? Maybe we can reduce number of components to the fit function. Are there some components which contribute relatively small amounts?

# Meeting link information

See email invitation, or contact David Armstrong, Kate Evans or Jennifer McAllister for Zoom link