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- CREX completion
- We need to select new "matching" conditions, calculate new acceptance function,for the corrected calibration. This was done ad hoc for the CREX unblinding. We should complete the calculation of the acceptance function.
- We already have CREX optics databases calculated for a variety of beam positions. I would like to better check our uncertainty in the beam position extrapolation by comparing results between the simulation and the reconstructed data using the various optics dbs.
- we should be finding similar results between PREX and CREX, so we should more carefully compare the left and right models between the two experiments.
- We should try to put in a realistic model for a rotation of the Q1 collimator. This may be a non-trivial effect, and might even be suggested by the shape of the acceptance.
- PREX completion:
- We didn’t account for this extrapolation problem for PREX. To do this, we need various optics dbs optimized for calibrations runs at various bpm positions, like we have for CREX. I'll talk to Siyu about what we have, and what we need.
- meanwhile, we should try to start by assuming a similar "optics residual" to CREX (ie. half milliradian per mm horizontal offset from db center) and see how big an effect this is. Initially indications from Bob's HrsTrkCorr were that the correction was significant, but there were also extrapolation issues with that approach.
- Weibin has implemented a guess at the reconstructed optics distortion, using 0.5 mrad/mm as for CREX, an x0 corresponding to the PREX run position, and the survey position for the PREX targets vs the CREX optics targets. The result is about 0.6% in asymmetry, about 0.4% in angle.
- Kent needs to do his homework:
- get databases from Siyu, get this Weibin
- get list of Q2 runs to Weibin
- review prex/crex survey data for rotation of Q1 collimator
- Weibin will
- Figure out how to implement a rotated-collimator cut
- Try to find previous log entries on the PREX optics calibration, to estimate the residuals vs. beam x position