20200922-Optics-Mtg

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Logistic information

 Time: 12:30-1:30
 Toll-Free Number (U.S.&  Canada):  888-240-2560
 PARTICIPANT CODE:                  #543 006 042 
 Room IRL:                            <none>
 https://bluejeans.com/543006042

Agenda

Please post slides in haplog or docdb, before the meeting

1. (Ryan) Checking acceptance aperture haplog:4245
2. (Ryan) Acceptance function: Polar angle comparison haplog:4246
3. Optics and Acceptance to do list

Minutes

1. The acceptance in G4HRS agrees with the collimator drawing, as it should, at least for the one arm that was checked.
   1. Ryan will plot the Q1 collimator coordinates for the other arm, to show they match.
   2. we should check the survey to see how far off design this realistically be.
   3. Ryan will pass the macro to draw the collimator lines to Devi, for his HAMC comparison
2. Ryan compares the polar angle from the data with the polar angle at the vertex for the simulation.
   1. We need to compare the data reconstructed polar angle with the post-target calculation of the implied polar angle from the simulation. This allows us to show the simulation and the data agree (or not).
   2. We need to plot the simulation vertex polar angle over the simulation "implied" post-target polar angle. This is our comparison for how much the post target variable matter
3. Hanjie shows the simulation passing through the simulation detector planes, and also the tune-P matrix elements vs. transport z.
   1. The standard HRS tune shows a change in slope of the <y|phi_tg> matrix element at the dipole entrance. This change in slope doesn't occur for the G4HRS model. Is the a failure to include some fringe effect in G4HRS, or ...?
   2. The th/phi distribution leaving Q3 looks very different than entering, and already appears to show the prominent theta peak that is the big difference between the data and the simulation. Why? Is the strength of the field wrong, or its geometry?
   3. The comparison at the detector plane was discussed. What is plotted is often x_det = x_tr + th_tr*dz (with dz=0.9m from the VDC center to the detector plane). But this x/y transport plane if 45 degrees to the horizontal, so an additional rotation is needed to correctly get the x coordinate.
   4. If the simulation fails to reproduce the focal plane distributions, we can't use it to test the dependence of the acceptance function on the uncertainty in the focal plane acceptance. This may be recoverable, if we can use the data to show that we are very insensitive to this.

Attendence

Present: Ryan, Chandan, Devi, Hanjie, Sanghwa, Chandan, Cip, Kent

Excused: Bob