[Moller_simulation] Modification to Collimator 4 sculpt

Cameron Clarke cameronc at jlab.org
Mon Nov 26 16:12:32 EST 2018


I have made a change to the "_merged" geometry in remoll. From commit
c1cd234a (from 4 days ago or so) and onward in the develop branch,
collimator 4's sculpt has been updated based on the new SBU moller envelope
information. Col4 is designed to accept exactly the same flux of mollers as
goes through the acceptance defining collimator (col2), and since the prior
envelopes used to define that sculpt were too course grained in magnetic
fields, the envelope and sculpt did not reflect the reality of the
particles traveling in the simulation. Unfortunately, this has been an
issue for as long as collimator 4 has been designed off of the old SBU
moller envelope (forever?).

I probably should have made this commit some more dramatic feature
inclusion rather than just a commit, since it may change the moller (and
other) flux that reaches the detector plane non-trivially, potentially
affecting even the radial detector segmentation if the original collimator
4 placement was off by a lot. I did leave the old sculpt values clearly
labelled in a comment though, and I have added two new sets of files,
"acceptanceDefinition" and "acceptanceDefinition_includeCol4" which are
used to define the moller envelope that hits in ring 5 (open, transition,
or closed sectors) and the same but including the appropriately sculpted
collimator 4 as well (for further cutting out other signals) respectively.

We may want to do a new comparison of a standard "ideal" all vacuum
configuration before and after this new update to see if the moller and ep
signals do change significantly.

Cameron Clarke
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