[Halld-cpp] CPP meeting minutes

[David Lawrence]

Hi Folks,

  I posted some minutes from Friday’s CPP meeting on the meeting page at the following link and copied below.

https://halldweb.jlab.org/wiki/index.php/%CE%A0_polarizability_Meeting_July_1,_2016 <https://halldweb.jlab.org/wiki/index.php/%CE%A0_polarizability_Meeting_July_1,_2016>

Regards,
-David

Minutes[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=5>]

Attendees: Rory M. (chair), David L., Elton S., Andrew S., Mark D., Ilia L., Serguei G.
Announcements[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=6>]

Chambers accidentally set 500V too high in lab. No obvious damage but brief procedure review will be done.
Ilia (in attendance) will officially start with UMass on Aug. 25th (delayed due to visa issues)
Bobby attended G4 workshop last week at MIT. Will be going to JLab in a couple of weeks and will work on simulation.
Carts[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=7>]

Initial design for cart to hold and transport MWPC was shown.
These are needed because the carts weigh a lot (couple of hundred pounds each) and have fragile electronics or gas couplings on every side and so must be held a couple of inches off the ground.
Considering using these for transport to JLab as well since a similar structure will be needed.
MWPC construction[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=8>]

HV boards have been attached to frame of full scale prototype
Al plate gouges smoothed out to make surface smooth to the touch
Machinist currently cutting grooves into G10. Some delays after first piece.
Elton: FDC had to paint epoxy in grooves to prevent gas leaks
Rory spoke with Lubomir about that and had an understanding of technique. Will first attempt to polish grooves to see if that will suffice.
Wire Stringing:
Using long threaded rod with thread pitch that is multiple of 1/10"
Typical threaded rod has poor accuracy over long lengths
More accurate to cut than to extrude (most are extruded)
Rod bows some under its own weight. Possible to prevent with a brace in the center
Looking for manufacturer willing to produce only a 1 or 2 rods
π+π- simulation[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=9>]

Elton simulated events produced by Justin's ρ -> π+π- generator
Generator required AmpTools <http://amptools.sourceforge.net/index.php/Main_Page> package
Configuration files documented in e-log entry (linked in agenda above)
Currently configured for proton target with Coherent photon peak at 9GeV. Will update for future studies
CPPsim[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=10>]

David showed comparison of CPPsim (GEANT 4) output with the hdgeant (GEANT 3) simulation
Reasonable agreement for TOF and FCAL
Some fine structure doesn't match, but broad structure does
FMWPC absorber needs to be verified (only present in CPPsim)
Next Meeting[edit <https://halldweb.jlab.org/wiki/index.php?title=%CE%A0_polarizability_Meeting_July_1,_2016&action=edit&section=11>]

The next meeting is scheduled for Fri. July 15th at 9:30 am JLab time
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