July 25, 2013 PID Upgrade

Meeting Time and Place

Friday July 25, 2013 at 1:30pm

To connect from the outside, please use ESNET or SeeVogh

) ESNET: 8542553
) SeeVogh: A conference has been booked under "GlueX PID Upgrade" from 1:00pm until 3:00pm (EDT).
1. ) To phone into an SeeVogh meeting, from the U.S. call (626) 395-2112 and then enter the EVO meeting code, 155025.
2. ) To use the SeeVogh Java script use the SeeVogh link.

1. Update to DIRC Design (Baptiste)

New information from Baptiste's discussion with SLAC folks is that we will not be removing the bars from the boxes they are currently contained in
Design proceeding with the assumption of using 4 Babar boxes (48 bars total) with full length bars, and "plugging" a focusing box on the end of each Babar box to focus and collect the light.
A focusing design has been studied at SLAC and they have already done some tests with a prototype
Work ongoing with GEANT4 to understand the rings we might see in the PMT array
Curtis will try to set up a visit to SLAC to see the DIRC bars and confirm our interest in them.

2. Angular Acceptance of gDIRC (Justin)

Previous studies showed that combining the Gas Threshold (CKOV) and the DIRC detectors did not contribute much to improving the integrated efficiencies relative to the DIRC only design
This study found that the efficiency vs polar angle (in GJ frame) is impacted differently for the DIRC and CKOV detectors, but that the combination gDIRC would not significantly improve the uniformity of the angular acceptance relative to the DIRC only
Plan to compile a document of this study with that presented in the PAC for the docDB

3. Impact of DIRC on FCAL (John)

Added a "sheet of quartz" in Geant to study the impact of the DIRC detector on photon reconstruction in the FCAL
The additional material results in a small reduction in efficiency, which is concentrated at low photon energies (E < 500 MeV)
Paul reminded that DNeutralParticleHypothesis should give 2 showers (photon and neutron). John will check to make sure only using photon, but results indicate this is being taken care of somehow.

General conclusions from 1 and 2:

The new DIRC design using full length bars and only one PMT array would make it very difficult (if not impossible) to focus the light from a Gas Threshold onto the same set of PMTs. So the CKOV would be an independent detector, and based on studies of the physics performance doesn't appear to be critical to the physics program given the estimated cost.
The plan then is to focus on the DIRC only option with the boxes as built from SLAC and designing a focusing readout scheme.