Minutes of PrimEx meeting ong Apr. 2 1999


In attendance: Eugene Chudakov, Hall Crannell, Sam Danagoulian, Ashot Gasparian, Liping Gan, Charles Hyde-Wright, Mark Ito, Dave Lawrence, Ralph Minehart, Rory Miskimen, Bill Stephens, Bogdan Wojtsekhowski.

1.) Dave presented the currented status of the trigger electronics design. A new method was outlined. Concerns were raised about how lowering the discriminator thresholds would affect the accidental rates. It was decided that further simulations will be needed to determine the optimal configuration of the trigger electronics. The idea to use analog delay chips was also brought up. Umass will purcahse a few of the 2211 types from Data Delay Devices for testing.

2.) Ashot presented the current design plans for the prototype. It will be a 5x5 array of PbWO4. Included in the prototype will be a temperature control system since the PbWO4 will need to be held within +/- 0.2 degees C to maintain constant light output. Ashot also presented a new method for doing energy calibration via the kinematics of compton scattering from electrons.
Transparencies (in no particular order).

3.) Sam presented a preliminary design for the light monitoring system. The system will incorporate a laser distributed through a fiber optic network to the front of each detector. There was a discussion over how to attach the fibers to the detectors. Concerns over air gaps were voiced due to doubts whether they could be mechanically rigid enough to maintain constant optical proprties. Concerns were also raised over how connectors glued to the detectors might affect the energy resolution. Simulations will likely be done to ensure the LMS doesn't adversely affect the calorimeter performance with normal data.

4.) It was decided the next full collaboration meeting should take place on Saturday May 8th with an emphasis on reviewing preliminary drafts of the CDR.


davidl@jlab.org
April 4, 1999