General Meeting Summary 10/9/14

NPS PROTOTYPE/STUDIES:

• Prototype was modified to eliminate light leaking from the blocks and tested with cosmics

• Results show that the modifications are working
• Also demonstrated that Gain Monitoring System (GMS) can be run in parallel with the IR curing system (both consist of LEDs)

• A spare SICCAS crystal was irradiated to check if the lack of effect of the radiation on the transmittance is due to the crystal geometry - so far much smaller crystal samples have been irradiated

• The radiation dose rate was 260 rad/hr
• No definite effect of the radiation was observed on the transmittance. The same had been observed for the smaller crystals. This seems to confirm that radiation damage depends strongly on dose rate and is not dependent on the geometry of the tested crystals
• Action Item: Prepare a global summary of what has been learned so far from the crystal radiation studies. In general, the conclusion is that the dose rate is too small to see an effect of radiation (Vardan, Hamlet, ...)

• DISCUSSION ABOUT THE PATH FORWARD WITH CRYSTAL RADIATION STUDIES

• Test the prototype and GMS, curing system in a situation similar to what is expected during NPS experiments

• Action Item: Check if the prototype can be placed in Hall A during DVCS in a location with sufficiently high radiation without disturbing the experiment, e.g., close to the forward direction. (Hamlet, Rolf)
• Action Item: Check expected dose rates. They should be similar to those in NPS proposal scaled with radiation length (Rolf, ...)

• Test the crystals in a well-defined radiation environment, e.g., at Idaho.

• Action Item: Ask for scheduling beam time in Idaho for 1-2 days in January (Carlos)
• Action Item: Prepare a plan of what measurements/tests should be done (TH, ....)
• Action Item: Check possibilities for future crystal purchases, e.g., lead time (Hamlet)

WACS POLARIZED

• Donal/Jixie present an interesting idea for experiments needing photon beam with polarized targets

• Use FZ magnet as vertical deflector creating a local beam dump
• Could be an attractive way to do transversely polarized target experiments and also LD2 and TCS
• Action Item: Check if it is possible to put required beam current on magnet in its current position. Need beam line drawing and check with Radcon (Rolf, Jixie, ...)

COLLABORATION MEETING: 19 NOVEMBER AT JLAB

• Discussion of draft agenda

• Include a discussion on opportunities with transverse targets, e.g., Jakub Wagner could give a theory perspective on TCS followed by an experimental perspective
• Include a talk on NPS magnet(s)
• additional topics...

ITEMS FOR NEXT MEETING:

• Summary of what we learned so far from crystal radiation and prototype studies

• Updates on long-term efforts for irradiation studies, e.g., HA possibilities and Idaho scheduling and plan for measurements

• Next collaboration meeting agenda

• Other...

NEXT MEETINGS: THUR, 30 OCTOBER at 9:00 AM (EST)

                             COLLABORATION MEETING: WED, 19 NOVEMBER