General Meeting Summary 10/22/15

MEETING WITH RAINER IN GIESSEN

• Discussion about SICCAS crystals

• Last 40 crystals Rainer received (produced in summer 2015) had good light yield and were radiation hard. However, slow component increased to 10% and almost all crystals fail transmittance requirements at all wavelengths. Worry is that doping resulted in increased light yield, but may have had other negative effects on the crystal growth process.
• 30 crystals were received at JLab in early October 2015. The company provided results on transmittance and light yield, which look ok overall. No details on crystal production process or the transmittance and light yield measurements were included. Action item: measure crystal properties.

Discussion on CRYTUR status

• The company is making good progress and Rainer has received another full-size crystal in early October 2015. He is planning to order a set of pre-production crystals over the next year.
• IPN-Orsay received a quote from Crytur (2000 euro/crystal) and will order 3 crystals for testing. Together with crystals available from Rainer this should give a big enough sample for conclusions on quality and possible prototype tests

Discussion about EU proposal submission for development of high quality PWO crystals

• Follows up on a previous proposal, but with modified scope and collaborating institutions
• Submission due date is end of October

PLANNING FOR CRYSTAL TESTING

• For specifications table include a description of what drives each specification and how they are to be measured

• Draft a plan on which tests will be done for the 30 SICCAS crystals, what institutions will perform them, how many crystals will be tested at each institution, and what the expected logistics/timeline will be.

• Initial list of capabilities of a few institutions:

• IPN-Orsay: transmittance with Varian photospectrometer, light yield (temperature control?), exploring options for irradiation
• Giessen: transmittance with modified Varian photospectrometer, light yield with temperature control to better than 1 degree Celsius, irradiation with Co-60
• CUA: transmittance with Perkin-Elmer photospectrometer, light yield with temperature control to 1 degree Celsius, exploring options for irradiation (e.g., with Xray system)
• JLab: transmittance with optical setup including an integrating sphere

NPS MAGNET

• Update from ongoing communications with HC engineers about design drawings

• SBS used steel from the BNL 48D48 magnets. Need to check if this steel would also be suitable for the NPS magnet

COLLABORATION MEETING: 21 JANUARY AT JLAB (time: TBD)

• General agenda topics as discussed previously include:

• existing thoughts to make the best optimal photon source needed for the approved polarized WACS experiment, but perhaps also beneficial for other already approved proposals
• updates on the progress with crystal tests/selection procedures
• update on magnet design
• update on PMT HV divider
• possibiliites for Timelike-Compton Scattering measurements with photon beam, NPS and polarized target in Hall C
• ...

ITEMS FOR NEXT MEETING:

• Background simulations

• Plan for crystal testing 2015/16+

• Update on magnet

• Readout

• NPS collaboration meeting planning

• Other...

NEXT MEETING: THUR 12 NOVEMBER, TIME: 9:00 AM (EDT)