[Halld-cal] Bcal Readout Minutes posted 6/03/2010 (fwd)

[Elton Smith]

= Minutes =
Attending: Pedro, Elton, Tim, Beni, Eugene, Chuck, John, Fernando (Jlab);
Zisis, Andrei (UofR); Will, Serguei, Alam (USM).

# Announcements
#* Responses to SiPM RFPs received, technical committee to meet next week.
#* Elton will be absent, so Zisis will run the next meeting,
# Review of Action Items
# Update - USM
##
[http://www.jlab.org/Hall-D/software/wiki/images/b/bb/MPPC_Test_Setup.V2.ppt
Alam's presentation from last week - update on USM MPPC test setup] (Alam)
##* Test stand design outlined with much discussion, some notes follow:
##* Test setup for testing 16 SiPMs simulataneously. Design under review,
especially to simplify insertion and removal of sensors to be tested.
##* Measurement of 16 expected to take 8 hours, with 2-3 hours of
setup/take down time.
##* Separate setup would be used to test all SiPMs on their corresponding
electronics board to be used in experiment.
##* Capability for testing at several different temperature, nominally 5,
10, 15, 20 and 25 deg C. Planning to purchase chiller to control
temperature. At the lower temperatures, condensation will need to be
controlled. Fernando noted that production testing may not require
multiple temperatures. Will states that the plan is to prepare for
exhaustive testing, a reduced list may evolve.
##* John: Concern with mechanical problems with multiple insertion and
removals of SiPMs into sockets. Fernando to suggest options for robust
mechanical and electrical connections of SiPMs to boards during testing
and production.
##* Serguei requested JLab send him the thermal properties of the SiPM
casing. Fernando volunteered.
##* Eugene: Why so many fibers? Could replace with single source and
illuminate all 16 units. [Concerns with fibers include issues of uniform
illumination and potentially saturating light into small region of SiPM].
Serguei indicates that light to SiPM may be adjusted by changing the
distance of fiber to sensor. Mechanical design might/should include
options for calibration  of light intensity from each fiber.
##* Status: Design advancing with feedback at each stage. Accumunating
equipment for setup; purchased VME crates with modules; chiller will be
ordered soon; start making mechanical parts for box in a couple of weeks.
##* Zisis: Suggestion to collect this information on the wiki for ease of
presenting information.
##
[http://www.jlab.org/Hall-D/software/wiki/images/c/c4/MPPC_Measurements.pdf
MPPC Measurements - time stability of current, effect of UPS] (Sergey)
##* Problem with draw current in current setup, traced to UPS powering of
SiPMs when main power was off.
##* Zisis: UofR invested in an isolation transformer, which has been very
effective at reducing noise.
## Comments on MOU (Will/Sergey). Suggested a change of date for readiness
for testing sensors from August to December, in agreement with the
schedule. Change ok'd by JLab.
## Progress on light guide prototyping (Sergey). Two guides are ready and
will be shipped to Athens. Four additional guides will be made and sent to
Regina. Inaki is working on various techniques for light guide production.
A laser cutting machine used for a test, hoping that polishing can be
avoided. Imperfections in the guides produced by the small CNC machine was
due to software mistake and should be able to be corrected.
# USM MOU/contract update (Elton)
# Simulation runs
# Cosmic-ray setup at UofR
#* Lab space being reclaimed after an interruption
#* All materials ordered.
#* Goal is to do some deliberate "gap" measurements to check with light
guide calculations. Then proceed with Npe measurements.
# Geometry [[http://www.jlab.org/~huttonc/ | Latest readout assy]]
#* Latest geometry presented with trapezoidal guides glued to module and
gap between guide and sensor.
#* Decision on geometry for sensor not finalized, but will be kept for
base mechanical design.
# [[SiPM Radiation Hardness Test]]  (Update from Yi)
#* I updated the recovery curves with more data i collected, no major
change
#* Hall A is still not ready for beam, hopefully by the end of this week
they can take beam;
#* Carl needs a little bit more time to give me the 1x1 mm SiPM and start
to test the dark rates of 3x3 SiPMs, hopefully early next week.
# SiPM - Test Electronics (Fernando)
#* PC boards for 1x1 and 3x3 mm2 units should arrive this week, tested
next week so they can be used for tests in Hall A.
#* Zisis: Asked about radiation damage to preamp boards. Fernando: No
degradation seen so far, nor is it expected because the front-end FET
should be radiation resistant.
#* Zisis request: consider positioning radiation monitor as close to
sensor as possible, as radiation "pockets" could occur in the hall.
According to Eugene the neutron fluxes should be relatively uniform in
this part of the hall.


Elton Smith
Jefferson Lab MS 12H5
12000 Jefferson Ave
Suite # 16
Newport News, VA 23606
elton at jlab.org
(757) 269-7625
(757) 269-6331 fax