[Halld-cal] Minutes of meeting posted

[Elton Smith]

Dear collaborators,

I have posted the minutes of today's minutes on the wiki, copied here for
convenience. Please update the notes as necessary, let me know of any
corrections. A straw-man schedule for testing the SiPMs is given.

Cheers, Elton.

=Minutes=

Attendees:JLab: Beni, Elton, Fernando, John, Eugene, Carl, USM: Will,
Sergey, Alam, ...

# Announcements
## Yuki Shiomi and Hui Yao from Kuraray are visiting the lab tomorrow.
Elton will give them a tour of the accelerator and Hall B. Beni will show
Yuki the lab where fibers are being tested.
## Hamamatsu has an update to the delivery schedule for their arrays:
current estimate is late October. Also they request a change of the pins
from 6mm down to 3mm. Fernando will check.
# BCAL Readout
# [http://www.jlab.org/Hall-D/reviews/Bcal_Readout_Jul09 Bcal Readout
Review (July 21)]
## Recommendations (my interpretation)
### Develop a comprehensive test plan for evaluating "production" SiPM
units
### Invest the time to test and evaluate the SiPM units before proceeding
with procurement
# Discussion of test plan for SiPM evaluation. A straw-man plan is shown
below based on discussions, and will be refined further
## Testing of electronic components (Fernando)
### Fernando showed a tentative
[[Media:SiPM_Dev_Schedule.pdf|SiPM_Dev_Schedule]], showing that testing of
the electronics should be completed by mid Sep.
### Output of the preamp will be one signal per array.
## Single sensor tests at room temperature (Carl)
### Check that all cells are operational by scanning across array.
### Calibrate a light source and determine a (relative) gain for each
cell. Determine PDE if possible.
### Measure dark current. (Dark rate is not possible at room temperature).
## Single sensor tests at 5 deg (nominal) (Carl)
### Install Peltier on each sensor gluing the Peltier to the "hot plate"
and attaching the hot plate to the sensor package using a thermal paste.
### Repeat measurements performed at room temperature, but at a nominal
operating temperature
### If possible measure the dark rate in this configuration.
## Track performance of sensors during light irradiation in the fiber lab
(low radiation, guestimated to be about 0.01 Gy/month)
### Place 6-8 arrays in a box with Sr source (Keep a few for reference)
### Arrays should be powered continuously
### Arrays should be operated at the nominal operating temperature (~5deg)
using Peltier
### Arrays should be exposed to temperature cycles
### Output may be monitored using a picoAmmeter
## Track performance of sensors during more realistic exposures to
radiation (e.g. Hall B).
# Discussion of further plans for testing light guides
## Elton obtained a quote from Plastic Craft on Monday for two types of
light guides (90 circular bend) and (90 mirror reflector).
## Quotes for 2 prototype pieces of each was about ~2k$ (4 weeks
delivery). We discussed whether we should purchase light guides for
testing and qualification of vendor, and who would do this. It was decided
that we might want to delay this decision until the situation vis-a-vis
the SiPMs was better understood.
## Vitali (from Hall B) mentioned to guarantee material quality, we might
want to provide qualified material.
## The 90 deg curve light guide has not been simulated and should be
checked before ordering the prototypes
## John: suggested that optimization/prototyping of the short light guides
for the SiPMs might be a good project to start with at USM. The
optimization would involve checking geometries that could work well with
an air light guide. Air coupling has considerable simplifications for the
mechanical design (thermal isolation from light guide, eliminating the
need for pressure adjustments on individual SiPMs, etc).
# Other business


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