[Halld-cal] Minutes of Cal Working group meeting

[Elton Smith]

=Minutes=

''Attendees: Yi, Elton, Tim, Eugene, Beni (JLab); Will, Alam (USM).

# Announcements
#* Due to change of time for the Lehman closeout, the meeting started at 
11:30.
#* Elton has requested that Zisis and Matt turn in their EVMS reports 
today in preparation for the progress meeting tomorrow.
# Review of Action Items
#* Magnetic measurements of the comparison of coated (new) and uncoated 
magnetic shields has been completed at 180 G. Tim will forward the 
results.
# FCAL
## (Update from Matt):  There are no major updates from the FCAL.  We were 
assembling the final batch of CW prototypes, but I have not yet heard 
whether they are all together and working.
# BCAL
## Readout
##* Alam has received components for the electronic test boards and will 
start assembly.
##* Will is waiting for feedback from Elton on division of 
responsibilities for various parts of the readout project. Elton and 
Eugene will discuss this afternoon and provide feedback.
##* Eugene: Notes that the schedule presently has the light guides as a 
large procurement in November. We will need to decide on whether it should 
be included into a single large contract with  USM. The design needs to be 
finalized and verified with measurements.
##* There is also substantial budget for the effort to cool the SiPMs. 
There have been discussions with the detector group, consulting with 
Fernando, to request some of their resources and expertise to be placed on 
the project. There is a draft agreement for electrical engineering time as 
well as time from Carl for testing of SiPMs.
## Construction Status
# [[SiPM Radiation Hardness Test | SiPM update]]
#* Recovery times, tau, are being tracked. At 60 degrees, tau~ 0.8 days, 
at 25 deg, tau=6 days, at -5 deg (fixing the unrecoverable damage to that 
at 25 and 60 deg) tau~47 days.
#* Revovery measurements will continue at -5 and 25 deg. The samples at 60 
deg will be re-irradiated to check whether baseline is affected by a 
second irradiation. The recovery of this set after second irradiation will 
be done at 40 deg to get another point on the recovery curve.
#* The recovery times were plotted vs temperature, and shown to have the 
SAME dependence as the dark rate. Yi does not think this is a coincidence, 
but indicates that temperature dependence of the charge mobility in the 
silicon affects both the dark rate and their recovery.
#* These data willl be very valuable in deciding on an operation plan for 
the SiPMs.
# Simulations
# Other Updates


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