[Halld-cal] Minutes Jul 29 posted

[Elton Smith]

Minutes have been posted on the wiki. Cheers, Elton.

Attendees: Yi, Fernando, Beni, John, Elton, Eugene, Chuck (JLab); Matt,
Dan (IU); Andrei, George (UofR); Pedro (USM).

# Announcements
# Review of Action Items
# Bcal thresholds and resolution at low energies
([http://dustbunny.physics.indiana.edu/~mashephe/bcal_dkrate.pdf PDF
Slides]) (Matt)
#* Model resolutions using MC reconstruction
#* Use old geometry (no summing, inner segments SiPMs, outer segments FM
pmts)
#* Optimistic, since summing will likely degrade performance. Dan is
implementing the new scheme and will rerun programs when complete.
#* New normalization comes from Andrei, corresponds to 165 photons/MeV in
fiber/side compared to nominal 75 photons/MeV in fiber/side.
#* Results show that a factor of 10 increase in dark current changes
resolution sigma by about a factor of 2.
#
[http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1553
Estimation of Cross Talk] GueX-doc-1553 (Yi)
# [[SiPM Radiation Hardness Test#Test with RadCon AmBe Source]]  (Update
from Yi)
#* See page for details. Radiation tests with RadCon calibrated AmBe
neutron source (En ~1-10 MeV).
#* [[SiPM Radiation Hardness Test#Fluence simulation of Hall D]] gives an
estimated 6.5 years for SiPMs (at 10**7 s/year) to increase dark rate by a
factor of 10.
#* One anomalous 1x1mm2 cell irradiated in Hall A shows a dark rate
increase by factors of 4 higher than other measurements and needs
checking.
#* Additional checks needed:
#*# Check annealing time for 1 and 9mm2 units irradiated with RadCon
source
#*# (Beni) Check if increasing temperature helps annealing process
#*# Check temperature dependence of annealing
#*# (Eugene) Silicon micro-strips at CERN are kept cold ( about -70 deg)
to increase radiation hardness from krad to Mrad. (Freeze out defects?) It
is worth understanding the mechanism.
# Geometry
# [http://www.jlab.org/~huttonc/gluing.pptx Light Guide Gluing] (Chuck)
#* Check options for gluing guides on module before installation into
magnet
#* Consider not gluing guides to each other using a band to secure them at
the base and the fitted plate with square holes at the other end.
# [http://www.jlab.org/~huttonc/HAMSEAT.pptx SiPM positioning] (Chuck)
#* Make window opening for sensor large enough so that it does not impede
adjustment of distance between sensor and guide
#* Next: must design the gas volume for dry air (or nitrogen), as well as
scheme to avoid problems with condensation.
# Update - USM
#* No report.
# Simulation runs
# Cosmic-ray setup at UofR
#* Will complete tests with calibrated pmt
#* Next measure response using SiPM array, air gap with a) WC and b)
trapezoidal guides


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