Meeting notes from cal working group meeting.

[Elton Smith <elton@jlab.org>]

=Minutes=

# Attending: JLab: Elton, Beni, Carl, Eugene, Fernando, Tim; UofR; Zisis,
Andrei; IU: Matt, Ryuan, Mihajlo, Claire; USM: Will.
# Announcements: Video is only working through EVO, so this is an
alternate way of connecting to the meeting. EVO is bridged to ESNET.
# Calibration (Athens)
#*
[http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1236
LED layout]
#* Athens has prepared a new circuit board which now fits into the
existing BCAL geometry with Winston cones. Could move the LED off the
board if more room is requried.
#* Eugene: It is difficult to make a small pulses with LEDs. Zisis
mentioned that there will be tests at Regina to investigate optimal
configuration of such a system, including neutral density filters,
installation to illuminate the far pmt, and experiment with setups that
allow near and far pmts to see the LED light.
#* Eugene: One should also shield the SiPM amplifiers from the LED pulsing
mechanisms.
#* Christine will attend one of the next two collaboration meetings, might
give a report in May.
# FCAL Update
#* MOU in circulation. We have received feedback from Allison. Will
discuss comments following this meeting.
#* Hardware tests of assembly individual module [older design] is
underway. Building a pulsed LED to monitor gain, including response of pmt
base. Paul Smith is interested and helping.
#* By summer/fall will have five operational assemblies of new pmt base
assembly design.
#* Still need final magnetic fields inside new shield assembly. Tim: Bill
has studied new ANSIS calculations of B-fields with new shield. Using a
0.5 mm gap and mu-metal they get a residual field of 1.7 G. Tim will make
plots of Bfield as a function of position.
#* Working with company to produce a phosphate (?) anti-corrosion coating.
Initial outdoor test is surviving without corrosion.
#* Looking for vendors of F-108 rad hard glass. Vendor is promising
50micron tolerances on transverse dimensions (which should be ok). Will
need polishing.
#* Data sheet is available, and Matt will post either to wiki or to
portal.
#* Electron storage ring now available at IU. Currently delivers 6 or 26
MeV. Goal is to increase energy to 100-200 MeV. Working with group on
possibility to use this device to irradiate Pb glass and investigate rad
damage in some detail. This will help studies of the effects of
transparency on resolution.
# Simulations
#* No update. Reconstruction meetings will resume on Tuesdays at 11:00 am,
and Blake will return focus on reconstruction.
# BCAL Update
## Preparations for construction
##* Elton: RFQ for fixed-price construction prototype procurement should
go out soon. Award can be made quickly as soon as UofR responds. Contract
for production is in the works and we hope will be awarded by mid summer.
##* Zisis:
##* Start operation May 1 with five students, and start swaging on May 18
using existing lead.
##* Bids for production quantities of lead should come in this week.
Expect samples of all sizes in June, with quantities for one module in
July. Full quantities will be delivered in four large shipments over the
next year.
##* Waiting on production schedule for fiber delivery. Expect first
shipments in early May.
##* Sending requests to Bicron and Eljen for purchases of epoxy.
##* Expect to complete production prototype in early September. Schedule
calls for first four modules to be completed by Feb 2010.
## Cooling of BCAL Readout
##*
[http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1214
Sensitivity to voltage temperature] (Elton)
##* Elton added section on sensitivity of SiPMs to voltage and temperature
to existing GlueX-doc. Will suggested a table be added with a list of
sensitivities to voltage.
##
[http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=1235
Update on Hamamatsu and Sensl Sipms] PPT:
[http://www.jlab.org/~zihlmann/SiPM_MPPC_update.ppt] (Carl)
##* Update on comparison between Hamamatsu and SensL devices.
##* Slides on portal come with accompanied reference notes which indicate
the source of the values.
##* Hamamatsu have higher PDE by factors of 2-3. However, there is
increased sensitivity to both voltage and temperature, due to the narrow
operating range (about 1 volt)
##* Will asked why the noise on the Hamamatsu spectra seems to be at high
(rather than low) amplitudes. Could be due to increased gain at the higher
voltages?
##* Will asked about the time dependence of the noise --does it keep
increasing over time, or burn in and stabilize? Carl had no direct
information about this.
##* SensL active area is about 77%, but Hamamatsu active area is about
50%.
##* Rise time of SensL devices are clearly longer than Hamamatsu for
measured devices.
##* Matt commented that the sensitivity to noise increases as the
slope*width of pulse. (Did I get this right?)
##* Will; Was the light collection (due to different windows) into the
sensor the same for SensL and Hamamatsu? Carl believes yes, at the 10%
level.
##* Electronic gain of both systems is similar for these tests, but pulses
are wider for SensL so integrals will be different than the amplitudes.
##* Tim asked about sensitivity to pressure during attachment? Eugene
asked Carl Jackson this question and he did not have an immediate answer.
The likely interface between SiPM and light guide will be a silicon
cookie.
# Agenda Collab. Meeting
[http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX-Collaboration-May-2009]
Suggested list to be refined at next working group meeting
#* Fcal update
#* Timing resolution of FADCs
#* Bcal construction
#* Update on Bcal readout
#* Report on tests of first article fibers
# Review of Action Items


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