May 3, 2011 Readout
From GlueXWiki
Teleconference Time: 11:00 a.m. EST
- ESNET 8542553 and EVO session
- JLab Phone: in CC F326 is 757-269-6337 (usual room)
- JLab Phone in CC L207 is 757-269-7084
- Phone in the Regina Videoconference Suite is 306-585-4204
- Athens Phone: in Christina's office is 011-30-210-727-6947
- Phone:
- +1-866-740-1260 : US and Canada
- +1-303-248-0285 : International
- then use participant code: 3421244# (the # is needed when using the phone)
- OR from www.readytalk.com type access code 3421244 into "join a meeting" without the # (you need java plugin)
Contents
Items for followup from previous meeting
-
Check if connections for cooling fluid can be bent radially outward to minimize affect on photons in the gap.Yes. Simulations of impact needed. - Need to get a firm number for the power dissipation in the monitoring control board (in case it is placed inside the housing box)
- SiPM: check cross talk between cells (Yi and Carl)
Documents to Review
Tentative Agenda
- Announcements
- Review of Action Items
- USM update More Pictures
- SiPM update
- Regina Preliminary Tests of Hamamatsu prototype
- Electrical/cooling (Elton)
- Geometry and light guides
- Simulations
Minutes
Attending:Beni, Yi, John, Tim, Elton, Eugene (JLab); Will (USM); Andrei (UofR); Christina (Athens)
- Announcements
- SiPM First Article arrays have been approved
- Jlab 6 month shutdown begins in 2 weeks. They plan to connect the accelerator north stub with the tunnel to the tagger hall during this period.
- Review of Action Items
- Monitoring (Christina)
- MOU signatures should be completed soon
- Started this week to measure the light distribution in a 1x1x0.15 m3 plexiglass pane to be used to determine how many LEDs will be needed for the Fcal monitoring system.
- Hope to have some results to present next week at the collaboration meeting.
- Asked about light guides from USM. The guides are cut but not polished. Need the guides to check the space for boards and cables.
- USM update More Pictures
- Will described the considerable progress at USM on several fronts. Check the presentations for photos.
- (Finally) received SIPM array out of customs (no cost, but time consuming)
- Took some photos of the SiPMs under a microscope, which showed some small specs on the surface. Visually, these specs appeared to cover sub-percent fractions of the surface, there is no quantitative evaluation yet. They also did not check if they could blow these off. The specs were not visible by eye.
- Further studies will proceed.
- Checked cooldown
- Cooldown time is about one hour (electronics not connected in this test)
- Dark box with cooling system has been placed in a dedicated room for this measurements.
- Electronic boards received
- Boards are populated and will start to get connected
- Eugene: Check that the connections have capacitance smaller than the array cell itself (~320 pf/16). The main effect of this will be timing.
- Light guide production
- Light guides have been produced (cut by CNC machine) but are not yet polished.
- Broken part on CNC machine was broken but is now repaired.
- Tim: Jlab can practice gluing with these guides when they arrive.
- Will described the considerable progress at USM on several fronts. Check the presentations for photos.
- SiPM update
- Regina Preliminary Tests of Hamamatsu prototype
- Links left from last meeting showing some oscilloscope measurements of uniformity between cells in a SiPM array.
- Electrical/cooling (Elton)
- Progress on several fronts:
- Mechanical cooling prototype parts have been ordered and expect to arrive at the end of the month
- Electronic boards have been designed and laid out
- Prototype of a complete sum unit is underway. It includes a cooling block with Peltier cooler, cooling plate, temperature compensation electronics, amplifiers and summed circuit.
- Geometry and light guides
- New Geometry
- Elton presented a new variation on phi-symmetric guide geometry. The new geometry has only 10 different light guide shapes.
- There is a small gap on the inner side with the present layout, which may need to covered by stretching the layout a slight amount.
- There are advantages in simplicity and symmetry for the new geometry.
- No objections, but many advantages are seen for the new geometry, so the decision was taken to move to the new geometry for production units. [Note that all ongoing prototyping efforts will proceed with the old geometry.]
- Current geometry of light guide in Monte Carlo
- Beni investigated the MC geometry of the light guides and finds that there is a mistake in the geometry for the outer light guides. These overlap with other volumes and must be fixed.
- Beni will implement the new geometry and fix the MC at the same time. Note that the MC geometry has always been phi-symmetric.
- The incorrect geometry has no direct effect on the present studies of granularity. The light guides (and incorrect geometry) primarily effect efficiency and background studies in this area.
- New Geometry
- Simulations
- Andrei emphasized that we do not understand the Bcal reconstruction software and ongoing studies cannot be interpreted reliably without well-defined inputs and reconstruction parameters.
- Suggested to document what is known about the program and evaluate what needs to be done to achieve a robust photon reconstruction.