Monday, June 10, 2013 11:00 AM - 12:00 PM EDT
From Hall A Wiki
Calling instructions: Toll-Free Number (U.S.& Canada): 866-740-1260 International toll number: 303-248-0285 PARTICIPANT CODE: 2315321#
- Updates on GEANT4 simulations of the detector/lightguide geometry: Peiqing Wang Slides or Link to DocDB
- Discussion of plans for building prototypes: Michael Gericke/Krishna Kumar
- Summary of UMass cosmic tests on PREX detectors
- Progress on detector cart design: Paul Souder/Krishna Kumar Slides from Paul Souder
- Discussion of detector related talks for MOLLER collaboration meeting
- Further discussion of Mainz beam test issues: Michael Gericke/Krishna Kumar/Frank Maas previous teleconference info
- Attendees: Mark Pitt, Peiqing Wang, Michael Gericke, Jon Tyler, KK, Juliette Mammei, Seamus Riordan, Dustin McNulty, Paul Souder, Mark Dalton, Frank Maas, Bob Michaels,
- Minute taker: Mark Pitt
- GEANT4 detector/lightguide simulation update (P. Wang)
- KK question: Slide 5: lower right plot clarification; not normalized to single electron, these are optical photons incident on the photocathode
- Dustin: how is polishing done? Sandpaper, then polishing powder and cream, ie. successively finer grits, hand polish
- Slide 19 question from Dustin: where is mean of peak? 400-500; what is rate? minute taker couldn't make out answer
- question from Frank: is 5-8 pe what is expected? Peiqing; probably yes because quartz in unpolished, light guide material not ideal, etc. (Michael points out that this was similar to what was obtained with Qweak scanner quartz tests, which used the same type of lightguide)
- KK comments
- not worth worrying yet about 5-8 until setup is optimized; only trying to show DAQ working
- decision not yet made that we go with this geometry; for now pursue both kinds of geometry; for now we should still consider straight and backwards as possibilities;
- Michael: discussion at a previous teleconference; we had agreed to try 3 different geometries with beam test
- Peiqing; will make three different prototypes; says one will be the above and another will be a straight geometry
- UMass Cosmic Tests of PREX detector (Jon Tyler)
- Question from Mark Pitt: air gap ~ 5 cm; ie. mirror reflectivity not a big issue for PREX detector
- Request from KK: There are ongoing tests at Smith looking at reflectivities of various lightguide materials with mercury lamps; requests that Manitoba bring a sample of their UVS material so the manufacturer's claimed reflectivities can be checked directly
- Frank question: Was there an estimate of the expected value? Jon says last number in simulation was ~ 40-50 pes for the thick quartz case (compared to 30-33 observed in his tests)
- Goal at UMass: benchmark PREX detectors as well as possible; make reflectivity measurements
- Michael; would prefer to make this as efficient as possible and not duplicate too much work
- Dustin at ISU has also set up a cosmic test stand and built preliminary prototype based on PREX design
- Michael, he would prefer that at some point there be an agreement of who does what
- Saturday morning; KK suggests that Michael, Dustin, KK, etc. meet to plan the detector prototyping activities.
- Michael example: nobody has worked about designing or prototyping the sandwich calorimeter detector yet
- Collaboration meeting talks:
- Michael; overview, including TRIUMF discussion (20 minutes)
- Peiqing; more details on detector/simulations (30 minutes)
- Paul Souder: discussion of detector mounting (20 minutes)
- Frank Maas: test beam possibilities at Mainz - plus HydroMoller (10 for beam test + 20 for hydro-MOLLER)
- Detector Mounting (P. Souder)
- KK comment: The red mounting brackets (slide 7) will help with alignment. They will be a relatively small amount of initial material that will be downstream, after the electrons have gone through the quartz.
- Michael question: Are we still considering the possiblity of lead shields around the tubes? KK: Yes, needs to be looked at when we determine final geometry.
- The current design envisions there will be overlaps between the detectors so the staggered design in z accommodates this.
- Juliette: rather than the alternating arrangement shown, one may want to consider that the symmetric detectors on either side of the highest rate middle MOLLER detector be either both downstream or both upstream
- KK: One can imagine that all the red frames are linked together in one unit that can be moved around for precision alignment.
- KK to Paul: complete this concept for the "straight" detectors and then revisit things.