################################################ Hall C GeN (E12-11-009) Oct 2013 Collab. Meeting ################################################ Slides can be found here: https://hallcweb.jlab.org/doc-public/DisplayMeeting?conferenceid=32 ################################################# Business Meeting (Kohl) ################################################# -- Brad will get out some notes with a nominal "todo list" -- Kohl will get out something on the charter (might be minimal) - Develop Magnet, Power Supply report laying out options, cost estimates - Hall C / Brad - DAQ/readout - Hall C / Brad - Polarimeter (need MRI, multiple groups expressed interest in support) - PMTs: $400k (?) - CFDs: Ortec 935 NIM units - Kent State has ~24 (not sure where they are -- should have Kent St. labels) - should have Kent State on them - MIT/BLAST may have CFDs 64--96 channels? - Tel-Aviv may have 10x 4-channel units - Amplifiers: - Kent State has (had) custom units that did a 90:10 split well suited to good timing (off the 90%) and reasonable energy resolution (off an in-unit amplified copy of the 10%) - unclear how many channels are on hand, could maybe use this with Jlab LE discrims? - Kent State has circuit design on hand, building more is possibility - Establish a collaboration website (Brad) - Wiki: https://wiki.jlab.org/E12-11-009/index.php/Main_Page - Steve Wood offers graphic design support for a catchy logo - We should get affirmation of the PAC37 user list - we need to identify primary collaborators - Leadership / Spokespeople summary Active: - Michael Kohl (Hampton/JLab) - Brad Sawatzky (JLab) - John Arrington (ANL) - Andrei Semenov (Regina) Inactive(?): - Dick Madey (Kent State) - Stan Kowalski (MIT) Resigned: - Brad Plaster: Requested that he be removed as co-spokesperson - still wants to be in touch, and may participate at a reduced level down the line if his schedule allows - Bryon Anderson: Reduced Role, Requested removal as co-spokesperson - will still remain active, but can't take the leadership role as he's done in the past Possible new leadership roles: - Abdellah Ahmidouch (North Carolina A&T State University) - very interested in taking a leadership role in the polarimeter construction - the collaboration has agreed that North Carolina A&T has the primary institutional responsibility for the veto counters. - Mostafa Elaasar (Southern University at New Orleans) - expressed/affirmed interest in developing the polarimeter - took the initiative of purchasing 6 PMTs + scintillator for 3 analyzer bars and 3 veto bars - Steve Wells (La Tech) - expressed/affirmed interest in smaller hardware work (prototypes), and/or simulation - has purchased materials for 1--2 analyzer bars that would be compatible with our proposed setup - We should develop a charter to assist in managing the collaboration * Michael Kohl will put a draft together and circulate among the group - generate a task list - simulation(s)? - Need to develop MRI for polarimeter - need to work out the application procedure and best approach - Abdellah is interested in supporting MRI for sure; Mostafa interested as well I think - would Adjunct Prof. position for Sawatzky help to support MRI application? - Simulation work: - finalize geometry - run flux from target and see what gets through to the forward vetos with the new configuration - what is projected background rate vs. Bdl? - we need to be able to back our understanding that we *need* the a high field (ie. 4 T-m) to suppress charged backgrounds - if we can get away with the 1 T-m (low field precession solution), then we have a *lot* more options for magnets - Should set up monthly collaboration phone calls ------------- Miscellaneous Notes from individual talks -------------- ################################################# - Steve's talk ################################################# - need to get a list of 'non-standard' requirements to Steve by December'ish timeframe - ie. readiness dates for our major equipment (magnets, polarimeter, target) - confirm allocated PAC days (Steve has 50 on his list, PAC37 requested 67?) ################################################# - Michael Kohl's talk ################################################# - see PRL111 (2013) 132504 -- A1 Collaboration (mainz) Gen extraction from He3 - how did they extract the neutron? ################################################# - Andrei's talk ################################################# - slide 10 shows we need to be able to put a good timing cut of +-1ns, so should shoot for 0.5ns sigma - reaffirms that background sims are needed - suggests Pavel (JLab) - 300-500 MeV/c protons - question of how good dE/E PID separation should be, verify it will be sufficient (should be in proposal) - Plan B design - vetos in front of each analyzer array? - what is total number of channels now? * important to look at support structure for polarimeter - are there problems getting the plan b array mounted? - Michael suggested revisiting the design with a view to making it more compact - perhaps use scintillating fibers for tracking so we need less drift, smaller package? ################################################# - Bryon Anderson's talk ################################################# - Plan B: - prefer to use the 160cm detectors from Hall A GEn neutron arm (Doug, Donal) - good list of what we have now, what we may need - Plan B: 168 ch of 10x10 *plus* vetos+dE - Andrie's bar count: PAC37 Plan B Analyzer (10x10 cm^2 bars) 48 28 Veto (1x10 cm^2) 12 28 E-bars (10x10 cm^2) 80 108 dE (1x10 cm^2) 78 52 "PAC37" version polarimeter contains 6 sections and 2-layers veto in front of the 1st section only. "Plan B" version contains 4 sections with a single-layer veto in front of every section. - Michael Kohl: BLAST bars: are available, would require cutting, machining ################################################# - Will Tireman (Northern Michigan University) ################################################# - Will was grad student on 1st Gen measurement - ToF and position resolution talk - Will's estimate is that it would take 2 days to cut the right angle light guides for Plan B - few weeks to sand and polish - each top/bottom '2 bar' assembly will weight 150--200 lbs each - tentative plan is to reuse the existing light guides - break them off the bars, insert the right-angle wedge and realign - for single bar w/ the 90 bend on one side (ie. Plan B, single bar) - 7--10cm resolution from timing with single 'trigger' bar on top, * geometric uncertainty with single trigger bar is on the order of 6--7cm so the total resolution could be driven by the cosmics trajectory uncertainty - Will's setup had native coincidence timing for Plan A (120deg bend) of 450ps FWHM on position timing, 320ps time dispersion on the bar - Will's setup had native coincidence timing for Plan B (90deg bend) of 333ps FWHM on position timing, 235ps time dispersion on the bar - Will is interested in getting a 160cm bar from HAND to work with - would like to have them by end of November (roughly) ################################################# - Sawatzky's talk ################################################# - power supply options: - could choose to not use the Hall C Moller and use the Moller power supply to power the precession magnet - extrapolate polarity from Hall A Moller since we don't need to known the precise beam polarization - Compton should also be running - HKS dipole power supplies might work too? - could shim the gap in the front magnet - improve collimation - improve fringe field impact along beam - perhaps use Charybdis as front magnet (does this help?) * Priority item is finalizing magnet: - Let's develop a short report outlining: - issues associated with the small vs. large precession options - what is % increase in estimated BG rates with low-field option? - document the math for statistics impact of pulling polarimeter back 2m to accommodate 2 magnets - take another look at shimming, what can be done with a single magnet... - get design support to drop the magnets and polarimeter into Hall C - closest approach of our magnet to beamline - perhaps use Charybdis for first magnet? - Simon Taylor may have some Charybdis magnet files - Tosca calculation was Steve Lassiter - Bryon comments on his fast amps that do a 90:10 split - unclear how many channels are on hand, could use this with LE - BNC (16 on back + 32 outputs on front), Will may have hardcopy photos he could send - not sure where they are... - CFDs from Ortec 935 NIM units - Kent State has ~24 maybe? - should have Kent State on them - MIT/BLAST may have CFDs 64--96 channels? - Tel-Aviv may have 10x 4-channel units - discriminators for dE, E bars for 1190 timing - 216 paddles - 432 PMTs, total count from Andre for Plan B - maybe don't need 1190 on dE ? - Light guide costs (120 units) - nominal $20k for student labor - $50 / angle light guide for the lucite