PREX Meeting Notes, Feb 8, 2010
Present: Bob Michaels, Ole Hansen, Mindy Jen, John LeRose,
Zafar Ahmed, Rupesh Silwal, Dustin McNulty, Kent Paschke,
Luis Mercado, Sasha Glamazdin, Megan Friend, Rich Holmes
REMINDER: Collaboration meeting planned for Feb 19-20.
Therefore no meeting on Feb 15.
- PREX target being made (Phil Adderley). Measuring foil thicknesses, etc.
- Septum is on pivot. Technician manpower very limited ! Could slow us down.
- Space being made for GEM DAQ (thanks Bogdan and Albert)
- Plan to install GEM DAQ on L-HRS this week with Alex's help.
- will do R-HRS GEM DAQ when detector stack goes back in
- Work on CompSimple scheme for Compton
- combines CMU-FADC crate with the ETROC
- runs at 240 Hz helicity flip rate
- coincidences simulated with pulsers
- simple analysis framework (merger of existing codes)
- Magnet and target installed on beam line
- Survey Group finished all surveys (field, targets, etc).
- Exercising target motion
- Will cool down after getting cryo-lines
- On track and looking good !
Zafar and Mindy
- Comparing their Moller rates and asymmetries. It's converging.
- Zafar discussed problems getting controlled rates with PMT
(idea to use randoms to test the DAQ, also useful for Compton)
- Dustin will help with the PMT problem.
- Mindy and Zafar have both volunteered for Compton work.
- Septum magnet looks good.
- Earlier reported field asymmetries were artefacts of probe positioning.
- Now looks very symmetric, agrees with TOSCA.
(with thanks to Javier Gomez, Jack Segal, Mindy Jen, and Paul Brindza)
- John to produce transfer functions for Podd (analyzer) and hamc (MC).
- Helicity multiplet analysis and noise studies - see HAPLOG entries
- Dramatic suppression of 60 Hz noise.
- Slightly wrong helicity pattern
- Kent thinks we could live with it, but Qweak will want it fixed.
- Riad Suleiman working on fixing it.
- Still see noise, probably the LED, will investigate
(extensive conversation with Kent suggesting tests such as
turning off LED, see h.c. diffs, cut on pair synch, etc.)
- SU scint checkout with Zafar :
- Long cosmics runs for pulse-height spectra. Looks good.
- Will check again after 15m cables, fanout, and amplifier
- Finished beam-right scint, next will do beam-left scint.
- To install with Sasha's guidance.
- New dithering :
- Func. generator being arranged with ACC-div support.
- Need cables to BSY. Discussion of who/when.
- Need to modify BMW software (Dustin, Kent)
- question re: post-pan analysis ? TBD.
- HAMC simulation of PREX focal plane distrib.
- for A_T detector and for thin targets
- trying to finalize detector designs.
- Wants to work with main detectors and GEMS in hall, soon.
- preparing trigger electronics, and general cleanup
- discussed relay switch: likely the old one is too noisy,
may need accesses to switch counting to integrating
- question: can we block A_T hole at high current ?
(need a long arm ...)
- GEM Analysis software making good progress.
Based on existing bigbite code.
Decoder - done
Weighting / averaging of hit positions
Taking out L/R ambiguity resolution
(Bigbite remnant code that is not needed.)
Need more coordinate directions (if I understood Ole)
Need refurbished target reconstruction code.
- FADC pedestal shifts with laser state, see HAPLOG.
- Crosstalk ?
- Discussion of implications -- it wasn't clear.
- Could check during downtime with various signals ?
- CMU/FADC does not see the BCM-detector crosstalk (see R. Holmes below)
- Getting summary of Optics data for HAPPEX-3 (Rupesh helping)
- Soon (~1 week) need injector DAQ for beam studies (Joe Grames)
- Laser table work (start ~2 weeks)
- Multi-element array for spot-size asy
- Cables run to HAPPEX DAQ in ISB.
- Discussed LED tests of new detector systems.
- to have separate sub-group meeting on detectors and noise
- See HAPLOG 2032 -- good summary of recent Compton issues.
- Asymmetry systematic -- ostensibly crosstalk of detector to BCM
- Might be a rate-dependent DAQ failure of unknown origin
- Creates a false asymmetry in BCMs and side bumps.
- Alex Camsonne to help investigate the hardware (no progress yet)
Note the Run Plan for the PREX run, to be discussed at the Collab. mtg Feb 19-20.
Index of Meetings