The EBEX Cryostat and Supporting Electronics
  We describe the cryostat and supporting electronics for the EBEX experiment.
EBEX is a balloon-borne polarimeter designed to measure the B-mode polarization
of the cosmic microwave background radiation. The instrument includes a 1.5
meter Gregorian-type telescope and 1432 bolometric transition edge sensor
detectors operating at 0.3 K. Electronics for monitoring temperatures and
controlling cryostat refrigerators is read out over CANbus. A timing system
ensures the data from all subsystems is accurately synchronized. EBEX completed
an engineering test flight in June 2009 during which the cryogenics and
supporting electronics performed according to predictions. The temperatures of
the cryostat were stable, and an analysis of a subset of the data finds no scan
synchronous signal in the cryostat temperatures. Preparations are underway for
an Antarctic flight.
