The electronics and data acquisition systems for the BESS-polar program

The Balloon-borne Experiment with a Superconducting Spectrometer, BESS, has been carried out to study elementary particle phenomena in the early Universe through cosmic-ray observation, including measurement of low energy antiprotons to investigate their origin and search for antihelium. The BESS-Polar is an evolutionary development of the BESS program to study these topics much further by using long-duration balloon flights over Antarctica. The front-end electronics and data acquisition systems of BESS-Polar were newly developed to adapt to severe requirements of the Antarctica flight. The low-power front-end-electronics, using techniques originally developed for space instruments at Goddard Space Flight Center, achieved a total power consumption of less than 450 W, which is close to one third of the power consumption of the previous BESS experiments. The high speed data acquisition system using USB2.0 interfaces and CompactPCI embedded computing system achieved full data processing and recording with dead time 23% under the condition of 3 kBytes typical event size and 3.4 kHz event rate in Solar minimum. These systems were flown nearly 38 days above Antarctica, successfully recording 5.5 billion events in the two BESS-Polar flights.