Real-Time Data Acquisition and Control System for A Neutron Polarisation Analysis Spectrometer (LONGPOL)

One of the key features of LONGPOL, the neutron polarisation analysis instrument running in ANSTO, Australia, is the development of a real-time data acquisition and control system. The system provides separation of neutron spin-flip and nonspin-flip events and provides energy analysis through the timeof-flight method. This system is composed of five DSP boards, one is the master board, and the others are slave boards. A firmware has been developed to drive the complete system. A pseudo-random sequence is generated with a minimum channel width of 0.156 μsec to control the neutron flipper, and the neutron counts from eight detectors, binned according to the sequence, are stored in the built-in RAM in real-time. The data are transferred to a host computer for the cross-correlation, and analysed by the LONGPOL DIF program.