Study of a circuit for low-energy gamma-ray detection applied to multi-phase flow tomography

For multi-phase flow in pipelines, the distributions of the individual phases are of significant importance. For this reason a low-energy gamma-ray tomography system has been designed. The set-up uses a 241Am source along with a CdZnTe array to acquire gamma ray attenuation data in different positions of a cross-section plane around a test pipe. A charge sensitive amplifier (CSA) and a fourth-order Gaussian pulse shaper have been designed. The voltage pulses generated by CSA are filtered inside the Gaussian pulse shaper to obtain maximum output signal-to-noise rate (SNR) before being fed to a digital spectrum analyzer. In this paper, CSA and the pulse shaper will be considered first, and some output waveforms of the real circuit will be given. Meanwhile, some details of the spectrum analyzer unit based on FPGA are also described. Raw data from the set-up will be used as the input of PC for image reconstruction.