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A: A 2D digital spectrometer for coincidence measurement of Doppler broadening of positron annihilation radiation is developed and tested. The spectrometer is based on a 14-bit waveform digitizer which gives the possibility of fast and direct sampling of the preamplifier signals of the HPGe detectors and preserves the information required by the physics of Doppler broadening spectroscopy. Some features of the digital spectrometer are compared with its analog counterpart. Superior energy resolution, better peak symmetry, effective elimination of ballistic deficit and better stabilization of peak position are the advantages of the digital spectrometer. The performance of the digital spectrometer to support the CDBS experiment is tested by investigation on the electronic structure of some elements at 1 st series of transition metals. The results show that the spectrometer is sensitive enough to distinguish the electronic structure of 3d metals differing a little in their valance band configuration.

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Digital signal processing has shown promise as a reliable approach for nuclear radiation spectroscopy. In this paper, the charge-to-digital conversion technique was applied to neutron-gamma discrimination. The method is based on the direct comparison of the charge at the fast and slow components of the anode signal of the scintillator detector. The performance of the technique was tested using experimental investigation by 252Cf source and D-D neutron generator. The minimum detectable energy for reasonable separation was found to be around 0.2 MeVee. The FOM of the discrimination parameter was maximized by the optimum selection of the charge integration parameters. Excellent discrimination between neutron and gamma signals was confirmed by the presented setup. The results confirmed that the presented technique can replace analog nuclear electronics conventionally uses for pulse shape discrimination.