Wavelength-based neutron/gamma ray discrimination in CLYC
We investigated the optical components of Cs2LiYCl6:Ce (CLYC) as a possible path to particle discrimination by measuring the effects of optical filters on the shape of the waveform and comparing filtered waveforms to unfiltered ones. Crystals packaged with two optical windows were viewed by two photomultiplier tubes operated in coincidence to be certain that the signals from the same event were analyzed. We applied long-pass optical filters with cut-off wavelengths from 280 to 455 nm, and bandpass filters with cut-off wavelengths at 313, 350, 385, and 425 nm. Waveforms from gamma rays were significantly sharpened by the 313 nm bandpass filter because this filter cut out self-trapped exciton luminescence, while neutron waveforms were largely unaffected by filtering. Cumulative distribution functions generated from average filtered waveforms indicate that the neutron/gamma assignment can be made 44 ns by applying a Kolmogorov-Smirnov test comparing an acquired waveform to the average filtered waveforms.
${\rm Cs}_{2}{\rm LiYCl}_{6}:{\rm Ce}$ Scintillator for Nuclear Monitoring Applications
This paper summarizes the initial investigation of large diameter (2-inch) Cs2LiYCl6:Ce (CLYC) crystals grown at RMD. Although the crystals had some cracks, the tested sample provided adequate results: It produced a clear thermal neutron peak, a difference in time profiles under gamma and neutron excitation was observed, and pulse shape discrimination (PSD) based on two integration windows and their ratios was achieved. The PSD provided an excellent separation between gamma and neutron events. The discrimination ratio was better than 1:1000 (based on 15,000 events). We have also tested a relatively smaller sample with excellent crystal quality for the energy resolution. The results surpassed those previously obtained. The recorded energy resolution at 662 keV was 4.7% (FWHM) using a standard bialkali PMT. This is better than the previously measured 5.1% value. A 4.3% energy resolution was obtained with a super bialkali PMT.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.