Low-background detection of fission neutrons produced by pulsed neutron interrogation

Abstract Measurements designed to detect shielded Special Nuclear Materials (SNM) have been carried out using a pulsed 8.5-MeV neutron source. Fission-neutron counts were detected as a function of time in the intervals between 100-μs neutron bursts at burst frequencies of 500, 1000, and 2000 Hz. The pulse timing sequences were chosen to optimize detection of fission neutrons produced by thermal-neutron-induced fission in the SNM. Fission neutrons were detected directly as proton, carbon, and silicon recoils in silicon carbide (SiC) semiconductor fast neutron detectors. SiC detectors recorded neutron counts during and immediately following the source neutron bursts, allowing detection of fission neutrons with short (120 μs) die-away times. The SiC detectors demonstrated excellent background discrimination with more than 2000 neutron counts observed in time intervals where zero background counts were detected.

[1]  G. Knoll Radiation detection and measurement , 1979 .

[2]  Tsahi Gozani,et al.  Remote thermal neutron die-away measurements to improve Differential Die-Away Analysis , 2007 .

[3]  David L. Chichester,et al.  Fast digitization and discrimination of prompt neutron and photon signals using a novel silicon carbide detector , 2007, SPIE Defense + Commercial Sensing.

[4]  K. A. Jordan,et al.  Detection of 235U in hydrogenous cargo with Differential Die-Away Analysis and optimized neutron detectors , 2007 .

[5]  Frank H. Ruddy,et al.  Demonstration of an SiC neutron detector for high-radiation environments , 1999 .

[6]  G. Bertuccio,et al.  Silicon carbide for high resolution X-ray detectors operating up to 100°C☆ , 2004 .

[7]  A. Scorzoni,et al.  Effects of Very High Neutron Fluence Irradiation on p+n Junction 4H-SiC Diodes , 2007 .

[8]  B. Petrovic,et al.  Neutron fluence rate measurements in a PGNAA 208-liter drum assay system using silicon carbide detectors , 2004 .

[9]  C. W. Cox,et al.  General Solution of the Reactor Kinetic Equations , 1960 .

[10]  A. Agarwal,et al.  The fast neutron response of 4H silicon carbide semiconductor radiation detectors , 2006, IEEE Transactions on Nuclear Science.

[11]  McIlwain,et al.  Experimental verification of modeling results for a PGNAA system for nondestructive assay of RCRA metals in drums , 2000, Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine.

[12]  Frank Ruddy,et al.  Pulsed neutron interrogation for detection of concealed special nuclear materials , 2006, SPIE Defense + Commercial Sensing.

[13]  J. Vujic,et al.  Improving differential die-away analysis via the use of neutron poisons in detectors , 2007 .

[14]  F. Ruddy,et al.  The effects of intense gamma-irradiation on the alpha-particle response of silicon carbide semiconductor radiation detectors , 2007 .

[15]  R. Gehrke,et al.  Detection limits of a laboratory pulsed gamma neutron activation analysis system for the nondestructive assay of mercury, cadmium, and lead , 1998 .

[16]  J. T. Caldwell,et al.  Experimental evaluation of the differential die-away pulsed-neutron technique for the fissile assay of hot irradiated fuel waste , 1982 .

[17]  Frank H. Ruddy,et al.  Special nuclear material detection using pulsed neutron interrogation , 2007, SPIE Defense + Commercial Sensing.

[18]  F. Ruddy,et al.  Fast neutron detection with silicon carbide semiconductor radiation detectors , 2007 .

[19]  Frank H. Ruddy,et al.  Development of a silicon carbide radiation detector , 1998 .