Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions
We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE NA NATIONAL NUCLEAR SECURITY ADMINISTRATION (NNSA)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1088159
- Report Number(s):
- BNL-90848-2009-CP; NN2001000
- Resource Relation:
- Conference: IEEE Nuclear Science Symposium; Orlando, Florida; 20091025 through 20091031
- Country of Publication:
- United States
- Language:
- English
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