International Conference on Nuclear Data for Science and Technology 2010
J. Korean Phys. Soc. 59, 1553-1557
Paper ID: ND-1233
DOI: 10.3938/jkps.59.1553
PACS: 26.20.+f
Neutron-emission Measurements at a White Neutron Source
R. C. Haight1
1 Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 USA
Abstract
Data on the spectrum of neutrons emitted from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A “white” neutron source (continuous in energy) allows measurements over a wide range of incident neutron energies all in one experiment. We use the fast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV. These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron- gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of neutron emission spectra from neutron-induced fission of 235U, 238U, 237Np and 239Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.
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