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Leung, Ka-Ngo

Publications and source records attributed to Leung, Ka-Ngo.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Design, construction, and characterization of a compact DD neutron generator designed for 40Ar/39Ar geochronology

A next-generation, high-flux DD neutron generator has been designed, commissioned, and characterized, and is now operational in a new facility at the University of California Berkeley. The generator, originally designed for 40 Ar/ 39 Ar dating of geological materials, has since served numerous additional applications, including medical isotope production studies, with others planned for the near future. In this work, we present an overview of the High Flux Neutron Generator (HFNG) which includes a variety of simulations, analytical models, and experimental validation of results. Extensive analysis was performed in order to characterize the neutron yield, flux, and energy distribution at specific locations where samples may be loaded for irradiation. A notable design feature of the HFNG is the possibility for sample irradiation internal to the cathode, just 8 mm away from the neutron production site, thus maximizing the neutron flux (n/cm 2 /s). The generator’s maximum neutron flux at this irradiation position is 2.58 x 10 7 n/cm 2 /s ± 5% (approximately 3 x 10 8 n/s total yield) as measured via activation of small natural indium foils. However, future development is aimed at achieving an order of magnitude increase in flux. Additionally, the deuterium ion beam optics were optimized by simulations for various extraction configurations in order to achieve a uniform neutron flux distribution and an acceptable heat load. Finally, experiments were performed in order to benchmark the modeling and characterization of the HFNG.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Plasma driven neutron/gamma generator

An apparatus for the generation of neutron/gamma rays is described including a chamber which defines an ion source, said apparatus including an RF antenna positioned outside of or within the chamber. Positioned within the chamber is a target material. One or more sets of confining magnets are also provided to create a cross B magnetic field directly above the target. To generate neutrons/gamma rays, the appropriate source gas is first introduced into the chamber, the RF antenna energized and a plasma formed. A series of high voltage pulses are then applied to the target. A plasma sheath, which serves as an accelerating gap, is formed upon application of the high voltage pulse to the target. Depending upon the selected combination of source gas and target material, either neutrons or gamma rays are generated, which may be used for cargo inspection, and the like.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Advanced Neutron Generator For SNM Imaging

Associated particle imaging (API) is a neutron interrogation technique for detecting concealed or heavily shielded objects such as special nuclear material (SNM), explosives, and other contraband. In API, 14 MeV neutrons are formed in the deuterium–tritium fusion reaction along with an associated 3.5 MeV alpha particle that travels in the opposite direction of the neutron as a result of conservation of linear momentum. Characteristic signatures (gamma rays, fission neutrons, etc.) produced from neutron target reactions in the interrogated object provide information on the target material. In contrast to traditional neutron interrogation techniques, API is a “self-collimating” method in which the alpha particles are used to determine the position and direction of the emitted neutrons, thereby significantly reducing the background noise by only selecting events caused by neutrons emitted in the direction of the interrogated object.

Leung, Ka-Ngo↗