Physics & Astronomy ETDs

Publication Date

9-10-2018

Abstract

A pulsed photoneutron source consisting of a beryllium sphere and a 5 MeV endpoint 30 ns bremsstrahlung beam emanating from the Mercury pulsed-power source was assembled and tested in October 2017 at the Naval Research Laboratory (NRL) in Washington, D.C. [1]. The objective of this experiment was to verify the feasibility of using a pulsed power source to create a large number of photoneutrons in a short period of time, leveraging the low photoneutron production threshold of 9Be to maximize neutron production. Several diagnostics were deployed to characterize the source and target, including indium and beryllium activation detectors that measured the total neutron yield in each pulse. The indium activation detectors were calibrated in December 2017, measuring detector response to a known neutron flux using the F-factor method [2,3]. The total photoneutron yield from the beryllium source was measured to be 3.8±1.6 × 109 neutrons per shot including the scatter background and 1.8±1.6 × 109 neutrons per shot with energy above 667 keV, in good agreement with the other diagnostics on this experiment. The shot-to-shot variation of the source was estimated to be 20%. These detectors were sensitive to signal variations arising from different photoneutron v production targets, were mechanically robust, and resistant to the high-RF noise environment inside the facility.

Degree Name

Physics

Level of Degree

Masters

Department Name

Physics & Astronomy

First Committee Member (Chair)

Paul Schwoebel

Second Committee Member

Gary Cooper

Third Committee Member

David Dunlap

Keywords

neutron, activation, nuclear, photoneutron

Document Type

Thesis

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