Nuclear Engineering ETDs


Joel Long

Publication Date



This thesis describes a heavy-ion recoil neutron spectrometer as an alternative to existing magnetic proton recoil neutron spectrometers for inertial confinement fusion experiments. Whereas existing designs elastically scatter neutrons o↵ protons or deuterons, which are then magnetically analyzed to infer energy, this device works by elastically scattering neutrons in a nanometer-scale film of a higher-Z material. The resulting heavy ions are then measured on a time- and space-resolved semiconductor detector. Using this time and location information, coupled with the equations governing the mechanics of elastic collisions, one can determine the energy of the neutron that scattered the ion. This thesis considers the many influential design factors, including cross sections, ion straggling, timing, and foil and sensor geometries with respect to the resulting viability and performance. Finally, two reference designs are presented for comparison with the magnetic proton recoil neutron spectrometer currently fielded at the National Ignition Facility. For a monoenergetic 14-MeV neutron source, the minimum achieved full-width-at-half-maximum is 0.33 MeV, compared with 0.69 MeV for the currently fielded detector. The maximum e ciency is found to be 2.94x10 10, compared with a current maximum of 8.48x10 11.


Neutron Spectrometer, Pulsed Power, Fusion, Energy, Semiconductor Sensor, Heavy Ions, Recoil Spectrometer


Sandia National Laboratories

Document Type




Degree Name

Nuclear Engineering

Level of Degree


Department Name

Nuclear Engineering

First Advisor

Cooper, Gary

First Committee Member (Chair)

Prinja, Anil

Second Committee Member

Porter, John