Nuclear Engineering ETDs

Publication Date

Fall 12-14-2018


Well-defined fission product yield data has been of increasing interest in various applications within the nuclear industry. With this need in mind, a fission fragment mass spectroscopy system was designed and developed at the University of New Mexico in collaboration with the Los Alamos National Laboratories with a stated goal of attaining a mass resolution of ≤ 1 % (FWHM/centroid) for light fragments and near 1 % for heavy fragments. The mass spectrometer utilized in this work consists of a transmission time-of-flight detection system to measure fission product velocity and an axial ionization chamber to measure the fission product energy, with measurements giving quasi-prompt (~50 - 100 ns) fission data. With these measured quantities of velocity and energy, the fission product mass can be calculated. As an additional feature, the ionization chamber was designed to serve as a time projection chamber, providing information regarding the fission product depth of penetration in the ionization gas, and thus information on the stopping power and the fission product atomic number, Z.

Measurements of mass and Z using the UNM spectrometer were performed on a 252Cf spontaneous fission source at UNM and 235U(nth, f)X at the LANSCE Lujan Center neutron beamline facility located at Los Alamos National Laboratory. The results of the experimental mass and Z measurements for both fission parent nuclides are compared to ENDF/B-VII fission product yield data files for analysis and discussion. An assessment of statistical and mass related uncertainties and their contributors is also presented for 252Cf and 235U measurements. Finally, remaining issues and ideas for future work are identified and possible solutions proposed.


Fission, Fission Yield, Fission Yield Measurements, Fission Products, Mass Spectroscopy

Document Type




Degree Name

Nuclear Engineering

Level of Degree


Department Name

Nuclear Engineering

First Committee Member (Chair)

Adam Hecht

Second Committee Member

Gary Cooper

Third Committee Member

Cassiano de Oliveira

Fourth Committee Member

Fredrik Tovesson