Analysis of the Nuclear Structure of Rhenium-186 Using Neutron-Induced Reactions

Author

David A. MattersFollow

Date of Award

3-26-2015

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

John W. McClory, PhD.

Abstract

Evaluated nuclear data for ¹⁸⁶Re identify the majority of spin-parity assignments as tentative, with approximate values for the energies of several levels and transitions. In particular, the absence of known transitions that feed the J = 8+ isomer ^186mRe motivates their discovery. This isomer, which has a half-life of 2 105 years, has a potential application in an isomer power source. Additionally, the isomer s role in certain nucleosynthesis processes is not well understood, so measured cross sections for transitions that feed the isomer would have astrophysical implications. Using the GErmanium Array for Neutron Induced Excitations (GEANIE) spectrometer at the Los Alamos Neutron Science Center (LANSCE), (n,2n ) and (n,n ) reactions in a 99.52% enriched ¹⁸⁷Re target were used to obtain -ray spectra from ¹⁸⁶Re and ¹⁸⁷Re, respectively. The experimental data reveal 5 new transitions in¹⁸⁶Re and 4 new transitions in ¹⁸⁷Re. Similarities between the level schemes of ¹⁸⁴Re and ¹⁸⁶Re suggest that one of the newly-observed transitions in ¹⁸⁶Re feeds the isomer from a level at 414.9 keV. The -ray energy measured for this transition implies an isomer energy of 148.2(5) keV, which is a significant improvement over the adopted value of 149(7) keV.

AFIT Designator

AFIT-ENP-MS-15-M-098

DTIC Accession Number

ADA616795

Comments

Title as it appears on title page:
Analysis of the Nuclear Structure of ¹⁸⁶Re Using Neutron-Induced Reactions

Recommended Citation

Matters, David A., "Analysis of the Nuclear Structure of Rhenium-186 Using Neutron-Induced Reactions" (2015). Theses and Dissertations. 85.
https://scholar.afit.edu/etd/85