Laser-Induced Breakdown Spectroscopy of Neptunium Deposited on a Nickel Foil: An Exercise in Nuclear Forensics
Open Access
- Author:
- Hopkins, Ann Marie
- Area of Honors:
- Nuclear Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Igor Jovanovic, Thesis Supervisor
Seungjin Kim, Thesis Honors Advisor - Keywords:
- nuclear
laser-induced breakdown spectroscopy
neptunium
radiation detection
laser
nuclear forensics - Abstract:
- Neptunium is an element of interest to nuclear security that is sometimes overlooked in favor of the weapons-usable elements uranium and plutonium. In this study, neptunium is examined using laser-induced breakdown spectroscopy (LIBS), a spectroscopic detection technique that has several features that make it promising for use in nuclear forensics. Prior to this study, very few LIBS studies of neptunium were published, and with conflicting reported emissions for the element. A characterization of the LIBS system at the Pennsylvania State University Intense Laser Laboratory is performed using copper and uranium samples, as well as a mercury-argon calibration lamp, to determine system performance and ideal settings for a neptunium study. A sample consisting of neptunium electroplated in a thin layer on a nickel foil is then examined with this system as an exercise in nuclear forensics. Two emission lines matching reported neptunium emissions, near 398.7 nm and 399.7 nm, are identified as characteristic of the LIBS plasma of the neptunium-containing sample and are not present in the nickel foil plasma. A comparative study of the LIBS plasmas of the neptunium-containing and non-neptunium-containing sample regions is performed, in which a variation of relative intensities of peaks is observed. This is attributed to changing plasma parameters, especially temperature, between the two sample regions. It is determined that, while neptunium can be detected by referencing the limited literature, an in-depth study of solid neptunium or neptunium oxide is needed to use LIBS to better detect neptunium, especially in mixed samples.