Miniature Dysprosium-Based Monitors of Thermal Neutron Exposure History

University Of New Mexico, Albuquerque NM

Investigators

Abstract

Fundamental research is proposed on a novel concept for combined neutron detection and retrieval of information about the level and timing of thermal neutron exposure that may have occurred prior to recovery of the data stored by a miniature, nanocrystal-based sensor. The concept is based on the unique properties of a dominant naturally occurring isotope of dysprosium,Dy, which upon exposure to thermal neutrons converts into a metastable state 165m, and then subsequently decays into a stable isotope of holmium, or, upon capturing a second neutron, into a stable erbium isotope. Combination of the high thermal neutron capture cross section of ~2,650 barns and transmutation into two other lanthanides makes dysporium a good candiate. Dy-containing nanocrystals of various chemical compositions will be synthesized, doped with Ho and Er, and optically characterized for maximum spectral differentiation between the three lanthanides. Reconstruction of data about neutron exposure will then be demonstrated by optical spectral analysis of the nanocrystalline samples. Fundamental research is proposed on a novel concept for combined neutron detection and retrieval of information about the level and timing of thermal neutron exposure that may have occurred prior to recovery of the data stored by a miniature, nanocrystal-based sensor. The concept is based on the unique properties of a dominant naturally occurring isotope of dysprosium, 164Dy, which upon exposure to thermal neutrons converts into a metastable state 165mDy, and then subsequently decays into a stable isotope of holmium 165Ho, or, upon capturing a second neutron, into a stable erbium isotope 166Er. Combination of the high thermal neutron capture cross section of ~2,650 barns and transmutation into two other lanthanides makes 164Dy very attractive for the proposed new sensor. Dy-containing nanocrystals of various chemical compositions will be synthesized, doped with Ho and Er, and optically characterized for maximum spectral differentiation between the three lanthanides. Reconstruction of data about neutron exposure will then be demonstrated by optical spectral analysis of the nanocrystalline samples. The educational component will emphasize collaboration and interactions across traditional academic disciplines, with the proposed project spanning the fields of chemistry, physics, electrical engineering, and nuclear engineering.