COATED MICRO-PARTICLES FOR IMPROVED NEUTRON DETECTION WITH 6LiF:ZnS(Ag)
Open Access
- Author:
- Logoglu, Faruk
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 01, 2019
- Committee Members:
- Marek Flaska, Thesis Advisor/Co-Advisor
Arthur Thompson Motta, Committee Member
Azaree Tresong Lintereur, Committee Member - Keywords:
- Coated micro-particles
6LiF:ZnS(Ag)
GEANT4
Optimization - Abstract:
- The supply of 3He has diminished due to the increased use in homeland security, medicine and science applications over the years, which has raised the price of the isotope.[1] This fact led to research on alternative ways of neutron detection. One of those ways is to use 6LiF:ZnS(Ag) scintillation detectors with 6Li acting as a neutron converter and the ZnS as inorganic scintillator that converts the energy of ionizing radiation into light to be detected by photon detectors. The Li is highly enriched in 6Li to a minimum of 95% to increase the neutron capture probability and therefore the tritium and alpha particle production. [2] The Li comes with the chemical compound of LiF since the Li metal has highly reactive chemical properties. The existing neutron detection technology employs mixing of 6LiF and ZnS(Ag) grains in an optically transparent binder which holds the mixture together. Although this detection approach works, it has some shortcomings such as opaqueness of ZnS to its own light, which limits the thickness of the detectors and clustering of grains of the same type. This effect results in deteriorated light production and light transport properties of the scintillator. The proposed way to overcome these problems is to design a coated micro-particle detector that utilizes 6LiF coated with ZnS and the distribution of these particles throughout the active volume of the detector. MCNP6, GEANT4 and custom Monte Carlo code have been used to optimize the 6LiF micro-particle radius. GEANT4 has been used to optimize the ZnS coating thickness and the pitch, which is the distance between the two micro-particles. Moreover, the commercially available EJ-426 detectors were modeled in GEANT4 using LiF and ZnS grains distributed throughout the detection medium which is between two clear polyester sheets and the simulation results were compared to the experimental results for model validation. The optimal dimension for the LiF radius was found to be 19μm and the optimal ZnS thickness was found to be 1μm. The best detectors were found to have the dimensions of 60μm pitch, 0.6mm thickness and 80μm pitch, 1mm thickness, on the average performing 1.7 times better than the best performing existing technology. A code was written in GEANT4 to simulate the randomly distributed particles with varying radii and thicknesses as well as position and shape to test the proposed technology.