Neutron Thermalization in Matter Modern Insights and Nuclear Engineering Applications (JOINT)

Event Date: October 21, 2015
Speaker: Ayman Hawari
Speaker Affiliation: North Carolina State University
Time: 3:30 pm
Location: WTHR 200
Priority: No
College Calendar: Show
Hawari headshot

Neutron Thermalization in Matter

Modern Insights and Nuclear Engineering Applications

In nuclear systems driven by thermal neutrons (e.g., nuclear reactors, critical and subcritical piles, etc.), the neutrons produced in nuclear reactions (fission and otherwise) will likely undergo a slowing-down and thermalization process in the system. Upon thermalization, a quasi-equilibrium energy spectrum for the neutrons is reached that defines the nuclear reaction rate of the neutrons with the system’s nuclei. Fundamentally, the description of the thermalization process requires knowledge of the double differential thermal neutron scattering cross section (ds/dWdE ) in a given material. This in turn requires establishing the scattering law, S(a,b), of the material. Traditionally, the calculation of S(a,b) (and the related ds/dWdE) proceeded using simplifications motivated mainly by computational feasibility. In addition, the available data (e.g., in the ENDF/B database) was limited to few typical materials. However, current advances in computational power and the development (at NCSU) of modern techniques using atomistic simulations render such simplifications and limitations unnecessary. Consequently, it is now possible to generate such fundamental data for any material in support of nuclear reactor design, nuclear criticality safety studies, neutron science, neutron detection and other applications where thermal neutrons are of engineering interest.

Nano Research Area

  • Nano-Energy & Environment
  • Nano-Characterization
  • Nano-Materials & Engineering

Research Summary

I am interested in performing experimental and computational investigations (simulations) to study the interaction of radiation with matter. The studies can be applied, for example, to design radiation based nondestructive examination experiments and systems, or fundamental, as in the measurement of basic nuclear data such as reaction cross-sections. As a result, my research extends into areas such as nuclear radiation spectrometry, dosimetry, and the utilization of radiation in nondestructive examination.

Currently, I am performing experimental and computational research (using ab initio and molecular dynamics methods) to develop improved thermal neutron scattering laws for Generation IV reactor design. In addition, I am interested in the application of atomistic modeling techniques to study the behavior of advanced nuclear fuel in extreme radiation and temperature environments. My work also focuses on utilizing radiation beams as probes of matter at the nano-scale. This includes the application of thermal neutron beams in imaging and scattering applications, and the use of slow positron beams to assay nano-porosity in matter. These types of beams can be generated using a nuclear reactor such as the PULSTAR reactor on the NC State campus. Therefore, I am interested in the use of reactors in research and teaching.

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2015-10-21 16:30:00 2015-10-21 17:30:00 America/New_York Neutron Thermalization in Matter Modern Insights and Nuclear Engineering Applications (JOINT) WTHR 200