"Radiation Detection Using Integrated Circuits,"
Ph.D. Dissertation, Nuclear Engineering, Texas A&M University, College Station, TX (2016).
The research objective of this dissertation is to evaluate the
capability of 'radiation' integrated circuits (RICs) to serve as a
new type of radiation detection medium. Designed at Texas A&M
University, the RIC contains both radiation-sensitive areas (RSAs)
and radiation-hardened areas (RHAs). RSAs are designed so that
their electrical properties change when exposed to
charged-particle. RHAs monitor such changes in RSAs to detect the
presence of radiation. Novel detector designs utilizing the same
RICs were assessed and optimized, using both analytical and
simulation methods, to register the major types of radiation: alpha
particles, beta particles, gamma rays, and neutrons. The detector
system materials and components were varied to characterize
different configurations and recommend optimized RIC detector
designs to perform beta-test.
The proposed revolutionary RIC-alpha/beta probe design has two
regions: one to detect alpha particles and another to detect betas
along with their Eβmax. In order to perform the Eβmax
discrimination, the maximum penetration depth property of betas in
attenuator was utilized. In MCNPX, plate glass, Pyrex® glass,
Lucite® and natural rubber were studied as attenuator materials.
For the proof of concept, materials in the wedged form were
analyzed. The natural rubber in the form of a wedged attenuator was
observed to show superior Eβmax discrimination compared to other
defined attenuators. The Eβmax resolution capability of 50-keV is
possible using natural rubber attenuator.
The proposed RIC-neutron detector design uses enriched boron
(96% 10B) as a neutron-reactive coating to generate secondary
charged particles. In MCNPX, other neutron-reactive materials
(natural boron, B4C, and LiF) were also studied. The interaction of
alpha was observed predominantly to facilitate the signal
generation in RSAs to detect neutrons. With the optimal thickness
of 3-μm enriched boron, the signal to noise ratio of thermal
neutrons was estimated better by a three orders of magnitude.
The proposed RIC-gamma ray detection system uses a sodium iodide
crystal, photocathodes, and RICs. Photocathodes are placed on all
crystal surfaces to collect optical photons and generate
photoelectrons. These photoelectrons interact to generate an
electrical signal in RSAs and thereby, the RIC detects gamma rays.
The collection ratio was found to be a function of the crystal
size, gamma-ray energy, and the source position. However, this
ratio was found to increase for all the defined scenarios. The
concentration of photoelectrons as a function of the RSA radius
size was assessed to optimize the RSA size.
Associated Project(s):Radiation Detection Using Integrated Circuits