Brian C. Archambault

Towards Leap-Ahead Advances in Radiation Detection

Tension metastable fluid states offer unique potential for leap-ahead advancements in radiation detection. Such metastable fluid states can be attained using tailored resonant acoustics to result in acoustic tension metastable fluid detection (ATMFD) systems. ATMFD systems are under development at Purdue University. Radiation detection in ATMFD systems is based on the principle that incident nuclear particles interact with the dynamically tensioned fluid wherein the intermolecular bonds are sufficiently weakened such that even fundamental particles can be detected over eight orders of magnitude in energy with intrinsic efficiencies far above conventional detection systems. In the case of neutron-nuclei interactions the ionized recoil nucleus ejected from the target atom locally deposits its energy, effectively seeding the formation of vapor nuclei that grow from the sub-nano scale to visible scales such that it becomes possible to record the rate and timing of incoming radiation (neutrons, alphas, and photons). Nuclei form preferentially in the direction of incoming radiation. Imploding nuclei then result in shock waves that are readily possible to not only directly hear but also to monitor electronically at various points of the detector using time difference of arrival (TDOA) methods. In conjunction with hyperbolic positioning, the convolution of the resulting spatio-temporal information provides not just the evidence of rate of incident neutron radiation but also on directionality — a unique development in the field of radiation detection. The development of superior intrinsic-efficiency, low-cost, and rugged, ATMFD systems is being accomplished using a judicious combination of experimentation-cum-theoretical modeling. Modeling methodologies include Monte-Carlo based nuclear particle transport using MCNP5, and also complex multi-dimensional electromagneticcum-fluid-structural assessments with COMSOL’s Multi-physics simulation platform. Benchmarking and qualification studies have been conducted with Pu-based neutron-gamma sources with encouraging results. This paper summarizes the modeling-cum-experimental framework along with experimental evidence for the leap-ahead potential of the ATMFD system for transformation impact on the world of radiation detection.Copyright

Transformational nuclear sensors — Real-time monitoring of WMDs, risk assessment & response

Transformational nuclear particle sensor systems have been developed for detecting a variety of radiation types via interactions with ordinary fluids such as water and acetone placed under metastable states of tensioned (yes, sub-zero or below-vacuum) liquid pressures at room temperature. Advancements have resulted in the development of lab-scale prototypes which provide real-time directionality information to within 10 degrees of a neutron emitting weapons of mass destruction (WMD) source, with over 90% intrinsic efficiency, with ability to decipher multiplicity and to detect WMD-shielded neutrons in the 0.01 eV range, to unshielded neutrons in the 1–10 MeV range, and with the ability to detect alpha emitting special nuclear material (SNM) signatures to within 1–5 keV in energy resolution, and detection sensitivities to ultratrace levels (i.e., to femto-grams per cc of SNMs such as Pu, and Am). The tension metastable fluid detector (TMFD) systems are robust, and are built in the laboratory with costs in the ∼

Gamma-blind transformational nuclear particle sensors

100+ range — with inherent gamma blindness capability. A multi-physics design framework (including nuclear particle transport, acoustics, structural dynamics, fluid-heat transfer, and electro-magnetics), has also been developed, and validated.

Threshold Rejection Mode Active Interrogation of SNMs Using Continuous Beam DD Neutrons With Centrifugal and Acoustic Tensioned Metastable Fluid Detectors

Purdue University is developing novel, multi-purpose tension metastable fluid nuclear particle detectors (TMFDs) by which multiple types of nuclear particles can be detected with high (90%+) intrinsic efficiency, directional specificity, spectroscopic capability, rapid response, large standoff and significant cost-savings compared with state-of-the-art systems. This paper presents uses of these novel detector systems specifically for neutron detection in the presence of extreme gamma fields. Various experimental results are presented in order to illustrate the unique ability of the TMFDs to discriminate out photon flux in the presence of neutron or alpha sources. Finally, a theoretical analysis is performed building upon experimental data which estimates the ultimate limits for gamma rejection/discrimination ability to be ~ 1023 γ/cc/s.

Development of a 4π directional fast neutron detector using tensioned metastable fluids

A threshold-mode based, first of its kind, portable, lightweight SNM active interrogation mode assessment system is under development by our group with the goal of detecting 1 kg HEU at 1 m under 2-min scan time. This system is comprised of a lightweight (<30 kg) inertial electrostatic confinement DD neutron source (emitting

Characterization and Optimization of a Tensioned Metastable Fluid Nuclear Particle Sensor Using Laser-Based Profilometry

\sim 5\times 10^{{\mathbf {7}}}

High-Efficiency Gamma-Beta Blind Alpha Spectrometry for Nuclear Energy Applications

n/s) and lightweight (<30 kg) panels of tensioned metastable fluid detector (TMFD) sensors. This paper presents results of studies conducted for detecting special nuclear materials (SNMs) such as HEU and Pu via active interrogation with a continuous source of 2.45 MeV neutrons from a DD accelerator system. The detector system utilizes either the centrifugally tensioned metastable fluid detector (CTMFD) or the acoustically tensioned metastable fluid detector (ATMFD). Evidence for TMFD sensors to be used in threshold mode monitoring mode for detecting SNMs while rejecting the vast majority of interrogating DD source neutrons is shown and discussed. Both TMFD sensors achieve this via tailoring the tensioned metastable negative pressure (Pneg) state so as to enable selective detection based on incoming neutron energy. Intrinsic neutron detection efficiencies of over 60% for fast (MeV) neutrons previously were attainable in CTMFDs with detection volumes of about 40 cm3, all the while remaining 100% blind to gamma photons from fission and DD neutron interactions with surrounding elements. We report results of assessments with CTMFDs of various sizes ranging from 4 cm3 to up to 40 cm3 and rejection ratios of >104:1 (i.e., over 15,000 DD neutrons rejected for each 252 Cf neutron detected). Similar experiments were also conducted with the ATMFD architecture (in which the sensing state oscillates at over 40 kHz from active to inactive). It was found that the rejection ratio rises from about 1:1 at a drive powers above ~7 W, towards ~10:1 at ~3 W, and to >102:1 below 1 W. In sharp contrast, using a 100cc NE-213 liquid scintillation detector under identical conditions, the rejection ratio varied from a high of ~12 (with 0% gamma rejection) down to only ~1.4 (with 99.9% gamma rejection).

Beyond He-3 nuclear sensors — TMFDs for real-time SNM monitoring with directionality

The development of directional-position sensing neutron detector technologies has the potential to embody transformational impact on to the field of nuclear security and safeguards. Directional neutron detectors offer vastly superior background suppression enabling the detection of smaller quantities of special nuclear materials (SNM) at larger standoffs. Additionally, the ability to image the SNM neutron source directly would be particularly advantageous in active interrogation scenarios where one needs to discriminate interrogating neutrons from neutrons resulting from SNMs. A directional fast neutron detector utilizing the acoustic tensioned metastable fluid detector (ATMFD) system has been developed that is not only comparable in technical performance with competing directional fast neutron technologies but also offers a significant reduction in both cost and size while remaining completely insensitive to gamma photons and non-neutron cosmic background radiation. Past assessments by our group have shown that an ATMFD system (with a 6cm × 10cm cross-sectional area) would be capable of detecting a 8 kg Pu source at 25m standoff with a resolution of 11.2°, with 68% confidence within 60 s. While previous ATMFD system configurations were limited to determining angular resolution in 2π, a new ATMFD sensor system capable of ascertaining directionality in 4π fields is now presented. Characterization and validation of the AMTFD system in cylindrical and spherical geometries as developed includes Monte-Carlo based nuclear particle transport assessments using MCNP-PoliMi and multi-physics based assessments accounting for acoustic, structural, and electromagnetic coupling of the ATMFD system via COMSOLs multi-physics platform. A methodology based on geo-positioning-scheme (GPS) and a higher harmonic based scheme were successfully developed. The spherical (higher-harmonic) technology offers the tantalizing capability for rapid-fire (within tens of seconds) the direct visualization based directionality of incoming neutron radiation via line-of-sight tracks - effectively comprising multiple single detectors within the envelope of a single spherical ATMFD.

Live demonstration: Femto-to-macro scale interdisciplinary sensing with tensioned metastable fluid detectors

State-of-the-art neutron detectors lack capabilities required by the fields of homeland security, health physics, and even for direct in-core nuclear power monitoring. A new system being developed at Purdue’s Metastable Fluid and Advanced Research Laboratory in conjunction with S/A Labs, LLC provides capabilities that the state-of-the-art lacks, and simultaneously with beta (β) and gamma (γ) blindness, high (>90% intrinsic) efficiency for neutron/alpha spectroscopy and directionality, simple detection mechanism, and lowered electronic component dependence. This system, the tensioned metastable fluid detector (TMFD), provides these capabilities despite its vastly reduced cost and complexity compared with equivalent present day systems. Fluids may be placed at pressures lower than perfect vacuum (i.e., negative), resulting in tensioned metastable states. These states may be induced by tensioning fluids just as one would tension solids. The TMFD works by cavitation nucleation of bubbles resulting from energy deposited by charged ions or laser photon pile-up heating of fluid molecules, which are placed under sufficiently tensioned (negative) pressure states of metastability. The charged ions may be created from neutron scattering or from energetic charged particles such as alphas, alpha recoils, and fission fragments. A methodology has been created to profile the pressures in these chambers by laser-induced cavitation (LIC) for verification of a multiphysics simulation of the chambers. The methodology and simulation together have led to large efficiency gains in the current acoustically tensioned metastable fluid detector (ATMFD) system. This paper describes in detail the LIC methodology and provides background on the simulation it validates.

Characterization and Optimization of a Tensioned Metastable Fluid Nuclear Particle Sensor Using Laser Based Profilimetry

A novel, centrifugally tensioned metastable fluid detector (CTMFD) sensor technology has been developed over the last decade to demonstrate high selective sensitivity and detection efficiency to various forms of radiation for wide-ranging conditions (e.g., power, safeguards, security, and health physics) relevant to the nuclear energy industry. The CTMFD operates by tensioning a liquid with centrifugal force to weaken the bonds in the liquid to the point whereby even femtoscale nuclear particle interactions can break the fluid and cause a detectable vaporization cascade. The operating principle has only peripheral similarity to the superheated bubble chamber-based superheated droplet detectors (SDD). Instead, CTMFDs utilize mechanical “tension pressure” instead of thermal superheat, offering a lot of practical advantages. CTMFDs have been used to detect a variety of alpha- and neutron-emitting sources in near real time. The CTMFD is blind to gamma photons and betas allowing for detection of alphas and neutrons in extreme gamma/beta background environments such as spent fuel reprocessing plants. The selective sensitivity allows for differentiation between alpha emitters including the isotopes of plutonium. Mixtures of plutonium isotopes have been measured in ratios of 1∶1, 2∶1, and 3∶1 Pu-238:Pu-239 with successful differentiation. Due to the lack of gamma-beta background interference, the CTMFD is inherently more sensitive than scintillation-based alpha spectrometers or SDDs and has been proved capable to detect below femtogram quantities of plutonium-238. Plutonium is also easily distinguishable from neptunium, making it easy to measure the plutonium concentration in the NPEX stream of a UREX reprocessing facility. The CTMFD has been calibrated for alphas from americium (5.5 MeV) and curium (∼6 MeV) as well. Furthermore, the CTMFD has, recently, also been used to detect spontaneous and induced fission events, which can be differentiated from alpha decay, allowing for detection of fissionable material in a mixture of isotopes. This paper discusses these transformational developments, which are also being considered for real-world commercial use.