J. Lapinskas

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 ∼

Tension Metastable Fluid Nuclear Particle Detector: Qualification and Comparisons

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.

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

Fluids in states of tension metastability offer unique capabilities for detection of nuclear emissions from fission and other nuclear phenomena. This includes the ability to completely avoid photonic interference when detecting neutrons in addition to being able to detect neutrons over eight orders of magnitude with spectroscopic capabilities, and the ability to provide directionality information, all from the same instrument; altogether, representing an unsurpassed capability for next-generation application of multi-disciplinary technology for diverse fields of application. In this paper we present the underlying principles of detection using tension (negative, i.e., sub-zero) pressure fluid states at room temperature and present results of qualification of performance in terms of intrinsic efficiency of detection of neutrons from fission and fusion sources. It is found that, unlike present day systems where intrinsic efficiencies are limited to about 20% for fast neutrons, the tension metastabile fluid detector (TMFD) systems offer intrinsic efficiencies of over 90% with the ability to readily scale-up in size for vastly improved effective detection.Copyright

Tensioned Metastable Fluid Detectors for active interrogation of Special Nuclear Materials

Due to He-3 shortages as well as other fundamental limitations of 60-y nuclear power technology being adapted for present-day sensor needs, transformational nuclear particle sensor system developments have sponsored by DARPA, DoE, DHS and NSF. These systems dispense with need for conventional He-3, liquid scintillation or solid-state devices. The novel systems detect 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 which: enable directionality information in 30s to within 10 degrees of a weapons of mass destruction (WMD) neutron source at 25m (80ft); offer over 90% intrinsic efficiency; offer the ability to decipher multiplicity of neutron emission characteristic of spontaneous and induced fission from fissile isotopes; and, enable one to detect WMD-shielded neutrons in the 0.01 eV range, to unshielded neutrons in the 1–10 MeV range, coupled with the ability to detect alpha emitting special nuclear material (SNM) signatures to within 1–5 keV in energy resolution, and detection sensitivities to ultra-trace levels (i.e., to femto-grams per cc of SNMs such as Pu, and Am). The novel tension metastable fluid detector (TMFD) systems are robust, and are presently built in the laboratory with material costs in the ∼

Ascertaining Directional Information From Incident Nuclear Radiation

50+ 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. Comparison against He-3 technology is presented along with adaptation to variety of scenarios ranging from border crossings, to spent nuclear reprocessing plants to portals and moving platforms.

Tension Metastable Fluid Detection Systems for Special Nuclear Material Detection and Monitoring

This paper describes the first step in developing a Tensioned Metastable Fluid Detector (TMFD) based method for active detection of Special Nuclear Materials (SNMs). One of the greatest difficulties in detection of SNMs by active interrogation is the task of distinguishing between the probing particles and the secondary particles that indicate the presence of SNMs. The TMFDs selective insensitivity and γ photon blindness features are advantageous for alleviating this problem. The working principle of the TMFD is discussed along with its applications for security. The experimental work to date involving detection of small quantities of uranium with conventional detectors is discussed along with results of fission neutron detection. Statistically significant detection was obtained within 5 minutes of counting to ascertain and measure conclusive evidence for the presence of a 25g sample of uranium containing ≪ 0.1g of 235U. Results of simulations of the TMFD experiments to come are presented, and the road map for developing the TMFD-based active interrogation detection system is laid out.

Neutron Detection with Centrifugally-Tensioned Metastable Fluid Detectors (CTMFD)

Unprecedented capabilities for the detection of nuclear particles are presented by tensioned metastable fluid states which can be attained via tailored resonant acoustic systems such as the acoustic tensioned metastable fluid detection (ATMFD) systems. Radiation detection in tensioned metastable fluids is accomplished via macro-mechanical manifestations of femto-scale nuclear interactions. Incident nuclear particles interact with the dynamically tensioned metastable fluid wherein the intermolecular bonds are sufficiently weakened such that the recoil of ionized nuclei generates nano-scale vapor cavities which grow to visible scales. Ionized nuclei form preferentially in the direction of incoming radiation, therefore, enabling the capability to ascertain information on directionality of incoming radiation — an unprecedented development in the field of radiation detection. Nuclear particle detection via ATMFD systems has been previously reported, demonstrating the ability to detect a broad range of nuclear particles, to detect neutrons over an energy range of eight orders of magnitude, to operate with intrinsic detection efficiencies beyond 90%, and to ascertain information on directionality of incoming radiation. This paper presents advancements that expand on these accomplishments, thereby increasing the accuracy and precision of ascertaining directionality information utilizing enhanced signal processing-cum-signal analysis, refined computational algorithms, and on demand enlargement of the detector sensitive volume. Advances in the development of ATMFD systems were accomplished utilizing a combination of experimentation and theoretical modeling. Modeling methodologies include Monte-Carlo based nuclear particle transport using MCNP5 and complex multi-physics based assessments accounting for acoustic, structural, and electromagnetic coupling of the ATMFD system via COMSOL’s Multi-physics simulation platform. Benchmarking and qualification studies have been conducted with special nuclear material (SNM), Pu-based neutron-gamma sources, with encouraging results. These results show that the ATMFD system, in its current configuration, is capable of locating the direction of a radioactive source to within 30° with 80% confidence.Copyright

Tensioned metastable fluids and nanoscale interactions with external stimuli—Theoretical-cum-experimental assessments and nuclear engineering applications

Tension metastable fluid states offer unique potential for radical transformation in radiation detection capabilities. States of tension metastability may be obtained in tailored resonant acoustic systems such as the acoustic tension metastable fluid detector (ATMFD) system or via centrifugal force based systems such as the centrifugal tension metastable fluid detector (CTMFD) system; both under development at Purdue University. Tension metastable fluid detector (TMFD) systems take advantage of the weakened intermolecular bonds of liquids in sub-vacuum states. Nuclear particles incident onto sufficiently tensioned fluids can nucleate critical size vapor bubbles which grow from nanoscales and are then possible to see, hear and record with unprecedented efficiency and capability [1]. Previous work by our group has shown the ability of TMFD systems to detect neutrons with energies spanning eight orders of magnitude with 95%+ intrinsic efficiency [2] while remaining insensitive to gamma photons and also giving directional information [3] on the source of the radiation. In this paper we describe research results with CTMFD systems for use in the detection of key actinide isotopes constituting special nuclear materials (SNMs) in spent fuel. Tests in a CTMFD system demonstrate the ability to detect alpha activity (at ∼100% efficiency) of U-isotopes at concentrations of ∼100 ppb (which is unprecedented and about x100–1000 more sensitive than from conventional liquid scintillation spectroscopy). An inherent capability of TMFD systems concerns on demand tailoring of fluid tension levels allowing for energy discrimination and spectroscopy. This appears especially useful to detect the key isotopes of U and other transuranic isotopes of Pu, Np, Am, and Cm that are at different stages of nuclear fuel reprocessing (i.e. UREX+).Copyright

Modeling, analysis and prediction of neutron emission spectra from acoustic cavitation bubble fusion experiments

Tensioned metastable liquid states at room temperature were utilized to display sensitivity to impinging nuclear radiation, that manifests itself via audio-visual signals that one can see and hear. A centrifugally-tensioned metastable fluid detector (CTMFD), a diamond shaped spinning device rotating about its axis, was used to induce tension states, i.e. negative (sub-vacuum) pressures in liquids. In this device, radiation induced cavitation is audible due to liquid fracture and is visible from formed bubbles, so called hearing and seeing radiation. This type of detectors is selectively insensitive to Gamma rays and associated indication devices could be extremely simple, reliable and inexpensive. Furthermore, any liquids with large neutron interaction cross sections could be good candidates. Two liquids, isopentane and methanol, were tested with three neutron sources of Cf-252, PuBe and Pulsed Neutron Generator (PNG) under various configurations of neutron spectra and fluxes. The neutron count rates were measured using a liquid scintillation detector. The CTMFD was operated at preset values of rotating frequency and a response time was recorded when a cavitation occurred. Other parameters, including ambient temperature, ramp rate, delay time between two consecutive cavitations, were kept constant. The distance between the menisci of the liquid in the CTMFD was measured before and after each experiment. In general, the response of liquid molecules in a CTMFD varies with the neutron spectrum and flux. The response time follows an exponential trend with negative pressures for a given neutron count rate and spectra conditions. Isopentane was found to exhibit lower tension thresholds than methanol. On the other hand, methanol offered a larger tension metastability state variation for the various types of neutron sources, indicating the potential for offering significantly better energy resolution abilities for spectroscopic applications.Copyright