This entry briefly describes the history and development of the International Union of Soil Sciences (IUSS) from its foundation as the International Society of Soil Science (ISSS) in 1924 through its change to the IUSS in 1998 and then up to 2016. Brief details of the changing scientific structure of ISSS and IUSS together with the officers of the society/union are provided.

An analysis of digitized pulse waveforms from experiments with LaBr3(Ce) and LaCl3(Ce) detectors is presented. Pulse waveforms from both scintillator types were captured in the presence of 22Na and 60Co sources and also background alone. Two methods to extract pulse shape discrimination (PSD) parameters and estimate energy spectra were compared. The first involved least squares fitting of the pulse waveforms to a physics-based model of one or two exponentially modified Gaussian functions. The second was the conventional gated integration method. The model fitting method produced better PSD than gated integration for LaCl3(Ce) and higher resolution energy spectra for both scintillator types. A disadvantage to the model fitting approach is that it is more computationally complex and about 5 times slower. LaBr3(Ce) waveforms had a single decay component and showed no ability for alpha/electron PSD. LaCl3(Ce) was observed to have short and long decay components and alpha/electron discrimination was observed.

The Canadian Armed Forces (CAF) identified a requirement for inert simulants to act as improvised, or homemade, explosives (IEs) when training on, or evaluating, ground penetrating radar (GPR) systems commonly used in the detection of buried landmines and improvised explosive devices (IEDs). In response, Defence R and D Canada (DRDC) initiated a project to develop IE simulant formulations using commonly available inert materials. These simulants are intended to approximate the expected GPR response of common ammonium nitrate-based IEs, in particular ammonium nitrate/fuel oil (ANFO) and ammonium nitrate/aluminum (ANAl). The complex permittivity over the range of electromagnetic frequencies relevant to standard GPR systems was measured for bulk quantities of these three IEs that had been fabricated at DRDC Suffield Research Centre. Following these measurements, published literature was examined to find benign materials with both a similar complex permittivity, as well as other physical properties deemed desirable - such as low-toxicity, thermal stability, and commercial availability - in order to select candidates for subsequent simulant formulation. Suitable simulant formulations were identified for ANFO, with resulting complex permittivities measured to be within acceptable limits of target values. These IE formulations will now undergo end-user trials with CAF operators in order to confirm their utility. Investigations into ANAl simulants continues. This progress report outlines the development program, simulant design, and current validation results.

A detailed study is undertaken to investigate the performance and phenomenology of electrical impedance tomography for underwater applications. Experiments are performed in an aquarium tank filled with water and a sediment layer. A 64-electrode square array, appropriately scaled down in size, and a previously developed data acquisition system are used. An evaluation is conducted of the ability to detect compact objects buried at various depths in the sediment, with different horizontal separations, and at various vertical separations between the electrode array and the sediment layer. The objects include metallic and nonmetallic mine-like objects and inert ammunition projectiles, all appropriately scaled down in size. The effects of a number of other physical factors are studied, including sediment type, water turbidity and salinity, and object coating integrity and rusting.

The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4) package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE) values of 5% in the visible near infrared (0.4–1 µm) and 8% in the shortwave infrared (1–2.5 µm). Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

As part of a collaborative project between BAS, DRDC Suffield (Canada) and ITRES Research Ltd., (Canada) the first known airborne hyperspectral dataset was acquired over the Antarctic in February 2011. The simultaneous deployment of commercially available visible-near infrared and shortwave infrared spectrometers generated a dataset covering 0.35 to 2.5 μm spectral range at a spectral resolution of 9.6-14 nm. To enable quantitative analysis of surface properties using imaging spectrometry data the removal of atmospheric absorption and scattering effects is an essential pre-processing step. The implementation of a sufficiently accurate and robust atmospheric correction methodology is of critical importance in ensuring that the results from spectral and spatial analysis algorithms are as accurate as possible. However, whilst methodologies are well established for most environments, there is currently no published methodology for correcting airborne hyperspectral data in the Antarctic region. This study presents initial results from an investigation into the applicability of the MODTRAN-5® radiative transfer model and the ATCOR-4 atmospheric correction package for producing atmospherically corrected hyperspectral data in the unique Antarctic environment; an environment that is cold, dry and has low levels of aerosols and atmospheric pollution. Initial results from radiative transfer modelling and atmospheric correction produce absolute reflectance spectra which are partially comparable to laboratory measured spectra. Improvements are seen with the hybrid approach of radiative transfer modelling and the empirical line method using in-scene ground targets. Residual noise remains present due to absorption by atmospheric gases and aerosols which are not appropriately modelled for this environment. Overall, this demonstrates that commercially available packages are not currently flexible enough to correct Antarctic hyperspectral data without the addition of in-scene ground calibration targets. The implementation of Antarctic aerosol and atmospheric profiles into the radiative transfer model would likely improve these corrections and remains an area of investigation for future hyperspectral campaigns in the region.

To date, the most successful nuclear methods to confirm the presence of bulk explosives have been radiative thermal neutron capture (thermal neutron activation) and prompt radiative emission following inelastic fast neutron scattering (fast neutron analysis). This paper proposes an alternative: photoneutron spectroscopy using monoenergetic gamma rays. If monoenergetic gamma rays whose energies exceed the threshold for neutron production are incident on a given isotope, the emitted neutrons have a spectrum consisting of one or more discrete energies and the spectrum can be used as a fingerprint to identify the isotope. A prototype compact gamma-ray generator is proposed as a suitable source and a commercially available 3He ionization chamber is proposed as a suitable spectrometer. Advantages of the method with respect to the previously mentioned ones may include simpler spectra and low inherent natural neutron background. Its drawbacks include a present lack of suitable commercially available photon sources, induced neutron backgrounds and low detection rates. This paper describes the method, including kinematics, sources, detectors and geometries. Simulations using a modified Geant4 Monte Carlo modelling code are described and results are presented to support feasibility. Further experiments are recommended.

First generation thermal neutron activation (TNA) sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on multi-sensor landmine detection systems. The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. The sensor is described, with emphasis on the improvements. Experiments to characterize the performance of the second generation TNA in detecting buried landmines and improvised explosive devices (IEDs) hidden in culverts are described. Performance results, including comparisons between the performance of the first and second generation systems are presented.

Previous research by many groups has shown that broad-band thermal infrared (TIR) imagers can detect buried explosive threat devices, such as unexploded ordnance (UXO), landmines and improvised explosive devices (IEDs). Broad-band detection measures the apparent temperature - an average over the wave band of the product of the true soil surface temperature and the emissivity. Broad-band detection suffers from inconsistent performance (low signal, high clutter rates), due in part to diurnal variations, environmental and meteorological conditions, and soil surface effects. It has been suggested that hyperspectral TIR imaging might have improved performance since it can, in principle, allow extraction of the wavelength-dependent emissivity and the true soil surface temperature. This would allow the surface disturbance effects to be separated from the soil column (bulk) effects. A significant, and as yet unanswered, question is whether hyperspectral TIR images provide better detection capability (higher probability of detection and/or lower false alarm rate) than do broad-band thermal images. TIR hyperspectral image data of threat objects, buried and surface-laid in bare soil, were obtained in arid, desert-like conditions over full diurnal cycles for several days. Regions of interest containing threat objects and backgrounds were extracted throughout the time period. Simulated broad-band images were derived from the hyperspectral images. The diurnal variation of the images was studied. Hyperspectral was found to provide some advantage over broad-band imaging in detection of buried threat objects for the limited data set studied.

Bulk explosives hidden in culverts pose a serious threat to the Canadian and allied armies. Culverts provide an opportunity to conceal insurgent activity, avoid the need for detectable surface disturbances, and limit the applicability of conventional sub-surface sensing techniques. Further, in spite of the large masses of explosives that can be employed, the large sensor target separation makes detection of the bulk explosive content challenging. Defence R&D Canada - Suffield and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives for over 15 years. The next generation TNA sensor, known as TNA2, incorporates a number of improvements that allow for increased sensor-to-target distances, making it potentially feasible to detect large improvised explosive devices (IEDs) in culverts using TNA. Experiments to determine the ability of TNA2 to detect improvised explosive devices in culverts are described, and the resulting signal levels observed for relevant quantities of explosives are presented. Observations confirm that bulk explosives detection using TNA against a culvert-IED is possible, with large charges posing a detection challenge at least as difficult as that of a deeply buried anti-tank landmine. Because of the prototype nature of the TNA sensor used, it is not yet possible to make definitive statements about the absolute sensitivity or detection time. Further investigation is warranted.

Defence R&D Canada - Suffield and Bubble Technology Industries have been developing thermal neutron activation (TNA) sensors for detection of buried bulk explosives since 1994. First generation sensors, employing an isotopic source and NaI(Tl) gamma ray detectors, were deployed by Canadian Forces in 2002 as confirmation sensors on the ILDS teleoperated, vehicle-mounted, multi-sensor anti-tank landmine detection systems. The first generation TNA could detect anti-tank mines buried 10 cm or less in no more than a minute, but deeper mines and those significantly displaced horizontally required considerably longer times. Mines as deep as 30 cm could be detected with long counting times (1000 s). The second generation TNA detector is being developed with a number of improvements aimed at increasing sensitivity and facilitating ease of operation. Among these are an electronic neutron generator to increase sensitivity for deeper and horizontally displaced explosives; LaBr3(Ce) scintillators, to improve time response and energy resolution; improved thermal and electronic stability; improved sensor head geometry to minimize spatial response nonuniformity; and more robust data processing. This improved sensitivity can translate to either decreased counting times, decreased minimum detectable explosive quantities, increased maximum sensor-to-target displacement, or a trade off among all three. Experiments to characterize the performance of the latest generation TNA in detecting buried landmines and IEDs hidden in culverts were conducted during 2011. This paper describes the second generation system. The experimental setup and methodology are detailed and preliminary comparisons between the performance of first and second generation systems are presented.

A commercialized thermal neutron analysis (TNA) sensor has been developed to confirm the presence of buried bulk explosives as part of a multi-sensor anti-tank landmine detection system. Continuing improvements to the TNA system have included the use of an electronic pulsed neutron generator that offers the possibility of applying fast neutron analysis (FNA) methods to improve the system's detection capability. This paper describes an investigation into the use of FNA as a complementary component in such a TNA system. The results of a modeling study using simple geometries and a full model of the TNA sensor head are presented, as well as preliminary results from an experimental associated particle imaging (API) system that supports the modeling study results. The investigation has concluded that the pulsed beam FNA approach would not improve the detection performance of a TNA system for landmine or buried IED detection in a confirmation role, and could not be made into a practical stand-alone detection system for buried anti-tank landmines. Detection of buried landmines and IEDs by FNA remains a possibility, however, through the use of the API technique.

Buried bulk explosive threats are a major concern to the armed forces and public security agencies of many countries. Nuclear methods to detect these threats have been studied extensively since the 1950s.1 Research in this area has concentrated on neutrons and photons as probing and emitted particles because of their deep penetration. Some reactions involving these particles and the buried materials can be used to identify explosive substances, making them good candidates for confirmation sensors: slower devices that confirm the presence of an explosive following initial detection by less-specific, fast-scanning sensors. Nuclear reactions that generate characteristic radiation capable of identifying an isotope generally have relatively low cross sections (low probability of the reaction happening). To provide results within practical interrogation times, techniques using such reactions require intense sources and consequently large amounts of radiation shielding for personnel and detectors. Though personnel shielding can be significantly reduced by remote operation, this generally relegates active interrogation methods with characteristic radiation emission to either fixedposition roles, such as portals, or vehicle-mounted applications. Our research, with Bubble Technology Industries (BTI, Chalk River, Canada), has led to the development of a thermal neutron analysis (TNA) sensor as part of a tele-operated vehiclemounted multi-sensor large-landmine detector.2 The technique confirms the presence of nitrogenous explosives by measuring characteristic capture gamma rays following absorption of thermal neutrons. Four multi-sensor systems with TNA were put into service with the Canadian Forces in Afghanistan in 2002, making them the first militarily fielded TNA sensors and confirmation sensors for landmines.3 We are developing an advanced next-generation TNA using an electronic neutron generator in place of the present isotopic source, faster higher resolution scintillators, improved Figure 1. Next-generation thermal-neutron-analysis sensor head in soil pit.

Threats associated with bioaerosol weapons have been around for several decades and have been mostly associated with terrorist activities or rogue nations. Up to the turn of the millennium, defence concepts against such menaces relied mainly on point or in-situ detection technologies. Over the last 10 years, significant efforts have been deployed by multiple countries to supplement the limited spatial coverage of a network of one or more point bio-detectors using lidar technology. The addition of such technology makes it possible to detect within seconds suspect aerosol clouds over area of several tens of square kilometers and track their trajectories. These additional capabilities are paramount in directing presumptive ID missions, mapping hazardous areas, establishing efficient counter-measures and supporting subsequent forensic investigations. In order to develop such capabilities, Defence Research and Development Canada (DRDC) and the Chemical, Biological, Radiological-Nuclear, and Explosives Research and Technology Initiative (CRTI) have supported two major demonstrations based on spectrally resolved Laser Induced Fluorescence (LIF) lidar: BioSense, aimed at defence military missions in wide open spaces, and SR-BioSpectra, aimed at surveillance of enclosed or semienclosed wide spaces common to defence and public security missions. This article first reviews briefly the modeling behind these demonstration concepts. Second, the lidar-adapted and the benchtop bioaerosol LIF chambers (BSL1), developed to challenge the constructed detection systems and to accelerate the population of the library of spectral LIF properties of bioaerosols and interferents of interest, will be described. Next, the most recent test and evaluation (T&E) results obtained with SR-BioSpectra and BioSense are reported. Finally, a brief discussion stating the way ahead for a complete defence suite is provided.

Accurate and timely detection of explosives, energetic materials, and their associated compounds would provide valuable information to military commanders in a wide range of military operations: protection of fast moving convoys from mobile or static IED threats; more deliberate countermine and counter-IED operations during route or area clearance; and static roles such as hasty or deliberate checkpoints, critical infrastructure protection and support to public security.The detection of hidden explosive hazards is an extremely challenging problem, as evidenced by the fact that related research has been ongoing in many countries for at least seven decades and no general purpose solution has yet been found. Technologies investigated have spanned all major scientific fields, with emphasis on the physical sciences, life sciences, engineering, robotics, computer technology and mathematics.This paper will present a limited, operationally-focused overview of the current status of detection technologies. Emphasis will be on those technologies that directly detect the explosive hazard, as opposed to those that detect secondary properties of the threat, such as the casing, associated wires or electronics. Technologies that detect explosives include those based on nuclear radiation and terahertz radiation, as well as trace and biological detection techniques. Current research areas of the authors will be used to illustrate the practical applications.

Defence R&D Canada -Suffield has conducted research and development on nuclear methods for detection of bulk explosives since 1994. Initial efforts were directed at confirmation of the presence of bulk explosives in land mines and improvised explosive devices (IEDs). In close collaboration with a few key Canadian companies, methods suitable for vehicle-mounted or fixed position applications and those suitable for person-or small robotportable roles have been studied. Vehicle-mounted systems mainly employ detection of characteristic radiation, whereas person-portable systems use imaging of back scattered radiation intensity distributions. Two key design tenets have been reduction of personnel shielding by the use of teleoperation and custom design of sensors to address the particular problem, rather than adapting an existing sensor to a problem. This is shown in a number of recent research examples.Among vehicle-mounted systems, recent research to improve the thermal neutron analysis (TNA) sensors, which were put into service with the Canadian Forces in 2002, are discussed. Research on fast neutron analysis (FNA) and associated particle imaging (API), which can augment or replace TNA, depending on the application, are described. Monoenergetic gamma ray induced photoneutron spectroscopy is a novel method which has a number of potential advantages and disadvantages over TNA and FNA. Sources, detectors and geometries have been identified and modelling studies have suggested feasibility. Among person-portable systems, research on neutron backscatter imaging and X-ray coded aperture backscatter imaging are discussed.

A neutron Albedo system has been developed for imaging of buried landmines and improvised explosive devices (IEDs). It involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons that return. A scintillating 6Li loaded ZnS(Ag) screen with a sensitive area of 40cm×40cm is used as a thermal neutron detector. Scintillation light is captured by orthogonal arrays of wavelength-shifting fibers placed on either side of the scintillator surface and then transferred to X and Y multi-pixel PMTs. A timing circuit, used with pulsed neutron sources, records the time when a neutron detection takes place relative to an external synchronization pulse from the pulsed source. Experimental tests of the Albedo system performance have been done in a sand box with a 252Cf neutron source (no time gating) and with pulsed D–D (2.6MeV) neutrons from the Defense R&D Ottawa Van de Graaff accelerator (with time gating). Information contained in the time evolution of the thermal neutron field provided improved detection capability and image reconstruction. The detector design is described and experimental results are discussed.

Research has been conducted since the 1950s on nuclear methods to confirm the presence of bulk explosives by detecting characteristic emitted radiation. In most practical situations, penetrating radiation is required, which restricts the problem to gamma rays and neutrons. The most successful reactions to date has been radiative thermal neutron capture (thermal neutron analysis) and prompt radiative emission following inelastic fast neutron scattering (fast neutron analysis). An alternative to these neutron-in, gamma ray-out reactions is photoneutron production. A gamma ray whose energy exceeds the threshold for neutron production in a particular atomic nucleus can cause a neutron to be emitted. For a given isotope and assuming monoenergetic photons, the emitted neutrons will have a spectrum consisting of one or more discrete energies. If the gamma ray source and neutron spectrometer are appropriately chosen, the neutron spectrum can be used as a fingerprint to identify the isotope. This photoneutron spectroscopy method has a number of potential advantages over thermal and fast neutron analysis, such as generally simpler spectra and low inherent natural neutron background. It also has drawbacks, such as possible induced neutron background and a present lack of suitable fieldable photon sources. This paper will describe the method and preliminary simulations and calculations to examine its feasibility. Possible sources, detectors and geometries will be discussed.

We have developed a small, relatively lightweight and efficient short range (<100 m) LIDAR instrument for remotely detecting harmful bioagents. The system is based on a pulsed, eye-safe, 355 nm laser exciting aerosols which then fluoresce with a typical spectrum. The system makes use of a novel technology for continuously monitoring for the presence of unusual concentrations of bioaerosols at a precise remote location within the monitored area, with response within seconds. Fluorescence is spectrally resolved over 32 channels capable of photon counting. Results show a sensitivity level of 40 ACPLA of Bacillus Globigii, an anthrax simulant, at a distance of 100 m (assumed worst case where 1 ppl = 1 ACPLA) considering particle sizes between 0.5 and 10 μm, with a geometric mean at 1 um. The apparatus has been tested in the field during three test and evaluation campaigns with multiple bioagents and public security products. Preliminary results show that the system is able to distinguish between harmful bioagents and naturally occurring ones. A classification algorithm was successfully tested with a single type of bioagent; experiments for daytime measurements are discussed.