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Relatively, recently, in the last 20 years, it was discovered that methane hydrate (MH) deposits are globally distributed in the permafrost and oceans. Before 1960s, when first deposits were discovered in Siberian permafrost, former USSR, it was believed that MH can occur only in laboratory conditions or in vast parts of the Universe. Presently, it is presumed that this solid crystalline compounds in which CH4 molecules occupies the water ice lattices (nominal chemical formula of MH is C4H62O23) can serve as an energy source favorably to the all of the world remaining conventional hydrocarbon sources. Moreover, MH deposits can become vulnerable to climate changes, which were already occurring in geological past with tremendous consequences for the global life on earth. Thus, further development of advanced techniques is needed to enhance our abilities to better characterize, quantify, and monitor MH deposits. In this paper presented, 14-MeV neutrons with associated alpha particle imaging technique were used to quantify the amount of MH in the sample. [ABSTRACT FROM AUTHOR]

In order to perform Quality Assurance/Quality Control (QA/QC) procedures for a system dedicated to the neutron interrogation of objects for the presence of threat materials one needs to perform measurements of reference materials (RM) i.e. simulants having the same (or similar) atomic ratios as real materials. It is well known that explosives, drugs, and various other benign materials, contain chemical elements such as hydrogen, oxygen, carbon and nitrogen in distinctly different quantities. For example, a high carbon-to-oxygen ratio (C/O) is characteristic of drugs. Explosives can be differentiated by measurement of both (C/O) and nitrogen-to-oxygen (N/O) ratios. The C/N ratio of the chemical warfare agents, coupled with the measurement of elements such as fluorine and phosphorus, clearly differentiate them from the conventional explosives. Here we present the RM preparation, calibration procedure and correlations attained between theoretical values and experimentally obtained results in laboratory conditions for C/O and N/C ratios of prepared hexogen (RDX), TNT, DLM2, TATP, cocaine, heroin, yperite, tetranitromethane, peroxide methylethylketone, nitromethane and ethyleneglycol dinitrate simulants. We have shown that analyses of the gamma ray spectra by using simple unfolding model developed for this purpose gave a nice agreement with the chemical formula of created simulants, thus the calibration quality was successfully tested. [ABSTRACT FROM PUBLISHER]

The aim of the research reported here is the development of a methodology for the measurement of small scale variations in chemical elements concentrations, in particular of carbon to oxygen ratio. Knowledge of the C/O ratio is of importance to many problems in various fields. Here we single out the application in obtaining important information about the oilfields. The most fundamental reservoir parameters–oil, gas and water content–are critical factors in determining how each oilfield should be developed. It is well established that carbon to oxygen ratio log yields accurate and repeatable data that can be used to identify and monitor reserves depletion. Recent improvements in neutron generator and gamma detector technologies resulted in small devices which allowed through-tubing measurements. Although the ratio of carbon and oxygen yields is a measure of the amount of oil around the tool it should be realized that a carbon signal can originate from several sources including the borehole, the cement behind the casing, the formation rock and the formation fluid. In order to evaluate these contributions individually we are proposing the modification of the neutron generator by insertion of segmented associated alpha particle detector. From the measurement of neutron time of flight spectra (alpha particle detector–start signal; gamma ray detector–stop signal) it would be possible to determine the location of gamma-ray production voxel and in such a way to determine radial variations in chemical elements concentrations, in particular of C/O ratio. [ABSTRACT FROM PUBLISHER]

Variety of objects found on the sea floor need to be inspected for the presence of materials that represent threat to the environment and human safety. We have demonstrated that a sealed tube 14 MeV neutron generator, with the detection of associated alpha particles, can be used underwater when mounted inside a remotely operated vehicle equipped with hydraulic legs and a variety of sensors for the inspection of such objects for the presence of threat materials. [ABSTRACT FROM AUTHOR]

As an upgrade of a robotic mobile system for anti-personnel landmine clearance, a fast neutron probe has been considered for the detection of mines and explosive residues. Laboratory tests were made by using the 14 MeV 6\times 10^7 neutrons/sec beams with the associated alpha particle detection and with a LaBr3 gamma-ray detector. Simulant of the anti-personnel mine was used as a target. Several measurements were made with the target buried into the soil at different depths. For each depth minimal time measurement was estimated for false negative 0.4% and false positive equal to 10%. Tests showed that it is possible to detect buried landmines as well as residual explosives; however, in order to reach the optimal speed of 10 cm/s of the demining vehicle it is necessarily to use several sealed tube neutron generators and few dozen of LaBr3 gamma-ray detectors. [ABSTRACT FROM AUTHOR]

Tagged neutron inspection system was used for the underwater detection of explosives. Neutrons were produced in the d+t nuclear reaction with API 120 sealed tube neutron generator. Five kilograms of TNT explosive were measured in a pool filled with water. Measurements were done in target in, target out configuration. Also, a sandwich made of 6 mm thick iron plates with explosive placed between two layers of sea sediments was measured under the same conditions. Sediments were collected in the Adriatic Sea. Measurements were repeated with TNT explosive replaced by rocks of similar size and shape. Neutron tube was rotated in order to find the position of explosive (rocks) in the sandwich. It was found that TNT can be detected underwater and that is possible to distinguish TNT from the sea rocks placed between 6 mm thick iron plates or between layers of sediments by their ratios of carbon and oxygen. [ABSTRACT FROM AUTHOR]