On-line determination of the water cut and chlorine impurities in crude oil using a pulsed beam of fast neutrons.

A neutron-based sensor has been developed able to measure the water cut and the chlorine content in crude oil. The sensor is based upon the use of a pulsed fast neutron source. Two different cases were studied. Case ''A'': chlorine detection with no water present and case ''B'': water cut measurements with no chlorine present. The minimum detection limits for case A and case B were found to be (62 ± 6) mg/L and (2 ± 2) vol%, respectively.

Evaluation of elemental composition of sediments from the Adriatic Sea by using EDXRF technique.

723 sediment samples collected along the eastern Adriatic coast have been analyzed using Energy Dispersive X-Ray Fluorescence. Factor Analysis and GIS have been used for the evaluation of the resulting data base containing information on K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, and Pb concentration levels in order to find spatial relationships in distribution of measured elements. This study can be used to identify background values and to evaluate sediment quality standards.

Quantitative comparison between experimental and simulated gamma-ray spectra induced by 14 MeV tagged neutrons.

Fast neutron interrogation with the associated particle technique can be used to identify explosives in cargo containers (EURITRACK FP6 project) and unexploded ordnance on the seabed (UNCOSS FP7 project), by detecting gamma radiations induced by 14 MeV neutrons produced in the 2H(3H,α)n reaction. The origin of the gamma rays can be determined in 3D by the detection of the alpha particle, which provides the direction of the opposite neutron and its time-of-flight. Gamma spectroscopy provides the relative counts of carbon, nitrogen, and oxygen, which are converted to chemical fractions to differentiate explosives from other organic substances. To this aim, Monte Carlo calculations are used to take into account neutron moderation and gamma attenuation in cargo materials or seawater. This paper presents an experimental verification that C, N, and O counts are correctly reproduced by numerical simulation. A quantitative comparison is also reported for silicon, iron, lead, and aluminium.

Acquisition of prompt gamma-ray spectra induced by 14 MeV neutrons and comparison with Monte Carlo simulations.

Gamma-ray spectra produced in carbon, nitrogen, oxygen, sodium, aluminium, silicon, chlorine, calcium, chromium, iron, nickel, copper, zinc, and lead by 14 MeV tagged neutrons have been collected with NaI(Tl) detectors of the EURITRACK system, which low-energy threshold has been reduced to 0.6 MeV to detect gamma rays of major elements like iron. The spectra have been compared with Monte Carlo simulations to check the tabulated gamma-ray production data. A quantitative approach to subtract the scattered neutron background is also reported.

Irradiation of 4''x4'' NaI(Tl) detector by the 14 MeV neutrons.

Within the EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) project, a new Tagged Neutron Inspection System (TNIS) has been developed and installed in the Port of Rijeka in Croatia. The system was based on the examination of sea containers with the 14 MeV neutron beam. During the operation the characteristic gamma rays were produced and measured by several 5''x5''x10'' NaI(Tl) detectors. During this procedure some of the detectors were exposed to an intensive neutron beam radiation. It was necessary to check for possible radiation damage of the NaI(Tl) scintillator during the gamma detector selection phase of the project. The 4''x4'' NaI(Tl) detector was exposed to 14 MeV neutrons for 20 h. From the presented results on energy resolution and activation measurements it could be concluded that there are no significant differences in energy resolution before and after the irradiation by 4.7x10(11) of 14 MeV neutrons. The only problem could be the high level of medium and long term induced activity in the energy region below 2 MeV.

Contamination of the coastal sea sediments by heavy metals.

The distribution of major and trace elements in the coastal sea sediments along the Eastern Adriatic coast was evaluated. The concentrations of K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, and Pb in 376 samples were measured on the grain fraction <2 mm by the use of energy dispersive X-ray fluorescence. Contour maps for concentrations of toxic elements Zn, Cu, As and Pb were produced in order to show metals accumulation areas.

Measurement of 14MeV neutron-induced prompt gamma-ray spectra from 15 elements found in cargo containers.

Within the EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) project, the gamma-ray spectra produced in a series of materials by 14-MeV tagged-neutron beams have been collected in the inspection portal equipped with large volume NaI(Tl) detectors, in order to build a database of signatures for various elements: C, N, O, Na, Al, Si, Cl, K, Ca, Cr, Fe, Ni, Cu, Zn, Pb. The measured spectra have been compared with prediction from Monte Carlo simulations to verify the consistency of the relevant nuclear data inputs. This library of measured 14-MeV neutron-induced gamma-ray spectra is currently used in a data processing algorithm to unfold the energy spectra of the transported goods into elementary contributions, thus allowing material identification.

Monte Carlo analysis of tagged neutron beams for cargo container inspection.

Fast neutrons produced via D+T reactions and tagged by the associated particle technique have been recently proposed to inspect cargo containers. The general characteristics of this technique are studied with Monte Carlo simulations by determining the properties of the tagged neutron beams as a function of the relevant design parameters (energy and size of the deuteron beam, geometry of the charged particle detector). Results from simulations, validated by experiments, show that the broadening of the correlation between the alpha-particle and the neutron, induced by kinematical as well as geometrical (beam and detector size) effects, is important and limits the dimension of the minimum voxel to be inspected. Moreover, the effect of the container filling is explored. The material filling produces a sizeable loss of correlation between alpha-particles and neutrons due to scattering and absorption. Conditions in inspecting cargo containers are discussed.

The detection of landmines by neutron backscattering: exploring the limits of the technique.

Neutron backscattering (NB) sensors have been proposed for Humanitarian De-mining applications. Recently, a prototype hand-held system integrating a NB sensor in a metal detector has been developed within the EU-funded DIAMINE Project. The results obtained in terms of performance of the NB systems and limitations in its use are presented in this work. It is found that the performance of NB sensors is strongly limited by the presence of the soil moisture and by its small-scale variations. The use of the neutron hit distribution to reduce false alarms is explored.

Regional biological dosimetry: radiation induced changes of elemental concentrations in hair.

Irradiation of skin by ionizing radiation is reflected by changes in hair growth. Changes in hair diameter, which follows irradiation, are the basis of a biological dosimetry technique. Nuclear microscopy has also been used to measure changes in concentrations of trace and minor elements in hair of radiation treated test animals. Some of the elements show change in both their longitudinal and transversal distribution. These changes are related to the skin dose received.

Results of the intercalibration study of laboratories involved in assessing the environmental consequences of the Chernobyl accident.

Within the framework of the International Chernobyl Project, the IAEA's Seibersdorf Laboratories organized an intercalibration exercise among some of the laboratories which were involved in assessing the environmental contamination in the USSR due to the accident. The objective was to assess the reliability of the radioanalytical data for food and environmental samples, which were used to assess the doses. In the initial study reference materials from the stocks of the IAEA's Analytical Quality Control Services (AQCS) were re-labelled and submitted to 71 laboratories as blind samples. These natural matrix materials included samples of milk (containing 2 different levels of radioactivity), soil, air filters and clover. The concentrations of radionuclides in these samples were known from previous intercalibration exercises. The overall range in performance was broad, which is similar to what has been observed in previous international intercomparisons. The results obtained by gamma-ray spectrometry tended to be somewhat underestimated, on average. On the other hand, the laboratories showed an overall tendency to overestimate 90Sr and possibly 239Pu, which were analysed radiochemically. The intercalibration exercise is continuing with nine materials, including: soil, grass, hay and milk powder contaminated with fallout from the Chernobyl accident. These materials, which were prepared by laboratories in the USSR, are now being tested by AQCS prior to future intercomparison exercises. Work with these materials is expected to continue for several years.

Analysis of metal diffusion from crown to the human teeth.

Proton induced X-ray emission spectroscopy (PIXE) has been used to determine the intensity of metals from crowns in human teeth. In order to measure elements distribution across the tooth section, proton beam (3 MeV) has been collimeted to provide a spatial resolution of 300 microns. The samples were selected according to the time of insertion of crowns and the kind of alloys they were made of. The results show the intensities of gold, zinc and copper in abutment teeth. It was not found any intensity of paladium and amount of silver was not significant.

[Concentration of trace elements in the inferior turbinates and in the nasal septum of the human]. / Konzentration der Spurenelemente in der unteren Nasenmuschel und im Septum des Menschen.

The trace elements in 47 inferior turbinates (concha nasalis inferior) and in the nasal septum were examined by means of synchrotron radiation, spectroscopy of characteristic x-rays, and "sub-micron elemental mapping with the Oxford scanning proton microprobe", and the results compared. Both first methods displayed an age-dependent reduction of Zn and an increase of Pb concentration. In some specimens the As concentration was very high. The disposition of all elements except Zn, As and Fe was uniform. Zn and As were concentrated on the surface of the septum and Fe in the region of vascular channels.

Incorporation of trace elements from environment into the hair structure.

A model describing the incorporation of trace elements from environment into the hair structure is presented. Model predictions for radial and longitudinal concentration profiles are given. Comparison with elemental data is satisfactory.

Distribution of trace elements within bones in nasal cavity and labyrinth in humans.

Measurements of trace element concentrations within bones in nasal cavity and labyrinth have shown large variations, both with a single bone and between different bones of a same individual. Factors that influence trace element levels include: metabolic activity, environmental effects, sex, and age. Detection of characteristic X-rays has been shown to be a convenient method for the measurement of concentration profiles, micropixe for micrometer variations, and X-ray centration profiles, micropixe for micrometer variations, and X-ray fluorescence for millimeter variations.

Analysis of trace elements in the human labyrinth by using proton microprobe.

The concentration of zinc in the spiral tract is age-dependent. The accumulation of zinc starts at the bone surface towards the fundus of the internal auditory meatus and continues throughout the whole thickness of the separating wall to reach in advanced age the bone surface towards the basal coil of the cochlea. The concentration of calcium decreases with age. These findings prove our previous histological and densitometric as well as macroscopical investigations of this region.

Incorporation routes of elements into human hair; implications for hair analysis used for monitoring.

A study has been made on the incorporation of some trace elements and minerals into human hair by measuring their distributions across hair diameters. For this study the Particle Induced X-ray Emission (PIXE) technique using the proton microbeam of the Vrije Universiteit of Amsterdam has been applied. Results of measurements on single hair strands at different positions in the root and outside the skin provide evidence that the elements not only can enter the cortex via the matrix but also via the hair root sheaths. Moreover, there are indications that the distribution of an endogenous element is not always homogeneously spread over a cross section of the hair. Endogenous Fe and Pb seem to be peaked on the periphery of the hair by natural means, while the elements S,Zn and Cu of the samples measured are found to be distributed homogeneously across the hair diameter. The consequences for hair analysis in use for monitoring the trace elements status of an individual are discussed.