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• Neutronography was employed for the investigation of the interaction between consolidants and Pietra di Lecce limestone. • Water motion inside the investigated limestones was visualized. • The effectiveness of the consolidants as protective agents against several artificial weathering tests was demonstrated. • A better performance of nanosilica with respect to nanolime was revealed. • The data could represent methodological proposal scheme in view of a proper restoration/conservation procedure. In this work a combined laboratory-based and neutronographic investigation was carried out on a type of limestone, known as Pietra di Lecce stone, widely used in Italian Baroque as construction material. The limestone was treated with two different commercially-available coatings, namely nanosilica and nanolime, and artificially weathered by salt crystallization and temperature/relative humidity jumps. The aim was to provide an experimental evidence of the protective and consolidating effectiveness of the two treatments by looking at the water absorption process occurring inside the pore network of the analyzed stones. The analysis of the wetting front position revealed significant variations in the water absorption kinetics among the investigated samples, suggesting different mechanisms of interaction between the inorganic consolidants and the underlying bulk stone. Finally, a quantitative evaluation of the best effectiveness of the two products was addressed, particularly useful in view of an appropriate choice of restoration procedures to be applied to building materials. [ABSTRACT FROM AUTHOR]

The article reviews thermal neutron detector developments in the Department of the IBR-2 Spectrometer Complex of the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (FLNP JINR). A variety of detector types are considered: neutron monitors, ring detectors, position-sensitive detectors (PSD), and scintillation detectors. The experience of exploitation of these detectors at the research facilities of the FLNP JINR is presented. [ABSTRACT FROM AUTHOR]

The experimental results of neutron diffraction studies of the crystal structure of the FeNiTi alloy after irradiation with fast neutrons and postradiation isochronous annealing are presented. It is shown that the structural state of the FeNiTi alloy for all external forces is determined by two competing processes: the creation or annealing of radiation defects and precipitation or dissolution of the metastable γ′ phase NiTi. [ABSTRACT FROM AUTHOR]

Validation of an experimental approach requires that both model and data errors are proved to be within acceptable ranges. In case of destructive testing none of the classic, statistically based methods can be applied for that task due to the lack of independent data series required for building data statistics. The aim of the paper is to present a non-statistical methodology for performing such validation, developed within the framework of physically based approximation (PBA). It has been developed to validate a neutron diffraction based experimental-numerical approach applied for studying 3D rail residual stress. It is for the PBA technique's capability to provide high quality physically reasonable data fits for one data set only, treated here as higher order reference fields that made it possible to develop this methodology and perform error analysis/validation. In many ways this approach is analogical to Zienkiewicz-Zhu type of error estimators, and its performance will be demonstrated for a defective RE136 rail sample that was installed in a US DOT test track. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, promising digital active pixel detector systems are available and make real time imaging with high sensitivity and broad dynamic range possible. The hybrid silicon pixel detector device Medipix-2 was originally designed for single X-ray photon detection. The device consists of a sensor chip with 256×256 square pixels of 55μm size. The detector can be adapted for neutron detection by deposition of a converter layer to its surface. Thermal neutrons are converted in the layer into the secondary radiation which can be subsequently detected by the pixel detector. Different types of converter materials were examined with the aim to reach maximal spatial resolution at reasonable detection efficiency. The results demonstrate superior properties of the Medipix-2-based thermal neutron imager with a 6LiF converter in terms of spatial resolution, signal-to-noise ratio, linearity and dynamic range. Several images of real objects demonstrating the capabilities of the device are presented. The performance of the imager was compared with several types of contemporary neutron imaging systems (Medipix-1, CCD camera, imaging plates). [Copyright &y& Elsevier]

Neutron transmission radiography (neutronography) is based on the attenuation of radiation passing through matter. Thanks to different values of neutron and X-ray attenuation coefficients in matter, neutronography can image material properties which cannot be obtained by roentgenography (e.g. materials containing light elements such as Hydrogen in plastic or biological samples). The reliable performance of the neutron detecting device is essential for the acquisition of high-quality neutronograms. A single neutron pixel detector based on a single X-ray photon pixel Medipix-1 detector device is presented. Slow neutrons are converted in a converter layer into heavy charged particles which are subsequently detected by the Medipix-1 device. Detection efficiency, spatial resolution and other detector properties are determined for different converter materials (6LiF, 10B) and compared with results of Monte-Carlo simulations. Several neutronograms of real objects demonstrating the capabilities and possible applications of the technique are presented. [Copyright &y& Elsevier]