Evidence of piezonuclear reactions: From geological and tectonic transformations to neutron detection and measurements

Neutron emission measurements, by means of helium-3 and neutron bubble detectors, were performed on solid specimens during three different kinds of mechanical tests: compression tests under displacement control, under cyclic loading, and by ultrasonic vibration. The material used for the tests was Green Luserna granite. Since the analyzed material contains iron, our conjecture was that piezonuclear fission reactions involving fission of iron into aluminum, and of iron into magnesium and silicon, should have occurred during compression damage and failure. It is also interesting to emphasize that the present natural abundances of aluminum (~8%), and silicon (28%) and scarcity of iron (~4%) in the continental Earth's crust should be possibly due to the piezonuclear fission reactions considered above

Criticality Hidden in Acoustic Emissions and in Changing Electrical Resistance during Fracture of Rocks and Cement-Based Materials

Acoustic emissions (AE) due to microcracking in solid materials permit the monitoring of fracture processes and the study of failure dynamics. As an alternative method of integrity assessment, measurements of electrical resistance can be used as well. In the literature, however, many studies connect the notion of criticality with AE originating from the fracture, but not with the changes in the electrical properties of materials. In order to further investigate the possible critical behavior of fracture processes in rocks and cement-based materials, we apply natural time (NT) analysis to the time series of AE and resistance measurements, recorded during fracture experiments on cement mortar (CM) and Luserna stone (LS) specimens. The NT analysis indicates that criticality in terms of electrical resistance changes systematically precedes AE criticality for all investigated specimens. The observed greater unpredictability of the CM fracture behavior with respect to LS could be ascribed to the different degree of material homogeneity, since LS (heterogeneous material) expectedly offers more abundant and more easily identifiable fracture precursors than CM (homogenous material). Non-uniqueness of the critical point by varying the detection threshold of cracking events is apparently due to finite size effects which introduce deviations from the self-similarity

Acoustic Emission and fracture energy dissipation in notched concrete beams subjected to three-point bending tests

In this study, three-point bending (TPB) tests on notched concrete beams having different size, have been carried out to evaluate the influence of propagation distance on the AE parameters. The most representative AE parameters have been measured by sensors at different distances from the source, in order to obtain detailed information on the type of cracks as well as on the source localization. The waves frequency and the rise angle are used to discriminate the prevailing cracking mode from pure opening or sliding [1]. The cumulated number of AE events and their amplitude are used to compute the signal energy. Each signal recorded during the bending test by the first sensor has been compared with the same signal captured by the other one. For all concrete beams, an average value of the AE parameters for each sensor has been made. The AE parameters average value indicates how important the propagation distance between the two sensors is for the AE analysis. However, AE waveform parameters are effected by strong attenuation and distortion due to propagation through an inhomogeneous medium, which should not be neglected in laboratory and, in particular way, on real structures. The AE results obtained from the three-point bending tests prove that the variation of the AE parameters during the loading process strictly depends on the specimen damage. A decrease in frequency may be provoked by large cracks progress both during tensile and sharing process, while an increase in AE signal energy content is detected approaching the final failure. A distinct element numerical model of the beam is described and used to model the energy dissipation during the three point bending test. The model accounts for the mesostructure of plain concrete in the region closed to the central notch. Each aggregate is modeled together with the bonding of the matrix. In this way it is possible to simulate numerically the concrete crushing, as well as the tensile cracking at the aggregate interface or through the matrix and, eventually, through the inclusions [2-4]. The model is able to simulate the Acoustic Emission localization and statistics, in addition to the fracture energy dissipation, allowing for a better understanding of the ongoing phenomen

Piezonuclear Fission Reactions from Earthquakes and Brittle Rocks Failure: Evidence of Neutron Emission and Non-Radioactive Product Elements

Neutron emission measurements, by means of He 3 devices and bubble detectors, were performed during three different kinds of compression tests on brittle rocks: (i) under monotonic displacement control, (ii) under cyclic loading, and (iii) by ultrasonic vibration. The material used for the tests was Luserna stone, with different specimen sizes and shapes, and consequently with different brittleness numbers. Some studies had been already conducted on the different forms of energy emitted during the failure of brittle materials. They are based on the signals captured by acous- tic emission measurement systems, or on the detection of electromagnetic charge. On the other hand, piezonuclear neutron emissions from very brittle rock specimens in com- pression have been discovered only very recently. In this paper, the authors analyse this phenomenon from an exper- imental point of view. Since the analyzed material contains iron, additional experiments have been performed on steel specimens subjected to tension and compression, observing, also in this case, neutron emissions well distinguishable from the background level. Our conjecture is that piezonu- clear reactions involving fission of iron into aluminum, or into magnesium and silicon, should have occurred during compression damage and failure. This hypothesis is con- firmed by the direct evidence of Energy Dispersive X-ray Spectroscopy (EDS) tests conducted on the specimens. It is also interesting to emphasize that the anomalous chemical balances of the major events that have affected the geo- mechanical and geochemical evolution of the Earth's Crust should be considered as an indirect evidence of the piezo- nuclear fission reactions considered above

Energy emissions from brittle fracture: Neutron measurements and geological evidences of piezonuclear reactions

Neutron emission measurements, by means of 3 He devices and neutron bubble detectors, were performed during three different kinds of compression tests on brittle rocks: (i) under displacement control, (ii) under cyclic loading and (iii) by ultrasonic vibration. The material used for the tests was Green Luserna Granite. Since the analyzed material contains iron, our conjecture is that piezonuclear fission reactions involving fission of iron into aluminum, or into magnesium and silicon, should have occurred during compression damage and failure. This hypothesis is confirmed by Energy Dispersive X-ray Spectroscopy (EDS) tests conducted on Luserna Granite specimens. It is also interesting to emphasize that the present natural abundances of aluminum (≈8%), and silicon (28%) and scarcity of iron (≈4%) in the continental Earth's crust should be possibly due to the piezonuclear fission reactions considered above

The Energy Emissions as Fracture and Seismic Precursors

The main purpose of this Doctorate Thesis is to set-up a multi-parameter monitoring system that takes into account the observation of several seismic precursors. A seismic precursor is a phenomenon which can take place largely in advance to quake occurrence, and also at large distance from the epicentre. It is well known that the dimension of the earthquake preparation area is a function of the magnitude of the incoming quake and it can consist in a geographical zone up to thousands of kilometres. Furthermore, these precursory phenomena are of various nature but, despite their obvious diversity, many of them reflect a common physical origin. In the last decades a great number of laboratory tests and experimental observations evidenced that mechanical, electromagnetic and neutron emissions, together with radon levels, carbon dioxide emanations and temperature variation, are the most reliable natural phenomena that can be linked to earthquake preparation. In the finalization of this research many experimental tests were conducted both on the laboratory rock samples, and in a suitable monitoring site. First of all, specific tests carried out in the Fracture Mechanics Laboratory of the Politecnico di Torino are presented. Through these tests it was possible to demonstrate that the failure phenomena, in particular when they occur in a brittle way, i.e. with a mechanical energy release, emit additional forms of energy related to the fundamental natural forces. By subjecting brittle or quasi-brittle materials, such as rock specimens, to mechanical stress tests, bursts of neutron emission (NE) during the failure process were produced, necessarily involving nuclear reactions, besides the well-known acoustic emission (AE), and the phenomenon of electromagnetic radiation (EME). The main idea is that, if all these phenomena are simultaneously analysed in suitable monitoring sites, they could provide the basis for prediction of the three main parameters of an earthquake: place and time of occurrence, and magnitude of the seismic event. The place where it occurs is to be understood around the monitoring site, and in an area where its effects are always instrumentally perceptible. Nevertheless, the most important problem with all these precursors is to distinguish signals from noise. A single precursor may not be helpful, the prediction program strategy must involve an integral approach including different precursors. For the in-site monitoring the "San Pietro - Prato Nuovo" gypsum mine located in Murisengo (Alessandria, Italy) was chosen. In this mine, to avoid interference with human activities, the instrumental control units have been located at one hundred meters underground. Finally, the experimental results obtained from July, 1st 2013 to December, 31 2015 (five semesters) are reported. The experimental observations reveal a strong correlation between acoustic, electromagnetic, and neutron emission peaks and the major earthquakes occurred in the closest area

X-ray photoelectron spectroscopy on fracture surfaces of carrara marble specimens crushed in compression

Neutron emission measurements were made, by means of a He3 detector, on Carrara marble rock specimens under compression. While granite generated neutrons −due to piezonuclear reactions involving fission of iron into aluminum− this phenomenon did not occur in marble under crushing. In this paper, the external and fracture surfaces belonging to Carrara marble specimens crushed during the compression tests were analyzed by X-ray Photoelectron Spectroscopy (XPS). XPS quantitative compositional analyses were carried out in order to detect any variation in Carrara marble composition due to brittle failure of cylindrical specimens. A decrease in O, Ca and Mg as well as an increase in C content was observed on the fracture surfaces with respect to the external ones. These transmutations involve elements (O, Ca and Mg) with an equal number of protons and neutrons, like their reaction products. For this reason the microchemical analyses suggest piezonuclear reactions without neutron emissions in marble crushed specimens

Elemental content variations in crushed mortar specimens measured by instrumental neutron activation analysis (INAA)

Previous investigations concerning neutron emission measurements highlighted piezonuclear fission reactions during mechanical tests on iron-rich materials. Based on our experimental evidences, iron can be considered one of the most convenient elements as regards fission into aluminium or into magnesium and silicon. In the present investigation, we apply the Instrumental Neutron Activation Analysis (INAA) in order to provide experimental evidence of elemental content variations in mortar specimens subjected to compression tests up to crushing failure. To emphasize such a phenomenon, the specimens were highly enriched with iron oxides. Twenty-four chemical elements, including iron, aluminum, magnesium, and silicon, were quantified before and after the mechanical tests by means of chemical and INAA analyses. Our intention was mainly that of confirming low energy nuclear reactions involving fission of iron into aluminum. To this purpose, the concentrations of aluminum before and after the compression tests of the mortar specimens are presented and discusse