Neutron emissions in brittle rocks during compression tests: Monotonic vs cyclic loading

Neutron emission measurements, by means of 3He devices and neutron bubble detectors, were performed during two different kinds of compression tests on brittle rocks: (i) under displacement control, and (ii) under cyclic loading. The material used for the tests was Green Luserna Granite, with different specimen sizes and shapes, and consequently with different brittleness numbers. Since the analyzed material contains iron, our conjecture is that piezonuclear reactions involving fission of iron into aluminum, or into magnesium and silicon, should have occurred during compression damage and failure. Some studies have been already conducted on the different forms of energy emitted during the failure of brittle materials. They are based on the signals captured by acoustic emission measurement systems, or on the detection of electromagnetic charge. On the other hand, piezonuclear neutron emissions from very brittle rock specimens in compression have been discovered only very recently. In this paper, the authors analyse this phenomenon from an experimental point of view.