In-situ element analysis from gamma-ray and neutron spectra using a pulsed-neutron source

The work of this thesis is based on a project in the framework of the EU programme GROWTH, to develop a multi-purpose instrumentation, NuPulse, capable to explore elemental concentrations for in situ measurements using a pulsed neutron source based on a D-T reaction. NuPulse provides time- and energy-information generated by neutron interactions with geological formations. The work of this thesis mainly represents the contribution of the RuG/KVI team to the NuPulse consortium. Our tasks included design and construction of control units, data modelling, validation and interpretation of laboratory and field measurements. At first, benchmark experiments were combined with Monte Carlo (MC) simulations, leading to the instrument’s design. Next, the instrument was tested and calibrated under well-defined laboratory conditions before deployment in field experiments. These experimental tests have shown on one hand the working and capabilities of the instrument but on the other hand showed unexpectedly, new challenges regarding the data interpretation via MC simulations. The objectives of the NuPulse programme were maybe too ambitious because of unforeseen difficulties in the Monte Carlo simulations. The NuPulse instrument could not yet fulfil all the objectives, nevertheless some promising results were obtained with the instrument and further test will be needed to optimise the various components for the anticipated multi-purpose function. The instrument still requires some physics research before it could be adopted for deployment in mineral exploration, contraband detection and searching for explosives.