neutron imaging; radiography; fast neutrons; neutron detectors; process tomography; multiphase flow
Adams Robert, Bort Lorenz, Zboray Robert, Prasser Horst-Michael (2015), Development and characterization of a D–D fast neutron generator for imaging applications, in Applied Radiation and Isotopes
, 96, 114-121.
Adams Robert, Zboray Robert, Cortesi Marco, Prasser Horst-Michael (2014), Conceptual design and optimization of a plastic scintillator array for 2D tomography using a compact D-D fast neutron generator, in Applied Radiation and Isotopes
, 86, 63-70.
Zboray Robert, Adams Robert, Cortesi Marco, Prasser Horst-Michael (2014), Development of a fast neutron imaging system for investigating two-phase flows in nuclear thermal-hydraulic phenomena: a status report, in Nuclear Engineering and Design
, 273, 10-23.
Adams Robert (2013), Development of a 2D fast neutron tomography system based on a DD fusion fast neutron generator and an array of plastic scintillator detectors, in The 12th International Symposium on Fluid Control, Measurement and Visualization
, Visualization Society of Japan (VSJ), Japan.
Adams Robert, Zboray Robert, Cortesi Marco, Prasser Horst-Michael, Design optimization of a 2D tomography facility based on a compact DD fast neutron generator and an array of plastic scintillator detectors, in Journal of Applied Radiation and Isotopes
In the context of non-intrusive measuring techniques and process tomography, imaging with neutrons has always been considered as a useful complement to the use of X-rays and gamma radiation thanks to their specific advantages: on one hand, neutrons are more sensible and contrast giving for materials containing light elements and on the other hand experience a much lower attenuation in the walls of bulky, robust objects containing heavy elements in construction materials. These features of neutron imaging provide significant advantages for studying two-phase and multi-phase flows occurring in energetic and process industries, but also for many other applications. Often additional challenges arise from the transient character of the flow, which requires high imaging rates. The majority of the neutron radiography/tomography studies are performed around a few large-scale, static devices like research reactors or large accelerator-based (spallation) sources, where mechanical rotation of the studied object is required to obtain a sufficient number of projections under different angles that is necessary for the numerical tomographic reconstruction process. This however cannot be performed with a high speed, i.e. high time resolution, for bulky, heavy specimens. The recent international trend is to develop time-resolved, high spatial resolution tomographic imaging techniques with X-rays controlled by deflecting or pulsing of electron beams to vary the aspect angle during acquisition of projections necessary for tomographic image reconstruction. The present PhD project will be part of a feasibility study on the application of similar techniques to apply neutrons instead of X-rays. The feasibility study will be performed as a combination of theoretical modeling and experiments. The method of choice for theoretical modeling of the interaction of neutrons and the detector system are Monte Carlo calculations. They allow predicting both efficiency and energy sensibility as well as spatial resolution of the neutron detection in the process of design iterations. The test of chosen detector configurations is carried out experimentally. In this line, the Laboratory of Nuclear Energy Systems (LKE) of ETH Zurich in cooperation with the Laboratory of Thermal-hydraulics (LTH) at PSI, is setting up a deuterium-deuterium (D-D) fusion based compact neutron generator. It is a one-of-a-kind device developed in cooperation with and constructed by Prof. Ka-Ngo Leung from the University of California, Berkley, producing pulses of an integral output of 10^8 neutrons per second with an energy of 2.45 MeV. This is sufficient to determine the efficiency of combinations of appropriate scintillator materials coupled to photon detectors, to demonstrate the spatial resolution necessary for radiographic and tomographic imaging and to perform first imaging experiments. On the other hand, the output of the source is not sufficient for fast imaging or tomography. For this, a considerable future effort is needed to upgrade the source or to change to alternative processes for the neutron generation, whereas the detector configurations resulting from the proposed PhD project can be directly used for the final purpose of tomography with fast neutrons. They are independent from the speed of the imaging in a wide range of measuring rates and can be applied for time averaging tomography as well. Options for a direct use of the results are therefore given. The scope of work is a challenging, multidisciplinary topic for a promotion of a graduate in physics or electronics. The present application requests the funding of the position of this PhD student, together with financial means in order to develop and construct a neutron detector assembly.