Geschwindigkeitsbestimmung neutronenreicher Projektilfragmente mit einem Ring- abbildenden Cherenkovdetektor

Technische Universität München, Diss., 199

Geant4 based simulations for novel neutron detector development

A Geant4-based Python/C++ simulation and coding framework, which has been developed and used in order to aid the R&D efforts for thermal neutron detectors at neutron scattering facilities, is described. Built upon configurable geometry and generator modules, it integrates a general purpose object oriented output file format with meta-data, developed in order to facilitate a faster turn-around time when setting up and analysing simulations. Also discussed are the extensions to Geant4 which have been implemented in order to include the effects of low-energy phenomena such as Bragg diffraction in the polycrystalline support materials of the detector. Finally, an example application of the framework is briefly shown.Comment: Proceedings for the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP

Stability of 10B4C thin films under neutron radiation

AbstractThin films of 10B4C have shown to be very suitable as neutron-converting material in the next generation of neutron detectors, replacing the previous predominantly used 3He. In this contribution we show under realistic conditions that 10B4C films are not damaged by the neutron irradiation and interactions, which they will be exposed to under many years in a neutron detector. 1μm thick 10B4C thin films were deposited onto Al or Si substrates using dc magnetron sputtering. As-deposited films were exposed to a cold neutron beam with fluences of up to 1.1×1014cm−2 and a mean wavelength of 6.9Å. Both irradiated and as-deposited reference samples were characterized with time-of-flight elastic recoil detection analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoemission spectroscopy, and X-ray diffraction. We show that only 1.8ppm of the 10B atoms were consumed and that the film composition does not change by the neutron interaction within the measurement accuracy. The irradiation does not deteriorate the film adhesion and there is no indication that it results in increased residual stress values of the as-deposited films of 0.095GPa. From what is visible with the naked eye and down to atomic level studies, no change from the irradiation could be found using the above-mentioned characterization techniques

I-BAND-GEM : a new way for improving BAND-GEM efficiency to thermal and cold neutrons

.The BAND-GEM detector represents one of the novel thermal neutron detection devices that have been developed in order to fulfil the needs of high intensity neutron sources that, like ESS (the European Spallation Source), will start operation in the next few years. The first version of this detector featured a detection efficiency of about 40% for neutrons with a wavelength of 4 angstrom, a spatial resolution of about 6mm and a rate capability in the order of some MHz/cm(2). The novelty of this device is represented by an improved 3D converter cathode (10 cm thick) based on (B4C)-B-10-coated aluminum grids positioned in a controlled gas mixture volume put on top of a Triple GEM amplifying stage. The position where the neutron interacts in the converter depends on their energy and it was observed that the first version of the detector would suffer from an efficiency decrease for long (>5 angstrom) neutron wavelength. This paper describes how the new 3D cathode allowed improving the detection efficiency at long neutron wavelengths while keeping all the benefits of the first BAND-GEM version

A high-efficiency thermal neutron detector based on thin 3D

A new position-sensitive thermal neutron detector based on boron-coated converters has been developed as an alternative to today's standard 3He-based technology for application to thermal neutron scattering. The key element of the development is a novel 3D 10B4C converter which has been ad hoc designed and realized with the aim of combining a high neutron conversion probability via the 10B(n, α)7Li reaction together with an efficient collection of the produced charged particles. The developed 3D converter is composed of thin aluminium grids made by a micro-waterjet technique and coated on both sides with a thin layer of 10B4C. When coupled to a GEM detector this converter allows reaching neutron detection efficiencies close to 50% at neutron wavelengths equal to 4 Å. In addition, the new detector features a spatial resolution of about 5 mm and can sustain counting rates well in excess of $1\ \text{MHz/cm}^2$ . The newly developed neutron detector will enable time-resolved measurements of different kind of samples in neutron scattering experiments at high flux spallation sources and can find a use in applications where large areas and custom geometries of thermal neutron detectors are foreseen