High resolution neutron imaging capabilities at BOA beamline at Paul Scherrer Institut

Abstract

a b s t r a c tThe cold neutron spectrum of the Beamline for neutron Optics and other Applications (BOA) at Paul Scherrer Institut enables high contrast neutron imaging because neutron cross sections for many materials increase with neutron wavelength. However, for many neutron imaging applications, spatial resolution can be as important as contrast. In this paper the neutron transmission imaging capabilities of an MCP/Timepix detector installed at the BOA beamline are presented, demonstrating the possibilities for studying sub-20 mm features in various samples. In addition to conventional neutron radiography and microtomography, the high degree of neutron polarization at the BOA beamline can be very attractive for imaging of magnetic fields, as demonstrated by our measurements. We also show that a collimated cold neutron beamline combined with a high resolution detector can produce image artifacts, (e.g. edge enhancements) due to neutron refraction and scattering. The results of our experiments indicate that the BOA beamline is a valuable addition to neutron imaging facilities, providing improved and sometimes unique capabilities for non-destructive studies with cold neutrons.

Evaluation of Wavelength-Dependent Detection Efficiency of Neutron-Sensitive Microchannel Plate Detector

“…In the IMAT beamline, a small GS1 Li glass scintillator, in which Li is in natural isotopic abundance, was used as reference detector. Neutrons are almost transparent to this detector because of its small size and low 6 Li content. This means that the detection efficiency is simply proportional to the neutron absorption cross section of 6 Li, which is proportional to the neutron wavelength or inversely proportional to the neutron velocity, and can easily be corrected.…”

“…Neutrons are almost transparent to this detector because of its small size and low 6 Li content. This means that the detection efficiency is simply proportional to the neutron absorption cross section of 6 Li, which is proportional to the neutron wavelength or inversely proportional to the neutron velocity, and can easily be corrected. In order to check the detector activation effect, we irradiated the detector for more than 4 h at the Larmor beamline.…”

“…In addition, the small pixel size of the Timepix chip can reduce count rates per pixel and allows operation under high flux conditions. (6,7) Some basic performances of the MCP/Timepix detector, such as the detection efficiency, and spatial and time resolutions, have already been investigated. (8,9) However, no detailed study on the energy-dependent or wavelength-dependent detection efficiency has been carried out for the present generation of devices, except for the theoretical predictions (4,10) and experimental data are sparse.…”

Neutron Imaging with Timepix Coupled Lithium Indium Diselenide

“…The Microchannel Plate (MCP) technology was adapted to neutron detection by integrating 10 B in the glass channel sidewall [8]. Coupled to a high resolution ASIC (application specific integrated circuit), the MCP has shown high speed detection windows at a resolution of roughly 10 µm, limited by the channel pore distance [9,10].…”

Characterization of a neutron sensitive MCP/Timepix detector for quantitative image analysis at a pulsed neutron source

“…Pulsed neutron source facilities have built or are preparing to build instruments for energy selective neutron imaging, such as RADEN in J-PARC and IMAT in ISIS, which is just now under commissioning [1][2][3]. Thus, this detector can operate under high flux conditions [7][8] and also perform time-resolved detection of each neutron using the event timing mode of the Timepix chip [5][6]. Therefore, the requirements for neutron imaging detectors include not only time-resolving capabilities but also stability under high neutron flux operation.…”