Advanced Energy-Resolving Imaging Detectors for Applications at Pulsed Neutron Sources

A number of unique non-destructive testing techniques and fundamental research studies are enabled by the modern bright pulsed neutron sources. In addition to all the methods previously developed at continuous neutron sources the pulsed structure of neutron beam enables a number of novel methods with the measurement of neutron energy through the time of flight technique. Despite the fact that the integral intensity of pulsed neutron sources in general is lower than that of the reactor based facilities, the unique capability to measure energy of each detected neutron provides the possibility to conduct experiments with all the energies at the same time, including epithermal, thermal and cold neutron ranges. Simultaneous detection of multiple Bragg edges, for example, enable unique studies in material science and engineering and provides the possibility to investigate crystallographic structure, strain, phase, texture and composition distribution. The challenge to the detection devices in those applications is the need to detect multiple particles arriving at a short period of time. We propose the development of efficient position sensitive detectors capable of time- tagging multiple neutrons with high accuracy and efficiency. These devices will be able to perform energy-resolved imaging at the pulsed neutron sources and detect every neutron with spatial resolution of & lt; 60 m and timing resolution & lt; 1 s for thermal neutrons and & lt;100 ns for epithermal neutrons and detection efficiency of 70 % for cold neutrons. The proposed detection technology will be complimentary to the large array detectors implemented currently at the neutron scattering facilities and will enable energy-resolved neutron transmission radiography where a large number of Bragg edge and resonance absorption spectra for different areas of the sample can be measured simultaneously. The detection devices will be based on the novel neutron sensitive Microchannel Plates (MCPs), developed by NOVA Scientific combined with the fast and high resolution readout electronics developed by the University of California. Our previous effort on the development of detection technology for neutron radiography enabled the possibility to count neutrons with high detection efficiency and spatial and timing resolution. The proposed detector technology will be optimized for the pulsed neutron applications with the aim of simultaneous detection of neutron energies available at the neutron beamlines with very high spatial and energy resolution and high detection efficiency. The unique capability of Timepix readout with UC Berkeley electronics to detect time of arrival of up to 25,000 particles in 1 ms within a 28 x 28 mm2 active area, very short readout time of 280 s, along with low readout noise will enable development of advanced detectors for the pulsed neutron applications in materials research, nuclear engineering, archeological studies, investigation of dynamic processes and many other areas of modern science.