Development of a Neutron Imaging Method Based on Particle Reaction Topology

Abstract

Radiation detection is a common tool covering all fields of physics and was started simultaneously with the discovery of X-rays and radiation at the end of the 19^th century. The principle of radiation detection has changed little since then, relying on the measurement of charges generated through ionization in a material by radiation or of photons generated by luminous phenomena in a material, such as scintillation. We have contrived a new method for radiation detection by measuring the reaction topology of a particle interaction with matter, such as Compton scattering of gamma rays, using a micro-pattern gas detector (MPGD). Here we applied this method to the detection of thermal neutrons using the reaction ³He+n→³H+p (Q=756 keV), and developed the micro Neutron Imaging Detector (μNID). Based on event counting, the μNID gives us the Time of Flight with sub-μs time resolution, a fine position resolution of 100 μm, and an excellent background rejection, easily satisfying the requirements for a neutron imaging detector at the J-PARC Pulsed Neutron Source. The development of the μNID is described and application results from J-PARC are introduced.