Development of a Time-resolved Neutron Imaging Detector Based on the {mu}PIC Micro-Pixel Chamber

We have developed a prototype time-resolved neutron imaging detector employing a micro-pattern gaseous detector known as the micro-pixel chamber ({mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system. Our detector system combines 100{mu}m-level spatial and sub-{mu}s time resolutions with a low gamma sensitivity of less than 10^-12 and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. In the present paper, we introduce the detector system and present several test measurements performed at NOBORU (BL10), J-PARC to demonstrate the capabilities of our prototype. We also discuss future improvements to the spatial resolution and rate performance.

Spatial resolution of a {mu}PIC-based neutron imaging detector

We present a detailed study of the spatial resolution of our time-resolved neutron imaging detector utilizing a new neutron position reconstruction method that improves both spatial resolution and event reconstruction efficiency. Our prototype detector system, employing a micro-pattern gaseous detector known as the micro-pixel chamber ({mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system, combines 100{mu}m-level spatial and sub-{mu}s time resolutions with excellent gamma rejection and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. From data taken at the Materials and Life Science Experimental Facility within the Japan Proton Accelerator Research Complex (J-PARC), the spatial resolution was found to be approximately Gaussian with a sigma of 103.48 +/- 0.77 {mu}m (after correcting for beam divergence). This is a significant improvement over that achievable with our previous reconstruction method (334 +/- 13 {mu}m), and compares well with conventional neutron imaging detectors and with other high-rate detectors currently under development. Further, a detector simulation indicates that a spatial resolution of less than 60 {mu}m may be possible with optimization of the gas characteristics and {mu}PIC structure. We also present an example of imaging combined with neutron resonance absorption spectroscopy.