Plastic microchannel plates with nano-engineered films

Abstract

Since their invention decades ago, microchannel plate (MCP) performance has been defined by the properties of the substrate material, which defines both mechanical structure and electron amplification within the device. Specific glass compositions have been developed to provide the conduction and electron emission layer at the surface of the pores. Alternative technologies using quartz and alumina substrates have not matured enough to become a viable substitute to lead–glass-based MCPs. In this paper we report on the development of new MCP devices from plastic substrates. The plastic substrate serves only as a mechanical structure: the electron amplification properties are provided by nano-engineered conduction and emission layers. The film deposition procedures were optimized for low temperatures compatible with the polymethyl methacrylate (PMMA) plastic chosen for this work. The gain of the PMMA MCP with aspect ratio of ∼27:1 and pore diameter ∼50 μm spaced on 70 μm hexagonal grid exceeded 200 at 470 V accelerating bias. Development of hydrogen-rich plastic MCPs should enable direct detection of fast neutrons through proton recoil reaction. Recoil protons with escape ranges comparable to the wall thickness will initiate an electron avalanche upon collision with the pore walls. The electron signal is then amplified within the MCP pore allowing high spatial and temporal resolution for each detected fast neutron. We expect to achieve ∼1% detection efficiency for 1–15 MeV neutrons with temporal resolution <10 ns, spatial resolution of <200 μm and very low background noise.