Large area event counting detectors with high spatial and temporal resolution

Abstract

Novel large area microchannel plates (MCPs) constructed using micro-capillary arrays functionalized by atomic layer deposition (ALD) have been successfully demonstrated in large format detectors (10 cm and 20 cm) with cross delay line and cross strip readouts. Borosilicate micro-capillary substrates allow robust MCPs to be made in sizes to 20 cm, the intrinsic background rates are low ( < 0.06 events cm−2 sec−1), the channel open area can be made as high as 85%, and the gain after preconditioning (vacuum bake and burn-in) shows virtually no change over > 7 C cm−2 extracted charge. We have constructed a number of detectors with these novel MCPs, including a 10 × 10 cm cross strip readout device and 20 × 20 cm delay line readout sensors. The cross strip detector has very high spatial resolution (the 20 μm MCP pores can be resolved, thus obtaining ∼ 5k × 5k resolution elements), good time resolution ( < 1 ns), and high event rate ( > 5 million counts/s at 20% dead time), while operating at relatively low gain ( ∼ 106). The 20 × 20 cm delay line detectors have achieved spatial resolutions of ∼ 50 μm and event rates of several MHz, with good gain and background uniformity and < 200 ps event time tagging. Progress has also been made in construction of a 20 × 20 cm sealed tube optical imager, and we have achieved > 20% quantum efficiency and good uniformity for large area (20 cm) bialkali photocathodes.