Development of Hard X-ray and Gamma-ray Detector With Transition Edge Sensor for Nuclear Materials Analysis

Abstract

We have designed and fabricated a hard X-ray and gamma-ray TES spectrometer for nuclear materials analysis. A superconducting tin (Sn) absorber is coupled to the TES film by using a gold (Au) bump post to improve the thermal contact between the absorber and the TES. To obtain a sufficient detection efficiency at the high energy photons near 100 keV, an 8-pixel array of TES microcalorimeters were developed. In this new device, the epoxy glue which is used to connect the absorber and the gold bump post was well controlled and hence the slow component of the decay time constant was improved from 7.82 ms to 4.46 ms compared to our old device. The energy resolution was 131 eV FWHM at 59.5 keV gamma rays, which is better than the limit of HPGe detectors (400 eV FWHM at 60 keV).Index Terms-Gamma-ray spectroscopy, gold bump post, microcalorimeter, transition edge sensor (TES).

Superconducting Transition Edge Sensor for Gamma-Ray Spectroscopy

“…The time constant of slow decay component improved from 24 ms of the epoxy post TES to less than 5 ms of the gold bump post TES. Although the origin of these two time components in the decay curve is still not clearly understood, we consider that the strong thermal coupling between the Ir/Au film and the Sn absorber, which is brought by the high thermal conductivity of the gold bump post, may suppress the decay time constant of the slow decay component [7], [8].…”

Carbon Nanotube Based γ Ray Detector

“…γ-Radiation detection and monitoring systems are important in applications in medical research and therapy, emergency response, national security, nondestructive inspection, nuclear facilities, and space exploration. A number of γ ray detectors have been introduced, which include high purity germanium (HPGe) detector, superconducting transition edge sensor microcalorimeter, scintillation γ ray detector, photoelectric radiation detector, and others. − Winkler et al reported a 256-pixel microcalorimeter array for high-resolution spectroscopy of mixed actinide materials, demonstrating an average pixel resolution of 55 eV and full-width at half-maximum of 100 keV . Cooper et al designed a planar high-purity Ge crystal with a reduced-capacitance strip electrode geometry, resulting in both high event throughput and high energy resolution at very high count rates .…”