Design of a Multi-Channel Ultra-High Resolution Superconducting Gamma-Ray Spectrometer

摘要

Superconducting Gamma-ray microcalorimeters operated at temperatures around ～ 0.1 K offer an order of magnitude improvement in energy resolution over conventional high-purity Germanium spectrometers. The calorimeters consist of a ～1 mm~3 superconducting or insulating absorber and a sensitive thermistor, which are weakly coupled to a cold bath. Gamma-ray capture increases the absorber temperature in proportion to the Gamma-ray energy, this is measured by the thermistor, and both subsequently cool back down to the base temperature through the weak link. We are developing ultra-high-resolution Gamma-ray spectrometers based on Sn absorbers and superconducting Mo/Cu multilayer thermistors for nuclear non-proliferation applications. They have achieved an energy resolution between 60 and 90 eV for Gamma-rays up to 100 keV. We also build two-stage adiabatic demagnetization refrigerators for user-friendly detector operation at 0.1 K. We present recent results on the performance of single pixel Gamma-ray spectrometers, and discuss the design of a large detector array for increased sensitivity.