High Rate Digital Signal Processing for Multi-Channel Microcalorimeters

US national laboratories are developing microcalorimeters for applications ranging from astronomy to materials analysis, including isotope analysis for nuclear attribution and non-proliferation. Based on superconducting transition edge sensors, microcalorimeters can be used as very precise detectors for electromagnetic radiation from the near infrared to gamma rays, with much better energy resolution than existing detectors. Since microcalorimeters are small, they must be fabricated in large, 100-1000 channel arrays that will require low cost readout electronics with good energy resolution and high count rate capability. This project will adapt high-precision digital-readout electronics and digital filter algorithms, developed for germanium gamma-ray detectors, to microcalorimeters, with energy resolution comparable to the existing electronics and with much higher count rates. The goal is to achieve processing electronics that can be built at a price of $100 per channel with automated software for setup, calibration, and monitoring for very large microcalorimeter arrays. Phase I will: (1) capture very long microcalorimeter traces; (2) demonstrate matching energy resolution of the digital (trapezoidal) filters; (3) explore tradeoffs between energy resolution and count rate; (4) develop algorithms to reject (and if possible correct) disturbances in the detector and preamplifier electronics; and (5) develop a preliminary analysis of the resources required to implement a multiplexed pulse processing scheme on the electronics hardware, which is the key to lowering the cost. Commercial Applications and other Benefits as described by the awardee: The instrument should have a wide area of applications in various scientific experiments employing arrays of microcalorimeters for X-ray or gamma-ray spectroscopy. A practical application would be precise isotope analysis of nuclear materials, contributing to the efforts of nuclear non-proliferation and nuclear attribution. Such instruments also would be needed for quality control in semiconductor processing.