This award supports the development of an optical calorimeter with nanoKelvin resolution which is estimated to improve upon the sensitivity of current laser calorimeters by more than three orders of magnitude, which will push the state-of-the-art in optical absorption measurements of 0.1 to 1 ppm (parts per million) to the ppb (parts per billion)region. This will allow the characterization of optical components with unprecedented sensitivity. Spectral resolution and measurements at 3 K combined with spatial resolution will yield unique information about the physical and chemical nature of native and laser induced material defects, which is necessary for the development of mitigation strategies. The new instrument will enable precision studies of optical/IR absorbance of materials used in low-temperature detectors with spectral, power, and spatial resolution, including the impact of adsorbed surface contamination. This will provide information on the position-dependent response of paramagnetic gamma-ray/particle detectors, which will result in lower operating temperatures for improved performance.
