Journal Article

Optimal Energy Measurement in Nonlinear Systems: An Application of Differential Geometry

Moseley, S. H., Gerrits, T., Lita, A. E., Fixsen, D. J., Nam, S. W.

2014

Overview

Design of TES microcalorimeters requires a tradeoff between resolution and dynamic range. Often, experimenters will require linearity for the highest energy signals, which requires additional heat capacity be added to the detector. This results in a reduction of low energy resolution in the detector. We derive and demonstrate an algorithm that allows operation far into the nonlinear regime with little loss in spectral resolution. We use a least squares optimal filter that varies with photon energy to accommodate the nonlinearity of the detector and the non-stationarity of the noise. The fitting process we use can be seen as an application of differential geometry. This recognition provides a set of well-developed tools to extend our work to more complex situations. The proper calibration of a nonlinear microcalorimeter requires a source with densely spaced narrow lines. A pulsed laser multi-photon source is used here, and is seen to be a powerful tool for allowing us to develop practical systems with significant detector nonlinearity. The combination of our analysis techniques and the multi-photon laser source create a powerful tool for increasing the performance of future TES microcalorimeters.

• Publisher: Springer US,Springer Nature B.V
• Subject: Algorithms / Calorimeters / Characterization and Evaluation of Materials / Condensed Matter Physics / Differential geometry / Dynamical systems / Energy / Energy measurement / Energy resolution / Lasers / Linearity / Low temperature physics / Magnetic Materials / Magnetism / Microcalorimeters / Nonlinear systems / Nonlinearity / Optimization / Photons / Physics / Physics and Astronomy / Pulsed lasers / Sensors / Spectral resolution / Spectrum analysis