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arXiv · 1611.07856

When "Optimal Filtering" Isn't

J. W. Fowler·B. K. Alpert·W. B. Doriese·J. Hays-Wehle·Y. -I. Joe·K. M. Morgan·G. C. O'Neil·C. D. Reintsema·D. R. Schmidt·J. N. Ullom·D. S. Swetz
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Abstract

The so-called "optimal filter" analysis of a microcalorimeter's x-ray pulses is statistically optimal only if all pulses have the same shape, regardless of energy. The shapes of pulses from a nonlinear detector can and do depend on the pulse energy, however. A pulse-fitting procedure that we call "tangent filtering" accounts for the energy dependence of the shape and should therefore achieve superior energy resolution. We take a geometric view of the pulse-fitting problem and give expressions to predict how much the energy resolution stands to benefit from such a procedure. We also demonstrate the method with a case study of K-line fluorescence from several 3d transition metals. The method improves the resolution from 4.9 eV to 4.2 eV at the Cu K$\alpha$ line (8.0keV).

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J. W. Fowler, B. K. Alpert, W. B. Doriese, J. Hays-Wehle, Y. -I. Joe, K. M. Morgan, G. C. O'Neil, C. D. Reintsema, D. R. Schmidt, J. N. Ullom, D. S. Swetz. 2016-11-23. When "Optimal Filtering" Isn't. https://doi.org/10.1109/tasc.2016.2637359

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