Implementation of complex signal-processing algorithms for position-sensitive microcalorimeters

We have recently reported on a theoretical digital signal-processing algorithm for improved energy and position resolution in position-sensitive, transition-edge sensor (PoST) X-ray detectors [Smith et al., Nucl. Instr. and Meth. A 556 (2006) 237]. PoSTʹs consists of one or more transition-edge sensors (TESʹs) on a large continuous or pixellated X-ray absorber and are under development as an alternative to arrays of single-pixel TESʹs. PoSTʹs provide a means to increase the field-of-view for the fewest number of read-out channels. In this contribution we extend the theoretical correlated energy-position optimal filter (CEPOF) algorithm (originally developed for 2-TES continuous absorber PoSTʹs) to investigate the practical implementation on multi-pixel single TES PoSTʹs or Hydras. We use numerically simulated data for a nine-absorber device, which includes realistic detector noise, to demonstrate an iterative scheme that enables convergence on the correct photon absorption position and energy without any a priori assumptions. The position sensitivity of the CEPOF implemented on simulated data agrees very well with the theoretically predicted resolution. We discuss practical issues such as the impact of random arrival phase of the measured data on the performance of the CEPOF. The CEPOF algorithm demonstrates that full-width-at-half-maximum energy resolution of<8 eV coupled with position-sensitivity down to a few 100 eV should be achievable for a fully optimized device.