We report on the development of large format arrays using multiabsorber transition edge sensors (TESs), commonly referred to as ‘hydras’. A hydra consists of multiple x-ray absorbers each with a different thermal conductance to a TES. Position information is encoded in the pulse shape. With some trade-off in performance, hydras enable the development of very large format arrays without the prohibitive increase in bias and read-out components associated with arrays on individual TES pixels. These devices are under development for the next generation of space telescope such as Lynx. Lynx is a mission concept under study for the Astro 2020 decadal review that will revolutionize x-ray astronomy by combining a < 1” angular resolution optic with 100,000-pixel microcalorimeter array that will achieve ~3 eV energy resolution in the soft x-ray energy range.
Here we present the design optimization and trade-off’s between key performance metrics such as resolution, position-discrimination and count-rate for multiabsorber TESs with up to 25-pixels/hydra. We present results from prototype hydras with pixels on a 25 micron and 50 micron pitch. Arrays incorporate, for the first time, microstrip buried wiring layers of suitable pitch and density required to readout a full-scale Lynx array. The average spectral energy resolution across all 25 pixels was <ΔEFWHM> = 2.51±0.97 eV and <ΔEFWHM> = 3.44±1.00 eV at an energy of 1.25 keV for the 25 and 50 micron pitch designs respectively.
To match the bandwidth and dynamic range requirements of the state-of-the-art multiplexing schemes TESs are typically operated in or close-to critical damping. Although some inductance can be used to reduce the pulse slew-rate it is undesirable to critically damp the hydra since this would suppress the position discrimination. We examine the trade-off between position discrimination and pulse slew-rate and explore alternative approaches to slow the pulse rise-time by optimization of the thermal design.
|Less than 5 years of experience since completion of Ph.D||N|
|Student (Ph.D., M.Sc. or B.Sc.)||N|