Future x-ray astrophysics experiments require high-fill-factor kilo-pixel arrays of transition-edge sensors (TESs), with very high spectral resolution over a broad range of energies (typically 0.1-12 keV). In this paper we report on Mo/Au TES designs that are being optimized to meet the stringent resolution, count-rate and uniformity requirements of this next generation of space-based instruments, such as the ATHENA X-IFU instrument, as well as for ground-based laboratory astrophysics experiments using electron-beam-ion-traps (EBITs). These pixels are being optimized for DC bias and time-division-multiplexed readout. In particular, we report on the performance of 50 micron TESs in uniform, kilopixel arrays. These TESs are smaller than those of previous generations and lack the noise-mitigation stripes atop the sensor. The strong geometry dependence of the transition shape means that these devices operate in a régime where the small-signal transition parameters (α and β) are significantly larger than those of their striped counterparts, and these higher values are accompanied by higher detector noise. We examine how these very different transition properties, in conjunction with the choice of the inductance of the detector-bias loop, impact various important performance characteristics of the device such as the time constants, energy resolution, linearity, and uniformity in large arrays and compare the measured performance to calculations from small- and large-signal detector models. We report excellent broadband energy resolution, including 1.9 eV at Al-Ka (1.5 keV), 2.2 eV at Co-Ka (6.9 keV), 2.9 eV at Br-Ka (12 keV), and 4.2 eV at Mo-Ka (18 keV). Tests on multiple pixels in a kilopixel array using TDM readout show these pixels have excellent transition-shape and resolution uniformity.
|Less than 5 years of experience since completion of Ph.D||N|
|Student (Ph.D., M.Sc. or B.Sc.)||N|