Characterization of a hybrid array of single and multi-absorber transition-edge sensor microcalorimeters for the Line Emission Mapper

Abstract

The Line Emission Mapper (LEM) is a proposed x-ray probe mission to study the physics of galaxy formation through spectral and spatial measurements of x-rays in the energy band of 0.2 to 2 keV. The LEM Microcalorimeter Spectrometer instrument on LEM will have a hybrid transition-edge sensor (TES) microcalorimeter array made up of an inner array of single-pixels with one x-ray absorber connected to one TES and an outer array of multi-absorber microcalorimeters, or “hydras,” with four absorbers connected to a single TES, each with a different thermal conductance. Here, we characterize the first hybrid array of single-pixel and multi-absorber microcalorimeters designed for LEM. We present the fundamental transition, noise, and detector performance properties to demonstrate their suitability for the mission. We also show that the spectral resolution at the Al Kα line is 1.92 ± 0.02 eV for the 4-pixel hydra (coadded) and 0.90 ± 0.02 eV for the single-pixels. This is significantly better resolution than the LEM mission level requirement. Finally, we demonstrate that the position discrimination between the four pixels of the hydra can be achieved down to 200 eV when measured with a time-division multiplexed readout using timings representative of the anticipated LEM requirements.