Single pixel performance of a 32$\times$32 Ti/Au TES array with broadband X-ray spectra

Abstract

We are developing a kilo-pixels Ti/Au TES array as a backup option for Athena X-IFU. Here we report on single-pixel performance of a 32×32 array operated in a Frequency Division Multiplexing (FDM) readout system, with bias frequencies in the range 1-5 MHz. We have tested the pixels response at several photon energies, by means of a 55 Fe radioactive source (emitting Mn-Kα at 5.9 keV) and a Modulated X-ray Source (MXS, providing Cr-Kα at 5.4 keV and Cu-Kα at 8.0 keV). First, we report the procedure used to perform the detector energy scale calibration, usually achieving a calibration accuracy better than ∼ 0.5 eV in the 5.4 -8.9 keV energy range. Then, we present the measured energy resolution at the different energies (best single pixel performance: ∆EFWHM = 2.40 ± 0.