Vaccaro, Davide, van der Kuur, Jan, van der Hulst, Paul, Vos, Tobias, de Wit, Martin, Gottardi, Luciano, Ravensberg, Kevin, Taralli, Emanuele, Adams, Joseph, Bandler, Simon, Bennet, Douglas, Chervenak, James, Doriese, Bertrand, Durkin, Malcolm, Gard, Johnathon, Reintsema, Carl, Sakai, Kazuhiro, Smith, Steven, Ullom, Joel, Wakeham, Nicholas, Herder, Jan-Willem den, jackson, Brian, Khosropanah, Pourya, Gao, Jian-Rong, Roelfsema, Peter, and Simionescu, Aurora
The X-ray Integral Field Unit (X-IFU) is an instrument of ESA's future NewAthena space observatory, with the goal to provide high-energy resolution ($<$ 4 eV at X-ray energies up to 7 keV) and high-spatial resolution (9") spectroscopic imaging over the X-ray energy range from 200 eV to 12 keV, by means of an array of about 1500 transition-edge sensors (TES) read out via SQUID time-division multiplexing (TDM). In 2022, to aid in the transfer of TDM readout technology from the laboratory toward flight hardware, our team commissioned a new TDM-based laboratory test-bed at SRON. This setup hosts an array of $75\times 75\ \mu$m$^2$ TESs that are read out via 2-column $\times$ 32-row TDM. A system component that is critical to high-performance operation is the wiring harness that connects the room-temperature electronics to the cryogenic readout componentry. In November 2023, we implemented a re-designed flex harness, which in the SRON test-bed has a length close to what is envisioned for the X-IFU flight harness. We report here on our characterization of the TDM system with the new flex harness, which allowed the system to achieve a co-added energy resolution at a level of 2.7~eV FWHM at 6~keV via 32-row readout. In addition, we provide an outlook on the upcoming integration of TDM readout into the X-IFU Focal-Plane Assembly Development Model., Comment: Submitted for publication to Journal of Astronomical Telescopes, Instrumentation and Systems. arXiv admin note: text overlap with arXiv:2403.02978