Performance of Miniature Coaxial Cabels for Read-Out of Superconducting Tunnel Junction Arrays

In order to realize fast readout and no‐cross talk among one hundred wiring cables for a superconducting tunnel junction detector array, coaxial cables with low‐thermal conduction were investigated. Through a steady‐state heat‐flow method, heat into a cryogen‐free cryostat 3He pot was confirmed to be 5.7 μW when one hundred 70–30 CuNi‐based assembled coaxial cable are wired between its 0.3 K and 3 K stages, which is less than 10 % of the heat caused by the support structure of 3He pot. The coaxial cables were actually installed to the cryostat and the detector stage could be kept at 0.3 K for an enough long time to perform time‐of‐flight mass spectrometry experiments. To our knowledge, this is the first time that such large number of the coaxial cables has been installed at 0.3 K successfully.