超伝導転移端検出器の多画素化に向けた マイクロ波多重読出回路による磁場応答の評価

抄録

The response characteristics of a 54-pixel transition edge sensor (TES) to an applied magnetic field B were evaluated with a superconducting solenoid coil and a microwave superconducting quantum interference device (SQUID) multiplexer (MW-Mux). Three figures of merits, i.e., height of output pulse current I_P, its fall time 𝜏, and noise referred to SQUID 𝑆_Φ are systematically measured as a function of B and bias point of TES 𝑅/𝑅_n where 𝑅 is the TES resistance at the operation point in the transition edge and 𝑅_n is that in its normal state. It has been found that 54 pixels can be categorized into three groups due to their behavior toward B. The first group, to which the majority of the pixels belongs, exhibits the clear B dependence of I_P and 𝜏, but not of 𝑆_Φ. The second group consisting of about 10 % of the pixels does not show obvious B dependence of I_P, 𝜏, and 𝑆_Φ. The third group provides 𝑆_Φ which reaches the local maxima at the specific value of B at the lower bias current region (𝑅/𝑅_n ≈ 9 % and 14 %). This indicates the importance of systematic characterization of multi-pixel TES with varying (B, 𝑅/𝑅_n ) and understanding of the optimal conditions prior to applications such as astronomical observations in space that are demanding in terms of measurement time. Combination of coil and MW-Mux is useful for this purpose and scalable for the future large format TES array.