Series-connected superconducting tunnel junction detectors and their future perspectives

Abstract

A study on the performance of newly designed series connected Superconducting Tunnel Junction (STJ) detectors is presented. New type series connected STJ detectors are proposed for further improvement of detection efficiency and energy resolution. As to position sensitivity, some results obtained with the small area detectors to reduce the noise are presented. This result clarifies the usefulness of position information for the important energy resolution of series junction detectors. As to the application to X-ray detection, a small area detector specially designed for the X ray detection has been fabricated and its performance has been examined with Mn-K X-rays. Main features of the series junction detector are summarized as a high detection efficiency, and a better linearity of pulse height versus energy. Finally, two types of series junction detector were proposed: (1) a detector which consists of four independent series connected STJs in a chip, and (2) a detector which consists of two groups of series connected STJs. The most important feature of the dispersed multitrap series junctions is not the multitrap layers, but the dispersed distribution of the tunnel junctions in the junction group.

本論文では、著者が新たに設計した直列接続超伝導トンネル接合(STJ)検出器の性能研究を概観し、新タイプの検出器の検出効率とエネルギー分解能の更なる改善を提案した。位置の感度に関して、充分な低ノイズとするための小面積検出器で得られた結果を提示した。この結果は、直列接続検出器のエネルギー分解能の重要性に対する位置情報の有用性を明らかにしている。X線検出への適用に関しては、特にX線検出器用に設計した小面積検出器を製作し、その性能をMn-KのX線で試験を行った。直列接続検出器の主な利点を集約し、高検出効率、パルス高さ/エネルギーのより良好な線形性などを挙げた。終わりに、2タイプの直列接続検出器を提案した。1個のチップ内に4個の独立の直列接続STJからなる検出器と2グループの直列接続STJからなる検出器である。分散多重トラップ直列接続の最も重要な特徴は多重層ではなく、接合グループ内のトンネル接合の分散分布である。