INVESTIGATION ON HIGH-RESOLUTION RADIATION-DETECTORS BY THE USE OF Nb-BASED TUNNEL JUNCTIONS

据推测，用于辐射探测的超导隧道结比半导体探测器具有更好的能量分辨率。对铌基隧道结在辐射探测中的应用进行了基础研究。采用光刻技术制备了结构简单的Nb/A1-A10x/Nb结，并对其进行了5.9 keV x射线测量。利用耦合玻尔兹曼方程分析了准粒子与声子的非线性相互作用，阐明了准粒子与声子在超导体中的行为。为了在现有技术条件下获得更好的能量分辨率，研究了铌基隧道结的最佳设计方法。发现正常电阻存在一个最佳值，当结点的正常电阻与最佳值不同时，能量分辨率会下降。最后，从多层隧道结和适用于辐射探测的材料两方面对先进隧道结进行了讨论。

It has been presumed that superconducting tunnel junctions for radiation detection show better energy resolution than semiconductor detectors. We made a basic research for applying niobium-based tunnel junctions to radiation detection.Nb/A1-A10x/Nb junctions of a simple structure was fabricated by photolithographic technique, and 5.9 keV X-ray was measured by them. Non-linear interaction between quasi-particles and phonons was analyzed by the coupled Boltzmann equations, and the behavior of quasiparticles and phonons in the superconductor was elucidated.In order to obtain better energy resolution under the present technical constraint, a study was made on the design method for the optimum niobium-based tunnel junctions. It was found that there exists an optimum value of normal resistance: The energy resolution is deteriorated when junctions have the normal resistance different from the optimum value.Finally, discussion about advanced tunnel junctions was made from the viewpoint of both multilayer tunnel junctions and materials suitable for radiation detection.