On the enlargement of active area of superconducting junction radiation detector with segmented absorbers

超导辐射探测器具有优异的能量分辨率，然而，它们也有缺点：它们的有效面积小。在实际应用辐射探测器时，具有较大有效面积的探测器是合理的。为了克服这一缺点，我们开始研究利用分段吸收体制作普通金属-绝缘体-超导体结探测器。由于每个分段吸收体的热容很小，NIS探测器的能量分辨率保持良好。NIS探测器的有效面积与分段吸收器的总面积一样大。每个分段的吸收器通过超导导线彼此连接，以具有相同的电势并彼此热隔离。首先，我们研制了磁控溅射装置，以Ag为普通金属，Al氧化后作为绝缘体，Nb为超导体。接着，对每种材料的溅射条件和氧化条件进行优化。最后，我们利用X-Y平台和荫罩来定义探测器的膜图案，制作了NIS探测器。在8 K ~ 0.3K的温度范围内，我们测量了NIS探测器的电流-电压（I-V）特性，探测器显示了NIS结的I-V曲线。

Superconducting radiation detectors have excellent energy resolution, however, they also have shortcomings : their small active areas. In applying radiation detectors for practice, a detector with a larger active area is plausible. To overcome this disadvantage, we started studying to fabricate normal metal-insulator-superconductor junction detector (NIS detector) with segmented absorbers. With the small heat capacitance of each segmented absorber, the energy resolution of the NIS detector is kept excellent. The active area of the NIS detector is as large as the summed area of segmented absorbers. Each segmented absorber is connected one another by superconducting leads, to have the same electric potential and to isolate thermally each other. A patent is submitted on the NIS detector with segmented absorbers.First, we developed magnetron sputtering device for Ag as normal metal, Al as insulator after oxidation, and Nb as superconductor. Next, the sputtering condition for each material and the oxidation condition were optimized. Finally, we fabricated NIS detectors with exploiting an X-Y stage and a shadow mask to define patterns of membranes of detectors. On these NIS detectors, we measured current-voltage (I-V) characteristics at the temperature from 8K to 0.3K.The detectors showed I-V curves which characterize NIS junctions.