Development of Submillimeter-wave Camera using SIS Photon Detectors

利用超导铌结研制了亚毫米波SIS光子探测器，实现了亚毫米波宽场、宽带宽观测。我们还制作了工作在350,650和850 GHz的三色辐射热计系统，利用ASTE（阿塔卡马亚毫米望远镜实验）亚毫米望远镜开始亚毫米波连续观测。在第一年的开发中，我们通过优化制造条件，成功制造了电流密度为1kA/cm2的低漏、小于10pa的隧道结。在接下来的一年里，我们分别使用4微米和3微米直径的结观察到440 GHz和650 GHz的亚毫米波响应。在过去的一年里，我们用光学方法评估了探测器的性能，如漏电流、电流噪声、电压响应性、量子效率、线性度、时间常数和光束模式。NEP显示10(-16)W/sqrt（Hz）。所测性能优于亚毫米波测热计。制造成品率提高到98%的单结和78%的探测器元件。研制三色测辐射热计系统是为了利用ASTE望远镜进行早期连续观测和评估天线性能。开发了0.3 K操作低温恒温器，以实现远程操作的低振动低温。我们已经开始用测热接收机进行科学观测。

Development of submillimeter-wave SIS photon detector is performed using superconducting niobium junctions to realize wide-field and wide-bandwidth observations in submillimeter-wave. We have also made 3-color bolometer system operating at 350,650 and 850 GHz to start submilllimeter-wave continuum observations with ASTE (Atacama Submillimeter Telescope Experiment) submillimeter telescope.In the first year of development, we have successfully fabricated low leakage, less than 10 pA, tunnel junction with 1kA/cm2 current density by optimizing the fabrication conditions. In the next year we have observed submillimeter-wave response at 440 GHz and 650 GHz using 4 micron and 3 micron diameter junctions, respectively. In the last year, we have evaluated the detector performance, such as leakage current, current noise, voltage responsivity, quantum efficiency, linearity, time constant and beam pattern with optics. NEP shows 10(-16)W/sqrt(Hz). The measured performance is superior to submillimeter-wave bolometers. The fabrication yield is improve to be 98% for single junctions and 78% for detector elements.The 3-color bolometer system is developed to make early continuum observations with ASTE telescope and to evaluate the antenna performance. Cryostat for 0.3 K operations is developed to realize remotely operable low vibration cryogenics. We have started scientific observing runs with the bolometric receivers.