Observation of TeV Electrons in Collaboration with NASA

我们研制了一种用于气球观测的新型电子探测器(BETS)，以解决超新星中电子的加速机制。我们已经在日本成功地进行了几次气球飞行，测量了从10GeV到几百GeV的电子能谱。为了测量TeV区的电子，有必要进行100天的长期观测，我们与NASA成员合作，试图为NASA的超长持续时间气球(ULDB)研究公告提出建议。我们为共同提案组织了一个日美合作小组，并在日本和美国都举办了一些研讨会。作为ULDB的其他机会，我们计划利用日本国家极地研究所(National Institute Of Polar Research)的极地巡逻气球(PPB)和空间与宇航科学研究所(ISAS)的跨洲长时间气球进行长期观测。我们的ISA成员已经访问了巴西进行规划。它们在几年内都非常有希望用于气球飞行。作为一个未来的项目，我们提议在国际空间站上的日本实验舱/曝光设备上进行为期3年的电子观测。为此，我们和美国的合作者讨论了一项合作计划。我们还利用质子束在GERN进行了仪器的开发。结果证明，滨松光电株式会社的阳极光电倍增管有足够的能力探测1 mm方形闪烁光纤的最小电离粒子。此外，我们还对探测器的设计进行了模拟计算，并对高能电子与伽马射线的关系以及电子在银河系中的扩散特性进行了理论研究。

We have developed a new-type electron detector(BETS) for balloon observations to resolve the acceleration mechanism of electrons in super nova. We have successfully carried out several balloon flights in Japan for measuring the electron energy spectrum from 10 GeV to a few hundred GeV. For measuring the electrons in TeV region, it is necessary to carry out a long term observation as 100 days, and we have tried to make a proposal for the NASA Research Announcement of Ultra Long Duration Ballooning(ULDB) in collaboration with NASA members. We have organized a Japan-US collaboration team for the common proposal, and we had some workshops both in Japan and US. The proposal was not accepted with a grade of "Very Good", and we are trying to be successful in next chance.As other opportunities of ULDB, we have a plan to do a long observation with a Polar Patrol Ballon(PPB) by National Institute of Polar Research in Japan and the trans-continental long duration ballooning between Brazil and Australia by Institute of Space and Astronautical Science(ISAS). Our ISAS members have visited Brazil for the planning. Both of them are very promising for balloon flights within a few years. As a future project, we are proposing a 3-year observation of electrons at Japanese Experiment Module/Exposure Facility on International Space Station. A collaboration plan for this was discussed between us and the US collaborators.We have also carried out developments of instruments at GERN by using the proton beams. As a result, it is proved the 64-anode PMT by Hamamatsu Photonics Co. Ltd has enough capability to detect a minimum ionizing particle for 1mm square scintillating fibers. We have, moreover, done simulation calculations for the detector design and theoretical studies on the relation between high-energy electrons and gamma-ray and for the diffusion characteristics of electrons in the Galaxy.