Search for Antimatters of Cosmic Origin with the BESS Spectrometer

1.从1999年到2001年，已经连续三次利用Bess超导光谱仪在气球上进行了实验，以寻找宇宙射线中的宇宙反物质。2.根据在Bess之前的飞行中获得的数据，在95%的置信度水平下，反氦和氦原子核的比率上限被设定为小于6.8×10-7。这一世界上最严格的上限直接表明我们银河系附近的宇宙是由物质组成的。3.为了进一步寻找更高灵敏度的反物质，在第七届Bess研讨会上讨论了用较小超导能谱仪进行的更长时间的气球载实验，并计划在南极进行长时间飞行。4.继续进行用长时间气球测量宇宙线的探测器研发，例如改善超导磁体的防水性能，低材料结构的管家和轻便漂移室分布式环境监测系统。5.提出并计划于2003年12月至2004年1月在南极进行长时间气球搭载的“Bess-Polar”实验。为了这项实验，研制了体积更小、重量更轻的新型超导光谱仪。

1.Three successive balloon-borne experiments with the BESS superconducting spectrometer have been carried out from 1999 to 2001 to serch for cosmic antimatters in cosmic rays.2.Togeter with data taken in the prebious BESS flights, an upper limit on a ratio on antiheliums to helium nuclei was placed to be less than 6.8 x 10-7 at the 95% confidence level. This most stringent upper limit in the world directly indicates that the Universe near our galaxy consists of matters.3.For further search for antimatters with the higher sensitivity, a longer balloon-borne experiment with smaller superconducting spectrometer was discussed in the 7th BESS workshop and planed by a long duration flight in Antarctica.4.Detector R＆D for the cosmic-ray measurement with the long duration balloon has been continued, for example, the improvement of the water-proof of the superconducting magnet, distributed environmental monitor system for the house-keeping and lighter drift chamber with low-material structure.5.A long duration balloon-borne "BESS-Polar" experiment in Antarctica was proposed and is planed to be carried out in December 2003 to January 2004. For this experiment, smaller and lighter new superconducting spectrometer has been developed and constructed.