THE OBSERVATION OF PRIMARY COSMIC-RAY BY JAPAN-RUSSIA COORPORATIVE BALLOON EXPERIMENT

这个实验从1995年开始每年进行一次，目的是为了弄清楚宇宙射线能谱中所谓的“拐点”，即光谱倾角的快速变化。1995年、1996年和1997年分别进行了两次、两次和三次从堪察加半岛到伏尔加河的长时间气球飞行，在总共9次飞行中成功地进行了8次宇宙射线观测。通过双方的互访，进行了回收室的拆卸、x射线胶片和核乳剂的处理、分析政策的讨论和分析数据的比较。这些通过互访进行的讨论和合作工作对研究的进展是非常有效的。此外，日本和俄罗斯研究组还共同开发了一种由显微镜、精密工作台和计算机组成的新型自动测量系统。该系统实现了梯级淋点溯源到核乳化液顶点点的省力工作，为长时间观测的大量数据分析提供了较大的容量。我们已经完成了1995年观测的数据分析，得到了按化学成分分类的能谱。虽然统计量不够，但结果与低能区能谱有很好的一致性。这些结果在1997年在南非达尔万举行的国际宇宙射线会议上发表。1996年和1997年观测的数据处理正在使用上述新系统进行分析，预计将在今年夏天取得结果。

This experiment has been carried out amually since I995, for the purpose of making clear so called "knee" in the cosmic-ray energy spectrum which is a rapid change in an inclination of spectrum. Long duration balloon flights from Kamchatka to Volga River were earried out twice in 1995, twice in 1996 and three times in 1997, and 8 flights in total 9 flights were succeeded in the observation of cosmic-ray. The disassembly of recovered chamber, proccessing of x-ray film and nuclear emulsion, the discussion about the policy of analysis and the comparison of analized data were performed through the mutual visit by both side. These discussions and cooperative works through mutual visit were quite effective for the progress in reaserach.Moreover, both side of Japanese and Russian group developed a new auto measuring system which consists of a microscope, precision stage and computer. This system realized the deduction of laborous work in the tracing back of the cascade shower to the vertex point in the nuclear emulsion, and give us a large capacity for the analysis of a large amount of data by the long dulation observation.We have already finished the data analysis for the observation in 1995 and obtained the energy spectra classified by chemical composition. The statistics is not enough but the results shows a good consistency with the energy spectra in low energy region. Convining the methodology as the energy and charge determination, these results were reported in 1997 international cosmic-ray conference held in Darvan, South Africa. The data processing for the 1996 and 1997 observation is under the analysis by use of the above mentioned new system, and the results are expected to be obtained in this summer.