Study of the Origin of the Cosmic-Ray Antiprotons using the BESS Spectrometer

为了研究宇宙线反质子的起源，1.在1999年和2000年，利用BESS超导谱仪连续进行了两次球载实验，测量了太阳活动极大期宇宙线的精确谱。在这些飞行中，累计发生了上千次反质子事件。通过这些飞行的数据，可以清楚地观察到电荷对太阳调制的依赖性，这对于理解次级反质子的能谱是不可避免的.对初级宇宙线中的反氦核进行了搜寻，提出了反氦核与氦核比值小于7×10^的上限<-7>，这是目前国际上最严格的.测量了原始质子的精确能谱，特别是在低于1GeV的低能区。利用气球升空期间的数据，观测了质子能谱与剩余压力的关系，以检验宇宙线在大气中发展的模型.第七届<th>BESS研讨会的目的是评估过去BESS实验的结果。为了进一步研究低能反质子的起源，该研讨会讨论并计划在南极洲进行一次长时间飞行，以进行一次更长时间的球载实验，使用更小的超导谱仪。

In order to study the origin of the cosmic-ray antiprotons,1. Two successive balloon-borne experiments with the BESS superconducting spectrometer have been carried out in 1999 and 2000 to measure precise spectrum of the cosmic rays at the solar maximum period. In these flights, more than thousand antiproton events were accumulated.2. By the data from those flights, charge dependence on the solar modulation was clearly observed, which is inevitable to understand the energy spectrum of secondary antiprotons.3. A search for antihelium nuclei in the primary cosmic rays has been carried out and an upper limit of the ratio of antiheliums to helium nuclei to be less than 7×10^<-7> was placed, which is most stringent in the world.4. Precise energy spectrum of primary protons was measured, especially in low energy region below 1 GeV.Using the data during the acsend of the balloon, residual pressure dependence on the proton spectrum was observed in order to check models of the development of cosmic rays in the atmosphere.5. The 7^<th> BESS workshop was held to evaluate the results from past BESS experiments. For further investigation of the primary origin of the low energy antiprotons, a longer balloon-borne experiment with smaller superconducting spectrometer was discussed and planed by a long duration flight in Antarctica in that workshop.