Precise measurement of ultra-heavy nuclei in cosmic rays

通过使用固态轨道探测器的气球实验以及Ariel-6、HEAO-3和Trek的卫星观测，观测到了trans-iron宇宙线。然而，由于其探测器的电荷分辨率低，测量精度不令人满意。此外，在宇宙射线中没有观察到反式铁同位素组成。这些成分的测量给出了对宇宙射线源和星系的化学演化，包括它们的加速和传播过程的关键约束。为未来计划在宇宙射线中进行这些观测，进行了反式铁同位素和超重核到锕系元素探测器的基本开发。在这项研究中，开发了具有高均匀性的大型硅探测器和具有0.20 amu rms的铁核高质量分辨率的固态径迹探测器，如CR-39。此外，为了建立宇宙线的分析方法，我们参加了TIGER气球观测小组。通过测量Si、Fe和Ni原子核的总电荷变化截面与能量的关系，得到了高精度的Si、Fe和Ni原子核碰撞平均自由程。此外，太阳大气和行星际空间高能现象的研究是发生在银河系中的缩影，为研究动力学天体物理过程提供了重要线索。为了理解这些现象，利用TSUBASA卫星上的HIT仪器的数据观测了辐射带中的重离子和太阳粒子事件。发现辐射带中氦同位素的通量比3 He/4 He比太阳丰度比大大提高了3-4个数量级。辐射带中~ 3 He的起源仍在研究之中。

The trans-iron cosmic rays were observed by balloon experiments using solid-state track detectors and satellite observation of Ariel-6,HEAO-3 and Trek. The measurement accuracies, however, were unsatisfactory because of low charge resolutions of their detectors. Moreover, these are no observations of trans-iron isotope compositions in cosmic rays. The measurement of these compositions gives crucial constrains on a cosmic ray source and a chemical evolution of the galaxy, including their acceleration and propagation processes.The basic developments of detectors for trans-iron isotopes and ultra-heavy nuclei up to actinides were performed for future planning of these observations in cosmic rays. Large silicon detectors with high uniformity and the solid-state track detectors such as CR-39 with a high mass resolution of 0.20 amu in rms for iron nuclei were developed in this study. Moreover, in order to establish the analyzing method of cosmic rays, we participated TIGER team of balloon observation. The collision mean-free-paths of Si, Fe and Ni in the atmosphere were obtained with high accuracy with the measurements of energy dependence of those nuclei for total charge-changing cross-sections. Furthermore, the study of high energy phenomena in the solar atmosphere and the interplanetary space is a miniature version occurring in the galaxy and gives an important clue to study dynamical astrophysical processes. In order to understand these phenomena, heavy ions in the radiation belts and from solar particle events were observed using the data from HIT instrument onboard TSUBASA satellite. It is found that the flux ration of helium isotopes, 3He/4He is greatly enhanced in the radiation belt by 3-4 orders of magnitude as compared with the solar abundance ratio. The origin of 3He in radiation belt is still under study.