Proton-Rich Nuclei Studied by Multi-Nucleon Transfer Reactions

本研究的目的是通过多核子转移反应来研究富质子核的结构。这些信息将有助于理解发生在恒星环境中的快速质子过程和宇宙中化学元素的演化。对于上述反应的实验研究，由于期望反应的横截面与巨大的背景反应的横截面相比非常小，因此开发具有高性能粒子识别性能的计数器系统至关重要。我们研究了BSO晶体作为粒子和伽马探测闪烁体的特性。在1996年，我们订购了一家公司制造一个大的BSO晶体。尺寸为30毫米× 30毫米× 200毫米，是世界上最大的水晶。这种晶体可以很容易地扩展到一个计数器系统，通过添加几个相同的集合来覆盖伽马探测的全立体角。1997年，在增加了一个光导和一个光倍增器后，用伽玛源进行了一次离线测试，以研究计数器的性能。此外，利用田西高能加速器研究机构电子同步加速器的电子束进行了广泛的研究。我们可以像预期的那样获得位置和能量分辨率。作为一项相关研究，我们还利用来自同一加速器的电子束研究了CsI和ppo晶体的性能。前者广泛应用于低能区，后者广泛应用于高能区。BSO可被视为介于两者之间。

The aim of this research is to study the structure of proton-rich nuclei by mutli-nucleon transfer reactions. The information will be useful for the understanding of the rapidproton process which occurs in stellar environments and of the evolution of chemical elements in the universe. For the experimental study of the above-mentioned reactions, the development of counter system with high performance of particle identification is essential because the cross section of the expected reaction is very small compared to the huge background ones.We studied the characteristics of the BSO crystal as a scintilator for particle and gamma detection. In 1996, we ordered a company to fabricate a large BSO crystal. The size was as large as 30mm x 30mm x 200mm which is the largest crystal ever made in the world. This crystal can easily be extended to a counter system which covers full solid angle for gamma detection by adding several identical sets.In 1997, after adding a light guide and a photo-multiplier, an offline test to investigate the performance of the counter was made with a gamma source. Further, an extensive study was made by using an electron beam from the electron synchrotron of High Energy Accelerator Research Organization at Tanashi. We could obtain position and energy resolutions as expected.As a related study, the performances of the CsI and the PWO crystals were also investigated using electron beams from the same accelerator. The former is widely used in the low-energy region, and the latter in the high-energy one. The BSO can be regarded as being located between them.