Development of the Gamma-ray detector for the measurement of helicity dependent photo-absorption cross-section for the nucleon at SPring-8.

通过测量核子的螺旋度相关的光吸收截面，我们可以通过积累能量相关的数据来验证GDH求和规则。执行这些任务的实验计划在春季-8。本研究的目的是通过研究和开发来构建实验中所需的伽马射线探测器。γ射线探测器应具有即使对于低能γ射线（小于100 MeV）也具有高效率、小的不敏感区域并且能够在高磁场条件下操作。2006年，进行了一系列宇宙射线基本试验。2007年，根据前一年进行的基本测试结果，计划建造原型。事实证明，有必要在机械结构上有更多的想法，以实现小的不敏感区域。基本上，由诸如铅的重金属制成的伽马射线检测器的大重量（对于当前的检测器为1吨）产生问题。我们多次修改了设计，并评估了结构的强度。最后我们成功地克服了这些问题，确定了最终的设计方案

Measurements of the helicity dependent photo-absorption cross-section for the nucleon allow us to verify the GDH sum rule by accumulating the energy dependent data. The experiment to perform them is planned at Spring-8. The purpose of the current research is construction of the gamma-ray detector which is necessary in the experiment by performing Research and Development. The gamma-ray detector should have high efficiency even for the low energy gamma-rays (less than 100 MeV), small insensitive area and be capable of being operated under high magnetic field condition. In 2006, a series of basic test with cosmic rays has been carried out. In 2007, In 2007, construction of the prototype had been planned based on the results of the basic tests performed in the previous year. It turned out that it is necessary to have more ideas on the mechanical structure for achieving a small insensitive area. Basically, the large weight of the gamma-ray detector made of heavy metal such as lead, 1 ton for the current detector, gives problems. We corrected the design many times and evaluated the strength of the structure. And finally we successfully overcome the problems and determined the final design