Acculate Stopping Power Measurements of Gases (O_2, N_2, NO, and N_2O) for 5-8 MeV Protons.

我们的计划是测量几种气体对MeV质子的停止力，其最高精度在* 1.0%以下。在1990年（平成2年）期间，我们购买了粒子检测系统（如硅探测器，前置放大器和放大器等），压力表和温度计。在1991年（平成3年），由我们自己的想法制造了两个毒气室的系统，其中一个用于气体靶，并且几乎所有气体停止功率测量必不可少的仪器都完成了。为了最准确地测量气体的停止能力，我们必须首先测试由“科学研究补助金”获得的新仪器的性能。在1992年，我们尝试测量了Ta箔对4.5- 18mev质子的阻挡力，以测试毒气室系统和探测系统的性能。Ta箔片被安装在一个毒气室的窗户上，而另一个毒气室的窗户是空的。气室系统设置在较大的真空室中，对4.5 ~ 18 MeV的质子在有Ta箔和没有Ta箔的情况下，在一次照射中同时测量脉冲高度。由此得到的Ta的停止功率值与我们之前的停止功率值符合得很好。因此，从目前的试验结果来看，新仪器的性能是令人满意的。利用这些仪器，不久将开始测量气体的停止力。

Our project is to measure the stopping powers of several gasses for MeV protons with the highest accuracy under *1.0 %.In the term of 1990 year (Heisei 2), we bought the detecting system of particles (e.g., silicon detectors, preamplifier and amplifier etc.), the pressure gage and the thermometer.In the term of 1991 year (Heisei 3) the system with two gas chambers, one of which is used in gas targets, was made by the idea of ourself and almost all the instruments that is indispensable to the stoppingpower measurement of gas became complete.To measure the stopping powers of gas with the highest accuracy, we must first test the performance of the new instruments obtained by " Grant-in- Aid for Scientific Research".In the term of 1992 year, we tried to measure the stopping powers of Ta foil for 4.5-18 MeV protons in order to test the performance of the gas chambers system and the detecting system. The Ta foil was mounted in the window of one of the gas chambers and the window of the other gas chamber is left empty. The gas chamber system was set in a larger vacuum chamber and for 4.5-18 MeV protons the pulse heights with and without the Ta foil were measured with the detecting system simultaneously in one exposure. Thus obtained stopping power values of Ta were in good agreement with our previous stopping power values. From the result of the present test experiment, therefore, it was concluded that the new instruments are satisfactory for the performance.Using the instruments, the measurements of the stopping powers of gas will be begun soon.