STUDY OF A HIGH RESOLUTION GERMANIUM ION CHAMBER FOR DOUBLE beta DECAYS

为了研究双β衰变，我们研究了建立一个含有四甲基锗(TMG)的高分辨(能量)温液体电离室的可能性。TMG包含了^&lt；76&gt；Ge可能的双β衰变源的7.6%。因此，如果建立了充满TMG的高分辨率电离室，那么该电离室将是观察无中微子双β衰变的良好探测器。为此，我们首先建立了一个TMG的纯化系统和一个带有两个平行板的电离室，并成功地观测到了来自~(？)然后，我们制作了一个在阴极和阳极之间设置栅极的新腔体，并比较了(1)不使用栅极和(2)使用栅极时的能量分辨率。结果表明，对于电子寿命为4musec的液体，(1)的Sigma/E-19%，(2)的Sigma/E-17%，表明能量分辨率有所提高。然而，对于寿命较长的液体，能量分辨率的进一步提高是可以预期的。

For the purpose of studying double beta decays, we have investigated possibility of constructing a high resolution (energy) warm liquid ionization chamber which contains Tetramethyl germanium (TMG). TMG contains 7.6% of possible double beta decay source of ^<76>Ge. Thus, if the high resolution ionization chamber filled with TMG is constructed, then the chamber will be a good detector for observing the neutrinoless double beta decays. However, high resolution in energy is essential for the observation.For this purpose, we first constructed a purification system for TMG and an ionization chamber with two parallel plates and succeeded in observing a signal from 976KeV conversion electrons from ^<207>Bi. Then, we made a new chamber with a grid between the cathode and the anode and compared the energy resolutions for (1) without using the grid and (2) with using the grid. The results were : sigma/E-19% for (1) and 17% for (2) for the liquid with electron lifetime of 4musec, indicating some improvement in the energy resolution. However, the further improvement in the energy resolution can be expected for the liquid with a longer lifetime.