本研究用Si( Li) 漂移探测器测量了137Cs 的β 衰变能谱和内转电子能谱，对β 衰变能谱进行了居里描绘和从内转电 子能谱取得了内转换系数.得到β 衰变的最大能量为( 513.11±1.76) keV，与参考值误差为0.17%; 得到内转换系数K/L = 5.712 ±0.217 和M/L= 0.264±0.018，与参考值的误差分别为0.92%和1.54%; 并确定了137Cs 在β 和γ 衰变中的跃迁级次，给出了137 Cs 及其衰变子核137Ba 各能级的自旋和宇称，绘制出了137Cs 的衰变纲图.说明该实验方法是可靠的，可用于实验方面的教学和 原子核结构的研究，并为其提供必要的实验数据.

The energy spectra of β decay and internal conversion electrons of 137Cs are measured by Si( Li) drift detector. The energy spectrum of β decay is studied by Curie plot and the internal conversion coefficients are obtained from the energy spectrum of internal conversion electron. The obtained maximum energy of β decay for 137Cs is ( 513.11±1.76) keV with an error 0.17% with respect to the reference data and the obtained internal conversion coefficients correspond to K/L = 5.712±0.217 and M/L = 0.264±0.018 with the errors 0.92% and 1. 54% with respect to the reference data，respectively. Then the transition levels of β and γ decays for 137Cs and its decayed daughter nucleus are determined. The spins and parities of 137Cs and its daughter nucleus 137Ba are obtained， then the decay scheme of 137Cs is plotted. As a result，it is indicated that the experimental technology is credible， and can be used for experimental teaching and study of nuclear structure as well as it can provide the necessary experimental data for nuclear structure.