^（20）Naβ延迟α衰变研究的新结果

New Results of β-delayed α Decay of￣(20)Na

以２５及３５．５ＭｅＶ质子轰击氖靶，对２０Ｎａ的β延迟α衰变作了重新研究．实验中使用了以气体电离室作为ΔＥ探测器的新型粒子望远镜系统，在所测带电粒子谱的０．６９５ＭｅＶ及０．９０７ＭｅＶ处，首次观察到两个新峰．根据粒子鉴别、分支比和寿命测量，确信它们是来自２０Ｎａ的低能β延迟α衰变，由此修改了２０Ｎａ的衰变纲图和低激发态纲图，并讨论了它在天体物理研究中的意义．

The β-delayed α decay of 20Na was restudied using neon target bombarded by 25 and 35.5 MeV protons.In this experiment a newly developed particle-telescope system including a gas ionization chamber as a thin ΔE detector was used. Two new peaks,one at 0.695 MeV and other at 0.907 MeV, were observed for the first time in the charged particle spectra. Based on particle identification, branching ratio and life time measurement,it is believed that these new peaks result fromβdelayed low energy αdecay of 20Na.The decay scheme and the low-lying level scheme of 20Na were thus revised.Its possible astrophysical implications were discussed.