合成和研究稀土区质子滴线附近的6种新核素

Six New Nuclides Near the Proton-drip Line in the Rare-earth Region

利用兰州重离子加速装置（HIRFL）的SFC加速器引出的能量为165—180MeV的36Ar重离子束，分别轰击92Mo、96Ru和106Cd缺中子同位位素靶，产生了稀土区质子滴线附近的新核素125Nd、128Pm、129Sm、137Gd1）、139Dy和139Tb.借助高灵敏度的氦喷嘴快速带传输系统和“p-γ”或“X-γ”符合测量方法对它们进行了分离鉴别，确定它们的半衰期分别为（0．60±0．15）s，（1．0±0．3）s，（0．55±0．10）s，（2．2±0．2）s，（0．6±0．2）s和（1．6±0．2）s，并测量了125Nd、128Pm、129Sm、137Gd和139Dy的β延发质子能谱，指认了能量为109．0和119．7keV的两条γ射线属于139Tb的EC／β＋衰变．

Unknown isotopes 125Nd, 128Pm, 129Sm, 137Gd1), 139Dy and 139Tb were produced using enriched targets 92Mo, 96 Ru and 106Cd, respectively, bombarded by 36Ar ion beam with the energies of 165-180MeV from the SFC cyclotron of HIRFL. The six new nuclides were separated and identified by a He-jet combined with a fast-tape transport system as well as 'p-γ' and 'X-γ' coincidence measurements. Their half-lives were determined to be (0.60 ± 0.15)s, (1.0 ±0.3)s, (0.55 ± 0.10)s, (2.2 ± 0.2)s, (0.6 ±0.2)s and (l.6 ±0.2)s, respectively. Energy spectra of β-delayed protons from 125Nd, 128Pm,129Sm, 137Gd and 139Dy decay were measured. Two γ-rays with the energies of 109.0 keV and 119.7 keV were assigned tO EC/β+ decay of 139Tb.