Nen β-Delayed Proton Decays in the Rare-Enrth Region Near the Proton Drip Line
- Received Date: 1900-01-01
- Accepted Date: 1900-01-01
- Available Online: 2000-07-15
Abstract: The β-delayed proton precursors 125Nd,128Pm,129Sm,137Gd and 139Dy near the proton dripline were produced by the irradiation of 92Mo,96Ru and 106Cd with an 36Ar beam,and conclusively identified for the first time by using proton-gamma coincidence in combination with a He-jet tape transport system.Their half-lives were determined to be 0.60(15)s,1.0(3)s,0.55(10)s,2.2(2)s and 0.6(2)s,respectively.The measured energy spectra of β-delayed protons and esimated proton branching ratios to the final states in "daughter"nuclei for the precursors 125Nd,129Sm,137Gd and 139Dy,as well as the previously reported ones for the precursors 135Gd and 121Ce,were fitted by a statistical model calculation.The ground-state spins and and parities of 121Ce,125Nd,129Sm,135Gd,137Gd and 139Dy were then assigned as 5/2±,5/2±,1/2+(or 3/2+),5/2±,7/2± and 7/2,respectly.The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that ground states of 121Ce,125Nd,129Sm,135Gd,137Gd and 139Dy are highly deformed with β2~0.3.