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 precursors125Nd,128Pm,129Sm,137Gd and139Dy near the proton dripline were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar 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 precursors125Nd,129Sm,137Gd and139Dy,as well as the previously reported ones for the precursors135Gd and121Ce,were fitted by a statistical model calculation.The ground-state spins and and parities of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy 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 of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2~0.3.

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