The (EC+β^(+)) decay of ^(128)Ce was reinvestigated in the^(116)Sn (l6O, 4n) reaction by using a helium-jet tape transport system. The decay γ rays of ^(128)Ce were unambiguously described from those of ^(129)Ce aft...The (EC+β^(+)) decay of ^(128)Ce was reinvestigated in the^(116)Sn (l6O, 4n) reaction by using a helium-jet tape transport system. The decay γ rays of ^(128)Ce were unambiguously described from those of ^(129)Ce after taking the comparing experiments of ^(16)O+^(116)Sn and ^(16)O+^(117)Sn. Based on x-γ and γ-γ coincidence measurements, a detailed (EC+β^(+)) decay scheme of ^(128)Ce has been proposed which modifies the previous one, and takes accounts of 100 observed γ-lines.展开更多
The nuclide ^(129)Ce was produced by a(^(16)O,4n)reaction on an enriched ^(117)Sn target.Reaction products were transported to a shielded location by using a helium-jet tape transport system.An activity of 4.1 min in ...The nuclide ^(129)Ce was produced by a(^(16)O,4n)reaction on an enriched ^(117)Sn target.Reaction products were transported to a shielded location by using a helium-jet tape transport system.An activity of 4.1 min in chemically separated cerium sample was identified as ^(129)Ce.Based on x-γ-t andγ-γ-t coincidence measurements,the(EC+β+)decay scheme of ^(129)Ce was proposed,and takes accounts of 50 observedγ-lines.展开更多
Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121...Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121 Ce decay was determined to be (1.1±0.1)s. Its energy spectrum of β delayed protons was measured and the β delayed proton branching ratio for 121 Ce decay was roughly estimated to be ～1%. After β delayed proton decay of the precursors \{ 119 Ba,\} \{ 121 Ba\} and 122 La, some of γ transitions from low lying states to the ground states in their "daughters" were observed for the first time.展开更多
The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line were produced by the irradiation of92Mo,96Ru and106Cd with an36Ar beam, and conclusively identified for the first time by using ...The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line 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,O.55(10)s,2.2(2)s and 0.6 (2)s, respectively. The measured energy spectra of β-delayed protons and estimated 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 parities of121Ce,125Nd,129Sm,139Gd,137Gd and139Dy were then assigned as 5/2±,5/2±, 1/2± (or 3/2+), 5/2+,7/2+- and 7/2, respectively. The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that the ground states of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2, - 0.3.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.19975057,and the Chinese Academy of Sciences。
文摘The (EC+β^(+)) decay of ^(128)Ce was reinvestigated in the^(116)Sn (l6O, 4n) reaction by using a helium-jet tape transport system. The decay γ rays of ^(128)Ce were unambiguously described from those of ^(129)Ce after taking the comparing experiments of ^(16)O+^(116)Sn and ^(16)O+^(117)Sn. Based on x-γ and γ-γ coincidence measurements, a detailed (EC+β^(+)) decay scheme of ^(128)Ce has been proposed which modifies the previous one, and takes accounts of 100 observed γ-lines.
基金Supported by the Chinese Academy of Sciencesthe National Natural Science Foundation of China under Grant No.19475055.
文摘The nuclide ^(129)Ce was produced by a(^(16)O,4n)reaction on an enriched ^(117)Sn target.Reaction products were transported to a shielded location by using a helium-jet tape transport system.An activity of 4.1 min in chemically separated cerium sample was identified as ^(129)Ce.Based on x-γ-t andγ-γ-t coincidence measurements,the(EC+β+)decay scheme of ^(129)Ce was proposed,and takes accounts of 50 observedγ-lines.
文摘Unknown β delayed proton precursor 121 Ce was produced via the reaction of 92 Mo( 32 S, 3n), and identified by an He jet fast tape transport system with "P γ" coincidence measurements. The half life of 121 Ce decay was determined to be (1.1±0.1)s. Its energy spectrum of β delayed protons was measured and the β delayed proton branching ratio for 121 Ce decay was roughly estimated to be ～1%. After β delayed proton decay of the precursors \{ 119 Ba,\} \{ 121 Ba\} and 122 La, some of γ transitions from low lying states to the ground states in their "daughters" were observed for the first time.
文摘The β-delayed proton precursors125Nd128Pm129Sm,137Gd and139Dy near the proton drip line 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,O.55(10)s,2.2(2)s and 0.6 (2)s, respectively. The measured energy spectra of β-delayed protons and estimated 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 parities of121Ce,125Nd,129Sm,139Gd,137Gd and139Dy were then assigned as 5/2±,5/2±, 1/2± (or 3/2+), 5/2+,7/2+- and 7/2, respectively. The consistency between the experimental spin-parity assignment and the predicted Nilsson diagrams indirectly indicates that the ground states of121Ce,125Nd,129Sm,135Gd,137Gd and139Dy are highly deformed with β2, - 0.3.
