M. P. Waring

Perturbed alignments within an [ital i][sub 13/2] neutron intruder band in [sup 141]Gd

The nucleus [sup 141]Gd was investigated at high spins for the first time via the reactions [sup 112]Sn([sup 32]S,2[ital pn])[sup 141]Gd at 155 MeV and [sup 112]Sn([sup 33]S,2[ital p]2[ital n])[sup 141]Gd at 170 MeV. The methods of in-beam [gamma]-ray spectroscopy were used to establish a number of different structures. These include a band assigned as the [nu][ital i][sub 13/2][660]1/2[sup +] intruder in the Nilsson scheme. This is the heaviest nucleus thus far in which this type of intruder band has been identified, and is the first case in which the 13/2[sup +] bandhead has been clearly observed. Cranked shell model (CSM) calculations predict the occurrence of backbends due to [ital h][sub 11/2] proton and [ital h][sub 9/2] neutron band crossings. Gradual upbends are observed in the experimental alignments, which suggests the interaction strengths are stronger than those predicted by the CSM.

First observation of a proton intruder band below the Z = 50 major shell gap. Spectroscopy of 111In

Abstract An intruder band based on an h 11/2 proton has been observed in 111In. This is the first case to be identified below the Z = 50 major shell gap. As such, it sheds light on the relative importance of the deformed 2p-2h Sn-core state and the πh 11/2 intruder orbital to the onset of deformation near the Z = 50 “magic” proton number.

First observation of a rotational band in odd 50Sn nuclei: 111Sn.

Proton particle-hole excitations across the {ital Z}=50 closed shell are responsible for inducing low-lying prolate deformation in even-{sub 50}Sn nuclei. Although related rotational bands have been studied in odd-{sub 51}Sb isotopes involving the coupling of a valence proton, none had been found in odd-{sub 50}Sn nuclei. Using the {sup 96}Ru({sup 19}F,3{ital pn}) reaction, a decoupled band has been observed in {sup 111}Sn extending to a spin-parity of (67/2{sup {minus}}) and feeding out at 23/2{sup {minus}} into spherical states. This band is interpreted as the {nu}{ital h}{sub 11/2} valence orbital coupled to the deformed [({pi}{ital g}{sub 7/2}){sup 2}{direct_product}({pi}{ital g}{sub 9/2}){sup {minus}2}] {sup 110}Sn core. The extracted band properties are compared to those in {sup 111}Sb with the same deformed core.

First observation of a rotational band in oddSn50nuclei:Sn111

Proton particle-hole excitations across the {ital Z}=50 closed shell are responsible for inducing low-lying prolate deformation in even-{sub 50}Sn nuclei. Although related rotational bands have been studied in odd-{sub 51}Sb isotopes involving the coupling of a valence proton, none had been found in odd-{sub 50}Sn nuclei. Using the {sup 96}Ru({sup 19}F,3{ital pn}) reaction, a decoupled band has been observed in {sup 111}Sn extending to a spin-parity of (67/2{sup {minus}}) and feeding out at 23/2{sup {minus}} into spherical states. This band is interpreted as the {nu}{ital h}{sub 11/2} valence orbital coupled to the deformed [({pi}{ital g}{sub 7/2}){sup 2}{direct_product}({pi}{ital g}{sub 9/2}){sup {minus}2}] {sup 110}Sn core. The extracted band properties are compared to those in {sup 111}Sb with the same deformed core.

First observation of a rotational band in odd {sub 50}Sn nuclei: {sup 111}Sn

Proton particle-hole excitations across the {ital Z}=50 closed shell are responsible for inducing low-lying prolate deformation in even-{sub 50}Sn nuclei. Although related rotational bands have been studied in odd-{sub 51}Sb isotopes involving the coupling of a valence proton, none had been found in odd-{sub 50}Sn nuclei. Using the {sup 96}Ru({sup 19}F,3{ital pn}) reaction, a decoupled band has been observed in {sup 111}Sn extending to a spin-parity of (67/2{sup {minus}}) and feeding out at 23/2{sup {minus}} into spherical states. This band is interpreted as the {nu}{ital h}{sub 11/2} valence orbital coupled to the deformed [({pi}{ital g}{sub 7/2}){sup 2}{direct_product}({pi}{ital g}{sub 9/2}){sup {minus}2}] {sup 110}Sn core. The extracted band properties are compared to those in {sup 111}Sb with the same deformed core.

Neutron i13/2 intruder band in Sm139

The high-spin structure of [sup 139]Sm has been investigated with the [sup 110]Pd([sup 34]S,5[ital n]) reaction at a beam energy of 159 MeV at the Stony Brook Tandem/Superconducting LINAC facility. The TESSA3 spectrometer array was used to collect [gamma]-[gamma] coincidence data from which an extended decoupled band structure has been found. It is proposed that this band is based on the [ital i][sub 13/2] ([Omega]=1/2) neutron intruder orbital. The decay pattern, enhanced dynamic moments of inertia, and aligned spins are consistent with the [nu][ital i][sub 13/2] bands in neighboring odd-neutron nuclides. Total Routhian surface and cranked shell model calculations reproduce qualitative features of these nuclides, further supporting the proposed interpretation.

Neutroni13/2intruder band inSm139

The high-spin structure of [sup 139]Sm has been investigated with the [sup 110]Pd([sup 34]S,5[ital n]) reaction at a beam energy of 159 MeV at the Stony Brook Tandem/Superconducting LINAC facility. The TESSA3 spectrometer array was used to collect [gamma]-[gamma] coincidence data from which an extended decoupled band structure has been found. It is proposed that this band is based on the [ital i][sub 13/2] ([Omega]=1/2) neutron intruder orbital. The decay pattern, enhanced dynamic moments of inertia, and aligned spins are consistent with the [nu][ital i][sub 13/2] bands in neighboring odd-neutron nuclides. Total Routhian surface and cranked shell model calculations reproduce qualitative features of these nuclides, further supporting the proposed interpretation.