SPECTROSCOPY OF THE LIGHT RARE-EARTH NUCLEI PM-133 AND SM-133 - CONFIGURATION-DEPENDENT PAIRING AND EVIDENCE FOR STRONG RESIDUAL PROTON NEUTRON INTERACTIONS IN NEIGHBORING ODD-N AND ODD-Z NUCLEI

TY - JOUR

T1 - SPECTROSCOPY OF THE LIGHT RARE-EARTH NUCLEI PM-133 AND SM-133 - CONFIGURATION-DEPENDENT PAIRING AND EVIDENCE FOR STRONG RESIDUAL PROTON NEUTRON INTERACTIONS IN NEIGHBORING ODD-N AND ODD-Z NUCLEI

AU - Regan, P H

AU - Wadsworth, R

AU - Hughes, J R

AU - Gyapong, G J

AU - Gelletly, W

AU - Godfrey, M J

AU - Jenkins, I

AU - He, Y J

AU - Mullins, S M

AU - Nolan, P J

AU - Simpson, J

AU - Varley, B J

AU - Watson, D L

PY - 1991/10/28

Y1 - 1991/10/28

N2 - The low-lying, rotational band structures of the highly neutron-deficient light rare-earth nuclei, 133Sm and Pm-133 have been investigated using the Ca-40 + Ru-96 reaction at a beam energy of approximately 180 MeV. Five new bands have been observed in both nuclei. 133Sm possesses two strongly coupled bands which are thought to be built upon the nu-h11/2[523]7/2- and nu-d5/2[402]5/2+ Nilsson configurations. In addition to the previously reported nu-i13/2 intruder band, there is also evidence for a second decoupled, negative-parity structure in 133Sm based on the nu-h9/2[541]1/2- orbital. In Pm-133 evidence is presented for both signature partners of the pi-h11/2 band. The expected h11/2 neutron alignment in these bands has not been observed. It is suggested that this provides evidence for a strong pn interaction. A strongly coupled band built on the pi-g7/2[413]5/2+ configuration has also been established. Both signature partners of this band show clear evidence for the alignment of a pair of h11/2 protons followed by a pair of h11/2 neutrons. A strongly coupled three quasi-particle configuration has also been identified which feeds into the unfavoured signature of the pi-h11/2 band. The results are discussed in terms of cranked shell model, total routhian surface calculations and the systematics of the A approximately 135 region.

AB - The low-lying, rotational band structures of the highly neutron-deficient light rare-earth nuclei, 133Sm and Pm-133 have been investigated using the Ca-40 + Ru-96 reaction at a beam energy of approximately 180 MeV. Five new bands have been observed in both nuclei. 133Sm possesses two strongly coupled bands which are thought to be built upon the nu-h11/2[523]7/2- and nu-d5/2[402]5/2+ Nilsson configurations. In addition to the previously reported nu-i13/2 intruder band, there is also evidence for a second decoupled, negative-parity structure in 133Sm based on the nu-h9/2[541]1/2- orbital. In Pm-133 evidence is presented for both signature partners of the pi-h11/2 band. The expected h11/2 neutron alignment in these bands has not been observed. It is suggested that this provides evidence for a strong pn interaction. A strongly coupled band built on the pi-g7/2[413]5/2+ configuration has also been established. Both signature partners of this band show clear evidence for the alignment of a pair of h11/2 protons followed by a pair of h11/2 neutrons. A strongly coupled three quasi-particle configuration has also been identified which feeds into the unfavoured signature of the pi-h11/2 band. The results are discussed in terms of cranked shell model, total routhian surface calculations and the systematics of the A approximately 135 region.

KW - NUCLEAR REACTIONS RU-96(CA-40, 2NP), (CA-40, 3P), E = 180 MEV

KW - MEASURED I-GAMMA, E-GAMMA

KW - SM-133 PM-133 LEVELS DEDUCED J, PI, CONFIGURATIONS

KW - LIFETIME MEASUREMENTS

KW - BAND STRUCTURES

KW - INTRUDER BAND

KW - DEFORMATION

KW - REGION

M3 - Article

SN - 0375-9474

VL - 533

SP - 476

EP - 504

JO - Nuclear Physics A

JF - Nuclear Physics A

IS - 3

ER -