Beta-decay spectroscopy of the neutron-rich rare-earth nuclei
Introduction
Neutron-rich nuclei in rare-earth region are the most collective nuclei in nature since their protons and neutrons are lying far away from the shell closure limit, which proton shell closure are Z=50 and Z=82, and neutron shell closure are N=82 and N=126[1]. For example, the doubly mid-shell nucleus 170Dy[1] which has proton number Z=66 and neutron number N=104 is considered as the most collective in that region. Until now, magic numbers which equal to 2, 8, 20, 28, 50, 82 and 128 or called main shell closures [2,3], are well studied. The mechanism of how nuclear structure changes between the main shell closures is still not well known. By measuring the nuclei between two main shell closure will directly provide valuable information of nuclear structure and shell evolution.
Motivation …show more content…
Isomer is the state that has a long lifetime. The lower lifetime limit of isomer is not well defined, but typically it is longer than nanoseconds [4]. K values are the angular-momentum which project on the nuclear symmetry axis [5]. Since only the collective nuclei have symmetry axis, K values are only found in those collective nuclei, or deformation nuclei. Therefore, K-isomer is the nuclear level states lying on the collective orbital with long lifetime [2]. The most famous discovery of K-isomer was found in 178Hf [5, 6], which has K=16 and 1.31y long lifetime. The configurations of K-isomers are expected to have larger than three quasiparticles [5].Therefore, learning K-isomers is a good way to study paring effect of nucleons. Recently, more and more K-isomers are found in neutron-rich nuclei in rare-earth region [5], which suggests that investigating this region can obtain massive information of paring
Introduction
Neutron-rich nuclei in rare-earth region are the most collective nuclei in nature since their protons and neutrons are lying far away from the shell closure limit, which proton shell closure are Z=50 and Z=82, and neutron shell closure are N=82 and N=126[1]. For example, the doubly mid-shell nucleus 170Dy[1] which has proton number Z=66 and neutron number N=104 is considered as the most collective in that region. Until now, magic numbers which equal to 2, 8, 20, 28, 50, 82 and 128 or called main shell closures [2,3], are well studied. The mechanism of how nuclear structure changes between the main shell closures is still not well known. By measuring the nuclei between two main shell closure will directly provide valuable information of nuclear structure and shell evolution.
Motivation …show more content…
Isomer is the state that has a long lifetime. The lower lifetime limit of isomer is not well defined, but typically it is longer than nanoseconds [4]. K values are the angular-momentum which project on the nuclear symmetry axis [5]. Since only the collective nuclei have symmetry axis, K values are only found in those collective nuclei, or deformation nuclei. Therefore, K-isomer is the nuclear level states lying on the collective orbital with long lifetime [2]. The most famous discovery of K-isomer was found in 178Hf [5, 6], which has K=16 and 1.31y long lifetime. The configurations of K-isomers are expected to have larger than three quasiparticles [5].Therefore, learning K-isomers is a good way to study paring effect of nucleons. Recently, more and more K-isomers are found in neutron-rich nuclei in rare-earth region [5], which suggests that investigating this region can obtain massive information of paring