Shape coexistence in nuclei appears to be unique in the realm of finite many-body quantum systems It differs from the various geometrical arrangements that sometimes occur in a molecule in that in a molecule the various arrangements are of the widely separated atomic nuclei In nuclei the various ''arrangements'' of nucleons involve (sets of) energy eigenstates with different electric quadrupole properties such as moments and transition rates, and different distributions of proton pairs and neutron pairs with respect to their Fermi energies Sometimes two such structures will ''invert'' as a function of the nucleon number, resulting in a sudden and dramatic change in ground-state properties in neighboring isotopes and isotones In the first part of this review the theoretical status of coexistence in nuclei is summarized Two approaches, namely, microscopic shell-model descriptions and mean-field descriptions, are emphasized The second part of this review presents systematic data, for both even- and odd-mass nuclei, selected to illustrate the various ways in which coexistence is observed in nuclei The last part of this review looks to future developments and the issue of the universality of coexistence in nuclei Surprises continue to be discovered With the major advances in reaching to extremes of proton-neutronmore » number, and the anticipated new ''rare isotope beam'' facilities, guidelines for search and discovery are discussed« less

Shape coexistence in atomic nuclei

Coexistence in even-mass nuclei

Nuclear Data Sheets for A=132

We present the first implementation in the $(\ensuremath{\beta},\ensuremath{\gamma})$ plane of the generator coordinate method with full triaxial angular momentum and particle number projected wave functions using the Gogny force. Technical details about the performance of the method and the convergence of the results in both the symmetry restoration and the configuration mixing parts are discussed in detail. We apply the method to the study of $^{24}\mathrm{Mg}$; the calculated energies of excited states as well as the transition probabilities are compared to the available experimental data, showing a good overall agreement. In addition, we present the RVAMPIR approach, which provides a good description of the ground and $\ensuremath{\gamma}$ bands in the absence of strong mixing.

/pdf/triaxial-angular-momentum-projection-and-configuration-3bqovstuz3.pdf

Triaxial angular momentum projection and configuration mixing calculations with the Gogny force

Rotational bands in the doubly odd nucleus 134Pr

New Nilsson (\ensuremath{\kappa},\ensuremath{\mu}) parameter sets for the proton N=4, 5, and 6 harmonic oscillator shells are deduced for the A\ensuremath{\approxeq}120--140 mass region by fitting a potential-energy-surface calculation, using the Nilsson-Strutinsky method, to 28 experimental bandhead energies. The results from both the standard and the fitted Nilsson (\ensuremath{\kappa},\ensuremath{\mu}) parameter sets are compared with experimental bandhead energies. The fitted (\ensuremath{\kappa},\ensuremath{\mu}) parameter sets achieve a significant improvement in the bandhead energies over this region. In addition, calculated single-particle levels using both the Woods-Saxon and the Nilsson potentials are compared.

Nilsson parameter set in the A≊120–140 region

Rotational states have been populated in {gamma}-soft {sup 132}Ba following the {sup 122}Sn({sup 13}C,3{ital n}{gamma}) reaction. The ground state of this nucleus is predicted to possess maximal triaxiality {gamma}{similar to}{minus}30{degree}. Two {Delta}{ital I}=2 bands were established, based on quasineutron configurations with large negative {gamma} deformations close to the collective oblate shape {gamma}={minus}60{degree}. The bandhead of one of these bands, associated with a ({nu}{ital h}{sub 11/2}){sup 2} configuration, was found to be isomeric with a mean lifetime {tau}=12.5{plus minus}0.3 ns. A third {Delta}{ital I}=2 band was observed, built on a two-quasiproton configuration with a near-prolate shape ({gamma}{similar to}0{degree}). In addition, two {Delta}{ital I}=1 bands, built on mixed proton-neutron four-quasiparticle configurations with oblate shapes ({gamma}{similar to}{minus}60{degree}), were established.

Shape coexistence in 132Ba.

Three decoupled ({Delta}{ital I}=2) rotational bands have been observed to rise out of irregular spherical excitations in {sub 51}{sup 117}Sb at moderate spin. These bands are interpreted as resulting from low-lying {pi}{ital g}{sub 7/2}, {pi}d{sub 5/2}, and {pi}{ital h}{sub 11/2} valence orbitals outside the {ital Z}=50 closed shell coupled to the deformed (({pi}{ital g}{sub 7/2}){sup 2}{direct product}({pi}{ital g}{sub 9/2}){sup {minus}2}){sup 116}Sn core state at the {ital N}=66 midshell. The valence orbitals do not significantly influence either the spherical or the deformed core shape; the latter is regulated by the {beta} at which the {pi}{ital g}{sub 7/2} and the intruder {pi}{ital g}{sub 9/2} levels cross. Two strongly coupled ({Delta}{ital I}=1) bands involving (({pi}{ital g}{sub 7/2}){sup 2}{direct product}({pi}{ital g}{sub 9/2}){sup {minus}1}) were also observed.

New deformed states near the Z=50 closed shell: 51117Sb66.

The 92Mo(27Al, 2p2n gamma ) reaction has been used to populate high-spin states in 115I. The dominant structures are associated with pi h112/(550)1/2- and pi g92/(404)9/2+ orbitals. At the highest spins, favoured states with Ipi =43/2- and 51/2-, associated with non-collective oblate configurations are yrast. The systematics of such states in the odd-A 115-121I isotopes are discussed.

Collective and non-collective high-spin states in 115I

Several rotational bands have been populated to high spin in $^{127}\mathrm{Cs}$ following the $^{120}\mathrm{Sn}$${(}^{11}$B,4n) reaction. Rotational bands built on low-lying proton ${\mathit{g}}_{7/2}$, ${\mathit{d}}_{5/2}$, and ${\mathit{g}}_{9/2}$ (hole) orbitals, and the unique-parity ${\mathit{h}}_{11/2}$ orbital were observed and identified. For the \ensuremath{\pi}${\mathit{g}}_{9/2}$ (hole) case, both signatures were seen in a strongly coupled \ensuremath{\Delta}I=1 band, while for the other cases, decoupled \ensuremath{\Delta}I=2 bands were observed with strong in-band quadrupole transitions. Through comparisons with cranked-shell-model calculations, these band structures are understood to be associated with a prolate (\ensuremath{\gamma}\ensuremath{\sim}0\ifmmode^\circ\else\textdegree\fi{}) deformed nuclear shape. At frequencies above \ensuremath{\Elzxh}\ensuremath{\omega}=0.3 MeV, the rotational alignment of a pair of ${\mathit{h}}_{11/2}$ neutrons was observed for each of the ${\mathit{h}}_{11/2}$, ${\mathit{g}}_{7/2}$, and ${\mathit{d}}_{5/2}$ bands. This neutron alignment is predicted to drive the nuclear core away from a prolate shape towards the collectively rotating oblate (\ensuremath{\gamma}=-60\ifmmode^\circ\else\textdegree\fi{}) shape. Changes in the measured signature splittings for the bands below and above the alignment are consistent with the shape changes.

Rotational band structures in 127Cs: Shape changes induced by h11/2 neutron alignment.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Yun Liang

Author Tools

Chat about Author