Coexistence in even-mass nuclei

The concept of spontaneous symmetry breaking is applied to the rotating mean field of nuclei. The description is based on the tilted-axis cranking model, which takes into account that the rotational axis can take any orientation with respect to the deformed density distribution. The appearance of rotational bands in nuclei is analyzed, focusing on weakly deformed nuclei at high angular momentum. The quantization of the angular momentum of the valence nucleons leads to new phenomena. Magnetic rotation represents the quantized rotation of the anisotropic current distribution in a near spherical nucleus. The restricted amount of angular momentum of the valence particles causes band termination. The discrete symmetries of the mean-field Hamiltonian provide a classification scheme of rotational bands. New symmetries result from the combination of the spatial symmetries of the density distribution with the vector of the angular momentum. The author discusses in detail which symmetries appear for a reflection-symmetric density distribution and how they show up in the properties of the rotational bands. In particular, the consequences of rotation about a nonprincipal axis and of breaking the chiral symmetry are analyzed. Also discussed are which symmetries and band structures appear for non-reflection-symmetric mean fields. The consequences of breaking the symmetry with respect to gauge and isospin rotations are sketched. Some analogies outside nuclear physics are mentioned. The application of symmetry-restoring methods to states with large angular momentum is reviewed.

Spontaneous symmetry breaking in rotating nuclei

Highly deformed intruder bands in the A≈130 mass region

Nuclear Data Sheets for A = 152

Electromagnetic transition probabilities have been measured for the intraband and interband transitions in the two sequences in the nucleus (135)Nd that were previously identified as a composite chiral pair of rotational bands. The chiral character of the bands is affirmed and it is shown that their behavior is associated with a transition from a vibrational into a static chiral regime.

From chiral vibration to static chirality in (135)Nd.

LBL-19598 Slow and Fast High-Spin Sequences in 158Er P.O. Tjom,+ R.M. Diamond, J.C. Bacelar, E.M. Beck, M.A. Deleplanque, J.E. Draper,+ and F.S. Stephens Nuclear Science Division Lawrence Berkeley Laboratory University of California Berkeley, California 94720 Two branches are observed feeding the 38+ level of the yrast line in 158Er. Two -i.2 MeV cascade transitions constitute a fast(< 1 ps) collective component, probably with only minor changes in shape and structure from those at lower spin. Four slower y rays (> 2 ps) suggest a transition to a different shape and structure, most likely to an oblate 46+ state with all valence particles maximally aligned, a band termination. This work was supported by the Director, Office of Energy Research, Division ~ of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Contract DE-AC03-76SF00098. + On leave from the Institute of Physics, University of Oslo, Norway +university of California, Davis

/pdf/slow-and-fast-high-spin-sequences-in-158er-582qbz823a.pdf

Slow and fast high-spin sequences in 158Er.

https://escholarship.org/content/qt8165t5g2/qt8165t5g2.pdf?t=p0wsch

High-spin state spectroscopy in 165, 166Yb

The Doppler-shift attenuation method was used to measure lifetimes of yrast states in $^{166}\mathrm{Yb}$. Values of $\ensuremath{\tau}$ range from 0.16(2) ps at ${24}^{+}$. to 0.05(1) ps at ${34}^{+}$. The $B(E2)$ values decrease from 240 to 120 single-particle units in this spin range, indicating a loss of collectivity which likely reflects a change of the nucleus towards triaxial shape. The side-feeding times are consistent with rotational cascades having moments of inertia 25% larger than the yrast sequence or $B(E2)$ values around 60 single-particle units.

Lifetime measurements of high-spin states in 166Yb.

Levels in /sup 158/Yb have been established up to 38h-bar in the yrast band and about 30h-bar in two sidebands. Below spin 20, the similarity to the isotone /sup 156/Er is striking, but up to spin 34 /sup 158/Yb remains rather collective while /sup 156/Er becomes triaxial and evolves toward an oblate shape. This appears to result from small shifts in particle-alignment (backbend) frequencies; a proton alignment occurs before neutron ones in /sup 158/Yb, whereas the reverse is true in /sup 156/Er.

Effect of alignments on the shape of 158Yb.

The Doppler-shift attenuation method was used to measure lifetimes of yrast states in /sup 166/Yb. Three different stopping materials were used and consistent results were obtained over a large range of spins. Values of tau range from 1.20(10) ps at 18/sup +/ to 0.05(1) ps at 34/sup +/. The B(E2) values steadily decrease from 200 to 120 single particle units as the spin increases above 24h-dash-bar. This loss of collectivity is likely to reflect a change toward triaxial shapes. The side-feeding times to these states are longer than the inband feeding times.

/pdf/line-shape-analysis-of-high-spin-states-collectivity-in-483h6b7i4r.pdf

Line-shape analysis of high spin states: Collectivity in 166Yb.

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.

E. M. Beck

Author Tools

Chat about Author