Nuclear Structure and Spectroscopy of Excited States

The study of nuclear structure and spectroscopy of excited states centres on elucidating how protons and neutrons arrange within the atomic nucleus and how these arrangements manifest in energy spectra and electromagnetic transitions. Modern approaches combine high-resolution γ-ray detection, precision laser spectroscopy and advanced theoretical models to probe both collective and single-particle excitations. This research has revealed phenomena such as shape coexistence, in which distinct deformation configurations occur at similar energies, and multiphonon vibrations linked to coherent nucleonic motion. Spectroscopic techniques measure transition rates, level lifetimes and moments, enabling stringent tests of shell evolution, symmetry-breaking effects and the onset of octupole correlations. Surveys of transition strengths across wide regions of the nuclear chart have identified patterns of regularity and chaos, guiding the refinement of density functional theories and algebraic models. Beyond fundamental insight, these investigations underpin applications in nuclear astrophysics and reactor physics by supplying critical data on nuclear stability, decay modes and reaction pathways.

Research from Nature Portfolio

Recent studies have introduced a novel signature of nuclear regularity based on experimental quadrupole transition rates. By analysing systematic repetition patterns in electric quadrupole (E2) transition probabilities for well-known regular nuclei, researchers have extended the investigation to isotopes without prior classification. The identified recurrence schemes offer a quantitative criterion for distinguishing between orderly collective behaviour and chaotic level structures. This framework, supported by algebraic modelling and random matrix theory, proposes several new regular nuclei candidates and establishes a basis for comprehensive surveys of spectroscopic data across the nuclear chart.

Nuclear Structure and Spectroscopy of Excited States publication trend

The graph below shows the total number of articles in nuclear structure and spectroscopy of excited states across all publications each year (not limited to Nature Index journals).

Technical terms

Excited state: A nuclear energy level above the ground state, populated through reactions or decay processes.

Quadrupole transition (E2): An electromagnetic transition between nuclear states involving a change in angular momentum of two units, sensitive to nuclear deformation.

Shape coexistence: The phenomenon whereby a single nucleus exhibits two or more distinct deformation configurations at similar excitation energies.

Level lifetime: The average time a nucleus remains in an excited state before emitting radiation to a lower energy level.

Hindrance factor: A measure of the deviation of an observed transition rate from theoretical predictions, often indicating configuration mixing or structural effects.

References

1. New pattern in regular nuclei based on their experimental quadrupole transition rates and some new candidates. Scientific Reports (2023).
2. Multifaceted character of shape coexistence phenomena in atomic nuclei. Progress in Particle and Nuclear Physics (2024).
3. Deformation versus Sphericity in the Ground States of the Lightest Gold Isotopes. Physical Review Letters (2023).
4. Nuclear level lifetime measurements across varied ranges using the digital INGA at TIFR. AAPPS Bulletin (2024).