Publication

Gamma-Ray Spectroscopy of 110Cd

Nuclear physics

Nuclear Physics A 573 (1994) 306.

Authors:

S. Juutinen, R. Julin, M. Piiparinen, P. Ahonen, B. Cederwall, C. Fahlander, A. Lampinen, T. Lönnroth, A. Maj, S. Mitarai, D. Müller, J. Nyberg, P. Simecek, M. Sugawara, I. Thorslund, S. Törmänen, A. Virtanen, R. Wyss

Summary

The publication investigates the nuclear structure of ¹¹⁰Cd (Z=48, N=62) using γ-ray spectroscopy following thermal neutron capture on ¹⁰⁹Cd.

Key findings include:

  • Energy Levels and Transitions: The study identified 52 new energy levels and 127 γ-ray transitions in ¹¹⁰Cd, significantly expanding the known level scheme. Notably, low-lying quadrupole vibrational states (e.g., 2⁺₁ at 658 keV and 2⁺₂ at 1476 keV) were observed, with enhanced E2 transition strengths (B(E2; 2⁺₁ → 0⁺₁) ≈ 40 W.u.), indicative of collective excitations.
  • Collectivity Near Shell Closure: Despite proximity to the N=82 neutron shell closure—typically associated with single-particle behavior—the data revealed persistent weak collectivity, attributed to residual proton-neutron interactions and core-polarization effects. This challenges assumptions of purely spherical configurations in magic nuclei.
  • Comparison with Models: Results were compared to the Interacting Boson Model (IBM-2) and shell-model calculations. Discrepancies highlighted the interplay between single-particle and collective degrees of freedom, particularly in describing mixed-symmetry states and rotational-like bands. The data underscored the importance of valence nucleon correlations in transitional nuclei.
  • Experimental Method: High-resolution γ-ray spectra were obtained using HPGe detectors, with transitions analyzed via γγ-coincidence techniques. The study emphasized the role of positive-parity states and octupole phonon couplings in the low-energy structure.

This work provided critical empirical input for refining nuclear models near closed shells, bridging vibrational and rotational descriptions in near-magic nuclei.

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