Evidence for Rigid Triaxial Deformation in ^{76}Ge from a Model-Independent Analysis

A D Ayangeakaa; R V F Janssens; S Zhu; D Little; J Henderson; C Y Wu; D J Hartley; M Albers; K Auranen; B Bucher; M P Carpenter; P Chowdhury; D Cline; H L Crawford; P Fallon; A M Forney; A Gade; A B Hayes; F G Kondev; Krishichayan; T Lauritsen; J Li; A O Macchiavelli; D Rhodes; D Seweryniak; S M Stolze; W B Walters; J Wu

doi:10.1103/PhysRevLett.123.102501

Evidence for Rigid Triaxial Deformation in ^{76}Ge from a Model-Independent Analysis

Phys Rev Lett. 2019 Sep 6;123(10):102501. doi: 10.1103/PhysRevLett.123.102501.

Authors

A D Ayangeakaa¹, R V F Janssens^{2

3}, S Zhu⁴, D Little^{2

3}, J Henderson⁵, C Y Wu⁵, D J Hartley¹, M Albers⁴, K Auranen⁴, B Bucher⁵, M P Carpenter⁴, P Chowdhury⁶, D Cline⁷, H L Crawford⁸, P Fallon⁸, A M Forney⁹, A Gade^{10

11}, A B Hayes⁷, F G Kondev⁴, Krishichayan^{3

12}, T Lauritsen⁴, J Li⁴, A O Macchiavelli⁸, D Rhodes^{10

11}, D Seweryniak⁴, S M Stolze⁴, W B Walters⁹, J Wu⁴

Affiliations

¹ Department of Physics, United States Naval Academy, Annapolis, Maryland 21402, USA.
² Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
³ Triangle Universities Nuclear Laboratory, Duke University, Durham, North Carolina 27708, USA.
⁴ Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
⁵ Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
⁶ Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA.
⁷ Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
⁸ Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
⁹ Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
¹⁰ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.
¹¹ Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA.
¹² Department of Physics, Duke University, Durham, North Carolina 27708, USA.

PMID: 31573317
DOI: 10.1103/PhysRevLett.123.102501

Abstract

An extensive, model-independent analysis of the nature of triaxial deformation in ^{76}Ge, a candidate for neutrinoless double-beta (0νββ) decay, was carried out following multistep Coulomb excitation. Shape parameters deduced on the basis of a rotational-invariant sum-rule analysis provided considerable insight into the underlying collectivity of the ground-state and γ bands. Both sequences were determined to be characterized by the same β and γ deformation parameter values. In addition, compelling evidence for low-spin, rigid triaxial deformation in ^{76}Ge was obtained for the first time from the analysis of the statistical fluctuations of the quadrupole asymmetry deduced from the measured E2 matrix elements. These newly determined shape parameters are important input and constraints for calculations aimed at providing, with suitable accuracy, the nuclear matrix elements relevant to 0νββ.