Independent Validation of Octupole Collectivity in radium-224 through lifetime measurements of low-lying negative-parity states
Abstract
The nucleus 224Ra is a key benchmark for octupole deformation and for theoretical descriptions of enhanced Schiff moments in reflection-asymmetric nuclei. While Coulomb-excitation measurements have established strong octupole collectivity in 224Ra, theoretical models predict that its intrinsic electric-dipole moment should be strongly quenched by a cancellation between macroscopic and microscopic contributions. Direct fast-timing measurements of the low-lying Jπ= 1-1 and 3-1 states populated following the β-decay of 224Fr at TRIUMF-ISAC were performed. Using the LaBr3(Ce) detectors of the GRIFFIN array, mean lifetimes of τ(1-1) = 444(6)~ps and τ(3-1) = 460(18)~ps were obtained. The corresponding reduced transition probabilities agree with values inferred from Coulomb excitation, but are determined with substantially improved precision. These results provide an independent validation of the electromagnetic matrix elements associated with octupole collectivity in 224Ra and confirm a strongly-quenched intrinsic dipole moment of D0 ≃ 0.032 efm. The present measurements therefore provide a stringent experimental benchmark for nuclear-structure models used in the interpretation of Schiff moments and future searches for non-zero electric dipole moments.
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BibTeX
@misc{white2026independent,
title = {{Independent Validation of Octupole Collectivity in radium-224 through lifetime measurements of low-lying negative-parity states}},
author = {D. White and D. O'Donnell and A. Avaa and J. R. Murias and S. Murillo Morales and R. Umashankar and V. Vedia and C. Andreoiu and D. W. Annen and A. D. Ayangeakaa and G. C. Ball and V. Bildstein and M. Bowry and I. Dillmann and E. G. Fuakye and L. P. Gaffney and A. B. Garnsworthy and P. E. Garret and E. D. Geerlof and S. Georges and A. L. Grimes and G. F. Grinyer and G. Hackman and P. M. Jones and J. Liu and B. Olaizola and S. D. Olorunfunmi and F. Rowntree and N. K. Syeda and D. Shah and P. Spagnoletti and C. E. Svensson and F. Wu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07556},
eprint = {2609.07556},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07556},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Independent Validation of Octupole Collectivity in radium-224 through lifetime measurements of low-lying negative-parity states
AU - D. White
AU - D. O'Donnell
AU - A. Avaa
AU - J. R. Murias
AU - S. Murillo Morales
AU - R. Umashankar
AU - V. Vedia
AU - C. Andreoiu
AU - D. W. Annen
AU - A. D. Ayangeakaa
AU - G. C. Ball
AU - V. Bildstein
AU - M. Bowry
AU - I. Dillmann
AU - E. G. Fuakye
AU - L. P. Gaffney
AU - A. B. Garnsworthy
AU - P. E. Garret
AU - E. D. Geerlof
AU - S. Georges
AU - A. L. Grimes
AU - G. F. Grinyer
AU - G. Hackman
AU - P. M. Jones
AU - J. Liu
AU - B. Olaizola
AU - S. D. Olorunfunmi
AU - F. Rowntree
AU - N. K. Syeda
AU - D. Shah
AU - P. Spagnoletti
AU - C. E. Svensson
AU - F. Wu
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07556
UR - https://arxiv.org/abs/2609.07556
AB - The nucleus ^224Ra is a key benchmark for octupole deformation and for theoretical descriptions of enhanced Schiff moments in reflection-asymmetric nuclei. While Coulomb-excitation measurements have established strong octupole collectivity in ^224Ra, theoretical models predict that its intrinsic electric-dipole moment should be strongly quenched by a cancellation between macroscopic and microscopic contributions. Direct fast-timing measurements of the low-lying J^π= 1^-_1 and 3^-_1 states populated following the β-decay of ^224Fr at TRIUMF-ISAC were performed. Using the LaBr_3(Ce) detectors of the GRIFFIN array, mean lifetimes of τ(1^-_1) = 444(6)~ps and τ(3^-_1) = 460(18)~ps were obtained. The corresponding reduced transition probabilities agree with values inferred from Coulomb excitation, but are determined with substantially improved precision. These results provide an independent validation of the electromagnetic matrix elements associated with octupole collectivity in ^224Ra and confirm a strongly-quenched intrinsic dipole moment of D_0 ≃ 0.032 efm. The present measurements therefore provide a stringent experimental benchmark for nuclear-structure models used in the interpretation of Schiff moments and future searches for non-zero electric dipole moments.
ER -