The European Physical Journal A (EPJ A)

Issue		Eur. Phys. J. A Volume 22, Number 1, October 2004
Page(s)		23 - 27
DOI		10.1140/epja/i2004-10025-9

Eur. Phys. J. A 22, 23-27 (2004)
DOI: 10.1140/epja/i2004-10025-9

K-Mixing and fast decay of a seven-quasiparticle isomer in ¹⁷⁹Ta

F. G. Kondev¹, G. D. Dracoulis², G. J. Lane², I. Ahmad³, A. P. Byrne^{2, 4}, M. P. Carpenter³, P. Chowdhury⁵, S. J. Freeman³, N. J. Hammond³, R. V. F. Janssens³, T. Kibédi², T. Lauritsen³, C. J. Lister³, G. Mukherjee^{3, 5}, D. Seweryniak³ and S. K. Tandel⁵

¹ Nuclear Engineering Division, Argonne National Laboratory, IL 60439, Argonne, USA
² Department of Nuclear Physics, R.S.Phys.S.E, Australian National University, ACT 0200, Canberra, Australia
³ Physics Division, Argonne National Laboratory, IL 60439, Argonne, USA
⁴ Department of Physics, The Faculties, Australian National University, ACT 0200, Canberra, Australia
⁵ Department of Physics, University of Massachusetts, MA 01854, Lowell, USA

kondev@anl.gov

(Received: 7 March 2004, Revised: 3 May 2004, Published online: 5 October 2004)

Abstract

A seven-quasiparticle isomer with $K^{\pi} = (49 /2^ + )$ and T _1/2 = 53 (^{+ 3} _-7) ns has been identified in ¹⁷⁹Ta. By comparing its excitation energy with results from multi-quasiparticle calculations that include the effects of blocking and residual nucleon-nucleon interactions, the isomer is assigned the $\pi^{3}$ (5/2⁺[402], 7/2⁺[404], $9/2^{-}[514]) \otimes \nu^{4}$ (5/2^-[512], 7/2^-[514], 7/2^-[503], 9/2⁺[624]) configuration. The decay of this isomer is found to be unusually fast, a feature that is attributed to a mixing with a specific collective level. The interaction strength is found to be orders of magnitude lower than that observed between interacting collective levels.

PACS
21.10.Re - Collective levels.
21.10.Tg - Lifetimes.
23.20.Lv - Gamma transitions and level energies.
27.70.+q - $150 \leq A \leq 189$ .

What is OpenURL?

K-Mixing and fast decay of a seven-quasiparticle isomer in 179Ta

K-Mixing and fast decay of a seven-quasiparticle isomer in ¹⁷⁹Ta