Investigation of the Δn = 0 selection rule in Gamow-Teller transitions: The β-decay of 207 Hg

T. A. Berry*, Zs Podolyák, R. J. Carroll, R. Lică, H. Grawe, N. K. Timofeyuk, T. Alexander, A. N. Andreyev, S. Ansari, M. J.G. Borge, J. Creswell, C. Fahlander, L. M. Fraile, H. O.U. Fynbo, W. Gelletly, R. B. Gerst, M. Górska, A. Gredley, P. Greenlees, L. J. Harkness-BrennanM. Huyse, S. M. Judge, D. S. Judson, J. Konki, J. Kurcewicz, I. Kuti, S. Lalkovski, I. Lazarus, M. Lund, M. Madurga, N. Mărginean, R. Mărginean, I. Marroquin, C. Mihai, R. E. Mihai, E. Nácher, S. Nae, A. Negret, C. Niţă, R. D. Page, S. Pascu, Z. Patel, A. Perea, V. Pucknell, P. Rahkila, E. Rapisarda, P. H. Regan, F. Rotaru, C. M. Shand, E. C. Simpson, Ch Sotty, S. Stegemann, T. Stora, O. Tengblad, A. Turturica, P. Van Duppen, V. Vedia, R. Wadsworth, P. M. Walker, N. Warr, F. Wearing, H. De Witte

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N>82) and Z=82 (for N>126). The level of forbiddenness of the Δn=1ν1g 9/2 →π0g 7/2 transition has been investigated from the β decay of the ground state of 207 Hg into the single-proton-hole nucleus 207 Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g 7/2 −1 state in 207 Tl, an upper limit of 3.9×10 −3 % was obtained for the probability of this decay, corresponding to log⁡ft>8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date.

Original languageEnglish
Pages (from-to)271-275
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Early online date24 Apr 2019
Publication statusE-pub ahead of print - 24 Apr 2019

Bibliographical note

© 2019 The Authors.

Cite this