학술논문
Measurement of the $2^+\rightarrow 0^+$ ground-state transition in the $\beta$ decay of $^{20}$F
Document Type
Working Paper
Author
Kirsebom, O. S.; Hukkanen, M.; Kankainen, A.; Trzaska, W. H.; Strömberg, D. F.; Martínez-Pinedo, G.; Andersen, K.; Bodewits, E.; Canete, L.; Cederkäll, J.; Enqvist, T.; Eronen, T.; Fynbo, H. O. U.; Geldhof, S.; de Groote, R.; Jenkins, D. G.; Jokinen, A.; Joshi, P.; Khanam, A.; Kostensalo, J.; Kuusiniemi, P.; Moore, I.; Munch, M.; Nesterenko, D. A.; Ovejas, J. D.; Penttilä, H.; Pohjalainen, I.; Reponen, M.; Rinta-Antila, S.; Riisager, K.; de Roubin, A.; Schotanus, P.; Srivastava, P. C.; Suhonen, J.; Swartz, J. A.; Tengblad, O.; Vilen, M.; Vińals, S.; Äystö, J.
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Subject
Language
Abstract
We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, ground-state transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}^+$ beam produced at the IGISOL facility in Jyv\"askyl\"a, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The $\beta$-decay branching ratio inferred from the measurement is $b_{\beta} = [ 0.41\pm 0.08\textrm{(stat)}\pm 0.07\textrm{(sys)}] \times 10^{-5}$ corresponding to $\log ft = 10.89(11)$, making this one of the strongest second-forbidden, non-unique $\beta$ transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on $^{20}$Ne is now known to within better than 25% at the relevant temperatures and densities.
Comment: 13 pages, 16 figures, 4 tables
Comment: 13 pages, 16 figures, 4 tables