Published 2021
| Version v1
Publication
Low-energy resonances in the 18O(p,γ)19F reaction
Creators
- F. R. Pantaleo
- A. Boeltzig
- A. Best
- R. Perrino
- M. Aliotta
- J. Balibrea-Correa
- F. Barile
- D. Bemmerer
- C. Broggini
- C. G. Bruno
- R. Buompane
- A. Caciolli
- F. Cavanna
- T. Chillery
- G. F. Ciani
- P. Corvisiero
- L. Csedreki
- T. Davinson
- R. J. deBoer
- R. Depalo
- G. D'Erasmo
- A. Di Leva
- Z. Elekes
- F. Ferraro
- E. M. Fiore
- A. Formicola
- Zs. Fülöp
- G. Gervino
- A. Guglielmetti
- C. Gustavino
- Gy. Gyürky
- G. Imbriani
- M. Junker
- I. Kochanek
- M. Lugaro
- E. Masha
- R. Menegazzo
- V. Mossa
- V. Paticchio
- D. Piatti
- P. Prati
- D. Rapagnani
- L. Schiavulli
- K. Stöckel
- O. Straniero
- T. Szücs
- M. P. Takács
- D. Trezzi
- M. Wiescher
- S. Zavatarelli
Contributors
Others:
- Pantaleo, F. R.
- Boeltzig, A.
- Best, A.
- Perrino, R.
- Aliotta, M.
- Balibrea-Correa, J.
- Barile, F.
- Bemmerer, D.
- Broggini, C.
- Bruno, C. G.
- Buompane, R.
- Caciolli, A.
- Cavanna, F.
- Chillery, T.
- Ciani, G. F.
- Corvisiero, P.
- Csedreki, L.
- Davinson, T.
- Deboer, R. J.
- Depalo, R.
- D'Erasmo, G.
- Di Leva, A.
- Elekes, Z.
- Ferraro, F.
- Fiore, E. M.
- Formicola, A.
- Fülöp, Zs.
- Gervino, G.
- Guglielmetti, A.
- Gustavino, C.
- Gyürky, Gy.
- Imbriani, G.
- Junker, M.
- Kochanek, I.
- Lugaro, M.
- Masha, E.
- Menegazzo, R.
- Mossa, V.
- Paticchio, V.
- Piatti, D.
- Prati, P.
- Rapagnani, D.
- Schiavulli, L.
- Stöckel, K.
- Straniero, O.
- Szücs, T.
- Takács, M. P.
- Trezzi, D.
- Wiescher, M.
- Zavatarelli, S.
Description
Background: Shell hydrogen burning during the asymptotic giant branch (AGB) phase through the oxygen
isotopes has been indicated as a key process that is needed to understand the observed 18O/16O relative abundance
in presolar grains and in stellar atmospheres. This ratio is strongly influenced by the relative strengths of the
reactions 18O(p,α) 15N and 18O(p,γ ) 19F in low-mass AGB stars. While the former channel has been the focus
of a large number of measurements, the (p,γ ) reaction path has only recently received some attention and its
stellar reaction rate over a wide temperature range rests on only one measurement.
Purpose: Our aim is the direct measurement of states in 19F as populated through the reaction 18O(p,γ ) 19F
to better determine their influence on the astrophysical reaction rate, and more generally to improve the
understanding of the nuclear structure of 19F.
Method: Branchings and resonance strengths were measured in the proton energy range Elab
p = 150–400 keV,
using a high-purity germanium detector inside a massive lead shield. The measurement took place in the ultralow-
background environment of the Laboratory for Underground Nuclear Astrophysics (LUNA) experiment at
the Gran Sasso National Laboratory, leading to a highly increased sensitivity.
Results: The uncertainty of the γ branchings and strengths was improved for all four resonances in the studied
energy range; many new transitions were observed in the case of the 334 keV resonance, and individual γ decays
of the 215 keV resonance were measured for the first time. In addition a number of transitions to intermediate
states that decay through α emission were identified. The strengths of the observed resonances are generally in
agreement with literature values.
Conclusions: Our measurements substantially confirm previous determinations of the relevant resonance
strengths. Therefore the 18O(p,γ ) 19F reaction rate does not change with respect to the reaction rate reported
in the compilations commonly adopted in the extant computations of red-giant branch and AGB stellar models.
Nevertheless, our measurements definitely exclude a nonstandard scenario for the fluorine nucleosynthesis and
a nuclear physics solution for the 18O depletion observed in Group 2 oxygen-rich stardust grains.
Additional details
Identifiers
- URL
- https://hdl.handle.net/11567/1053821
- URN
- urn:oai:iris.unige.it:11567/1053821
Origin repository
- Origin repository
- UNIGE