https://doi.org/10.1140/epja/i2019-12791-5
Letter
Identification of
-decaying resonant states in 26Mg and their importance for the astrophysical s process
1
Department of Physics, University of Surrey, GU2 7XH, Guildford, UK
2
National Physical Laboratory, TW11 0LW, Teddington, Middlesex, UK
3
Argonne National Laboratory, 60439, Argonne, Illinois, USA
4
Department of Chemistry and Biochemistry, University of Maryland, 20742, College Park, Maryland, USA
5
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, 27599, Chapel Hill, North Carolina, USA
6
Triangle Universities Nuclear Laboratory, Duke University, 27708, Durham, North Carolina, USA
7
School of Physics & Astronomy, University of Edinburgh, EH9 3JZ, Edinburgh, UK
* e-mail: g.lotay@surrey.ac.uk
Received:
20
February
2019
Accepted:
3
June
2019
Published online:
18
July
2019
The 22Ne(, n) reaction is expected to provide the dominant neutron source for the weak s process in massive stars and intermediate-mass (IM) Asymptotic Giant Branch (AGB) stars. However, the production of neutrons in such environments is hindered by the competing 22Ne(
,
)26Mg reaction. Here, the 11B(16O,p) fusion-evaporation reaction was used to identify
-decay transitions from 22Ne +
resonant states in 26Mg. Spin-parity restrictions have been placed on a number of
-unbound excited states in 26 Mg and their role in the 22Ne(
,
)26Mg reaction has been investigated. In particular, a suspected natural-parity resonance at E
c.m. = 557(3) keV, that lies above the neutron threshold in 26Mg, and is known to exhibit a strong
-cluster character, was observed to
decay. Furthermore, a known resonance at
keV has been definitively assigned 2+ spin and parity. Consequently, uncertainties in the 22Ne(
,
) stellar reaction rate have been reduced by a factor of ∼ 20 for temperatures ∼ 0.2 GK.
© The Author(s), 2019