Measurement of Radiative Proton Capture on 18F and Implications for Oxygen-Neon Novae

GammaNovaePPeer ReviewedScience
The rate of the 18F(p,g)19Ne reaction affects the final abundance of the gamma-ray observable radioisotope 18F, produced in novae. However, no successful measurement of this reaction exists and the rate used is
calculated from incomplete information on the contributing resonances. Of the two resonances thought to
play a significant role, one has a radiative width estimated from the assumed analogue state in the mirror
nucleus, 19F. The second does not have an analogue state assignment at all, resulting in an arbitrary
radiative width being assumed. Here, we report the first successful direct measurement of the
18F(p,g)19Ne reaction. The strength of the 665 keV resonance (Ex = 7.076 MeV) is found to be over
an order of magnitude weaker than currently assumed in nova models. Reaction rate calculations show
that this resonance therefore plays no significant role in the destruction of 18F at any astrophysical
Author: C. Akers
Journal: Phys. Rev. C

Strength of the Ec.m. = 1113 keV resonance in 20Ne(p, γ) 21Na

PPeer ReviewedScience
The 20Ne(pγ)21Na reaction is the starting point of the NeNa cycle, which is an important process for the production of intermediate mass elements. The Ec.m. = 1113 keV resonance plays an important role in the determination of stellar rates for this reaction since it is used to normalize experimental direct capture yields at lower energies. The commonly accepted strength of this resonance, ωγ = 1.13±0.07 eV, has been misinterpreted as the strength in the center-of-mass frame when it is actually the strength in the laboratory frame. This has motivated a new measurement of the Ec.m. = 1113 keV resonance strength in 20Ne(pγ)21Na using the DRAGON recoil mass spectrometer. The DRAGON result, 0.972 ± 0.11 eV, is in good agreement with the accepted value when both are calculated in the same frame of reference.
Author: G. Christian, D. Hutcheon, C. Akers, D. Connolly, J. Fallis, and C. Ruiz
Journal: Phys. Rev. C, Brief Reports

One fewer solution to the cosmological lithium problem



Data from a recent 9Be(3He,t )9B measurement are used to rule out a possible solution to the cosmological lithium problem based on conventional nuclear physics.
Author: O. S. Kirsebom and B. Davids
Journal: Physical Review C

Brief Talk at NUPECC meeting

Author: D'Auria, J. M.

DRAGON people photo

Author: n/a