The strength of beta-decays to the continuum

Abstract

The beta-strength in beta-delayed particle decays has up to now been defined in a somewhat ad hoc manner that depends on the decay mechanism. A simple, consistent definition is presented that fulfils the beta strength sum rules. Special consideration is given to the modifications needed when employing R-matrix fits to data. As an example the 11Be(beta-p) decay is investigated through simple models.Comment: 18 pages, 4 figure

Direct Observation of Proton Emission in Be11

“…Using accelerated mass spectroscopy, they measured the amount of 10 Be (T 1/2 = 1.5 · 10 6 years) in the samples, obtaining b p = 8.3(9) · 10 −6 . Theoretical predictions using the 11 B nuclear structure suggest that the β − p + branch should have been orders of magnitude lower than observed [1,8,12].…”

“…In nuclei like 11 Be, called halo nuclei, the last neutron is so weakly bound that it orbits far from an inert core [5][6][7]. The β − p + decay mechanism has been modeled as a decay of the halo neutron into a proton that is either in a high-energy resonant state above its separation energy or directly in the continuum, free to be emitted [8]. This is similar to the β-delayed deuterium emission in the two-neutron halo nucleus 11 Li.…”

“…In order to efficiently detect and identify every particle emitted in the β-decay of 11 Be, specially protons of ∼ 200 keV of energy [4,8], the experiment was performed with the prototype Active Target Time Projection Chamber (pAT-TPC) [17]. This device allows for efficient and high-resolution measurement of very low energy particles.…”

“…We also estimated the β-decay rate of 11 Be into a proton-emitting resonance of 11 B, using a simple model to compute the overlap O = φ n |φ p between the halo neutron φ n (2s 1/2 ) in 11 Be and the final single-proton resonance φ p (2s 1/2 ) of 11 B, as well as the width Γ p of the resonance. Both states are calculated making use of Woods-Saxon potentials similar to those used in [8], complemented with the Coulomb interaction in the proton case. Setting the resonance energy at the experimental value, the overlap and the width are found to be O = 0.53 and Γ p = 44 keV, respectively.…”

The C12(α,γ)O16deBoer1, Görres2, Wiescher3 et al. 2017Rev. Mod. Phys.20881431View full textAdd to dashboardCite

“…The 12 C/ 16 O profile in the remnant white dwarf impacts the ignition of Type Ia supernovae, one of the premier probes for measuring the cosmological properties of the Universe (e.g., Perlmutter et al, 1999;Riess et al, 1998). The carbon mass fraction impacts the overall energy release, expansion velocity, silicon-group and irongroup ejecta profiles (Calder et al, 2007;Höflich et al, 1998;Miles et al, 2016;Raskin et al, 2012;Röpke et al, 2006;Seitenzahl et al, 2016) in progenitor systems involving either one white dwarf (single degenerate channel) or two white dwarfs (double degenerate channel).…”