Clarification of large-strength transitions in the beta decay of 11Be

Abstract

The shape and normalisation of the beta-delayed alpha spectrum from 11Be was measured by implanting 11Be ions in a segmented Si detector. The spectrum is found to be dominated by a well-known transition to the 3/2+ state at Ex = 9.87MeV in 11B. A significant increase in the observed decay strength towards the higher end of the Q window means, however, that the 9.87MeV state cannot alone be responsible for the transition. Using the R-matrix framework we find that the inclusion of an extra 3/2+ state at Ex = 11.49(10)MeV is required in order to obtain a satisfactory description of the spectrum. Both states show large widths towards alpha decay, exhausting significant fractions of the Wigner limit, a typical signature of alpha clusterisation. The observed Gamow-Teller strength indicate large overlaps between the two states and the ground state of 11Be.

arXiv commentSeveral comments were added and Fig. 6 were modified to show fits and residuals for all three models

References in corpus (14)

• The R-matrix theory
• Dark Matter Interpretation of the Neutron Decay Anomaly
• Superallowed nuclear beta decays: A critical survey with tests of CVC and the standard model
• An Alternative Parameterization of R-matrix Theory
• Halos and related structures
• 11Be(beta-p), a quasi-free neutron decay?
• Dark Side of the Neutron?
• On the possibility to observe neutron dark decay in nuclei
• Rare $\beta$p decays in light nuclei
• Beta-delayed deuteron emission from 11Li: decay of the halo
• Precise Coulomb wave functions for a wide range of complex l, eta and z
• Measurement of the branching ratio for beta-delayed alpha decay of 16N
• The strength of beta-decays to the continuum
• Broad resonances and beta-decay

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• Assessment of the beta-delayed proton decay rate of ${}^{11}$Be
• $\beta$-delayed proton emission from ${}^{11}$Be in effective field theory
• Neutron lifetime anomaly and mirror matter theory
• ${\beta }^{-}\mathrm{p}$ and ${\beta }^{-}\alpha$ decay of the ${}^{11}$Be neutron halo ground state
• The role of low-lying resonances for ${}^{10}$Be(p,$\alpha$) reaction rate and implications for the formation of the Solar System