Beta-delayed proton emission from 20 Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station (IDS) setup including both charged-particle and gamma-ray detection capabilities. A total of 26 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in 20 Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State (IAS) in 20 Na is observed. This may allow studies of the 4032.9(2.4) keV resonance in 19 Ne through the beta decay of 20 Mg, which is important for the astrophysically relevant reaction 15 O(α, γ) 19 Ne. Beta-delayed protons were used to obtain a more precise value for the half-life of 20 Mg, 90.9(1.2) ms. PACS. 23.20.Lv γ transitions and level energies-26.30.Ca Explosive burning in accreting binary systems (novae, x-ray bursts)-27.30.+t 20 ≤ A ≤ 38-29.30.Ep Charged-particle spectroscopy

Excited states in 133 Sn were investigated through the β decay of 133 In at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for 133 In, allowing us to study separately, and in detail, the β-decay branch of 133 In J π = (9/2 +) ground state and its J π = (1/2 −) isomer.

The 12 C(α, γ) 16 O reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced α width, γ11, of the bound 1 − level in 16 O is particularly important to determine the cross section. The magnitude of γ11 is determined via sub-Coulomb α-transfer reactions or the β-delayed α decay of 16 N, but the latter approach is presently hampered by the lack of sufficiently precise data on the β-decay branching ratios. Here we report improved branching ratios for the bound 1 − level [b β,11 = (5.02 ± 0.10) × 10 −2 ] and for β-delayed α emission [b βα = (1.59 ± 0.06) × 10 −5 ]. Our value for b βα is 33% larger than previously held, leading to a substantial increase in γ11. Our revised value for γ11 is in good agreement with the value obtained in α-transfer studies and the weighted average of the two gives a robust and precise determination of γ11, which provides significantly improved constraints on the 12 C(α, γ) cross section in the energy range relevant to hydrostatic He burning.

A multi-particle decay experiment was successfully performed at the ISOLDE Decay Station. In this new permanent station, devoted to β-decay studies, the novel MAGISOL Si-Plugin Chamber was installed to study the exotic decay modes of the proton drip-line nucleus 31 Ar. The motivation was to search for β3p and β3pγ channels, as well as to provide information on resonances in 30 S and 29 P relevant for the astrophysical rp-process. Description of the experimental set-up and preliminary results are presented.

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