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The 19Ne(p,γ)20Na reaction is the second step of a reaction chain which breaks out from the hot CNO cycle, following the O15(a,γ)19Ne reaction at the onset of x-ray burst events. We investigate the spectrum of the lowest proton-unbound states in 20Na in an effort to resolve contradictions in spin-parity assignments and extract reliable information about the thermal reaction rate. The proton-transfer reaction 19Ne(d,n)20Na is measured with a beam of the radioactive isotope 19Ne at an energy around the Coulomb barrier and in inverse kinematics. We observe three proton resonances with the 19Ne ground state, at 0.44, 0.66, and 0.82 MeV c.m. energies, which are assigned 3+, 1+, and (0+), respectively. In addition, we identify two resonances with the first excited state in 19Ne, one at 0.20 MeV and one, tentatively, at 0.54 MeV. These observations allow us for the first time to experimentally quantify the astrophysical reaction rate on an excited nuclear state. Our experiment shows an efficient path for thermal proton capture in 19Ne(p,γ)20Na, which proceeds through ground state and excited-state capture in almost equal parts and eliminates the possibility for this reaction to create a bottleneck in the breakout from the hot CNO cycle. [ABSTRACT FROM AUTHOR]

A 13F resonance was observed following a charge-exchange reaction between a fast 13O beam and a 9Be target. The resonance was found in the invariant-mass distribution of 3p+10C events and probably corresponds to a 5/2+ excited state. The ground state was also expected to be populated, but was not resolved from the background. The observed level decays via initial proton emissions to both the ground and first 2+ state of 12O, which subsequently undergo 2p decay. In addition, there may also be a significant proton decay branch to the second 2+ level in 12O. The wave function associated with the observed level may be collectivized due to coupling to the continuum as is it located just above the threshold for proton decay to the 2+2 state of 12O. [ABSTRACT FROM AUTHOR]

We report the first observation of the 108Xe→104Te→100Sn α-decay chain. The α emitters, 108Xe [Eα=4.4(2)  MeV, T1/2=58+106-23 μs] and 104Te [Eα=4.9(2)  MeV, T1/2<18  ns], decaying into doubly magic 100Sn were produced using a fusion-evaporation reaction 54Fe(58Ni,4n)108Xe, and identified with a recoil mass separator and an implantation-decay correlation technique. This is the first time α radioactivity has been observed to a heavy self-conjugate nucleus. A previous benchmark for study of this fundamental decay mode has been the decay of 212Po into doubly magic 208Pb. Enhanced proton-neutron interactions in the N=Z parent nuclei may result in superallowed α decays with reduced α-decay widths significantly greater than that for 212Po. From the decay chain, we deduce that the α-reduced width for 108Xe or 104Te is more than a factor of 5 larger than that for 212Po. [ABSTRACT FROM AUTHOR]

A beam containing a substantial component of both the Jp=5+, T1/2=162 ns isomeric state of 18F and its 1+, 109.77-min ground state is utilized to study members of the ground-state rotational band in 19F through the neutron transfer reaction (d,p) in inverse kinematics. The resulting spectroscopic strengths confirm the single-particle nature of the 13/2+ band-terminating state. The agreement between shell-model calculations using an interaction constructed within the sd shell, and our experimental results reinforces the idea of a single-particle-collective duality in the descriptions of the structure of atomic nuclei. [ABSTRACT FROM AUTHOR]

The existence of 26Al (t1/2=7.17×105 yr) in the interstellar medium provides a direct confirmation of ongoing nucleosynthesis in the Galaxy. The presence of a low-lying 0+ isomer (26Alm), however, severely complicates the astrophysical calculations. We present for the first time a study of the 26Alm(d,p)27Al reaction using an isomeric 26Al beam. The selectivity of this reaction allowed the study of ℓ=0 transfers to T=1/2, and T=3/2 states in 27Al. Mirror symmetry arguments were then used to constrain the 26Alm(p,γ)27Si reaction rate and provide an experimentally determined upper limit of the rate for the destruction of isomeric 26Al via radiative proton capture reactions, which is expected to dominate the destruction path of 26Alm in asymptotic giant branch stars, classical novae, and core collapse supernovae. [ABSTRACT FROM AUTHOR]

The boundaries of the chart of nuclides contain exotic isotopes that possess extreme proton-to-neutron asymmetries. Here we report on strong evidence of ^{9}N, one of the most exotic proton-rich isotopes where more than one half of its constitute nucleons are unbound. With seven protons and two neutrons, this extremely proton-rich system would represent the first-known example of a ground-state five-proton emitter. The invariant-mass spectrum of its decay products can be fit with two peaks whose energies are consistent with the theoretical predictions of an open-quantum-system approach; however, we cannot rule out the possibility that only a single resonancelike peak is present in the spectrum.