Coulomb breakup at high energy in inverse kinematics of proton-rich 31 Cl was used to constrain the thermonuclear 30 S(p,γ ) 31 Cl capture reaction rate under typical Type I x-ray burst conditions. This reaction is a bottleneck during rapid proton-capture nucleosynthesis (rp process), where its rate depends predominantly on the nuclear structure of 31 Cl. Two low-lying states just above the proton-separation threshold of S p = 296(50) keV in 31 Cl have been identified experimentally using the R 3 B-LAND setup at the GSI Helmholtzzentrum für Schwerionenforschung GmbH. Both states are considered to play a key role in the thermonuclear 30 S(p,γ ) 31 Cl capture reaction. Excitation energies of the first J π = 1/2 + ,5/2 + states have been extracted and the reaction rate for proton capture on 30 S under typical rp-process temperatures has been investigated.
The coupling between bound quantum states and those in the continuum is of high theoretical interest. Experimental studies of bound drip-line nuclei provide ideal testing grounds for such investigations since they, due to the feeble binding energy of their valence particles, are easy to excite into the continuum. In this Letter, continuum states in the heaviest particle-stable Be isotope, 14Be, are studied by employing the method of inelastic proton scattering in inverse kinematics. New continuum states are found at excitation energies E*=3.54(16) MeV and E*=5.25(19) MeV. The structure of the earlier known 2(1)+ state at 1.54(13) MeV was confirmed with a predominantly (0d5/2)2 configuration while there is very clear evidence that the 2(2)+ state has a predominant (1s1/2, 0d5/2) structure with a preferential three-body decay mechanism. The region at about 7 MeV excitation shows distinct features of sequential neutron decay via intermediate states in 13Be. This demonstrates that the increasing availability of energetic beams of exotic nuclei opens up new vistas for experiments leading towards a new understanding of the interplay between bound and continuum states.
Determination of the neutron-capture rate of ^{17}C for rprocess nucleosynthesis With the R 3 B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of 18 C at a projectile energy around 425 AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of 17 C into the ground state of 18 C. Those data have been used to constrain theoretical calculations for transitions populating excited states in 18 C. This allowed to derive the astrophysical cross section σ * nγ accounting for the thermal population of 17 C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures 2 T9 ≤ 1 GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of 17 C on the production of second-and third-peak elements in contrast to earlier sensitivity studies.
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