Three-body effects in the Hoyle-state decay

We use a sequential $R$-matrix model to describe the breakup of the Hoyle state into three $\alpha$ particles via the ground state of $^8\mathrm{Be}$. It is shown that even in a sequential picture, features resembling a direct breakup branch appear in the phase-space distribution of the $\alpha$ particles. We construct a toy model to describe the Coulomb interaction in the three-body final state and its effects on the decay spectrum are investigated. The framework is also used to predict the phase-space distribution of the $\alpha$ particles emitted in a direct breakup of the Hoyle state and the possibility of interference between a direct and sequential branch is discussed. Our numerical results are compared to the current upper limit on the direct decay branch determined in recent experiments

HIE-ISOLDE: the Scientific Opportunities

The HIE-ISOLDE project aims at substantial improvements of the energy range, the intensity and the quality of the secondary radioactive beams produced at the ISOLDE facility at CERN. This report presents the questions within nuclear physics and related areas, including nuclear astrophysics, Standard Model tests and condensed matter physics, that scientists will be able to address at HIE-ISOLDE and gives specific examples of how the upgrades will improve the experimental conditions. The physics possibilities at HIE-ISOLDE were reviewed at the NuPAC meeting (Nuclear Physics and Astrophysics at CERN) held at CERN in October 2005; this report gives a more comprehensive overview and incorporates technical and scientific developments that have taken place since then

Measurement of the full excitation spectrum of the 7Li(p,{\gamma}){\alpha}{\alpha} reaction at 441 keV

A current challenge for ab initio calculations is systems that contain large continuum contributions such as 8Be. We report on new measurements of radiative decay widths in this nucleus that test recent Green's function Monte Carlo calculations. Traditionally, {\gamma} ray detectors have been utilized to measure the high energy photons from the 7Li(p, {\gamma}){\alpha}{\alpha} reaction. However, due to the complicated response function of these detectors it has not yet been possible to extract the full {\gamma} ray spectrum from this reaction. Here we present an alternative measurement using large area Silicon detectors to detect the two {\alpha} particles, which provides a practically background free spectrum and retains good energy resolution. The resulting spectrum is analyzed using a many-level multi channel R-matrix parametrization. Improved values for the radiative widths are extracted from the R-matrix fit. We find evidence for significant non-resonant continuum contributions and tentative evidence for a broad 0+ resonance at 12 MeV.Comment: Accepted version. Fixed Fig. 5 ordinate label

Branching ratios in the β decays of N12 and B12

Absolute branching ratios to unbound states in C12 populated in the β decays of N12 and B12 are reported. Clean sources of N12 and B12 were obtained using the isotope separation on-line (ISOL) method. The relative branching ratios to the different populated states were extracted using single-alpha as well as complete kinematics triple-alpha spectra. These two largely independent methods give consistent results. Absolute normalization is achieved via the precisely known absolute branching ratio to the bound 4.44 MeV state in C12. The extracted branching ratios to the unbound states are a factor of three more precise than previous measurements. Branching ratios in the decay of Na20 are also extracted and used to check the results. © 2009 The American Physical Society.Supported by the Academy of Finland (Project No. 44875), by the Spanish Agency CICYT (Nos. FPA2007–62170 and FPA2007–62216), by the European Union Sixth Framework Programme “EURONS” (No. 506065), by the Swedish Research Council, and the Knut and Alice Wallenberg foundation.Peer Reviewe

Coulomb dissociation of N 20,21

Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at

Beta decay to continuum states: the case of

Beta decay in exotic nuclei can lead to multi-particle final states. This contribution discusses briefly what decay mechanisms may enter in such decays and presents, on behalf of the IS541 collaboration at ISOLDE/CERN, preliminary data from a search for the beta-delayed proton decay of the halo nucleus 11Be

ISOLDE Workshop and Users meeting 2014 "50th Anniversary Edition"

In the years leading up to the first beams in LHC in the autumn 2008 most CERN efforts were focussed on finishing the LHC. Still, ISOLDE managed to evolve and broaden its physics scope. I shall give a brief overview of the main events taking place at ISOLDE in the period 2005-2008, including the consolidation of the existing infrastructure and the preparations for the HIE-ISOLDE project, and remind about some of the physics results coming out. I shall also mention the developments in and around the ISOLDE Collaboration

HIE-ISOLDE, the project and the physics opportunities

20 págs.; 20 figs.; 2 tabs.The ISOLDE facility at CERN offers the largest selection of ISOL beams today. The overall aim of the HIE-ISOLDE project is to enlarge the physics domains achievable with these beams, in particular by raising the maximum energy of post-accelerated beams to more than 10MeV/u. An outline of the history of the project is followed by a succinct description of the superconducting linac chosen for acceleration and an overview of the parts of the project aiming to the improvement of the beam quality and intensity. Concrete examples are given of experiments that will be performed at HIE-ISOLDE c Società Italiana di FisicaFonds Wetenschappelijk Onderzoek, FWO, Big Science 1 (BE); Special thanks to CERN and the ISOLDE Collaboration, without their support this project will have not been realised.Peer Reviewe