0000000000147476
AUTHOR
J. Büscher
Precise Determination of the UnperturbedB8Neutrino Spectrum
A measurement of the final state distribution of the B-8 beta decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvaskyla [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 ( 2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fi…
STUDIES OF 12C USING β-DECAYS
The nuclear structure of states in 12 C have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0+ and 2+ states in the triple alpha continuum. A series of experiments have been performed using β-decay of 12 N and 12 B to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three α-particles directly. Preliminary results from this experiment will be presented.
Early onset of deformation in the neutron-deficient polonium isotopes
In-source laser spectroscopy has been performed at CERN-ISOLDE with the RILIS laser ion source on Po-191-204,Po-206,Po-208-211,Po-216,Po-218. New information on the beta decay of Po-199 were extracted in the process, challenging previous results. Large-scale atomic calculations were performed to extract the changes in the mean-square charge radius delta from the isotope shifts. The delta for the even-A isotopes reveal a large deviation from the spherical droplet model for N < 116.
R-matrix analysis of theβdecays ofN12andB12
The β decays of 12N and 12B have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2+ strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the 12…
The β-decay approach for studying 12C
6 pags., 3 figs. -- 9th International Conference on Clustering Aspects of Nuclear Structure and Dynamics (CLUSTERS'07) 3–7 September 2007, Stratford upon Avon, UK
Precise Determination of the Unperturbed 8B Neutrino Spectrum
The measurement was performed at the Kernfysisch Versneller Instituut (KVI) at the University of Groningen, The Netherlands.; A measurement of the final state distribution of the 8B $\beta$ decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyvâskylä [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly ex…
Precise branching ratios to unbound 12C states from 12N and 12B β-decays
6 pages, 2 tables, 4 figures.--PACS nrs.: 21.45.-v; 23.40.-s; 27.20.+n; 21.60.De.--Printed version published Aug 3, 2009
Gamow–Teller transitions in exotic pf-shell nuclei relevant to supernova explosion
Gamow–Teller (GT) transitions starting from unstable pf-shell nuclei are of interest not only in nuclear physics, but also in astrophysics, e.g. in violent neutrino induced reactions at the core-collapse stage of type II supernovae. In the β-decay study of these pf-shell nuclei, half-lives can be measured rather accurately. On the other hand, in high-resolution (3He, t) charge-exchange reactions at 0°, individual GT transitions up to high excitations can be studied. Assuming the isospin symmetry for the strengths of Tz = ±1 → 0 analogous GT transitions, we present a unique 'merged analysis' for the determination of absolute B(GT) values.
Structure of191Pb from α- and β-decay spectroscopy
International audience; Complementary studies of 191 Pb have been made in the β decay of 191 Bi at LISOL (CRC) and in the α decay of 195 Po at ISOLDE (CERN). Fine structures in the α decay of the low-spin and high-spin isomers of 195 Po have been fully resolved. Identification of the parent state is made possible via isomer selection based on narrowband laser frequency scanning. The α-particle and γ-ray energies have been determined with greater precision. New α-particle and γ-ray energies are identified. Branching ratios in the decay of 195 Po and 191 Pb have been examined. Structure of 191 Pb from α- and β-decay spectroscopy 2 PACS numbers: 23.20.Nx Internal conversion, 23.60.+e α decay, …
Charge radii of odd-A 191–211Po isotopes
Isotope shifts have been measured for the odd-A polonium isotopes 191–211Po and changes in the nuclear mean square charge radii δr2 have been deduced. The measurements were performed at CERN-ISOLDE using the in-source resonance-ionization spectroscopy technique. The combined analysis of these data and our recent results for even-A polonium isotopes indicates an onset of deformation already at 197,198Po, when going away from stability. This is significantly earlier than was suggested by previous theoretical and experimental studies of the polonium isotopes. Moreover and in contrast to the mercury isotopes, where a strong odd–even staggering of the charge radii of the ground states was observ…