F. Sarazin

First Penning-trap mass measurement of the exotic halo nucleus 11Li.

M. Smith, M. Brodeur, T. Brunner, S. Ettenauer, A Lapierre, R. Ringle, V. L. Ryjkov, F. Ames, P. Bricault, G. W. F. Drake, P. Delheij, D Lunney, and J. Dilling TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver BC, Canada Technische Universität München, E12, James Franck Strasse, Garching, Germany Department of Physics, University of Windsor, Windsor, Ontario, Canada and CSNSM/CNRS/IN2P3, Universite de Paris-Sud, F-91405, Orsay, France (Dated: July 21, 2008)

A gas jet target for radioactive ion beam experiments

New radioactive ion beam (RIB) facilities, like FRIB in the US or FAIR in Europe, will push further away from stability and enable the next generation of nuclear physics experiments. Thus, the need for improved RIB targets is more crucial than ever: developments in exotic beams should coincide with developments in targets for use with those beams, in order for nuclear physics to remain on the cutting edge. Of great importance to the future of RIB physics are scattering, transfer and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure, and conventional targets often suffer too many drawbacks to allow for such experimental designs. Targets must also accommodate the use of large area, highly-segmented silicon detector arrays, high-efficiency gamma arrays, and novel heavy ion detectors to efficiently measure the reaction products. To address this issue, the Jet Experiments...

β-delayed deuteron emission from Li11: decay of the halo

The deuteron-emission channel in the beta decay of the halo nucleus (11)Li was measured at the Isotope Separator and Accelerator facility at TRIUMF by implanting postaccelerated (11)Li ions into a segmented silicon detector. The events of interest were identified by correlating the decays of (11)Li with those of the daughter nuclei. This method allowed the energy spectrum of the emitted deuterons to be extracted, free from contributions from other channels, and a precise value for the branching ratio B(d)=1.30(13)x10(-4) to be deduced for E(c.m.)>200 keV. The results provide the first unambiguous experimental evidence that the decay takes place essentially in the halo of (11)Li and that it proceeds mainly to the (9)Li+d continuum, opening up a new means to study the halo wave function of (11)Li.

Digital Electronics For The Versatile Array Of Neutron Detectors At Low Energies

A χ2 minimization algorithm has been developed to extract sub‐sampling‐time information from digitized waveforms, to be used to instrument the future Versatile Array of Neutron Detectors at Low energies. The algorithm performance has been characterized with a fast Arbitrary Function Generator, obtaining time resolution better than 1 ns for signals of amplitudes between 50 mV and 1V, with negligible walk in the whole range. The proof‐of‐principle measurement of the beta‐delayed neutron emission from 89Br indicates a resolution of 1 ns can be achieved in realistic experimental conditions.

Development of a Versatile Array of Neutron Detectors at Low Energy

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new array of plastic scintillator bars under development for measurements at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The array is highly modular allowing the configuration of the individual elements to be optimized for particular experimental requirements, such as (d,n) and beta‐delayed neutron‐decay measurements with neutron‐rich rare isotope beams.

β-delayed deuteron emission from 11Li: Decay of the halo

The deuteron-emission channel in the beta decay of the halo nucleus (11)Li was measured at the Isotope Separator and Accelerator facility at TRIUMF by implanting postaccelerated (11)Li ions into a segmented silicon detector. The events of interest were identified by correlating the decays of (11)Li with those of the daughter nuclei. This method allowed the energy spectrum of the emitted deuterons to be extracted, free from contributions from other channels, and a precise value for the branching ratio B(d)=1.30(13)x10(-4) to be deduced for E(c.m.)>200 keV. The results provide the first unambiguous experimental evidence that the decay takes place essentially in the halo of (11)Li and that it proceeds mainly to the (9)Li+d continuum, opening up a new means to study the halo wave function of (11)Li.

Line-shape analysis of Doppler-broadened {gamma} lines following the {beta} decay of {sup 11}Li

The {beta} decay of {sup 11}Li is studied at the TRIUMF Isotope Separation and Acceleration (ISAC) facility using the 8{pi} {gamma}-ray spectrometer coupled with an inner array of 20 plastic scintillators for {beta} detection. Doppler-broadened line shapes resulting from the decay of the excited states in {sup 10}Be populated by {beta}-delayed one-neutron emission are analyzed using Monte Carlo simulations. New {beta}-delayed neutron decay branches are shown to contribute to the complex decay of {sup 11}Li. The half-lives of all but one bound excited state in {sup 10}Be are also deduced from this work. Among them, the half-life of the 2{sup -} state in {sup 10}Be is shown to be much shorter than previously thought, yielding a new experimental B(E1) now well within the range of theoretical predictions and providing further evidence that the 2{sup -} state in {sup 10}Be is an excited halo state. The nature of the 8.82-MeV state in {sup 11}Be and its decay paths to excited states in {sup 10}Be are found to be consistent with the {beta} decay of the core proceeding through this particular state.

β-Delayed Deuteron Emission fromLi11: Decay of the Halo

The deuteron-emission channel in the beta decay of the halo nucleus (11)Li was measured at the Isotope Separator and Accelerator facility at TRIUMF by implanting postaccelerated (11)Li ions into a segmented silicon detector. The events of interest were identified by correlating the decays of (11)Li with those of the daughter nuclei. This method allowed the energy spectrum of the emitted deuterons to be extracted, free from contributions from other channels, and a precise value for the branching ratio B(d)=1.30(13)x10(-4) to be deduced for E(c.m.)>200 keV. The results provide the first unambiguous experimental evidence that the decay takes place essentially in the halo of (11)Li and that it proceeds mainly to the (9)Li+d continuum, opening up a new means to study the halo wave function of (11)Li.

Exotic molecular and halo states in 12,14Be

The two nuclei {sup 12}Be and {sup 14}Be have been studied using breakup reactions on p, {sup 12}C and {sup 208}Pb targets. The decay of {sup 12}Be into two helium clusters ({sup 6}He+{sup 6}He and {sup 4}He+{sup 8}He) was observed from a series of excited states between 10 and 25 MeV, with spins in the range 4{sup +} to 8{sup +}. The single neutron angular distributions for {sup 14}Be exhibit the narrow forward peak characteristic of a halo. The widths of these distributions in coincidence with {sup 12}Be fragments are {gamma}{sub L}=78{+-}6 and 80{+-}1 MeV/c for breakup on carbon and lead.

Charged‐particle channels in the β‐decay of 11Li

We measured the {beta}-decay of the halo-nucleus {sup 11}Li, with particular attention to the deuteron- and triton-emission channels. We employed a post-accelerated beam of {sup 11}Li ions, and the implantation technique in a finely-segmented silicon detector. The channels of interest were identified through the time and space correlations between the implantation events and the parent and daughter decays. We obtained the branching ratios, as well as the spectra of the emitted ions.