32 research outputs found
Half-lives of neutron-rich Cd 128-130
R. Dunlop et al. ; 6 págs.; 7 figs.; 1 tab. ; Rapid CommunicationsThe β-decay half-lives of Cd128-130 have been measured with the newly commissioned GRIFFIN γ-ray spectrometer at the TRIUMF-ISAC facility. The time structures of the most intense γ rays emitted following the β decay were used to determine the half-lives of Cd128 and Cd130 to be T1/2=246.2(21) ms and T1/2=126(4) ms, respectively. The half-lives of the 3/2+ and 11/2- states of Cd129 were measured to be T1/2(3/2+)=157(8) ms and T1/2(11/2-)=147(3) ms. The half-lives of the Cd isotopes around the N=82 shell closure are an important ingredient in astrophysical simulations to derive the magnitude of the second r-process abundance peak in the A∼130 region. Our new results are compared with recent literature values and theoretical calculations. ©2016 American Physical SocietyThis work has been partially supported by the Natural Sciences
and Engineering Research Council of Canada (NSERC)
and the Canada Research Chairs Program. I.D. and R.C.-F. are
supported by NSERC Discovery Grants SAPIN-2014-00028
and RGPAS 462257-2014. A.J. acknowledges financial support
by the Spanish Ministerio de Ciencia e Innovación under
contract FPA2011-29854-C04 and the Spanish Ministerio
de Economía y Competitividad under contract FPA2014-
57196-C5-4-P. S.L.T acknowledges financial support from
the U.S. National Science Foundation under contract NSF-
14-01574. E.P.-R. acknowledges financial support from the
DGAPA-UNAM under the PASPA program. The GRIFFIN
spectrometer was funded by the Canada Foundation for
Innovation, TRIUMF, and the University of Guelph. TRIUMF
receives federal funding via a contribution agreement with the
National Research Council of Canada.Peer Reviewe
The GRIFFIN facility for Decay-Spectroscopy studies at TRIUMF-ISAC
Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new high-efficiency γ-ray spectrometer designed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF\u27s Isotope Separator and Accelerator (ISAC-I) facility. GRIFFIN is composed of sixteen Compton-suppressed large-volume clover-type high-purity germanium (HPGe) γ-ray detectors combined with a suite of ancillary detection systems and coupled to a custom digital data acquisition system. The infrastructure and detectors of the spectrometer as well as the performance characteristics and the analysis techniques applied to the experimental data are described
Decay spectroscopy of Cd-129
Excited states of In populated following the -decay of
Cd were experimentally studied with the GRIFFIN spectrometer at the
ISAC facility of TRIUMF, Canada. A 480-MeV proton beam was impinged on a
uranium carbide target and Cd was extracted using the Ion Guide Laser
Ion Source (IG-LIS). - and -rays following the decay of
Cd were detected with the GRIFFIN spectrometer comprising the plastic
scintillator SCEPTAR and 16 high-purity germanium (HPGe) clover-type detectors.
%, along with the -particles were detected with SCEPTAR. From the
-- coincidence analysis, 32 new transitions and 7 new
excited states were established, expanding the previously known level scheme of
In. The values deduced from the -feeding intensities
suggest that some of the high-lying states were populated by the allowed Gamow-Teller (GT) transition, which
indicates that the allowed GT transition is more dominant in the Cd
decay than previously reported. Observation of fragmented Gamow-Teller
strengths is consistent with theoretical calculations.Comment: 13 pages, 9 figures, to be published in Physical Review
CHIME/FRB Detection of Eight New Repeating Fast Radio Burst Sources
We report on the discovery of eight repeating fast radio burst (FRB) sources
found using the Canadian Hydrogen Intensity Mapping Experiment (CHIME)
telescope. These sources span a dispersion measure (DM) range of 103.5 to 1281
pc cm. They display varying degrees of activity: six sources were
detected twice, another three times, and one ten times. These eight repeating
FRBs likely represent the bright and/or high-rate end of a distribution of
infrequently repeating sources. For all sources, we determine sky coordinates
with uncertainties of 10. FRB 180916.J0158+65 has a
burst-averaged DM = pc cm and a low DM excess over the
modelled Galactic maximum (as low as 20 pc cm); this source also
has a Faraday rotation measure (RM) of rad m, much
lower than the RM measured for FRB 121102. FRB 181030.J1054+73 has the lowest
DM for a repeater, pc cm, with a DM excess of 70
pc cm. Both sources are interesting targets for multi-wavelength
follow-up due to their apparent proximity. The DM distribution of our repeater
sample is statistically indistinguishable from that of the first 12 CHIME/FRB
sources that have not repeated. We find, with 4 significance, that
repeater bursts are generally wider than those of CHIME/FRB bursts that have
not repeated, suggesting different emission mechanisms. Our repeater events
show complex morphologies that are reminiscent of the first two discovered
repeating FRBs. The repetitive behavior of these sources will enable
interferometric localizations and subsequent host galaxy identifications.Comment: 40 pages, 11 figures; accepted by ApJL on 28 September 2019; added
analysis of correlation between width and max. flux densit