549 research outputs found
Empirical description of beta-delayed fission partial half-lives
Background: The process of beta-delayed fission (bDF) provides a versatile
tool to study low-energy fission in nuclei far away from the beta-stability
line, especially for nuclei which do not fission spontaneously. Purpose: The
aim of this paper is to investigate systematic trends in bDF partial
half-lives. Method: A semi-phenomenological framework was developed to
systematically account for the behavior of bDF partial half-lives. Results: The
bDF partial half-life appears to exponentially depend on the difference between
the Q value for beta decay of the parent nucleus and the fission-barrier energy
of the daughter (after beta decay) product. Such dependence was found to arise
naturally from some simple theoretical considerations. Conclusions: This
systematic trend was confirmed for experimental bDF partial half-lives spanning
over 7 orders of magnitudes when using fission barriers calculated from either
the Thomas-Fermi or the liquid-drop fission model. The same dependence was also
observed, although less pronounced, when comparing to fission barriers from the
finite-range liquid-drop model or the Thomas-Fermi plus Strutinsky Integral
method.Comment: accepted for publication in Phys. Rev.
Pairing-excitation versus intruder states in 68Ni and 90Zr
A discussion on the nature of the 0+ states in 68Ni (Z=28, N=40) is presented
and a comparison is made with its valence counterpart 90Zr (Z=40, N=50).
Evidence is given for a 0+ proton intruder state at only ~2.2 MeV excitation
energy in 68Ni, while the analogous neutron intruder states in 90Zr reside at
4126 keV and 5441 keV. The application of a shell-model description of 0+
intruder states reveals that many pair-scattered neutrons across N=40 have to
be involved to explain the low excitation energy of the proton-intruder
configuration in 68Ni.Comment: 10 pages, 2 figures, 1 tabl
A Case of Urogenital Human Schistosomiasis from a Non-endemic Area
© 2015 Calvo-Cano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
Development of a thermal ionizer as ion catcher
An effective ion catcher is an important part of a radioactive beam facility
that is based on in-flight production. The catcher stops fast radioactive
products and emits them as singly charged slow ions. Current ion catchers are
based on stopping in He and H gas. However, with increasing intensity of
the secondary beam the amount of ion-electron pairs created eventually prevents
the electromagnetic extraction of the radioactive ions from the gas cell. In
contrast, such limitations are not present in thermal ionizers used with the
ISOL production technique. Therefore, at least for alkaline and alkaline earth
elements, a thermal ionizer should then be preferred. An important use of the
TRIP facility will be for precision measurements using atom traps. Atom
trapping is particularly possible for alkaline and alkaline earth isotopes. The
facility can produce up to 10 s of various Na isotopes with the
in-flight method. Therefore, we have built and tested a thermal ionizer. An
overview of the operation, design, construction, and commissioning of the
thermal ionizer for TRIP will be presented along with first results for
Na and Na.Comment: 10 pages, 4 figures, XVth International Conference on Electromagnetic
Isotope Separators and Techniques Related to their Applications (EMIS 2007
beta-decay study of Cu-77
A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator
with the aim to deduce its beta-decay properties and to obtain spectroscopic
information on Zn-77. Neutron-rich copper isotopes were produced by means of
proton- or neutron-induced fission reactions on U-238. After the production,
Cu-77 was selectively laser ionized, mass separated and sent to different
detection systems where beta-gamma and beta-n coincidence data were collected.
We report on the deduced half-live, decay scheme, and possible spin assignment
of 77Cu
Beta-delayed deuteron emission from 11Li: decay of the halo
The deuteron-emission channel in the beta-decay of the halo-nucleus 11Li was
measured at the ISAC facility at TRIUMF by implanting post-accelerated 11Li
ions into a segmented silicon detector. The events of interest were identified
by correlating the decays of 11Li 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) x 10-4 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 11Li, and that it proceeds mainly to the
9Li + d continuum, opening up a new means to study of the halo wave function of
11Li.Comment: 4 pages, 3 figure
Evolutionary Analysis of Mitogenomes from Parasitic and Free-Living Flatworms
Copyright: © 2015 Solà et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
Early onset of ground-state deformation in the neutron-deficient polonium isotopes
In-source resonant ionization laser spectroscopy of the even- polonium
isotopes Po has been performed using the
to ( nm) transition in the polonium atom
(Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope
shifts in Po with a previous data set allows to test for the first
time recent large-scale atomic calculations that are essential to extract the
changes in the mean-square charge radius of the atomic nucleus. When going to
lighter masses, a surprisingly large and early departure from sphericity is
observed, which is only partly reproduced by Beyond Mean Field calculations.Comment: As submitted to PR
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