2,078 research outputs found
In-gas-cell laser ionization spectroscopy in the vicinity of 100Sn: Magnetic moments and mean-square charge radii of N=50-54 Ag
In-gas-cell laser ionization spectroscopy studies on the neutron deficient
97-101Ag isotopes have been performed with the LISOL setup. Magnetic dipole
moments and mean-square charge radii have been determined for the first time
with the exception of 101Ag, which was found in good agreement with previous
experimental values. The reported results allow tentatively assigning the spin
of 97,99Ag to 9/2 and confirming the presence of an isomeric state in these two
isotopes, whose collapsed hyperfine structure suggests a spin of 1/2 . The
effect of the N=50 shell closure is not only manifested in the magnetic moments
but also in the evolution of the mean-square charge radii of the isotopes
investigated, in accordance with the spherical droplet model predictions
Hole spin relaxation and coefficients in Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs
We investigate the temperature dependence of the coefficients in the
Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs by employing the Zener
model. We first calculate the hole spin relaxation time based on the
microscopic kinetic equation. We find that the hole spin relaxation time is
typically several tens femtoseconds and can present a nonmonotonic temperature
dependence due to the variation of the interband spin mixing, influenced by the
temperature related Zeeman splitting. With the hole spin relaxation time, we
are able to calculate the coefficients in the Landau-Lifshitz-Gilbert equation,
such as the Gilbert damping, nonadiabatic spin torque, spin stiffness and
vertical spin stiffness coefficients. We find that the nonadiabatic spin torque
coefficient is around at low temperature, which is
consistent with the experiment [Adam {\em et al.}, Phys. Rev. B {\bf 80},
193204 (2009)]. As the temperature increases, monotonically increases
and can exceed one in the vicinity of the Curie temperature. In the low
temperature regime with , the Gilbert damping coefficient
increases with temperature, showing good agreement with the experiments [Sinova
{\em et al.}, Phys. Rev. B {\bf 69}, 085209 (2004); Khazen {\em et al.}, {\em
ibid.} {\bf 78}, 195210 (2008)]. Furthermore, we predict that
decreases with increasing temperature once near the Curie
temperature. We also find that the spin stiffness decreases with increasing
temperature, especially near the Curie temperature due to the modification of
the finite . Similar to the Gilbert damping, the vertical spin stiffness
coefficient is also found to be nonmonotonically dependent on the temperature.Comment: 10 pages, 7 figure
Geographical variation in mortality from leukaemia and other cancers in England and Wales in relation to proximity to nuclear installations, 1969-78.
The distribution of mortality from 11 causes of death (lymphoid leukaemia, other leukaemia, leukaemia of all types, Hodgkin's disease, other lymphomas, all lymphomas, multiple myeloma, lung cancer, other malignancies, all malignancies and all other causes) has been examined in three age groups throughout England and Wales over the period 1969-78. The reorganisation of local authority administration in 1974 meant that the smallest areas that could be examined were 400 county districts or (in some cases) approximate county districts formed by aggregating pre-1974 local authority areas. The variation in the numbers of deaths observed about the numbers expected was assessed using log-linear models to estimate the effect on the relative risk in each district associated with social class, rural status, population size, health authority region and proximity to one of 15 nuclear installations. Trends in risk with increasing proximity to an installation (as judged by the proportion of the population resident within 10 miles) were examined after adjustment for the other four variables. The results showed that in districts near to an installation there were significant excess mortalities in persons under 25 years of age from leukaemia (RR = 1.15, P = 0.01) and especially from lymphoid leukaemia (RR 1.21, P = 0.01) and from Hodgkin's disease (RR 1.24, P = 0.05) and a significant deficiency of mortality from lymphoid leukaemia in persons aged 25-64 years. No significant trends were observed with an increasing proportion of the population near to the installations and the greatest excess mortality from lymphoid leukaemia in young persons was observed in the districts with the intermediate proportion of the population (10.0-65.9%) near an installation
More than sense of place? Exploring the emotional dimension of rural tourism experiences
It is widely suggested that participation in rural tourism is underpinned by a sense of rural place or “rurality”. However, although nature and the countryside have long been recognised as a source of spiritual or emotional fulfilment, few have explored the extent to which tourism, itself often claimed to be a sacred experience, offers an emotional/spiritual dimension in the rural context. This paper addresses that literature gap. Using in-depth interviews with rural tourists in the English Lake District, it explores the extent to which, within respondents’ individual understanding of spirituality, a relationship exists between sense of place and deeper, emotional experiences and, especially, whether participation in rural tourism may induce spiritual or emotional responses. The research revealed that all respondents felt a strong attachment to the Lake District; similarly, and irrespective of their openness to spirituality, engaging in rural tourism activities resulted in highly emotive experiences for all respondents, the description/interpretation of such experiences being determined by individual “beliefs”. However, sense of place was not a prerequisite to emotional or spiritual experiences. Being in and engaging with the landscape � effectively becoming part of it � especially through physical activity is fundamental to emotional responses
Orbital dependent nucleonic pairing in the lightest known isotopes of tin
By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we
observe low-lying states in 101Sn, the one-neutron system outside doubly magic
100Sn. We find that the spins of the ground state (J = 7=2) and first excited
state (J = 5=2) in 101Sn are reversed with respect to the traditional level
ordering postulated for 103Sn and the heavier tin isotopes. Through simple
arguments and state-of-the-art shell model calculations we explain this
unexpected switch in terms of a transition from the single-particle regime to
the collective mode in which orbital-dependent pairing correlations, dominate.Comment: 5 pages 3 figure
First observation of excited states in 173Hg
The neutron-deficient nucleus 173Hg has been studied following
fusion-evaporation reactions. The observation of gamma rays decaying from
excited states are reported for the first time and a tentative level scheme is
proposed. The proposed level scheme is discussed within the context of the
systematics of neighbouring neutron-deficient Hg nuclei. In addition to the
gamma-ray spectroscopy, the alpha decay of this nucleus has been measured
yielding superior precision to earlier measurements.Comment: 5 pages, 4 figure
Beta decay of 71,73Co; probing single particle states approaching doubly magic 78Ni
Low-energy excited states in 71,73Ni populated via the {\beta} decay of
71,73Co were investigated in an experiment performed at the National
Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU).
Detailed analysis led to the construction of level schemes of 71,73Ni, which
are interpreted using systematics and analyzed using shell model calculations.
The 5/2- states attributed to the the f5/2 orbital and positive parity 5/2+ and
7/2+ states from the g9/2 orbital have been identified in both 71,73Ni. In 71Ni
the location of a 1/2- {\beta}-decaying isomer is proposed and limits are
suggested as to the location of the isomer in 73Ni. The location of positive
parity cluster states are also identified in 71,73Ni. Beta-delayed neutron
branching ratios obtained from this data are given for both 71,73Co.Comment: Accepted for publication in PR
Boolean delay equations on networks: An application to economic damage propagation
We introduce economic models based on Boolean Delay Equations: this formalism
makes easier to take into account the complexity of the interactions between
firms and is particularly appropriate for studying the propagation of an
initial damage due to a catastrophe. Here we concentrate on simple cases, which
allow to understand the effects of multiple concurrent production paths as well
as the presence of stochasticity in the path time lengths or in the network
structure.
In absence of flexibility, the shortening of production of a single firm in
an isolated network with multiple connections usually ends up by attaining a
finite fraction of the firms or the whole economy, whereas the interactions
with the outside allow a partial recovering of the activity, giving rise to
periodic solutions with waves of damage which propagate across the structure.
The damage propagation speed is strongly dependent upon the topology. The
existence of multiple concurrent production paths does not necessarily imply a
slowing down of the propagation, which can be as fast as the shortest path.Comment: Latex, 52 pages with 22 eps figure
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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