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Recycling
The environmental problems generated by our consumer societies require immediate measures that respect the principles of long term sustainability. However, in response to the rising amount of wastes (on average, per capita arising municipal wastes increased by 26
between 1970 and the late 1980s in the OECD) various (mostly end-of-pipe) waste management strategies have been advocated, while a real questioning of what constitutes
'wastes' is still desperately needed
Transport of a quantum degenerate heteronuclear Bose-Fermi mixture in a harmonic trap
We report on the transport of mixed quantum degenerate gases of bosonic 87Rb
and fermionic 40K in a harmonic potential provided by a modified QUIC trap. The
samples are transported over a distance of 6 mm to the geometric center of the
anti-Helmholtz coils of the QUIC trap. This transport mechanism was implemented
by a small modification of the QUIC trap and is free of losses and heating. It
allows all experiments using QUIC traps to use the highly homogeneous magnetic
fields that can be created in the center of a QUIC trap and improves the
optical access to the atoms, e.g., for experiments with optical lattices. This
mechanism may be cascaded to cover even larger distances for applications with
quantum degenerate samples.Comment: 7 pages, 8 figure
On kaonic hydrogen. Quantum field theoretic and relativistic covariant approach
We study kaonic hydrogen, the bound K^-p state A_(Kp). Within a quantum field
theoretic and relativistic covariant approach we derive the energy level
displacement of the ground state of kaonic hydrogen in terms of the amplitude
of K^-p scattering for arbitrary relative momenta. The amplitude of low-energy
K^-p scattering near threshold is defined by the contributions of three
resonances Lambda(1405), Lambda(1800) and Sigma^0(1750) and a smooth elastic
background. The amplitudes of inelastic channels of low-energy K^-p scattering
fit experimental data on near threshold behaviour of the cross sections and the
experimental data by the DEAR Collaboration. We use the soft-pion technique
(leading order in Chiral Perturbation Theory) for the calculation of the
partial width of the radiative decay of pionic hydrogen A_(pi p) -> n + gamma
and the Panofsky ratio. The theoretical prediction for the Panofsky ratio
agrees well with experimental data. We apply the soft-kaon technique (leading
order in Chiral Perturbation Theory) to the calculation of the partial widths
of radiative decays of kaonic hydrogen A_(Kp) -> Lambda^0 + gamma and A_(Kp) ->
Sigma^0 + gamma. We show that the contribution of these decays to the width of
the energy level of the ground state of kaonic hydrogen is less than 1%.Comment: 33 pages, 1 figure, latex, References are adde
Electron Scattering on 3He - a Playground to Test Nuclear Dynamics
The big spectrum of electron induced processes on 3He is illustrated by
several examples based on Faddeev calculations with modern nucleon-nucleon and
three-nucleon forces as well as exchange currents. The kinematical region is
restricted to a mostly nonrelativistic one where the three-nucleon c.m. energy
is below the pion production threshold and the three-momentum of the virtual
photon is sufficiently below the nucleon mass. Comparisons with available data
are shown and cases of agreement and disagreement are found. It is argued that
new and precise data are needed to systematically check the present day
dynamical ingredients.Comment: 27 pages, 24 figure
Strong Coulomb effects in hole-doped Heisenberg chains
Substances such as the ``telephone number compound''
Sr14Cu24O41 are intrinsically hole-doped. The involved interplay of spin and
charge dynamics is a challenge for theory. In this article we propose to
describe hole-doped Heisenberg spin rings by means of complete numerical
diagonalization of a Heisenberg Hamiltonian that depends parametrically on hole
positions and includes the screened Coulomb interaction among the holes. It is
demonstrated that key observables like magnetic susceptibility, specific heat,
and inelastic neutron scattering cross section depend sensitively on the
dielectric constant of the screened Coulomb potential.Comment: 5 pages, 6 figures, to be published in Eur. Phys. J.
Radial solitons in armchair carbon nanotubes
Radial solitons are investigated in armchair carbon nanotubes using a
generalized Lennard-Jones potential. The radial solitons are found in terms of
moving kink defects whose velocity obeys a dispersion relation. Effects of
lattice discreteness on the shape of kink defects are examined by estimating
the Peierls stress. Results suggest that the typical size for an unpinned kink
phase is of the order of a lattice spacing.Comment: 11 pages, 3(eps) figure
Accumulation of chromium metastable atoms into an Optical Trap
We report the fast accumulation of a large number of metastable 52Cr atoms in
a mixed trap, formed by the superposition of a strongly confining optical trap
and a quadrupolar magnetic trap. The steady state is reached after about 400
ms, providing a cloud of more than one million metastable atoms at a
temperature of about 100 microK, with a peak density of 10^{18} atoms.m^{-3}.
We have optimized the loading procedure, and measured the light shift of the
5D4 state by analyzing how the trapped atoms respond to a parametric
excitation. We compare this result to a theoretical evaluation based on the
available spectroscopic data for chromium atoms.Comment: 7 pages, 5 Figure
Probing the QCD equation of state with thermal photons in nucleus-nucleus collisions at RHIC
Thermal photon production at mid-rapidity in Au+Au reactions at
= 200 GeV is studied in the framework of a 2D+1 hydrodynamical
model that describes efficiently the bulk identified hadron spectra at RHIC.
The combined thermal plus NLO pQCD photon spectrum is in good agreement with
the yields measured by the PHENIX experiment for all Au+Au centralities. Within
our model, we demonstrate that the correlation of the thermal photon slopes
with the charged hadron multiplicity in each centrality bin provides direct
empirical information on the underlying degrees of freedom and on the equation
of state, , of the strongly interacting matter.Comment: Version to appear in EPJ-C (extended discussion and refs. and a few
corrections
Modeling the Pion and Kaon Form Factors in the Timelike Region
New, accurate measurements of the pion and kaon electromagnetic form factors
are expected in the near future from experiments at electron-positron
colliders,using the radiative return method. We construct a model for the
timelike pion electromagnetic form factor, that is valid also at momentum
transfers far above the resonance. The ansatz is based on vector
dominance and includes a pattern of radial excitations expected from dual
resonance models.The form factor is fitted to the existing data in the timelike
region, continued to the spacelike region and compared with the measurements
there and with the QCD predictions. Furthermore, the model is extended to the
kaon electromagnetic form factor. Using isospin and SU(3)-flavour symmetry
relations we extract the isospin-one contribution and predict the kaon weak
form factor accessible in semileptonic decays.Comment: 31 pages, 7 figures,latex, one reference changed, version to appear
in Eur.Phys.J
Near-threshold production of omega mesons in the pn -> d omega reaction
The first measurement of the p n -> d omega total cross section has been
achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium
cluster-jet target. The momentum of the fast deuteron was measured in the ANKE
spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from
the p d -> p(sp) d omega reaction in a silicon telescope placed close to the
target. The cross sections lie above those measured for p p -> p p omega but
seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has
been added; results changed insignificantly, EPJ in pres
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