5,682 research outputs found
Long range action in networks of chaotic elements
We show that under certain simple assumptions on the topology (structure) of
networks of strongly interacting chaotic elements a phenomenon of long range
action takes place, namely that the asymptotic (as time goes to infinity)
dynamics of an arbitrary large network is completely determined by its boundary
conditions. This phenomenon takes place under very mild and robust assumptions
on local dynamics with short range interactions. However, we show that it is
unstable with respect to arbitrarily weak local random perturbations.Comment: 15 page
Broad applications of diffusion bonding
Solid state joining of materials by diffusion bondin
Curved planar quantum wires with Dirichlet and Neumann boundary conditions
We investigate the discrete spectrum of the Hamiltonian describing a quantum
particle living in the two-dimensional curved strip. We impose the Dirichlet
and Neumann boundary conditions on opposite sides of the strip. The existence
of the discrete eigenvalue below the essential spectrum threshold depends on
the sign of the total bending angle for the asymptotically straight strips.Comment: 7 page
Stochastic stability versus localization in chaotic dynamical systems
We prove stochastic stability of chaotic maps for a general class of Markov
random perturbations (including singular ones) satisfying some kind of mixing
conditions. One of the consequences of this statement is the proof of Ulam's
conjecture about the approximation of the dynamics of a chaotic system by a
finite state Markov chain. Conditions under which the localization phenomenon
(i.e. stabilization of singular invariant measures) takes place are also
considered. Our main tools are the so called bounded variation approach
combined with the ergodic theorem of Ionescu-Tulcea and Marinescu, and a random
walk argument that we apply to prove the absence of ``traps'' under the action
of random perturbations.Comment: 27 pages, LaTe
Precision measurement of the half-life and the decay branches of 62Ga
In an experiment performed at the Accelerator Laboratory of the University of
Jyvaskyla, the beta-decay half-life of 62Ga has been studied with high
precision using the IGISOL technique. A half-life of T1/2 = 116.09(17)ms was
measured. Using beta-gamma coincidences, the gamma intensity of the 954keV
transition and an upper limit of the beta-decay feeding of the 0+_2 state have
been extracted. The present experimental results are compared to previous
measurements and their impact on our understanding of the weak interaction is
discussed.Comment: 7 pages, 7 figures, submitted to EPJ
Beta-decay branching ratios of 62Ga
Beta-decay branching ratios of 62Ga have been measured at the IGISOL facility
of the Accelerator Laboratory of the University of Jyvaskyla. 62Ga is one of
the heavier Tz = 0, 0+ -> 0+ beta-emitting nuclides used to determine the
vector coupling constant of the weak interaction and the Vud quark-mixing
matrix element. For part of the experimental studies presented here, the
JYFLTRAP facility has been employed to prepare isotopically pure beams of 62Ga.
The branching ratio obtained, BR= 99.893(24)%, for the super-allowed branch is
in agreement with previous measurements and allows to determine the ft value
and the universal Ft value for the super-allowed beta decay of 62Ga
TWO-PROTON RADIOACTIVITY: THE INTERESTING CASE OF 67Kr AND FURTHER STUDIES
We report on the observation of 67Kr that has been produced in an experiment
performed at the RIKEN/BigRIPS facility. The two-proton decay
of 67Kr has been evidenced and this nucleus is thus the fourth observed long
lived ground-state two-proton emitter, after 45Fe, 48Ni and 54Zn. In addition,
the decay of several isotopes in the mass region has been investigated.
While for previous cases of two-proton radioactivity, the theoretical models
could reproduce the measured data, this is not the case anymore for
67Kr. Two interpretations have been proposed to explain this discrepancy:
a transition between real two-proton and sequential decay or the influence
of deformation. These hypotheses will be tested in future experiments by
measuring the angular and energy correlations of the emitted proton
High-precision measurement of the half-life of Ga
The beta-decay half-life of 62Ga has been studied with high precision using
on-line mass separated samples. The decay of 62Ga which is dominated by a 0+ to
0+ transition to the ground state of 62Zn yields a half-life of T_{1/2} =
116.19(4) ms. This result is more precise than any previous measurement by
about a factor of four or more. The present value is in agreement with older
literature values, but slightly disagrees with a recent measurement. We
determine an error weighted average value of all experimental half-lives of
116.18(4) ms.Comment: 9 pages, 5 figures, accepted for publication in PR
Multicomponent dynamical systems: SRB measures and phase transitions
We discuss a notion of phase transitions in multicomponent systems and
clarify relations between deterministic chaotic and stochastic models of this
type of systems. Connections between various definitions of SRB measures are
considered as well.Comment: 13 pages, LaTeX 2
Local probing of coupled interfaces between two-dimensional electron and hole gases in oxide heterostructures by variable-temperature scanning tunneling spectroscopy
The electronic structure of an epitaxial oxide heterostructure containing two spatially separated two-dimensional conducting sheets, one electronlike (2DEG) and the other holelike (2DHG), has been investigated using variable temperature scanning tunneling spectroscopy. Heterostructures of LaAlO3/SrTiO3 bilayers on (001)-oriented SrTiO3 (STO) substrates provide the unique possibility to study the coupling between subnanometer spaced conducting interfaces. The band gap increases dramatically at low temperatures due to a blocking of the transition from the conduction band of the STO substrate to the top of the valence band of the STO capping layer. This prevents the replenishment of the depleted electrons in the capping layer from the underlying 2DEG and enables charging of the 2DHG by applying a negative sample bias voltage within the band gap region. At low temperatures the 2DHG can be probed separately with the proposed experimental geometry, although the 2DEG is located less than 1 nm belo
- …