459 research outputs found
Adiabatic noise-induced escape rate for nonequilibrium open systems
We consider the motion of an overdamped particle in a force field in presence
of an external, adiabatic noise, without the restriction that the noise process
is Gaussian or the stochastic process is Markovian. We examine the condition
for attainment of steady state for this nonequilibrium open system and
calculate the adiabatic noise-induced rate of escape of the particle over a
barrier.Comment: 6 pages, 3 figure
Modified Bloch equations in presence of a nonstationary bath
Based on the system-reservoir description we propose a simple solvable
microscopic model for a nonequilibrium bath. This captures the essential
features of a nonstationary quantum Markov process. We establish an appropriate
generalization of the fluctuation-dissipation relation pertaining to this
process and explore the essential modifications of the Bloch equations to
reveal the nonexponential decay of the Bloch vector components and transient
spectral broadening in resonance fluorescence. We discuss a simple experimental
scheme to verify the theoretical results.Comment: Revtex, 27 pages, 2 ps figures. To appear in European Physical
Journal
ATLAS IBL Pixel Upgrade
The upgrade for ATLAS detector will undergo different phase towards
super-LHC. The first upgrade for the Pixel detector will consist of the
construction of a new pixel layer which will be installed during the first
shutdown of the LHC machine (LHC phase-I upgrade). The new detector, called
Insertable B-Layer (IBL), will be inserted between the existing pixel detector
and a new (smaller radius) beam-pipe at a radius of 3.3 cm. The IBL will
require the development of several new technologies to cope with increase of
radiation or pixel occupancy and also to improve the physics performance which
will be achieved by reducing the pixel size and of the material budget. Three
different promising sensor technologies (planar-Si, 3D-Si and diamond) are
currently under investigation for the pixel detector. An overview of the
project with particular emphasis on pixel module is presented in this paper.Comment: 3 pages, 3 figures, presented at the 12th Topical Seminar on
Innovative Particle and Radiation Detectors (IPRD10) 7 - 10 June 2010, Siena
(IT). Accepted by Nuclear Physics B (Proceedings Supplements) (2011
Quantum Kramers' equation for energy diffusion and barrier crossing dynamics in the low friction regime
Based on a true phase space probability distribution function and an ensemble
averaging procedure we have recently developed [Phys. Rev. E 65, 021109 (2002)]
a non-Markovian quantum Kramers' equation to derive the quantum rate
coefficient for barrier crossing due to thermal activation and tunneling in the
intermediate to strong friction regime. We complement and extend this approach
to weak friction regime to derive quantum Kramers' equation in energy space and
the rate of decay from a metastable well. The theory is valid for arbitrary
temperature and noise correlation. We show that depending on the nature of the
potential there may be a net reduction of the total quantum rate below its
corresponding classical value which is in conformity with earlier observation.
The method is independent of path integral approaches and takes care of quantum
effects to all orders.Comment: 26 pages, RevTe
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