538 research outputs found
Route to Direct Multiphoton Multiple Ionization
We address the concept of direct multiphoton multiple ionization in atoms
exposed to intense, short wavelength radiation and explore the conditions under
which such processes dominate over the sequential. Their contribution is shown
to be quite robust, even under intensity fluctuations and interaction volume
integration, and reasonable agreement with experimental data is also found.Comment: Close to the version to be published in Phys. Rev. A. Additional
supplementary material can be found ther
Evaluation of Compton scattering sequence reconstruction algorithms for a portable position sensitive radioactivity detector based on pixelated Cd(Zn)Te crystals
We present extensive simulation studies on the performance of algorithms for
the Compton sequence reconstruction used for the development of a portable
spectroscopic instrument (COCAE), with the capability to localize and identify
radioactive sources, by exploiting the Compton scattering imaging. Various
Compton Sequence reconstruction algorithms have been compared using a large
number of simulated events. These algorithms are based on Compton kinematics,
as well as on statistical test criteria that exploit the redundant information
of events having two or more photon interactions in the active detector's
volume. The efficiency of the best performing technique is estimated for a wide
range of incident gamma-ray photons emitted from point-like gamma sources.Comment: 16 pages, 17 figure
Electronic structure and carrier transfer in B-DNA monomer polymers and dimer polymers: Stationary and time-dependent aspects of wire model vs. extended ladder model
We employ two Tight-Binding (TB) approaches to study the electronic structure
and hole or electron transfer in B-DNA monomer polymers and dimer polymers made
up of monomers (base pairs): (I) at the base-pair level, using the on-site
energies of base pairs and the hopping integrals between successive base pairs,
i.e., a wire model and (II) at the single-base level, using the on-site
energies of the bases and the hopping integrals between neighboring bases,
i.e., an \textit{extended} ladder model since we also include diagonal
hoppings. We solve a system of ("matrix dimension") coupled equations [(I)
= , (II) = ] for the time-independent problem, and a system of
coupled order differential equations for the time-dependent
problem. We study the HOMO and the LUMO eigenspectra, the occupation
probabilities, the Density of States (DOS) and the HOMO-LUMO gap as well as the
mean over time probabilities to find the carrier at each site [(I) base pair or
(II) base)], the Fourier spectra, which reflect the frequency content of charge
transfer (CT) and the pure mean transfer rates from a certain site to another.
The two TB approaches give coherent, complementary aspects of electronic
properties and charge transfer in B-DNA monomer polymers and dimer polymers.Comment: 20 pages, 23 figure
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