16,431 research outputs found
Reactions induced by Be in a four-body continuum-discretized coupled-channels framework
We investigate the elastic scattering of Be on Pb at beam
energies above (50 MeV) and below (40 MeV) the Coulomb barrier. The reaction is
described within a four-body framework using the Continuum-Discretized
Coupled-Channels (CDCC) method. The Be projectile states are generated
using the analytical Transformed Harmonic Oscillator (THO) basis in
hyperspherical coordinates. Our calculations confirm the importance of
continuum effects at low energies.Comment: 2 pages, 1 figure. Proceedings of the International Scientific
Meeting on Nuclear Physics, RABIDA15, La R\'abida (Spain), June 1-5, 201
Controlling the ellipticity of attosecond pulses produced by laser irradiation of overdense plasmas
The interaction of high-intensity laser pulses and solid targets provides a
promising way to create compact, tunable and bright XUV attosecond sources that
can become a unique tool for a variety of applications. However, it is
important to control the polarization state of this XUV radiation, and to do so
in the most efficient regime of generation. Using the relativistic electronic
spring (RES) model and particle-in-cell (PIC) simulations, we show that the
polarization state of the generated attosecond pulses can be tuned in a wide
range of parameters by adjusting the polarization and angle of incidence of the
laser radiation. In particular, we demonstrate the possibility of producing
circularly polarized attosecond pulses in a wide variety of setups.Comment: 6 pages, 3 figure
Analytical transformed harmonic oscillator basis for three-body nuclei of astrophysical interest: Application to 6He
Recently, a square-integrable discrete basis, obtained performing a simple
analytical local scale transformation to the harmonic oscillator basis, has
been proposed and successfully applied to study the properties of two-body
systems. Here, the method is generalized to study three-body systems. To test
the goodness of the formalism and establish its applicability and limitations,
the capture reaction rate for the nucleosynthesis of the Borromean nucleus 6He
(4He + n + n) is addressed. Results are compared with previous publications and
with calculations based on actual three-body continuum wave functions, which
can be generated for this simple case. The obtained results encourage the
application to other Borromean nuclei of astrophysical interest such as 9Be and
12C, for which actual three-body continuum calculations are very involved.Comment: Accepted in Phys. Rev.
Circumstellar rings, flat and flaring discs
Emission lines formed in the circumstellar envelopes of several type of stars
can be modeled using first principles of line formation. We present simple ways
of calculating line emission profiles formed in circumstellar envelopes having
different geometrical configurations. The fit of the observed line profiles
with the calculated ones may give first order estimates of the physical
parameters characterizing the line formation regions: opacity, size, particle
density distribution, velocity fields, excitation temperature.Comment: 3 pages ; to appear in the proceedings of the Sapporo meeting on
active OB stars ; ASP Conference Series ; eds: S. Stefl, S. Owocki and A.
Okazak
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