2,529 research outputs found
The statistics of the trajectory in a certain billiard in a flat two-torus
We consider a billiard in the punctured torus obtained by removing a small
disk from the two-dimensional flat torus, with trajectory starting from the
center of the puncture. In this case the phase space is given by the range of
the velocity only. We prove that the probability measures on
associated with the first exit time are weakly convergent when the size of the
puncture tends to zero and explicitly compute the density of the limit.Comment: 21 pages, 6 figure
Two-dimensional nuclear inertia : analytical relationships
The components of the nuclear inertia tensor, functions of the separation distance R and of the radius of the light fragment R2, BRR(R,R2), BRR2(R,R2), and BR2R2(R,R2) are calculated within the Werner-Wheeler approximation, by using the parametrization of two intersected symmetric or asymmetric spheres. Analytical relationships are derived. When projected to a path R2=R2(R), the reduced mass is obtained at the touching point. The two one-dimensional parametrizations with R2=const, and the volume V2=const previously studied, are found to be particular cases of the present more general approach. Illustrations for the cold fission, cluster radioactivity, and α decay of 252Cf are given
Potential energy surfaces for cluster emitting nuclei
Potential energy surfaces are calculated by using the most advanced
asymmetric two-center shell model allowing to obtain shell and pairing
corrections which are added to the Yukawa-plus-exponential model deformation
energy. Shell effects are of crucial importance for experimental observation of
spontaneous disintegration by heavy ion emission. Results for 222Ra, 232U,
236Pu and 242Cm illustrate the main ideas and show for the first time for a
cluster emitter a potential barrier obtained by using the
macroscopic-microscopic method.Comment: 10 pages, 21 figures, revtex
New island of cluster emitters
A new region of proton-rich parent nuclei decaying by spontaneous cluster emission with a measurable branching ratio relative to alpha decay is predicted within the analytical superasymmetric fission model. After a brief presentation of the model and of the seven mass tables used to calculate the released energy, the obtained results are discussed. Measurable half-lives and branching ratios are estimated for 12C, 16O, 28Si, and other cluster radioactivities of some nuclides having proton and neutron numbers in the range Z=56â64 and N=58â72. Such nuclei far from stability could be produced in reactions induced by radioactive beams
T-duality of the Green-Schwarz superstring
We study T-duality in the Green-Schwarz formalism to all orders in superspace
coordinates. We find two analogs of Buscher rules for the supervielbein and
clarify their meaning from the superstring point of view. The transformation
rules for the dilaton, spin 1/2 fermions and Ramond-Ramond superfields are also
derived.Comment: 21 pages, late
Polarized neutron channeling as a tool for the investigations of weakly magnetic thin films
We present and apply a new method to measure directly weak magnetization in
thin films. The polarization of a neutron beam channeling through a thin film
structure is measured after exiting the structure edge as a microbeam. We have
applied the method to a tri-layer thin film structure acting as a planar
waveguide for polarized neutrons. The middle guiding layer is a rare earth
based ferrimagnetic material TbCo5 with a low magnetization of about 20 mT. We
demonstrate that the channeling method is more sensitive than the specular
neutron reflection method
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