372 research outputs found
The DIRC-like FTOF: A Time-of-Flight Cherenkov Detector for Particle Identification at SuperB
International audienc
Comment on "Acoustics of tachyon Fermi gas" [E. Trojan and G.V. Vlasov, arXiv:1103.2276 (hep-ph)]
In contrast to Trojan and Vlasov [arXiv:1103.2276 (hep-ph)], it is found that
an ideal Fermi gas of tachyons has a subluminous velocity of sound for any
particle density and, therefore, the causality condition for a tachyon gas
holds always true. Also, an ideal Fermi gas of tachyons never possesses an
exotic equation of state with the pressure exceeding the energy density.Comment: 1 page + Ref
Underbarrier nucleation kinetics in a metastable quantum liquid near the spinodal
We develop a theory in order to describe the effect of relaxation in a
condensed medium upon the quantum decay of a metastable liquid near the
spinodal at low temperatures. We find that both the regime and the rate of
quantum nucleation strongly depend on the relaxation time and its temperature
behavior. The quantum nucleation rate slows down with the decrease of the
relaxation time. We also discuss the low temperature experiments on cavitation
in normal He and superfluid He at negative pressures. It is the sharp
distinctions in the high frequency sound mode and in the temperature behavior
of the relaxation time that make the quantum cavitation kinetics in He and
He completely different in kind.Comment: 10 pages, 2 figure
Two-instanton approximation to the Coulomb blockade problem
We develop the two-instanton approximation to the current-voltage
characteristic of a single electron transistor within the
Ambegaokar-Eckern-Sch\"on model. We determine the temperature and gate voltage
dependence of the Coulomb blockade oscillations of the conductance and the
effective charge. We find that a small (in comparison with the charging energy)
bias voltage leads to significant suppression of the Coulomb blockade
oscillations and to appearance of the bias-dependent phase shift
On the spectrum of facet crystallization waves at the smooth 4He crystal surface
The wavelike processes of crystallization and melting or crystallization
waves are well known to exist at the 4He crystal surface in the rough state.
Much less is known about crystallization waves for the 4He crystal surface in
the smooth well-faceted state below the roughening transition temperature. To
meet the lack, we analyze here the spectrum of facet crystallization waves and
its dependence upon the wavelength, perturbation amplitude, and the number of
possible facet steps distributed somehow over the wavelength. All the
distinctive features of facet crystallization waves from conventional waves at
the rough surface result from a nonanalytic cusplike behavior in the angle
dependence for the surface tension of smooth crystal facets.Comment: 7 pages, 3 figures, 1 tabl
Optical fiber beam loss monitor for the PHIL and ThomX facilities
ISBN 978-3-95450-132-8International audienceFiber beam loss monitor (FBLM) is an attractive solution to measure beam losses intensity and position in real time. It is a very useful tool, especially, for the commissioning and the beam alignment. In this article we report on the development of the FBLM at PHIL (PHotoinIector at LAL, Orsay, France) as a prototype of the beam loss monitor for the ThomX machine, the compact Compton based X-ray source being in the construction phase in Orsay
Backflow and dissipation during the quantum decay of a metastable Fermi liquid
The particle current in a metastable Fermi liquid against a first-order phase
transition is calculated at zero temperature. During fluctuations of a droplet
of the stable phase, in accordance with the conservation law, not only does an
unperturbed current arise from the continuity at the boundary, but a backflow
is induced by the density response. Quasiparticles carrying these currents are
scattered by the boundary, yielding a dissipative backflow around the droplet.
An energy of the hydrodynamic mass flow of the liquid and a friction force
exerted on the droplet by the quasiparticles have been obtained in terms of a
potential of their interaction with the droplet.Comment: 5 pages (REVTeX), to be published in Phys. Rev.
Energy relaxation in the spin-polarized disordered electron liquid
The energy relaxation in the spin-polarized disordered electron systems is
studied in the diffusive regime. We derived the quantum kinetic equation in
which the kernel of electron-electron collision integral explicitly depends on
the electron magnetization. As the consequence, the inelastic scattering rate
is found to have non-monotonic dependence on the spin polarization of the
electron system
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