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 $^3$He and superfluid $^4$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 $^3$He and $^4$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