Showing 4677–4690 of 4,998 results for "A. Vasiliev"

Journals 2016 EN

Generation of 3D ellipsoidal laser beams by means of a profiled volume chirped Bragg grating

Sergey Mironov · A. Poteomkin · E. I. Gacheva +7 more

A method for shaping photocathode laser driver pulses into 3D ellipsoidal form has been proposed and implemented. The key idea of the method is to use a chirped Bragg grating recorded within the ellipsoid volume and absent outside it. If a beam with a constant (within the grating reflection band) spectral density and uniform (within the grating aperture) cross-section is incident on such a grating, the reflected beam will be a 3D ellipsoid in space and time. 3D ellipsoidal beams were obtained in experiment for the first time. It is expected that such laser beams will allow the electron bunch emittance to be reduced when applied at R± photo injectors.

IOP Publishing
Journals 2016 EN

Strange hadron production at SIS energies: an update from HADES

M. Lorenz · J. Adamczewski-Musch · O. Arnold +102 more

We present and discuss recent experimental activities of the HADES collaboration on open and hidden strangeness production close or below the elementary NN threshold. Special emphasis is put on the feed-down from φ mesons to antikaons, the presence of the Ξ− excess in cold nuclear matter and the comparison of statistical model rates to elementary p+p data. The implications for the interpretation of heavy-ion data are discussed as well.

IOP Publishing
Journals 2016 EN

Trapped positrons observed by PAMELA experiment

V. V. Mikhailov · О. Адриани · G. C. Barbarino +56 more

Measurements of electron and positron spatial distributions in energy range from 80 MeV to several GeV below the geomagnetic cutoff rigidity were carried out using the PAMELA magnetic spectrometer. The instrument is installed on board the Resurs-DK satellite which was launched June 15th 2006 on an elliptical orbit with the inclination 70 degrees and the altitude 350-600 km. The procedure of trajectories calculations in the geomagnetic filed gives a way to separate stably trapped and short lived albedo components produced in interactions of cosmic ray protons with the residual atmosphere. The work presents spatial distributions of trapped, quasitrapped and short-lived albedo electrons and positrons in the near Earth space. Electron to positron ratio points out on different production mechanism of trapped and quasitrapped particles.

IOP Publishing