Vortices in a Bose-Einstein condensate confined by an optical lattice

We investigate the dynamics of vortices in repulsive Bose-Einstein condensates in the presence of an optical lattice (OL) and a parabolic magnetic trap. The dynamics is sensitive to the phase of the OL potential relative to the magnetic trap, and depends less on the OL strength. For the cosinusoidal OL potential, a local minimum is generated at the trap's center, creating a stable equilibrium for the vortex, while in the case of the sinusoidal potential, the vortex is expelled from the center, demonstrating spiral motion. Cases where the vortex is created far from the trap's center are also studied, revealing slow outward-spiraling drift. Numerical results are explained in an analytical form by means of a variational approximation. Finally, motivated by a discrete model (which is tantamount to the case of the strong OL lattice), we present a novel type of vortex consisting of two pairs of anti-phase solitons.Comment: 10 pages, 6 figure

The Atmospheric Monitoring System of the JEM-EUSO space mission

An Atmospheric Monitoring System (AMS) is mandatory and a key element of a space-based mission which aims to detect Ultra-High Energy Cosmic Rays (UHECR). JEM-EUSO has a dedicated atmospheric monitoring system that plays a fundamental role in our understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. Our AMS consists of an infrared camera and a LIDAR device that are being fully designed with space qualification to fulfil the scientific requirements of this space mission. This AMS will provide information of the cloud cover in the FoV of JEM-EUSO, as well as measurements of the cloud top altitudes with an accuracy of 500 m and the optical depth profile of the atmosphere transmittance in the direction of each air shower with an accuracy of 0.15 degree and a resolution of 500 m. This will ensure that the energy of the primary UHECR and the depth of maximum development of the EAS (Extensive Air Shower) are measured with an accuracy better than 30% and 120 g/cm2, for EAS occurring either in the clear sky or with the EAS depth of maximum development above optically thick cloud layers. Moreover novel stereoscopic and radiometric retrieval techniques are under development to infer the Cloud Top Height (CTH) from the brightness temperature patterns obtained from the infrared camer