Exotic break-up modes in heavy ion reactions up to Fermi energies

We discussed recent studies, within the framework of transport theories, on heavy ion reactions between charge asymmetric systems, from low up to Fermi energies. We concentrated on the analysis of ternary breakup events of dynamical origin occurring in semi-central reactions, where the formation of excited systems in various conditions of shape, excitation energy and spin is observed. At beam energies around 20 A Me V, we showed how this fragmentation mode emerges from the combined action of surface(neck) instabilities and angular momentum effects, leading to the observation of three aligned massive fragments in the exit channel. At Fermi energies, a transition towards a prompt emission of small fragments from the neck region with larger relative velocity with respect to projectile and target remnants is observed. We also focus on isospin sensitive observables, aiming at extracting information on the density dependence of the isovector part of the nuclear effective interaction and of the nuclear symmetry energy.

A high-resolution self-consistent whole sky foreground model

The neutral hydrogen 21 cm line is potentially a very powerful probe of the observable universe, and a number of on-going experiments are trying to detect it at cosmological distances. However, the presence of strong foreground radiations such as the galactic synchrotron radiation, galactic free-free emission and extragalactic radio sources make it a very challenging task.For the design of 21 cm experiments and analysis of their data, simulation is an essential tool, and good sky foreground model is needed. With existing data the whole sky maps are available only in low angular resolutions or for limited patches of sky,which is inadequate in the simulation of these new 21 cm experiments. In this paper, we present the method of constructing a high resolution self-consistent sky model at low frequencies, which incorporates both diffuse foreground and point sources.Our diffuse map is constructed by generating physical foreground components including the galactic synchrotron emission and galactic free-free emission. The point source sample is generated using the actual data from the NRAO VLA Sky Survey(NVSS)and the Sydney University Molonglo Sky Survey(SUMSS) where they are available and complete in flux limit, and mock point sources according to statistical distributions. The entire model is made self-consistent by removing the integrated flux of the point sources from the diffuse map so that this part of radiation is not double counted. We show that with the point sources added, a significant angular power is introduced in the mock sky map, which may be important for foreground subtraction simulations.Our sky maps and point source catalogues are available to download.