Summary of studies of the η meson production with polarized proton beam at COSY‐11
We report on the COSY‐11 measurements of the analysing power for the pp→ppη reaction and interpret the results in the framework of the meson exchange models.
POLARIZATION PHENOMENA IN NUCLEAR REACTIONS.
The recent appearance of high-intensity polarized beams with a small energy spread has made feasible a number of experiments which could not have been considered just a few years ago. In many reactions, polarization parameters can often be measured almost as easily as cross sections. The volume of experimental data can thus be expected to increase rapidly; the results should be precise and reliable. The problem of explaining the measurements and drawing from them all the information about nuclear structure and nuclear reaction mechanisms that they contain is likely to severely challenge standard reaction theories.
Mass Loss History of Evolved Stars
We provide high-resolution maps of the circumstellar dust shells of several dozen Asymptotic Giant Branch (AGB) stars using data from the Spitzer space telescope Multiband Imaging Photometer (MIPS) imaged at 70μm. AGB stars are the major contributors of chemical elements such as carbon, oxygen and silicon, which are essential to the existence of life in the universe, through mass loss processes that take place at the surface of the star. We probe the spatial distribution of cold (∼40 K) dust grains in order to trace the history of mass loss from the observed radial density variation in these shells. Our images illustrate that different morphologies may evolve because AGB stars can already interact with the interstellar medium (ISM) that surrounds them even at these early stages of the AGB mass loss history. Relative motion of the star as well as the ISM with respect to the local environment may be of particular importance for shell structure evolution.