GAIN - GAllium In the slow Neutron capture process

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The explanation of the origin of heavy elements in the Universe is a fascinating and interdisciplinary challenge. When we look at the Sun and the elements on Earth, we see the combined results of the production of elements in stars. Starting from the lightest element Hydrogen, passing elements like Carbon and Iron, stars can produce all the elements up to Lead or even Uranium. All these elements are necessary for our life on earth. We aim at reproducing the abundances of the elements by nuclear reaction measurements in the laboratory and nucleosynthesis simulations on large computer farms.Most of the elements heavier then Iron are produced by neutron capture reactions. An atom consists of a nucleus with positively charged protons and uncharged neutrons. A nucleus can capture a neutron and thereby increase its mass. After one or more neutron captures the nucleus may become unstable, and a neutron will convert into a proton. With the additional proton, the atom belongs to the next heavier element.The slow neutron capture process takes place in massive stars which are more than eight times heavier than our Sun. The nuclei capture neutrons at a time scale of a few years. The heavy elements are formed over a period of ten thousands of years. The element Gallium is produced in this scenario. However, accurate data for the probability of neutron capture reactions that produce or destroy Gallium are not available. The project GAIN therefore aims at measuring the probabilities of neutron capture reactions on Gallium with two complementary methods. The data will be used to run nucleosynthesis simulations to quantify the amount of Gallium which different stars produce. Following the evolution of the Galaxy, where many generations of stars successively produced heavy elements, we will obtain accurate abundances and compare them to the observed abundances in our Solar System.