Marian Smoluchowski
Institute of Physics

Spallation is a high-energy nuclear reaction in which a target nucleus struck by an incident particle of energy greater than about 50 MeV/nucleon ejects numerous nucleons and composite particles leaving the product nucleus significantly lighter than the original one.

The knowledge of the mechanism of spallation reactions is indispensable for understanding of various astrophysical phenomena as, e.g., modification of content of the cosmic rays (i.e. atomic nuclei) due to their propagation through the interstellar matter which is mainly built of protons. Such a knowledge is necessary for extraction of information on cosmic rays content at their source (e.g. heavy exploding stars) from their content observed in the Solar system.

The spallation reactions induced by protons found numerous technical and scientific applications due to the fact that they are accompanied by abundant emission of high energy neutrons as well as emission of exotic nuclei. All these applications as e.g., efficient operation of powerful neutron sources which are used in condensed matter and material studies, for transmutation of nuclear waste, for production of rare isotopes etc. are conditioned by good knowledge of the spallation reactions.

Unfortunately, all existing models of the spallation reactions are not able to predict results of the spallation reactions with the satisfactory accuracy. In recent publication of our group (ref. 1) we have shown that even the most basic, inclusive observables, i.e. ,isotopic production cross sections sigma(A,Z) are reproduced satisfactorily (i.e. with the accuracy of 10%) by the most involved present day models only for approximately 12 % of investigated cross sections.

Therefore our Kraków group takes intensively part in experimental and theoretical studies of the spallation reactions. In the next future we plan to perform theoretical investigation of data existing in the literature as well as to extract new observables from recent experiment of the HADES collaboration on p+Nb reactions at proton beam energy of 3.5 GeV.