The research of the Nuclear Chemistry Group explores fundamental properties of nuclear matter and the dynamics of complex nuclear reactions induced by heavy ions or relativistic protons/antiprotons. Such information is relevant for understanding the structure of cosmological objects (neutron stars), as well as for processes like the production of heavy elements during the evolution of stars, the generation of cosmic rays, and supernova dynamics. Experimental and theoretical studies of nuclear fragmentation into clusters are conducted to explore in-medium nucleonic interactions and microscopic correlations. This research contributes to the fundamental interdisciplinary task of understanding formation, decay, and properties of clusters as microscopic, quantum objects. New accelerator facilities have opened a new area of research: the study of phenomena associated with the neutron-proton asymmetry, e.g., the isospin dependence of nuclear interactions and of the nuclear equation of state.
Interesting reaction phenomena include the survival of massive projectile and target remnants even in energetic head-on collisions, as well as the emission of simple and complex nuclear fragments on a fast time scale. Consistency and kinematics of these products are indicative of non-equilibrium cluster decay processes reminiscent of the sudden fracture of disordered media. Specific goals of the research program include tests for the equilibration of excitation energies and mass-to-charge densities of colliding projectile and target nuclei. A search is being conducted for limits to the stability of hot nuclear systems undergoing novel decay processes. This study utilizes relativistic protons and antiprotons, in addition to heavy ions.
Relativistic nucleons are also used to induce cascades of spallation reactions in different materials, processes which are both of theoretical interest and practical relevance for the transmutation of materials.
Unique experimental techniques employed by the nuclear chemistry group include the use of combinations of highly efficient 4p charged-particle detector arrays and neutron calorimeters, of sophisticated time-of -flight spectrometers, multi-element solid-state detectors, and detector telescopes of broad dynamic range. The group develops signal-processing electronics at the leading edge of present-day technology. Experiments have been performed at various nuclear research centers in the United States and Europe.
