Crystal-GRID: What can we learn about interatomic solid state potentials?

Crystal-GRID is a new and complementary method for studying interatomic solid state potentials in the energy range 1 eV to 1 keV. Due to a neutron capture induced photon emission an atom of the crystal starts moving with an energy of some hundreds of eV. Information on the movement of this nuclear probe can be read out by measuring the Doppler shift of a second in-flight emitted photon. The amount of information depends strongly on the nuclear level lifetime in between the two photon emissions and on the interatomic interaction. Systematic theoretical investigations will be presented showing under which requirements, e.g. for count rates or lifetimes, interatomic potentials can be investigated. Experimental results for ZnS and TiO2 will be presented. In these cases it was possible to simultaneously extract the nuclear level lifetime and the screening length of the screened Coulomb potential.