Potential investigation for ZnS using Crystal-GRID high-precision gamma spectroscopy and MD computer simulations

Crystal-GRID is a new and complementary method for studying interatomic potentials in crystals at intermediate energies between 1 eV and 1 keV. After a neutron capture reaction a first photon emission leads to a recoil of the still excited nucleus. While moving through the crystal a second photon is emitted. When observing many recoil events a structured and Doppler broadened gamma line shape is obtained due to the anisotropic slowing down in the crystal. Experimental findings from the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL are compared to predictions from molecular dynamics (MD) simulations. Thereby information about the interatomic potential can be obtained. Results will be presented for ZnS single crystals, showing that the universal screened Coulomb potentials (ZBL, KrC) are not appropriate in the examined energy region. A new potential for that region will be presented.