The present invention provides scintillation material having good stability at continuous operating temperatures of at least 175° C. The scintillation material includes a cross linked copolymer with improved aromatic character that form a host plastic having properties of a thermoset polymer. The host plastic contains a primary fluorescent agent and a wavelength shifter. Preferably, the copolymer is comprised of a styrene derivative such as, for example, p-t-butylstyrene, and a higher melting point compound such as, for example, 4-vinylbiphenyl. In accordance with one aspect of the present invention, the scintillation material possesses properties of: good mechanical properties at high temperature (e.g., a Tg of about 180° C.); excellent light output (e.g., energy transfer efficiency); high hydrogen content for fast neutron detection; good optical transparency; and stable operation at temperature.