Crystal growth and characterization of calcium metaborate scintillators

Calcium metaborate CaB2O4 single crystals were grown by the Czochralski (CZ) method with the radio-frequency (RF) heating system. In these crystals, a plane cleavage was observed along the growth direction. The crystals had an 80% transparency, and no absorption bands were detected in the 190–900 nm wavelength range. The 241Am 5.5 MeV α-ray-excited radioluminescence spectrum of CaB2O4 demonstrated a broad intrinsic luminescence peak at 300–400 nm, which originated from the lattice defects or an exciton-based emission. According to the pulse height spectrum, when irradiated by neutrons from a 252Cf source, the scintillation light yielded approximately 3200 photons per neutron (ph/n).