Ga2O3 crystals doped with nominally 1% ns(2) ions (In, T1, Sn, Pb, Sb and Bi) were synthesized by the Floating Zone (FZ) method, and we systematically evaluated the optical and scintillation properties. The peak emission was observed around 2.8 eV in photoluminescence (PL) under the excitation energy of 4.68 eV and around 3.0 eV in scintillation under X-ray irradiation. The PL and scintillation decay times were approximated by a sum of three exponential decay functions; and the derived decay times ranged several tens of nanoseconds, hundreds of nanoseconds and several microseconds. The slowest component was ascribed to the nsnp-ns(2) transitions while the fastest and intermediate components were blamed for the defect-related emission. Among the present samples, Sn-doped Ga2O3 showed the highest scintillation light yield. (C) 2017 Elsevier Ltd. All rights reserved.