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In Hyperball-J experiments, the lutetium oxyorthosilicate (Lu2SiO5:Ce, LSO) scintillators are constantly used to monitor and calibrate the Ge detectors. The LSO crystal has 176Lu as a natural radioactive source. A new CsI:Na crystal that contains a 133Ba radioactive source was developed in this study. This developed crystal can be used for detector calibration instead of LSO scintillators. The crystal was grown using a 2-zone vertical Bridgman method with a pulling speed of 0.5 mm/h. The CsI:Na, 133Ba crystal was cut to Φφ 10 mm x 5 mm. Under X-ray excitation, the emission band of the crystal was observed between 330 nm and 650 nm. The scintillation properties of the CsI:Na, 133Ba crystal such as light yield, energy resolution and decay time, were also measured using a 137Cs γ-ray source. A High Purity Germanium (HPGe) detector was used to estimate the radioactivity in the crystal. The γ-ray peaks were identiήed from 133Ba decay in the CsI:Na, 133Ba crystal with a HPGe detector.