Abstract: The measurement of tritium activity concentration in high-purity ³He gas products imposes stringent requirements on the detection limit and sample consumption of analytical devices. To address the requirements for measuring tritium activity concentration in high-purity ³He gas, this study developed an analytical device using a proportional counter as the detection component through structural design and material optimization. The key parameters of the device, such as plateau characteristics, detection efficiency, and detection limit, were systematically evaluated. The results show that the plateau length of the device is 150 V with a plateau slope of 4.31% per 100 V. The measured tritium signal spectrum shows significant differences from the background signal spectrum. The detection efficiency for tritium reaches 66.78%, and the detection limit is 2.55 Bq/L, with a sample consumption of only 2 mL per measurement. The device demonstrates reliable performance and provides effective technical support for accurate tritium measurement in high-purity ³He gas.

Key words: ³He gas, tritium analysis device, proportional counter, detection limit