A new movable 3PM-γ coincidence system, based on 4πβ(LS)−γ coincidence counting, for activity measurement of β-γ emitters has been designed at the Korea Research Institute of Standards and Science (KRISS). The system incorporates 3 PM tubes on the plane and two detectors placed above and below the center of the plane. The 3 PM tubes for β–counters in the plane are movable up to 100 mm from a liquid scintillation vial, thus enabling the variation of β−detection efficiencies by a geometrical technique. A NaI(Tl) γ-counter was set above for the present work. The β-event is determined by counting the logical sum of three double coincidences. All the necessary electronics, i.e., logical sum, adjusting the duration of dead-time of each counting channel and coincidence resolving times, and analyzing coincidence relation, were specially designed to be fabricated in an integrated circuit. Details of the detectors, the electronics, the overall movable 3PM-γ coincidence system are presented, as well as the results of investigations to assess its operating characteristics. Validation measurements have been performed with ⁶⁰Co and ⁵⁷Co sources. The highest β−detection efficiency achieved with ⁶⁰Co and ⁵⁷Co was 97% and 95%, respectively. The activity concentration determined with a new system agreed with calibrated values within the uncertainty range. Further results from validation measurements and the corresponding uncertainty budgets are presented.

韩国标准科学研究院（KRISS）设计了一种新的可移动3PM-γ符合系统，该系统基于4πβ（LS）-γ符合计数，用于测量β-γ发射体的活性。该系统在飞机上装有3个PM管，并在飞机中心上方和下方装有两个探测器。平面中用于β计数器的3个PM管可从液体闪烁小瓶移动到100 mm，从而可以通过几何技术改变β-检测效率。上面为当前工作设置了NaI（Tl）γ计数器。β事件是通过对三个双重符合的逻辑和进行计数来确定的。所有必要的电子元件，即逻辑和，调整每个计数通道的停滞时间的持续时间和重合解决时间，以及分析重合关系，专为在集成电路中制造而设计。介绍了探测器，电子设备，整个可移动3PM-γ符合系统的详细信息，以及评估其工作特性的调查结果。验证测量已通过⁶⁰ Co和⁵⁷ Co来源。用⁶⁰ Co和⁵⁷ Co达到的最高β-检测效率分别为97％和95％。用新系统测定的活性浓度与不确定度范围内的校准值一致。给出了验证测量和相应不确定性预算的进一步结果。