Fast timing detectors are an essential element in the experimental setup for time-of-flight (ToF) mass measurements of unstable nuclei. We have upgraded the scintillator detectors used in experiments at the National Superconducting Cyclotron Laboratory (NSCL) by increasing the number of photomultiplier tubes that read out their light signals to four per detector, and characterized them in a test experiment with ⁴⁸Ca beam at the NSCL. The new detectors achieved a time resolution ($\sigma$) of 7.5 ps. We systematically investigated different factors that affect their timing performance. In addition, we evaluated the ability of positioning the hitting points on the scintillator using the timing information and obtained a resolution ($\sigma$) below 1 mm for well-defined beam spots.

快速定时检测器是用于不稳定核的飞行时间（ToF）质量测量的实验装置中的基本要素。我们已经增加了在国家超导回旋加速器实验室（NSCL）的实验中使用的闪烁探测器的数量，增加了将每个探测器读出光信号的光电倍增管的数量增加到四个，并在NSCL的⁴⁸ Ca光束测试实验中对它们进行了表征。新的探测器达到了时间分辨率（$\sigma$）的7.5 ps。我们系统地研究了影响其计时性能的不同因素。此外，我们使用时间信息评估了将闪烁体定位在闪烁体上的能力，并获得了分辨率（$\sigma$）在1毫米以下以获得清晰的光束斑。