金刚石探测器脉冲响应特性实验研究

Experimental Study of the Impulse Response of a Diamond Detector

  • 摘要: 脉冲辐射场具有瞬时剂量率高、持续时间短的特性,传统核辐射探测器在脉冲辐射场中存在信号堆叠、离子复合、死时间等问题,难以实现对脉冲辐射剂量的准确测量。金刚石探测器具有禁带宽度大、载流子迁移率高、抗辐照能力强、时间响应快等优点,本研究利用毫秒级与纳秒级脉冲X射线参考辐射场、高剂量率γ照射装置对TW60019型单晶金刚石探测器开展脉冲辐射场响应特性测试。结果表明,金刚石探测器的单脉冲响应随脉冲剂量的增大而减小,探测器收集效率随单脉冲剂量的增大而减小。基于该实验现象,分析了人工合成金刚石薄膜中的杂质与缺陷对探测器收集效率的影响规律,讨论了在金刚石探测器信号收集过程中后端电子学系统对收集效率的影响,验证了金刚石探测器能够满足快响应、高瞬时剂量率的脉冲辐射测量要求,为后续进一步实现脉冲辐射剂量实时监测,解决医疗诊断、工业探伤等领域中广泛存在的脉冲辐射剂量监测技术需求提供了基础。

     

    Abstract: Pulsed radiation field is characterized by short duration and high instantaneous dose rate compared with steady state radiation field, and has been widely used in the development of new detectors, radiological examination, X-ray diagnosis, nuclear accident emergency response and scientific research. Traditional nuclear radiation detectors in the pulsed radiation field often have problems such as signal stacking, ion composite, dead time, etc., which makes it difficult to realize the accurate measurement of pulsed radiation dose. Diamond detectors have the advantages of large bandwidth, high carrier mobility, strong anti-irradiation ability, fast time response, etc. In this paper, we utilize millisecond and nanosecond pulsed X-ray reference radiation field, high dose rate γ irradiation device to carry out the pulsed radiation field response test of single crystal diamond detector TW60019 produced by German PTW company, and we conclude that: the single-pulse response of diamond detector decreases with the increase of pulsed dose, and the single-pulse response of the single-pulse detector decreases with the increase of pulsed dose, and the single-pulse response of the single-pulse detector increases with the increase of pulse dose. It is concluded that the single-pulse response of the diamond detector decreases with the increase of the pulse dose, and similar to the ion complex effect in the ionization chamber in the pulsed radiation field, the diamond detector also suffers from the phenomenon of unsaturated collection in the measurement of large-dose and short-time pulsed radiation, and the detector's collection efficiency decreases with the increase of the single-pulse dose. Based on the experimental phenomenon, the influence of impurities and defects in the synthetic diamond film on the collection efficiency of the detector is analyzed, the impact of back-end electronics systems on collection efficiency during diamond detector signal collection is discussed and it is verified that the diamond detector can meet the requirements of fast response and high instantaneous dose rate of pulsed radiation measurements, which provides a basis for the further realization of the real-time monitoring of the pulsed radiation dose and the solution of the widely existed technical needs of the pulsed radiation dose monitoring in the fields of medical diagnosis and industrial flaw detection. The detector has been used in the following fields: medical diagnosis, industrial flaw detection, etc.

     

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