摘要
通过实验和模拟计算研究了无损检测用15MeV电子直线加速器X射线主束内的中子剂量．加速器采用了铜复合靶和钨加含硼聚乙烯的屏蔽结构,能够有效地减少光中子的产生,中子产额在 1/1000n/γ以下．但由于主束内光子剂量很大,中子的绝对强度也不容忽视．针对加速器周围强X射线脉冲辐射场的特点,采用了被动型的中子剂量测量方法,加速器正常工作情况下,使用CR-39片和双电离室测量了等中心处中子对X射线的剂量当量比率,分别为0．19mSv／Gy X-ray和0．060mSv／Gy X-ray．利用MCNP5模拟计算了实验相应点的中子对X射线的剂量当量比率,为0．092mSv／Gy X-ray,与实验测量结果在数量级上一致．加速器主射束上Dn／Dγ<1／1000,小于辐射防护标准对中子泄漏剂量的规定值,从而验证了屏蔽结构的安全性．
Photoneutrons produced in the 15MeV electron accelerator for radiography application were measured and calculated. With passive methods of CR-39 and TE/C ion chamber, the photoneutron dose at the isocenter was 0.19mSv/Gy X-ray and 0.06mSv/Gy X-ray. For comparison, the whole accelerator system was simulated by Monte-Carlo method of MCNP5. The ratio or the neutron dose and the photon dose was 0.092mSv/Gy X-ray, less than the limited value of radiation protection standard. The results of the measurement and the calculation agreed well in the same order.
出处
《高能物理与核物理》
CSCD
北大核心
2006年第z1期63-65,共3页
High Energy Physics and Nuclear Physics
基金
国家自然科学基金(10135040)资助~~
