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目的 研究用测量体表 2 4 Naγ初始计数率评价事故中子照射注量和剂量的新方法。方法 实验用拟人模体进行。模体由头、颈、躯干、臀部和上臂构成。模体中具有按中国参考人大小的模拟器官脑、肝、肺、心脏和真骨。软组织用组织当量材料 (液体 )替代。组织当量材料中的氢、氮、氧、碳的质量比为10 .6∶ 2 .5∶ 6 3.2∶ 2 3.7,密度为 1.0 0 7g/ cm3(2 0°C) ,肺的密度是 0 .3g/ cm3。一个 2 52 Cf中子源用于照射实验。中子对于模体的照射方向包括前面 (AP)、后面 (PA)、右侧 (RL AT)及左侧 (L L AT)。2 52 Cf中子源到模体的照射距离有 1.1,2 .1,3.1和 4 .1m。在照射后用 76 mm× 76 mm的 Na I和多道分析仪在模体体表的 8个位置测量 2 4 Naγ。结果 中子瞬时照射后 ,人体头顶部位的 2 4 Naγ在 1.36 8Me V到 2 .75 4Me V能量区间每单位中子注量产生的初始计数率 B随照射距离的增大而增大 ,但随照射方向的变化较小。如果模体内模拟器官和组织替代物中的钠含量与中国参考人一致 ,则可以推算出 B的最大值 Bm=0 .4 8× 10 - 7cm2 · s- 1 。结论 对于裂变中子照射 ,在事故后利用头顶部位测量到的 2 4 Naγ初始计数率及Bm 值可在几小时内估算出个人受照射的中子注量和剂量。按 10 min的计数时间 ,该方法的?
Objective To study a new method for measuring the dose and volume of accidental neutron irradiation by measuring the initial count rate of 24 Na γ in the body surface. Methods Experiments were performed using anthropomorphism. The motif consists of the head, neck, trunk, buttocks and upper arm. The phantom has brain, liver, lung, heart and true bone simulated by Chinese reference size. Soft tissue is replaced with tissue equivalent material (liquid). The mass ratio of hydrogen, nitrogen, oxygen and carbon in the tissue equivalent material is 10.6: 2.5: 6 3.2: 2 3.7, and the density is 1.0 07g / cm3 (20 ° C). The density of the lungs is zero. 3g / cm3. A 2 52 Cf neutron source was used for the irradiation experiment. The neutron irradiation direction for the phantom includes anterior (AP), posterior (PA), right (RL AT), and left (L L AT). 2 52 Cf neutron source to the phantom irradiation distance 1.1,2 .1,3.1 and 4. .1 m. After irradiation, 24 Na γ was measured at 8 positions on the body surface using I76 mm × 76 mm Na I and multi-channel analyzers. Results After the neutron instantaneous irradiation, the initial count rate B per unit neutron fluence of 24 Naγ in the head of the human body increased from 1.36 8Me V to 2.75 4Me V, but increased with the irradiation distance Changes in the direction of irradiation is small. If the amount of sodium in simulated phantom and tissue substitutes is the same as the Chinese reference, the maximum value of B, Bm = 0.48 × 10 -7 cm 2 · s -1, can be deduced. Conclusions For fission neutrons, the individual irradiated neutron fluence and dose can be estimated within a few hours using the initial 24 count rate and Bm values measured at the top of the head following an accident. Press 10 min count time, the method?