A method of spontaneous deposition of 210Po on a silver disc was used to prepare the standard plane source in a 210Pb solution. The prepared source was measured by an alpha spectrometer. There was a unique alpha peak of 5.304 MeV with a full width at half maximum of 23.92 keV in the measured spectrum. A plateau length of about 1000 V was given in the plateau curve measued with a multi-wire proportional counter. The determined surface emission rate was 2.565 ×104 min-1 at JAN. 3RD , 2019, with the extended uncertainty of 2.7% (k=2). Some MPC9604 gas-flow low background gross alpha and gross beta counters were used to test the source according to the verification regulation JJG 1100-2014. All the α detection efficiencies were not less than 77%, the repeatability within 1.5% and the α interference to β channel not greater than 2.5%. It’s showed that the prepared source was in good quality and performance to meet the calibration of gas-flow low background gross alpha and gross beta counters.

实验确认治疗束的谱源项参数是硼中子俘获治疗(BNCT)物理剂量学研究的重要环节之一,全面细致地掌握相关信息,对精准制定临床治疗计划进而准确评估患者的给予剂量十分重要.为验证理论计算源项光子能谱的可靠性,设计适用于BNCT治疗束特点(宽能量范围、高强度n/γ混合束)的新型光子谱仪.通过蒙特卡罗模拟方法优化探测器内的中子注量率、光子计数率及次级光子占比(次级光子计数率/初级光子计数率)三个重要参数,在降低辐射强度以避免探测器的辐射损伤和死时间过大的同时,尽可能抑制中子诱导次级光子的产生,将次级光子占比降至5.45,以实现BNCT治疗束光子谱的快速准确测量.同时,开展谱仪对不同能量光子响应的校准方法研究,以便得到准确的响应函数,为光子谱的解谱工作奠定基础.

利用大面积低本底α电离室和反宇宙射线低本底γ谱仪对低本底测量中氡的影响和去除进行研究.大面积低本底α电离室采用流气模式充入高纯氮气去除探测器中的氡,可以将本底计数率从0.83/s降低到0.037/s,消除氡的影响.反宇宙射线低本底γ谱仪将高纯锗探测器液氮罐挥发出来的氮气充入屏蔽室中去除氡,可以将本底的计数率从0.31/s降低到0.11/s,并消除氡子体的干扰峰.该研究证实在低本底测量中氡的影响是显著的且对氡的去除是必要的.

为准确校准惰性气体监测仪对气体源的γ射线全能峰效率,制备了以可发性聚苯乙烯（EPS）颗粒为基质材料的马林杯放射性模拟气体标准源,模拟气体标准源装样密度为4.1 kg/m~3,其中含 241 Am、 109 Cd、 57 Co、 51 Cr等8种单能γ射线发射核素。利用该模拟气体标准源,对反应堆惰性气体现场监测仪的HPGe探测器γ射线全能峰效率进行了校准,校准覆盖能区为60～1 836 keV,校准的效率标准不确定度最大为4.4%。同时采用点源代表点法进行了效率校准,并将模拟气体标准源与代表点位置处的点源效率校准结果进行对比,发现在校准能区内二者的效率比不为常数,效率偏差最大达28%,通过效率传递系数可减小偏差,且可得到效率传递系数拟合曲线。最后在81 keV能量点处,得到模拟气体标准源与标准气体源的效率比为1.26,此值可作为模拟气体标准源的实际应用参考。

常用的元件破损在线监测方法受外在因素影响较大,以γ能谱中关键裂变产物核素比活度进行在线定量分析是一种可靠的元件破损监测方法.针对新型LaBr3 (Ce)元件破损监测仪,设计了元件破损模拟实验,对逸出的裂变产物采用HPGe和LaBr3 (Ce)探测器进行了对比测量.通过不同冷却时间γ能谱的核素分析,确定了135Xe,88Kr,138Xe,88Rb,138Cs等可作为LaBr3 (Ce)元件破损γ能谱监测的关键核素.同时,制备了覆盖能量范围(250～2 400) keY,含60Co,137Cs,133Ba;241Am,152Eu;109Cd,88Y,57Co及24Na的4组放射性标准溶液,在建立的效率校准系统上,校准了LaBr3 (Ce)在线监测仪的效率.在反应堆一次异常情况分析中,已校准的LaBr3 (Ce)元件破损监测仪对关键核素的现场分析结果与HPGe的取样分析结果一致,表明效率校准结果准确,校准方法可靠.

在核事故的条件下,边界土壤中的放射性分布难以确定,需研制一种含60Co、90Sr、137Cs、241Am等多种放射性核素的土壤标准物质,用于分析过程中的监督和校准.由于满足条件的受偶然放射性污染的土壤较难寻找,故采用人工添加目标放射性核素的方法制备放射性土壤标准物质.在制备过程中,土壤局部组成和颗粒大小的差异对所添加核素的吸附差别可能形成所谓的“热点”,造成最终标准物质的均匀性检验无法通过.为解决该难题,选择几个核素进行逐级添加与稀释制备土壤标准物质,并研究其在不同步骤中如溶液和固体粉末混合时和固体粉末的逐级稀释时的均匀性.通过单因素方差分析方法的检验证明,在制备方法进行改进后其均匀性满足要求,为下一步的正式制备奠定基础.

An ionization chamber was developed for measuring alpha particle emissivity at ultra-low background levels.The ionization chamber is filled with high purity gas and operated in flow mode.Consequently the ionization chamber is insensitive to muon showers in cosmic ray and gamma ray from environment.After removing the radon by flowing gas,the alpha background mostly emanates from different surfaces inside the chamber.The pulse shape analysis method was employed to distinguish the location of emanation of each alpha particle.While alpha particles from chamber surfaces are rejected,only alpha particles emanating from the sample are finally counted at ultra-low levels.The chamber has a 1 521 cm2 sample area and a background of 3×10-4 cm-2 · h-1.

According to the present situation that key nuclides in primary coolant can not be monitored in real-time ,various influencing factors of rapidly measuring nuclides were analyzed ,and the improved key nuclide method was proposed based on the decay prop-erties of nuclides .T he results indicate that the speed and accuracy of measuring short-lived fission nuclides are improved by packet-segmentation measurement with portable γspectrometer .

To separate short-lived nuclide 138Cs or 89Rb from fission products,the separation could be started from their parent nuclides (Xe or Kr). A setup with frozen cold trap is designed to separate such kinds of inert gas nuclides. The principle is based on that different gases have different saturated vapor tensions. With isotopic exchanging technology,the setup has been applied successfully in the separation of 138Cs or 89Rb from complicated fission products. Decontamination factors of main γ-emitters are higher than 1 × 104.

The characteristic parameters of the neutron radiation fields produced by an in-hospital neutron irradiatior for boron neutron capture therapy(BNCT), such as neutron energy spectra, neutron flux density and neutron absorbed dose rate and their spatial distributions in free air, etc., were measured to verify the design effect. According to the traits of the irradiators, a measuring system composed of a multi-sphere spectrometer, a 235U fission ionization chamber, gold foils, a tissue equivalent proportional counter and thermoluminescent detectors was established. In order to improve the energy resolution in epithermal energy range and the ability to discriminate different neutron components, the Monte Carlo method was used for optimizing the detectors. The preliminary results show that the neutron flux densities of the irradiators achieve the expected levels.

Based on material shielding,a newly developed anti-cosmic low-background γ-ray spectrometer is used to conduct experimental study on background reduction of secondary cosmic muons and neutrons by combining anticoincidence shielding with thermal neutron shielding.The results show that the anticoincidence shielding(plastic scintillation detector) can reduce the μ background significantly on the HPGe detector,while effectively suppressing the background from the fast neutron inelastic scattering on the Ge crystal and shielding materials.The suppression factor of the anticoincidence integrated background is up to 8 in the energy region of 100-2000 keV.The addition of thermal neutron shielding(Cd absorber) can obviously reduce the background generated by the thermal neutron captured in the Ge and shielding materials,increasing the suppression factor of 511 keV γ-ray annihilation peak background from 5.8 to 20.7,and the suppression factor of anticoincidence integrated background in 100-2000 keV to 13.2.

<正>建立了国内首台反宇宙射线低本底γ谱仪测量装置,结构示意图及电子学线路框图见图1。采用10cm厚的塑料闪烁体作为反宇宙射线屏蔽探测器,与被动的物质屏蔽方法相结合,有效降低了谱仪装置的环境天然放射性核素和宇宙射线本底。HPGe探测器相对效率105%,100～2000keV能区积分本底6.3min-1(2.6×10-2s-1),40K的1460.8keVγ射线本底峰计数率为4.4×10-4s-1,使用反符合技术后同样能区本底抑制系数可达

<正>铕-152在电离辐射计量领域各种标准测量装置具有广泛应用,如应用于γ谱仪的效率刻度。为了保证所研制的铕-152标准溶液放射性活度测量量值的准确、可靠,也为了实现国内相关实验室对该核素放射性活度测量量值的传递和统一及在放射性活度测量方面的能力验证,国防科技工业电离辐射一级计量站于2008年10月组织了铕-152放射性标准溶液活度测量比对工作。共有7个实验室参

<正>为了满足热功率为10μW水平的α和β放射源活度校准需要,研制了1台等温双杯活度微量热计测量装置。该装置采用半导体测温元件组合(Bi2Te3+Sb2Te3p型与Bi2Te3+Bi2Se3n型)作为测温元件、

A microcalorimeter used for radioactivity measuring of nuclides with pure β-emission was developed, and the dual-compensated isothermal microcalorimeter was designed. The best number of thermocouples was calculated. The data acquisition and processing software were programmed. The thermal power calibration for the equipment was carried out for designed and developed microcalorimeter. The uncertainty of calibration at 15 μW of input thermal power is within 2% for this microcalorimeter.

<正>133Ba在电离辐射计量领域各种标准测量装置的使用方面具有非常广泛的应用价值,比如应用于γ谱仪的效率刻度。为了更好地保证所研制的133Ba标准溶液放射性活度测量量值的准确可靠,

A comparison on determining activities of 238U and 232Th based on transfer samples is reported in the paper. Especially, disturbance of X-ray from out-sources i.e. non-nucleus-self are studied and more detailed. And other factors that influence this time comparison result are discussed too in the work. In the paper it is pointed out definitely that the characteristic peaks that are disturbed by characteristic X-rays from out-sources ought to be not adopted to determine activities of the samples. In final some associations of ideas for some investigation passed of environment radiation are also described.

A remarkable systemic error which was unknown in past long time has been indicated. The error appears in the calibration methods of determining activity of 238U is used with γ-spectrometer with high resolution. When the γ-ray of 92.6 keV as the characteristic radiation from 238U is used to determine the activity of 238U in natural environment samples, the disturbing radiation produced by external excitation (or called outer sourcing X-ray radiation) is the main problem. Because the X-ray intensity is changed with many indefinite factors, it is advised that the calibration methods should be put away. As the influence of the systemic errors has been left in some past research papers, the authors suggest that the data from those papers should be cited carefully and if possible the data ought to be re-determined.

<正>在放射源生产中,由于放射源的活度很高,量热计是一种方便有效的活度直接测量方法,在国内外得到广泛使用。量热计的原理是放射源在一定时间t内放出的射线能量的总和E除以它放出的射线的平均能量

OBJECTIVE:To investigate the influence of intraoperative implantation of radioactive (125)I seeds on healing of surgical anastomosis.METHODS:The jejunum was cut, and end-to-end anastomosis was made in 12 healthy dogs. In the experimental group (n = 8), the (125)I seeds were implanted into the two sides of the anastomosis. The total radiation dosage at the anastomosis was 116 Gy. The other 4 dogs were in the included control group. At the 7th, 14th postoperative day, specimens were obtained from 4 dogs in the experimental group and 2 dogs in the control group respectively. The healing of the anastomosis was observed grossly; hydroxyproline content, as well as histopathological and ultrastructural changes of the anastomotic tissue were studied.RESULTS:Gross observation showed healing of the anastomosis of the experimental animals. The hydroxyproline contents were 0.578 +/- 0.020 microg/mg proteins in the experimental group and 0.631 +/- 0.012 microg/mg proteins in the control group (P > 0.05). Histopathological and ultrastructural changes of the anastomotic tissue were not significant in healing as compared to the control group. One of 29 patients had anastomotic leakage.CONCLUSIONS:Intraoperative implantation of (125)I has no adverse effect on healing of surgical anastomosis; it is safe and feasible in clinical practice.