BESⅢ漂移室模型的宇宙线测试

利用宇宙线并采用新设计的前置放大器测试了一个BESⅢ漂移室模型在He／C3H8(60／40)下的性能。模型在2200V工作高压下空间分辨达到100μm。这表明了BESⅢ漂移室的物理设计能满足其对空间分辨的要求，前置放大器的设计是成功的。为进一步检验BESⅢ漂移室物理设计需要对模型进行束流测试。     

BESIII漂移室模型的宇宙线测试

利用宇宙线并采用新设计的前置放大器测试了一个BESIII漂移室模型在He/C3H8(60/40)下的性能.模型在2200V工作高压下空间分辨达到100μm.这表明了BESIII漂移室的物理设计能满足其对空间分辨的要求,前置放大器的设计是成功的.为进一步检验BESIII漂移室物理设计需要对模型进行束流测试.     

在He/C3H8(60/40)混合气体中电子的漂移和倍增

报道用均匀场漂移室测量得到在He/C3H8 (60/40) 混合气体中的电子饱和漂移速度为3.8cm/μs.气体增益在2×104以上将出现饱和效应.由于很好地降低了放大器的噪音干扰,在55Fe能谱的低端观察到1.5keV Al的特征KX射线在He原子上产生的的全能光电峰.     

天体物理感兴趣的^2H（^8Li，^9Li）^1H反应截面测量

大爆炸原初核合成的标准模型假定重子密度均匀分布,由于没有A =5和 8的稳定核,核合成的反应流在该处终止。在重子密度不均匀的非标准原初核合成模型 [1] 中,该稳定核空隙可通过4He(3H,?7Li(n,?8Li(幔琻)11B(n,?12B(e-n)12C...4He(3H,)7Li(n,?8Li(n,?9Li(e-n)9Be(n,?10Be(     

几种常用漂移室单元电场的测量

近几年来:由于漂移室具有’一系列优越性能,使它住原子核物理、宇宙线、X射线晶体学、生物学、核医学等方面展示了广阔的应用前景。 漂移室的大小由从几厘米到2—3米,丝数从几十恨到几万根,都是由若干漂移小单元组成。漂移小单元内各电极的几何位置及所加电压的大小决定了电场等电位面的形状及电场强度的分布。漂移室的工作原理是基于电子在电场中的漂移。当带电粒子穿过凛移室     

锆基MOF材料Zr-CAU-24对Th（Ⅳ）和Ce（Ⅳ）的吸附性能研究

<正>Zr-CAU-24是一种具有小孔径、结构稳定的新型锆基MOF材料,晶体结构中具有八面体和四面体两种孔笼结构,孔笼内径分别为5.3×10.5?和2.4×3.5?,具有良好的吸附性能。本研究使用硝酸锆(98%,ZrO(NO_3)_2·xH_2O)为反应原料,以1,2,4,5-四(四羧基苯基)苯(98%,H_4TCPB)为配体,在100℃下水热反应12h制得Zr-CAU-24晶体,晶体产率为60%(基于配体H4TCPB)。使用ASAP-2020容量吸附装置(超高纯级He,99.999%)测     

4．8m63外冷式隔板冷凝器在UF6生产过程中的应用研究

研究分析了4．8m^3外冷式隔板冷凝器在成品混合气中的UF6捕集、固态UF6液化、液相UF6转移等单元操作过程中各种影响因素的作用规律，探讨了其在UF6生产过程中的使用效果。研究结果表明：4．8m^3外冷式隔板冷凝器具有安全性能好、UF6冷凝装填量大、耗能低的特点，适于立式炉氟化反应器、卧式氟化反应器、卧式炉氟化反应器成品混合气的收集。该冷凝器的结构简单、运行中性能稳定、连续能力强、操作方便、易于控制和调节。     

用屏栅电离室测量~6Li(n,t)~4He反应微分截面

用屏栅电离室对 3.6 7MeV与 4 .4 2MeV中子6Li(n ,t) 4He反应微分截面进行了测量。利用氘气体靶通过D(d ,n) 3 He反应产生中子 ,用BF3 和液闪探测器 (NE2 13)进行相对中子通量监测 ,绝对中子通量用2 3 8U(n ,f)与H(n ,p)反应来刻度。测量结果表明 ,氚的质心系微分截面在中子能量为 3.6 7MeV时很接近 90°对称 ,而到 4 .4 2MeV时则明显前倾     

Ar+CH4混合气体中电子漂移速率的双栅法测量

提出了一种快速、准确测量电子在气体中漂移速率的新方法。通过分析电子在双栅电离室中两个栅极上产生的感应信号波形来确定电子漂移的起止时刻,从而得出电子在一定约化场强下的漂移速率。采用数据采集卡（waveformdigitizer）对电离室的极板信号进行记录。测量了电子在8种混合比例的Ar+CH₄气体中漂移速率随约化场强的变化曲线。通过分析实验数据,得到任意混合比例的Ar+CH₄气体中电子漂移速率的计算公式。     

环境和生物样品中3H和14C的测量

研究了环境和生物样品中^3H和^14C的测量方法。^3H测量步骤包括：样品氧化燃烧,使有机结合氚(OBT)转化为氚化水,用液闪法测量^3H活度。该方法的探测下限为1．2Bq／L。^14C测量步骤包括：将8g左右的样品经过燃烧爆炸后转变为CO2,并最终合成苯,用液闪法测量^14C的活度。该方法的探测下限(以C质量计)为1．0Bq／kg。文章同时给出了树叶、牛奶、动物、土壤等多种生物样品中^3H和^14C的测量结果。     

Pressure Dependence of the Relativistic Rise in Neon and Highest Attainable Ionization Sampling Resolution in Neon, Argon, Ethylene and Propane

A full-scale detector segment with 128 samples of 2 cm and a 50 cm drift space was used to measure precisely the relativistic rise of ionization from 5 to 70 GeV/c in Ne at 1, 2 and 4 atm. The pressure dependence of dE/dx resolution and of particle separation efficiency was determined at 15 GeV/c in several Ne/CnHm mixtures, in Ar/CH4, pure C2H4 and pure C3H8. The results are used for optimization of parameters of a compact colliding beam detector suitable for particle identification up to the 30-50 GeV/c momentum range. The ?/K/p separation is found to be better in Ne, but extends to higher momenta in Ar. Ar is more efficient for e/? separation. The gain in resolution at higher pressures is to certain extent compensated by reduction of the relativistic rise slope, so that the separation efficiency is reduced when the detector dimensions are scaled down with pressure. At 4-5 atm. we obtained slightly better resolution than the 6.0% FWHM (? = 2.5%) record performance of the EPI. In pure C3H8 a resolution below ? = 2.0% was reached. Measurements of drift velocities in various Ne mixtures are presented, showing saturated behaviour already at low E/p values.     

富勒烯赖氨酸衍生物的合成及对AHH-1细胞的辐射防护效应

本研究通过富勒烯与赖氨酸直接反应,合成了一种富勒烯赖氨酸衍生物(C60-Lys),并通过元素分析、红外光谱、1H-NMR、13C-NMR等对其分子结构进行了表征。细胞毒性研究发现C60-Lys对人淋巴母细胞AHH-1的毒性较小,在1200mg/L浓度以下的细胞存活率和未用药对照组相比无明显差异。辐射生物效应研究发现400mg/L以上C60-Lys预处理能显著提高受照细胞的存活率,并降低辐射诱发的凋亡率,其辐射保护效应具有明显的剂量依赖性。说明C60-Lys预处理对受4Gyγ射线照射的AHH-1细胞具有一定的保护作用。     

Conversion of coalbed methane surrogate into hydrogen and graphene sheets using rotating gliding arc plasma

The use of atmospheric rotating gliding arc(RGA) plasma is proposed as a facile, scalable and catalyst-free approach to synthesizing hydrogen(H_2) and graphene sheets from coalbed methane(CBM). CH_4 is used as a CBM surrogate. Based on a previous investigation of discharge properties, product distribution and energy efficiency, the operating parameters such as CH_4 concentration, applied voltage and gas flow rate can effectively affect the CH_4 conversion rate,the selectivity of H_2 and the properties of solid generated carbon. Nevertheless, the basic properties of RGA plasma and its role in CH_4 conversion are scarcely mentioned. In the present work, a 3D RGA model, with a detailed nonequilibrium CH_4/Ar plasma chemistry, is developed to validate the previous experiments on CBM conversion, aiming in particular at the distribution of H_2 and other gas products. Our results demonstrate that the dynamics of RGA is derived from the joint effects of electron convection, electron migration and electron diffusion, and is prominently determined by the variation of the gas flow rate and applied voltage. Subsequently,a combined experimental and chemical kinetical simulation is performed to analyze the selectivity of gas products in an RGA reaction, taking into consideration the formation and loss pathways of crucial targeted substances(such as CH_4, C_2H_2, H_2 and H radicals) and corresponding contribution rates. Additionally, the effects of operating conditions on the properties of solid products are investigated by scanning electron microscopy(SEM) and Raman spectroscopy. The results show that increasing the applied voltage and decreasing CH_4 concentration will change the solid carbon from its initial spherical structure into folded multilayer graphene sheets, while the size of the graphene sheets is slightly affected by the change in gas flow rate.     

ZrCl4蒸汽沉积法制备高温气冷堆包覆燃料颗粒ZrC涂层

采用ZrCl₄蒸汽、H₂和C₃H₆作为化学反应体系，以Ar为载气，在流化床沉积炉中制备高温气冷堆包覆燃料颗粒ZrC涂层。对所制备涂层进行了分析表征，结果显示：ZrC涂层剖面均匀光滑，无明显孔洞；与内致密热解炭层的界面清晰，厚度约为35μm；涂层主要成分为Zr和C，Zr/C摩尔比接近化学计量比1∶1，其主要相组成为面心立方的ZrC；晶粒生长无明显的择优取向。     

Study of partial discharge characteristics in HFO-1234ze(E)/N2 mixtures

HFO-1234ze(E)(trans-1,3,3,3-tetrafluoropropene, chemical formula: C₃H₂F₄) is an extremely environmentally friendly SF₆ alternative gas with high electrical strength. In this paper, the partial discharge (PD) characteristics of HFO-1234ze(E)/N₂ mixtures were studied using the gas insulation test platform. The PD inception voltage of insulating gas under positive and negative half cycles of power frequency was tested. Using SF₆/N₂ mixtures as a control group, the effects of electrode spacing, mixing ratio and pressure on the insulation performance of HFO-1234ze(E)/N₂ mixtures were explored. The test results show that the PD inception voltage of the negative half-cycle of pure HFO-1234ze(E) under short electrode spacing can reach 0.96–1.04 times of pure SF₆ under different pressures; the PD inception voltage of 40%HFO-1234ze(E)/60%N₂ mixtures at 0.3 MPa is 0.67–0.89 times that of SF₆/N₂ mixtures under the same conditions, which has great application prospect.     

喇曼光谱法研究辐照聚合物的气体产值

本文研究了两种典型交联型聚合物在~(60)Coγ射线辐照条件下放出的气体的激光喇曼光谱,通过波数2917cm~(-1),2954cm~(-1)和4157cm~(-1)三处特征谱峰高度与标准谱图的比较,测得辐照聚二甲基硅氧烷放出的各种气体产值:G_(CH_4)=1.05,G_(C_2H_6)=0.23,G_(H_2)=0.58,气体总产值:G_(CH_4-C_2H_6+H_2)=1.86,实验结果表明,在500Mrad剂量以下,辐照样品放出气体的总产值和各种气体的分产值不随剂量而变化,从而给予交联度与剂量成正比以直接证明。用同样方法测得辐照聚乙烯放出的气体产值(G_(CH_2)=2.7),也与辐照剂量无关。     

Longitudinal Drift and Fine dE/dx Sampling in Various Gas Mixtures

Results of measurements realized at 15 GeV/c in a tagged e/?/p beam are presented. A longitudinal drift detector of 88 cm total length consisting of 16 stages of 4.7 cm drift each was used. Fast shaped signals from the detector were processed in a set of Flash ADC's with 25 ns sampling interval, corresponding to 0.3 - 2.6 mm distance in the drift space. Resolution and particle separation efficiency obtained in mixtures of Ne + 10% C3H8, Ar + 5% C3H8, Ar + 20% CO2, C3H8 + 20% C2H6 and in pure CH4 are compared to the performance of a classical method of charge integration over large samples.     

铀矿井独头巷道最大掘进长度的研究

为了改善地下铀矿井作业空间的辐射条件,本文阐述铀矿独头巷道通风气流中氡及其子体α潜能浓度的数学描述公式,推导出独头巷道按照排氡和排氡子体最大掘进长度的计算公式.研究了独头巷道通风量Q、巷道断面积S、入风氡浓度C0、入风氡子体α潜能浓度E0和巷道氡析出密度DV与最大掘进长度Lmax的关系,结论为:独头巷道的最大掘进长度Lmax随着C0、E0、S、和DV的增大而减小,随着Q的增大而增大;同时还发现:当氡析出密度DV=1.463 Bq/(m3s)时,Lmax,Rn=Lmax,α;当DV<1.463 Bq/(m3s)时,Lmax,Rn>Lmax,α;而DV>1.463 Bq/(m3s)时,Lmax,Rn相似文献   

Insulation characteristics of triple mixtures of c-C4F8/N2/CO2 under lightning impulse voltage

This paper has researched the insulation characteristics of 10%c-C₄F₈/N₂/CO₂ mixtures under lightning impulse voltage by experiment. It is shown that the positive and negative lightning impulse breakdown voltages of 10%c-C₄F₈/N₂/CO₂ gas mixtures rise linearly as the electrode gap distance and gas pressure increase and under the same conditions, the positive lightning impulse breakdown voltage of the gas mixtures is always higher than the negative lightning impulse breakdown voltage. As the gas mixtures have a little higher liquefied temperature than SF₆ and the comprehensive GWP is about 5% of SF₆ , and the positive and negative lightning impulse breakdown voltages can both reach 60% of SF₆ , 10%c-C₄F₈/N₂/CO₂ gas mixtures can be applied as insulation gas in electrical equipment such as C-GIS, GIT, GIL and so on.     

Reactive ion etching of PECVD silicon nitride in SF6 plasma

The reactive ion etching of PECVD silicon nitride thin films has been investigated using SF₆ plasma. Effects of variations of process parameters such as pressure (50–350 mTorr), RF power (50–250 W), gas flow rate (3–130 sccm) and additions of O₂ and He (0–50%) in SF₆, on the PECVD silicon nitride etch rate and selectivity to the AZ 1350J photoresist were examined. An etch rate of 1 μm/min has been obtained under the condition of 150 mTorr, 100 W and 60 sccm. Experimental results also indicated a maximum etch rate at approximately 30% O₂ while addition of He showed only dilution effect. A nitride/photoresist selectivity ranging from 1 to 3:1 has been obtained.