钨酸铅晶体光产额的温度效应的测量

介绍了在钨酸铅晶体发光特性研究中温度效应的影响、钨酸铅晶体从１２￣３６℃变化时测量温度系数的方法，以及钨酸铅晶体安装过程中稳定性的研究。     

钨酸铅晶体荧光衰减时间特性的内容

用单光子技术研究了钨酸铅晶体荧光发射光谱和衰减时间的关系,测量了不同生长条件了钨酸铅晶体的时间特性,对辐照前后晶体的衰减时间进行了比较,实验结果表明掺镧有助于提高钨酸铅晶体快成分的比重。     

钨酸铅晶体荧光衰减时间特性的研究

用单光子技术研究了钨酸铅晶体荧光发射光谱和衰减时间的关系,测量了不同生长条件下钨酸铅晶体的时间特性,对辐照前后晶体的衰减时间进行了比较实验结果表明掺镧有助于提高钨酸铅晶体快成分的比重     

钨酸铅晶体性能研究

对钨酸铅晶体的激发光谱和荧光光谱、绝对光产额和相对光产额以及发光衰减时间的测试结果表明，钨酸铅晶体可在高能物理实验中用于测量高能电磁簇射粒子。     

钨酸铅晶体阵列的能量重建及π0/γ分辨

通过模拟CMS电磁量能器中钨酸铅晶体阵列的物理响应，全面分析了其性能。对各种可能的能量重建方法及其相应的能量分辨本领进行了仔细的研究和探讨。并通过神经元网络方法研究了在高动量情况下对γ事例中π^0本底的排除本领。     

用APD和钨酸铅构造新型电磁量能器的实验进展

介绍了在中国参加的ＣＭＳ国际合作组用新型雪崩光电二极管和新型钨酸铅晶体构造新型电磁量能器实验研究的进展情况。     

钨酸铅晶体对0.2MeV γ射线的相对灵敏度及其特性测量

利用三通道加速器(平均能量约0．2MeV)、DPF中子源和直线拟合方法,通过实验测定和理论计算,得到了钨酸铅晶体对ST-401闪烁体的7相对灵敏度(约为1：2),晶体的中子与γ灵敏度之比(约为1：6)和晶体的衰减时间(约为6ns)。     

不同形貌钨酸铋对γ射线的屏蔽性能研究

为制备性能优良的辐射防护材料,通过水热法合成钨酸铋（Bi₂WO₆）纳米晶体,并制得水性聚氨酯基-钨酸铋复合材料,研究钨酸铋的晶体结构和形貌对其γ射线屏蔽性能的影响。结果表明,前驱体溶液pH对钨酸铋的合成影响显著,酸性和中性条件下生成正交相钨酸铋,强碱条件下则为四方相钨酸铋（Bi_0.875W_0.125O_1.6875）;随着前驱体溶液pH增加,钨酸铋晶体形貌由花状微球逐渐过渡到柿饼状,再转变为随机堆积的纳米片。正交相柿饼状钨酸铋对81 keV γ射线的屏蔽效果较佳,而四方相钨酸铋则对59.5和121.8 keV γ射线的屏蔽效果更佳;另外,不同晶相钨酸铋制得的复合材料力学性能差异明显。研究结果可为无毒、质轻、高效的新型γ射线屏蔽材料的开发提供参考。     

EGSnrc系统在计算闪烁探测器响应函数矩阵中的应用

在Linux操作系统上使用EGSnrc系统中的PEGS4程序离线计算光子及电子与茋晶体、铝和铅相互作用的截面数据库，并利用计算的截面数据库作为该系统中Dosnrc程序的输入数据计算得到了铅屏蔽晶体对光子各能量点的响应函数，并将其组成矩阵。通过测量几种标准γ源来检验响应函数矩阵的准确程度。     

混凝土墙体防辐射砂浆的蒙特卡罗研究

分别选取重晶石、钨酸铅和Ba Pb0.75Bi0.25O3这三种不同的防辐射填料按照一定的比例掺和到砂浆基材中,得到不同的防辐射砂浆。针对天然放射系铀系、锕系和钍系放出的特征γ射线,采用蒙特卡罗数值模拟方法计算了防辐射砂浆混凝土墙体的γ射线透射率与线性衰减系数。结果表明,三种不同防辐射砂浆对γ射线均有一定的防护作用,其中钨酸铅砂浆对γ射线的防护性能最好,且砂浆层厚度越厚,防护效果越好。     

防辐射超细钨酸铅的制备及其手套对γ射线屏蔽的研究

钨酸铅集中了钨和铅的辐射屏蔽特性的优点,制造超细的钨酸铅可以提高辐射屏蔽的能力。利用软模板合成法研究超细PbWO4的制备工艺。以表面活性剂作软模板,用S-60为水体系的W/O微乳液区成功地合成了超细PbWO4。实验结果证明,以S-60为分散剂的软模板制备的超细PbWO4,粒度分布均匀。采用正交实验法探索最佳实验条件为:以S-60为表面活性剂,分散剂浓度为稀释30倍,溶液pH值为9,Pb(Ac)2和Na2WO4的浓度均为0.01 mol/L,搅拌速率1 300 rpm,将Pb(Ac)2溶液缓慢滴加到Na2WO4溶液中,得到超细钨酸铅产物。超细钨酸铅产品用于防辐射的填料,比原配方对59.5 keVγ射线的辐射屏蔽率可提高5%左右。     

Positorn annihilation study on point defects in lead tungstate

A study on point defects in leas tungstate(PbWO4) by using positron annihilation lifetime method is presented,The measurement was carried out for the cases of untreated,vacuum-annealed,oxygen-annealed and La-doped PbWO4 crystals,It was found that the components T2,which reflect the positron annihilation in point defects ,are different from each other for each case,Some tentative models for the defects are dicussed.     

Photoinduced Short-Lived Absorption in PbWO4:Nb Scintillation Crystals

This work is the first investigation of the spectral and relaxation characteristics of photoinduced short-lived absorption in lead tungstate scintillation crystals activated with niobium ions (PbWO₄:Nb). At wavelengths 300–900 nm the induced absorption is characterized by an absorption band with a maximum near 340, 420, 520, 670, and 850 nm. It is shown that the induced losses are characterized by a long lifetime – from 100 msec to several seconds. It is established that the photoinduced absorption process in the experimental crystals is due to UV radiation with wavelength <380 nm. 3 figures, 7 references.     

A Study on Correlations Between the Initial Optical and Scintillation Properties and Their Radiation Damage for Lead Tungstate Crystals

This paper presents a study of correlations between the initial optical and scintillation properties and their radiation damage for mass produced lead tungstate crystals. A correlation was observed between crystal's initial light outputs and the values of its initial longitudinal transmittance at 360 nm. A strong correlation was found between the emission weighted radiation induced absorption coefficients and the relative losses of the longitudinal transmittance at 440 nm. Correlations were also observed between the relative losses of crystal's light output and the relative losses of its longitudinal transmittance at 440 nm, or the emission weighted radiation induced absorption coefficients. No correlations were observed between crystal's radiation hardness and its initial longitudinal transmittance or the slope of the initial longitudinal transmittance across the band edge     

Chemically produced nanostructured ODS-lanthanum oxide-tungsten composites sintered by spark plasma

High purity W and W-0.9La₂O₃ (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous solutions. High resolution electron microscopy investigations revealed that the tungstate particles were coated with oxide precipitates. The precursor powder was reduced to tungsten metal with dispersed lanthanum oxide. Powders were consolidated by spark plasma sintering (SPS) at 1300 and 1400 °C to suppress grain growth during sintering. The final grain size relates to the SPS conditions, i.e. temperature and heating rate, regardless of the starting powder particle size. Scanning electron microscopy revealed that oxide phases were mainly accumulated at grain boundaries while the tungsten matrix constituted of nanosized sub-grains. The transmission electron microscopy revealed that the tungsten grains consist of micron-scale grains and finer sub-grains. EDX analysis confirmed the presence of W in dispersed oxide phases with varying chemical composition, which evidenced the presence of complex oxide phases (W-O-La) in the sintered metals.     

Radiation-Induced Optical Absorption in PbWO4:La Scintillation Crystals

The radiation resistance of scintillation lead tungstate crystals (PbWO₄) activated with lanthanum ions is investigated as part of an international project. The transmission spectra of various sections of standard PbWO₄:La crystals before and after irradiation of the crystals with doses 10, 10², 10³, 2·10⁴ rad with dose rate 0.24 R/sec and doses 2·10⁴, 10⁵, 10⁶, and 10⁷ rad with dose rate 97 R/sec from a ⁶⁰Co source are measured in the wavelength range 400–700 nm. The change in the radiation resistance of a crystal along the growth axis is analyzed on the basis of the data obtained. The nature of the -induced absorption is discussed. The effect of irradiation with fast neutrons up to fluence 10¹²–10¹⁴ cm^–2 on the radiation resistance of these crystals is studied. The contribution of rays and neutrons to the radiation-induced absorption is estimated.     

Head-on collision between single- and multi-soliton heavy ion acoustic waves in multi-ion plasmas

Head-on collisions among the single-and multi-soliton’s heavy ion acoustic waves (HIAWs) of multi-ion plasma are studied. The plasma consists of adiabatic positively charged inertial heavy ions, Boltzmann energy distributed light ions and kappa energy distributed electrons. The extended poincaré-Lighthill-Kuo (ePLK) method is applied for the derivation of two-sided Korteweg–de Vries (KdV) equations (KdVEs). The KdV single-soliton solutions (KdVSSs) are determined using the hyperbolic secant method and the KdV multi-soliton solutions (KdVMSs) are obtained using the Hirota method. The effects of superthermality of electrons, temperature ratios of electron to light ion and heavy ion to electron, and the density ratio of electron to heavy ion on phase shifts are investigated for the head-on collisions between two-soliton HIAWs. The effects of plasma parameters on angular frequency, phase speed, production of multi-soliton structures, and the head-on collisions among single-, double-, triple-, quadruple-, and quintuplesolitons are also studied.     

99Tc在模拟地质条件下的迁移行为研究概况

介绍了99Tc在模拟地质条件下迁移行为研究概况,主要阐明了99Tc在模拟地质条件下迁移行为的研究意义、99Tc的水溶液化学性质、影响99Tc在地质介质中迁移的因素及99Tc在近场和远场的释放和迁移,并就国内外的研究概况进行了概要评述.