Detector Effects on the Response of a Highly Granular Hadron Calorimeter to Single Hadrons

In the detectors currently being developed for experiments on the next-generation lepton colliders, highly granular calorimeters are to be used. In particular, the hadron calorimeter is planned to be assembled from scintillation cells with direct readout of light by silicon photomultipliers. According to the results of experimental measurements of the light collection in a cell developed for the CALICE prototype hadron calorimeter, when detecting minimum ionizing particles, an estimate of the detector effects was obtained. The detector effect on the resolution of the ILD hadron calorimeter was studied by modeling the response of the detector to single neutral kaons. It was shown that the contribution of experimentally measured detector effects to the resolution for single particles is on the order of 0.5–1% in the range of hadron energy of 5–60 GeV.     

组合闪烁探测系统的中子能量响应研究

组合闪烁探测系统由"Pb过滤片加塑料闪烁探测器"组成. 采用直流标定方法,实验研究了ST401、ST1422、ST1423组合探测系统对0.565MeV-14.16MeV能量范围的6个能点的中子灵敏度,得到了探测系统的中子灵敏度随Pb过滤片厚度的变化、随闪烁体厚度的变化和随中子能量的变化关系. 利用理论计算和实验测量结果相结合,获得了3种组合闪烁探测系统的中子灵敏度能量响应曲线.     

Stress Response of Granular Systems

We study persistence probabilities for random walks in correlated Gaussian random environment investigated by Oshanin et al. (Phys Rev Lett, 110:100602, 2013). From the persistence results, we can deduce properties of critical branching processes with offspring sizes geometrically distributed with correlated random parameters. More precisely, we obtain estimates on the tail distribution of its total population size, of its maximum population, and of its extinction time.     

Nonlinear Response of Granular Composite Mediurn

In this paper, the linear and nonlinear responses of granular composite medium consisting of spherical grains with coating shells embedded in a host medium are studied. We assume that the shell and the host medium are linear (the dielectric constants of which are ε⁰ and ε_m⁰ respectively), while the spherical grain is nonlinear (the diektric constant of which is ε_c = ε_c⁰ + χ_c|E_c|^β). Starting from the definition (D) = ε_eff and taking in to account the corrections to the local field within the spherical grains, expressions for the linear and high-order nonlinear susceptibilities are presented.     

狭长CsI(Tl)闪烁体发光效率的研究

提出了基于狭长CsI（Tl）闪烁体和面阵CCD器件,采用光纤和光纤面板进行光耦合及传输,以扇形束线阵扫描方式实现对X射线探测与成像的工业X-CT系统探测器方案.基此,通过物理分析及数学建模,利用Matlab模拟研究了X光能量小于450 keV时狭长CsI（Tl）闪烁体的发光效率等性能指标.研究结果表明：当光电吸收截面μph和康普顿吸收截面μc分别为0.000313和0.0000295、反射层反射系数R和衬底反射系数Rs分别取0.95和0.8、荧光线性吸收系数σ取0.000222 μm－1时,得到狭长CsI(Tl)闪烁晶体的长度l、高度h和宽度w取值范围分别是926～4512 μm、242～5000 μm和242～5000 μm的结论.在此范围内,既可使闪烁晶体有较好的空间分辨率又可获得最高的发光效率.     

Optical Response of Granular YBCO Weak Link

1.IntroductionRecently,thcrehasbecnintcrcstinthephot0resp0nse0fhigh-7'.oxidcsuperconductingfilms,espcciallywithregardtdthedctailsofthephysics0ftheph0toresponse['~'J.Fr0mtheviewpointoftheapplicationinthesuperconductingclectr0nics,thecharacteristicsofphotore-sponcse0fJosephsonjuncti0nfabricated\viththcsehigh-T.0xidcsupercondictorsandthepho-toinducedn0ncquilibriumproPerties0fthesematerialsmustbecxaminedandeva1uatcdforthedeve1opmcntofnQveIsL1pcrc0n(luctingdcviccsandJ0scphsoncbnjuncti0n.Itisf0un…     

仪用LED光源均匀性及稳定性研究

研究了采用发光二极管（LED）作为光谱仪器光源所涉及的相关技术。LED的发光光谱具有一定的带宽,用滤光片滤波得到带宽少于10nm的窄带光源,并根据LED在不同波段的的光强设定相应的脉冲驱动电流,在一定波长范围内实现平坦的光强输出;除了通过精密恒流源提供电流驱动LED稳定发光外,采用双光路的方法可以进一步减少光源稳定性对检测系统的影响。     

基于SiPM读出的塑料闪烁体探测器时间性能研究

研究了基于硅光电倍增管(SiPM)双端读出的面积为10 cm ×10 cm的薄塑料闪烁体探测器的时间性能。239Pu放射源测试结果显示:(1)在多支SiPM串连读出方式下,随着SiPM数量的增加,探测器时间分辨逐渐变好;(2)在固定12支SiPM数量不变的情况下,并联支路越多,探测器时间分辨越差;(3)采用快时间塑料闪烁体并增加其厚度,可有效提高探测器时间分辨;(4)采用比束斑尺寸更大的塑料闪烁体,可有效提高探测器时间分辨的位置均匀性;(5)对于1 mm厚的EJ232塑料闪烁体探测器,在单端12支SiPM串行连接的情况下,可获得好于131 ps的时间分辨。这一研究对RIBLL2起始时间探测器的升级改造具有重要的指导意义。     

光子在塑料闪烁体内的传输速率测量

选用90Sr-90Yβ放射源照射自制的塑料闪烁探测器,测量了光子在塑料闪烁体内部的传输时间,计算出传输速率和不确定度,为以后的核物理实验计算以及闪烁体参数测量提供相关数据参考。     

Wide-Aperture Liquid Calorimeters for Measuring the Energy of Powerful Microwave Radiation Pulses

Russian Physics Journal - An overview was done of the efficient devices designed to measure the energy of powerful electromagnetic radiation pulses of the relativistic microwave sources –...     

闪烁体瓦片/光纤量能器辐照损伤的进一步研究

研究了由不同闪烁体瓦片/光纤材料组成,或材料相同但构造不同的量能器模型的辐照损伤.用北京正负电子对撞机(BEPC)的电子试验束(1.1或1.3GeV)辐照了十个量能器模型.通过测量在不同累积剂量和在量能器内的不同位置上的光输出,对辐照损伤作出定量分析.还研究了损伤后的恢复及损伤与环境气体的关系.通过数据拟合发展了辐照损伤对剂量及对深度断面的校正方法.     

Optimal Control of Uniformly Heated Granular Fluids in Linear Response

We present a detailed analytical investigation of the optimal control of uniformly heated granular gases in the linear regime. The intensity of the stochastic driving is therefore assumed to be bounded between two values that are close, which limits the possible values of the granular temperature to a correspondingly small interval. Specifically, we are interested in minimising the connection time between the non-equilibrium steady states (NESSs) for two different values of the granular temperature by controlling the time dependence of the driving intensity. The closeness of the initial and target NESSs make it possible to linearise the evolution equations and rigorously—from a mathematical point of view—prove that the optimal controls are of bang-bang type, with only one switching in the first Sonine approximation. We also look into the dependence of the optimal connection time on the bounds of the driving intensity. Moreover, the limits of validity of the linear regime are investigated.     

低本底液闪中子探测器的材料测试研究

为测量中国锦屏地下实验室（China JinPing underground Laboratory,CJPL）极低通量的中子本底,需要建造大型快中子液体闪烁体探测器。建造探测器需要选用低放射性本底材料,并且化学性质稳定,不与液体闪烁体发生反应而影响液体闪烁体（EJ-335）的性能。为此,建造了小型液闪探测器,在其中分别放入聚四氟乙烯、无氧铜、氟橡胶、全氟醚橡胶这4种材料进行长期浸泡,并分别进行了如下测试:液闪长时间浸泡各种材料前后液闪的吸收光谱测试;用60Co γ源检测小型液闪探测器光产额随时间的变化情况;用Am-Be中子源检验探测器在浸泡前后的n-γ甄别性能。最终实验结果表明,聚四氟乙烯和全氟醚这2种材料与液闪有很好的兼容性,可作为大型快中子液闪探测器的容器和密封圈的备选材料。In order to measure the flux and spectrum of neutron background which is extremely low in China JinPing underground Laboratory (CJPL), liquid scintillator detector with large scale used to detect fast neutron need to be fabricated. Surrounding materials used in detector require the excellent performance, such as low radioactivity as well as stable chemical properties, which do not react with liquid scintillator, so as to avoid affecting the performance of detector. Polytetrafluoroethylene(PTFE), highly purified no-oxygen copper, fluororubber and perfluoroelastomer had been put in a small detector and soaked for a long time. The change of absorption spectrum and light yield along with time as well as the performance of n-γ discrimination after soaked were tested. The results show that PTFE and Perfluoroelastomer are compatible with liquid scintillator, which offers a reference for the selection of material used in container and seal of liquid scintillator detector used to detect fast neutron.     

塑料闪烁体中子探测效率及相对发光产额的标定

利用加速器中子源研究了用于标定塑料闪烁体中子探测效率及相对发光产额的实验技术 ,在四川大学原子核科学技术研究所 2 .5MeV静电加速器上 ,利用T(p,n)和D(d ,n)核反应作为中子源 ,在 0 .6—5MeV中子能区对直径为 40mm ,厚度为 5mm的 1 42 1塑料闪烁体的中子探测效率及相对发光产额进行了测定.A method used for the calibration of neutron efficiency and the relative photo yield of plastic scintillator is studied. T(p,n) and D(d,n) reactions are used as neutron resources. The neutron efficiencies and the relative photo yields of plastic scintillators 1421 (40 mm in diameter and 5 mm in thickness) are determined in the neutron energy range of 0.655—5 MeV.     

凤阳明中都遗址出土琉璃瓦胎体制作工艺研究

为探索明代初期中国琉璃瓦制作工艺技术水平与工艺特点,运用能量色散X射线荧光光谱法（energy disperse X-ray fluorescence, EDXRF）,对安徽凤阳明中都及南京明故宫遗址出土69件琉璃瓦样品胎体化学组成进行了测定,同时利用热膨胀仪、吸水率测定仪和偏光显微镜等仪器设备对样品胎体的烧成温度、吸水率、显气孔率、体积密度与显微结构等进行了分析。分析结果显示,明中都样品胎体根据元素化学组成差异可分为高钙高铁、低钙高铁和低钙低铁三种类型,表明该遗址琉璃瓦样品胎体制作原料可能具有不同来源,同时,部分明中都样品的化学组成与南京明故宫样品较为接近,而上述两处遗址样品与北京故宫样品在化学组成上皆具有显著差异。烧成温度、物理性能和显微结构分析结果显示,明中都琉璃瓦瓷质胎体样品的烧成温度较高,达到了1 141 ℃,且吸水率和显气孔率明显较低,达到了瓷胎的标准,而陶质胎体琉璃瓦样品的烧成温度约为880~1 100 ℃,吸水率和显气孔率较大,且不同样品间差异明显,这可能是由于明中都琉璃瓦胎体的来源不同,导致不同样品在烧成温度、吸水率、显气孔率等方面差异较大。与北京、南京二处的琉璃瓦样品相比,明中都样品吸水率及显气孔率稍微高于二处,但三处陶胎琉璃瓦样品胎体的烧成温度基本都在1 100 ℃以下。明中都三种不同类型样品胎体显微结构差异较小,矿物颗粒粒径和孔隙大小相近,其中部分石英晶体具有明显的熔蚀边。此外,明中都和明故宫样品的显微结构特点显示两处遗址样品胎体原料加工皆较为精细,原料淘洗和烧结程度较高,琉璃瓦物理性能较好。对明初洪武时期明中都出土琉璃瓦烧制工艺的研究结果,不仅可为了解我国琉璃瓦工艺发展历程、还可对探索明初琉璃制作工艺和明中都营建的组织形式等提供科学依据。     

闪烁体探测器中光的衰减通式(英文)

闪烁体探测器被广泛应用于当今粒子物理与原子核物理实验中。研究闪烁探测器的光衰减规律（LASD）对时间和能量的准确测量都十分重要,这一点对条形闪烁探测器尤为如此。本文以圆柱闪烁探测器为例,对各向同性的闪烁光进行立体角积分,进而研究不同立体角下光程差异对结果的影响。在数值计算的基础上,导出了描述LASD的通用公式。在一定条件下,公式可以约化为双指数衰减形式。对于DAMPE上PSD的实验数据,该公式能使闪烁体远端的拟合偏差从大约10%降低至2%以下。同时,模型也能够很好地描述Kaiser实验、Gierlik实验和Platino实验的实验数据。Scintillator detectors are widely used in modern nuclear and particle physics experiments. Studying the light attenuation of scintillator detector (LASD) is vitally important for extracting proper measurements of energy and time. In this paper, we integrate the isotropic fluorescence over solid angle to study the influence on overall light-intensity from varying optical path at different angle. Based on numerical results, a universal formula for describing LASD is derived. Under certain condition, our formula can be written as a form of widely-used double-exponential function. The universal formula describes the experimental data of PSD at DAMPE, reducing the maximum deviation at far-side of the scintillator from~10% to less than 2%. Moreover, our model also deciphers Kaiser's experiment, Gierlik's experiment and Platino's experiment successfully.     

Rheological Study of Loosened Bulk Granular Materials

Loosened bulk materials occur, for example, during grinding in a tube mill. Thus, a rheological study of bulk granular materials which are loosened by fluidisation should lead to a better characterization of the flow and conveying properties of the material when ground in the mill. For this measurement of fluidised bulk materials an agitating device and a rotary viscosimeter have been developed, designed and tested. First results are presented and discussed showing the fluidisation behaviour and density of the bulk material as a function of grain size as well as the flow properties as a function of the grain size and degree of fluidisation. Finally, a projection of further research work is given.