高能激光能量计溯源问题研究北大核心

由于高能激光能量计标定过程中没有标准的能量测量装置和标准的激光源,无法采用常规方法对其进行标校。提出了一种利用现有小能量计从低到高逐级多次传递不确定度的方法,以及一种利用能量等效原理对激光能量计进行标校的方法。不确定度传递法方法简单,但环节较多导致不确定度较大。等效标定法包括电标法和光标法,电标法对设计要求较高,但求解过程相对简单。光标法工程实现难度要低得多,但必须事先对灯组余热及热损失进行测算。等效法的三个条件与误差大小关系紧密,在结构设计中必须严格考虑,它是提高测量准确性的根本,其次要尽量减少不确定度传递的中间环节,最后需要对误差项进行科学分析和测定,在此基础上对这些项进行相应的修正和补偿。     

高功率激光能量测试的卡计系数标定技术

提出在卡计系数标定中采用直线拟合方法,综合考察相关系数、斜率、截距、斜率和截距标准偏差等参数,以斜率相对标准偏差作为采用何种直线拟合的主要判断依据;若过零直线拟合的斜率相对标准偏差小于不过零的斜率相对标准偏差,认为截距为随机误差,卡计系数标定按照非等精度的加权平均法求解;反之,应按照不过零直线拟合,截距为测试的系统误差,根据定位回归误差大小判断并剔除粗大误差;这样可以合理给出激光能量测试的卡计标定系数。     

Jet energy measurements in CMS

The expected performance of CMS for jet energy measurements is discussed. The use of the different calibration methods allows one to restore the linearity of the CMS calorimeter relative to jets and to improve the jet energy resolution. The text was submitted by the author in English.     

Barrel calorimeter of the CMD-3 detector

The structure of the barrel calorimeter of the CMD-3 detector is presented in this work. The procedure of energy calibration of the calorimeter and the method of photon energy restoration are described. The distinctive feature of this barrel calorimeter is its combined structure; it is composed of two coaxial subsystems: a liquid xenon calorimeter and a crystalline CsI calorimeter. The calorimeter spatial resolution of the photon conversion point is about 2 mm, which corresponds to an angular resolution of ～6 mrad. The energy resolution of the calorimeter is about 8% for photons with energy of 200 MeV and 4% for photons with energy of 1 GeV.     

Tau reconstruction, energy calibration and identification at ATLAS

Tau leptons play a central role in the LHC physics programme, in particular as an important signature in many Higgs boson and supersymmetry searches. They are further used in Standard Model electroweak measurements, as well as detector-related studies like the determination of the missing transverse energy scale. Copious backgrounds from QCD processes call for both efficient identification of hadronically decaying tau leptons, as well as large suppression of fake candidates. A solid understanding of the combined performance of the calorimeter and tracking detectors is also required. We present the current status of the tau reconstruction, energy calibration and identification with the ATLAS detector at the LHC. Identification efficiencies are measured in W ?? ??? events in data and compared with predictions from Monte Carlo simulations, whereas the misidentification probabilities of QCD jets and electrons are determined from various jet-enriched data samples and from Z ?? ee events, respectively. The tau energy scale calibration is described and systematic uncertainties on both energy scale and identification efficiencies discussed.     

Investigation of LYSO and GSO crystals and simulation of the calorimeter for comet experiment

The research results of parameters of LYSO and GSO crystals—candidates for being used in an electronic calorimeter for the COMET experiment—are described. The research has been made at the specially created high precision measuring setup. Measurements of uniformity of LYSO and GSO crystals along the crystal length were made. The energy resolution of crystals, their light output and processing speed were measured. The energy calibration of crystals was also performed. The research results were used for GEANT4 simulation of the calorimeter for COMET experiment. As a result of simulation of the calorimeter on the collimated 105 MeV electrons source with use of real optical parameters, the energy resolution of 5.0% was obtained for a calorimeter on GSO crystals and 2.5% for a calorimeter on LYSO crystals.     

Magnetic calorimeter for registration of small energy release

A scheme of magnetic calorimeter for registration of rare events characterized by small energy release (cosmic rays, WIMPs, solitary X-ray quanta) is proposed. The calorimeter is brought to operation by adiabatic demagnetization, and its magnetic response is measured by a quantum interferometer (SQUID, A. Barone and G. Paterno, Physics and applications of Josephson Effect). Special consideration is given to the specific features of calorimeter operation in the ferromagnetic transition region. The trigger registration of ultrasmall energy release by a ferromagnetic system in the metastable state is described.     

石墨量热计测量相对论电子能谱的数值模拟

采用数值实验的方法对石墨量热计测量电子能谱的过程进行了模拟,并对解谱方法进行了研究。使用MCNP软件建立了实验模型,根据不同能量入射电子能量沉积分布情况确立了入射电子能量-沉积能量的传递函数,研究确定合适的函数求解方法,并采用添加人为扰动的方式对该函数求解方法的可靠性进行分析,最终得到了有效的解谱方法。     

Acoustic energy output of a transducer unit

The acoustic energy output of a magnetostrictive transducer unit has been observed by the calorimetric method. The object was to observe the energy output of the unit from low to high ultrasonic intensities under identical conditions of transducer frequency and acoustic load. The design and construction of the calorimeter and its mode of operation are discussed in some detail.     

新型全吸收式高功率微波能量计

为解决高功率微波源传输线内能量的测量,研制了一种全吸收式液体高功率微波能量计。能量计采用乙醇、去离子水等混合液作为吸收液,吸收液吸收微波后体积膨胀,探测器内的液面升高,通过控制系统得到液面升高引起的电压变化值,从而得到被测能量的大小。该套能量计具有结构简单、测量准确度高等特点,经过实验,测得能量计端口的电压反射系数小于-20 dB,具有较好的匹配性,能够开展10~600 J能量的测量,5次测量结果标准偏差优于3%,可满足高功率微波源传输线内或空间辐射能量的测量。     

水流吸收型高能激光能量计溯源方法及其溯源体系研究

提出了一种利用电加热丝作为校准源的高能激光能量计校准方法,将水流从吸收腔前端导入至加热容器,在加热后流入吸收腔。通过精确计量水流吸收的热能并与能量计测量结果进行比较,达到对高能激光能量计校准的目的。研究表明校准系统的热交换模型与吸收腔内的热交换模型一致,均经历了储能和功率平衡两个阶段。水流及相变气体的散射效应对测量结果的影响较小,经过修正后可以忽略其影响。通过深入分析各个环节的测量不确定度表明,残留能量和流量变化对测量不确定度的影响最显著,增加水箱的容积可以有效降低残留能量对测量不确定度的影响。在对各个环节的影响修正后估算出系统的测量不确定度约为4.8%(k=2),被校高能激光能量计校准后的测量结果与其他类型的参考高能激光能量计进行比对,两者具有很好的一致性,修正因子仅为1.006,标准偏差为1.4%。     

Styrofoam calorimeter for high energy CO2 lasers

A simple calorimeter that has been used to measure pulse energy and energy distribution of a pulsed gas-dynamic laser is described. The pulses had an energy density 10 J cm^-2 and width 0.1 s. Energy is determined from the volume of styrofoam melted by the pulse. Results showing the linearity of the method are given.     

Hall-A上小角度GDH实验中量能器的刻度修正

在JLab的A大厅上的小角度GDH实验中, 采用了Fumili拟合方法对位于高分辨谱仪上的量能器进行刻度. 因为实验过程中硬件条件的变化以及大量的运动学数据的存在, 对该实验数据分批进行了刻度. 刻度结果表明, 此刻度修正是合适的. 在散射电子动量为1GeV的时候, 量能器对该粒子的分辨率为0.06GeV.     

飞焦级激光能量计校准系统及方法研究

为了解决飞焦级激光能量计的校准问题,提出了一种专用的校准系统和方法。该系统采用固定和可变二级衰减机构相结合的方式,实现了对响应波长1 064 nm、脉宽5 ns～1 μs、飞焦量级的激光能量计的校准。阐述了校准系统的工作原理、设备组成和方法。对系统的关键组件和整机性能进行了描述,并给出了相应的测试结果,能量重复测量的不确定度为3%,系统的测量不确定度可以达到11%。最后,提出了该校准系统未来的改进方向。     

An improved method of energy calibration for position-sensitive silicon detectors

Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced.The energy resolution of the 8.088 Me V α decay of213 Rn is determined to be about 87 ke V(FWHM), which is better than the result of the traditional method, 104 ke V(FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances.     

绝对吸收式激光能量计高准确度校准技术研究

采用量热法的高能激光能量计用于测量能量大于50 kJ的连续波高能激光能量,通常用已知功率的连续激光开展激光能量计的光电校准需要激光照射时间超过20 min,而由于热损失等原因,进行长时间激光能量校准时,校准不确定度高达12%。以量热式平面吸收高能激光能量计为模型,从理论上分析了热辐射、热对流对连续波高能激光能量测量结果的影响,得到了较准确的平面吸收腔激光能量计冷却数学模型,实现了能量计热损失补偿,并通过建立相应的实验装置验证了该模型,用其对装置的测量结果加以修正,可使光电校准的测量不确定度减小到1%以下。     

现场用激光能量计校准方法的实验研究

在激光功率能量测量当中,军用激光现场检测环境温度和实验室环境温度相差很大,而激光能量计的传感器灵敏度与环境温度条件有关,不对激光能量计进行温度灵敏度校准,将严重影响测量结果。针对目前存在的问题,本文提出将激光能量计放置于温控制箱中,脉冲激光器输出的激光经过分光镜分束后分为2束激光,其中透射光由标准能量计或现场激光能量计接收,反射光由参考能量计接收,在-50℃～70℃的温度范围内进行校准的一种新方法,并进行原理性的验证实验及结果分析,得到了能量计灵敏度系数关于环境温度的函数关系,使得能量计在非标准环境下进行准确测量成为可能。为激光能量计现场测试校准技术的研究提供了一种可靠的新途径。     

A total energy trigger at large angles used in a calorimetric study of 150 GeV and 300 GeV pion and proton interactions on hydrogen

Hard hadronic scattering was studied by selecting 150 GeV and 300 GeV π^?p and pp events with large energy in a 240 cell calorimeter covering 452 to 1352 in the c.m.s. polar angle and the full 2π azimuth. A downstream calorimeter measured the remaining energy flow at smaller angles. For large energy deposited in the segmented calorimeter the proton induced cross section drops below the pion induced cross section, as expected in a constituent scattering picture. However, neither a simple energy scaling of the cross section nor a dominant jet structure of the events is observed. No evidence was found for recently proposed higher-twist mechanisms leading to events     

Thermal phase change and activation energy of crystallization of Ge-Sb-Te-Sn thin films

To improve the optical storage performance, Sn was doped into Ge2Sb2Te5 phase change thin films. The optical and thermal properties of Sn-doped Ge2Sb2Te5 film were investigated. The crystal structures of the as-sputtered and the annealed films were identified by the X-ray diffraction (XRD) method. The differential scanning calorimeter (DSC) method is used to get the crystallization temperature and crystallization energy (Ea). It was found that proper Sn-doping could highly improve storage performance of the Ge2Sb2Te5 media.     

Study of the energy response of high pressure ionization chamber for high energy gamma-ray

The energy response calibration of the commonly used high pressure ionization chamber is very difficult to obtain when the gamma-ray energy is more than 3 MeV.In order to get the calibration of the higher part of the high pressure ionization chamber,we use the Fluka Monte Carlo program to perfclrm the energy response in both the spherical and the cylindrical high pressure ionization chamber which are full of argon gas.The results compared with prior study when the gamma-ray energy is less than 1.25 MeV.Our result of Monte Carlo calculation shows agreement with those obtained by measurement within the uncertainty of the respective methods.The calculation of this study is significant for the high pressure ionization chamber to measure the high energy gamma-ray.