高精密自动绝热量热计

介绍了中国计量科学研究院用新近开发的高精密自动绝热量热计的测量控制系统对美国国家标准技术研究院（NIST）的标准物质α-Al2O3进行的比热测量,并对测量结果和不确定度作了分析。该自动绝热量热计是中国计量科学研究院原有的绝热量热计的发展,它继承了原有量热计的本体,又开发了高精度量热和温度自动测量控制系统。进行了与NIST的数据和其它数据对比以及不确定度分析。测量结果与NIST的数据相比,其相对均方根偏差为0．447％,一致性为0．167％。合成相对标准不确定度为0．333％。结果表明,该自动绝热量热计具有高精密量热和比热测量的能力。     

Calorimeter tests with liquid ionization chambers

Configurations of sampling calorimeters with iron, lead and uranium as absorbers have been investigated using liquid ionization chambers as active elements. As liquid tetramethylsilane has been used. Results of beam tests with electrons, pions and muons in the energy range of 2 to 6 GeV are presented and compared with Monte Carlo simulations. In particular the questions regarding which configuration can compensate and the separation of sampling from intrinsic fluctuations have been studied.     

热量表温度示值误差测量不确定度评定

以超声热量表的配对温度传感器为研究对象,根据JJG225-2001热能表检定规程的要求,以二等标准铂电阻温度计和配套电测设备为测量标准,详细分析了温度、温差测量值的不确定度来源,从而得到超声热量表温度、温差的示值误差扩展不确定度。     

Bakelite RPCs for Digital Hadron Calorimeter

This paper presents the test results of Bakelite RPCs using readout pads with an area of 1 cm×1 cm and 1-bit resolution per pad (binary readout). The results include noise rate, detection efficiency and pad multiplicity as well as comparisons of different surface treatments for Bakelite plates. Pad multiplicity’s dependence on surface resistivity at the readout side is also reported. This study shows Bakelite RPCs can be used as the active elements of digital hadron calorimeter.     

Intrinsic response time of graphene photodetectors

Graphene-based photodetectors are promising new devices for high-speed optoelectronic applications. However, despite recent efforts it is not clear what determines the ultimate speed limit of these devices. Here, we present measurements of the intrinsic response time of metal-graphene-metal photodetectors with monolayer graphene using an optical correlation technique with ultrashort laser pulses. We obtain a response time of 2.1 ps that is mainly given by the short lifetime of the photogenerated carriers. This time translates into a bandwidth of ～262 GHz. Moreover, we investigate the dependence of the response time on gate voltage and illumination laser power.     

双读出量能器用闪烁晶体研究进展

双读出量能器是一种全新设计的高能粒子探测装置, 它能同时测量到Cherenkov光和闪烁光, 因而能更全面地获得高能粒子的信息。目前, 双读出量能器主要有三种设计方式: (1)采用石英纤维产生Cherenkov光, 塑料闪烁纤维生成闪烁光; (2)分别以未掺杂的晶体纤维作为Cherenkov辐射体、Ce掺杂的同种晶体纤维作为闪烁体; (3)采用同种闪烁晶体有效分离Cherenkov光和闪烁光。第三种设计可以消除取样涨落、提高量能器的分辨率, 因而备受关注。本文基于第三种设计方式探讨了钨酸铅(PbWO₄)、锗酸铋(Bi₄Ge₃O₁₂)、硅酸铋(Bi₄Si₃O₁₂)和镥铝石榴石(Lu₃Al₅O₁₂)四种。闪烁晶体在双读出量能器方面的研究进展和可能的应用。Pr掺杂PWO晶体以及硅酸铋晶体都有可能用于双读出量能器, 而后者由于吸收边比锗酸铋更短, 更易于分离Cherenkov光和闪烁光, 在双读出量能器应用方面显示出明显的优势。稀土离子掺杂有望进一步提高硅酸铋晶体的性能, 开发出更适合双读出应用的闪烁材料。     

基于氧弹热量计测量天然气发热量标准装置及方法的研究

根据天然气能量计量的研究现状和应用需求,研究了天然气发热量测量标准装置,采用绝热式氧弹热量计测量高纯甲烷气体发热量,使测量结果通过燃烧热标准物质溯源到国际单位上。设计并研制了平衡取气装置系统,实现了燃烧前样气的采集。高纯甲烷发热量测量结果为39900 J/m3,扩展不确定度为0.6%（k=2）。     

Predicting electrospray response from chromatographic retention time

The relationship between electrospray ionization response and HPLC retention time was explored. For the series of small peptides studied, higher ESI response was observed for analytes with longer reversed-phase HPLC retention times. This correlation existed for both experimentally measured retention times and those calculated from amino acid retention coefficients. This study is useful t     

Transient shell response by numerical time integration

In using the finite element method to compute a transient response, two choices must be made. First, some form of mass matrix must be decided upon. Either the consistent mass matrix prescribed by the finite element method can be employed or some form of diagonal mass matrix may be introduced. Secondly, some particular time integration procedure must be adopted. The procedures available divide themselves into two classes: the conditionally stable explicit schemes and the unconditionally or conditionally stable implicit schemes. The choices should be guided by both economy and accuracy. Using exact discrete solutions compared to the exact solutions of the differential equations, the results of these choices are displayed. Concrete examples of well-matched methods, as well as ill-matched methods, are identified and demonstrated. In particular, the diagonal mass matrix and the explicit central difference time integration method are shown to be a good combination in terms of accuracy and economy.     

Improvements in a Calorimeter for High-Power CW Lasers

Measurement certainty with the BB series of electrically calibrated calorimeters for high-energy lasers has been enhanced by the addition of monitors for energy backscattered from the meter and for energy missing the entrance aperture (overspill). The performance and design features of the recently constructed BB2 meter are compared with the previously described BB1 meter. Direct intercomparison shows the agreement between meters to be 1 percent.     

Fabrication of Metallic Magnetic Calorimeter X-ray Detector Arrays

Microcalorimeters with metallic magnetic sensors show great promise for use in astronomical X-ray spectroscopy. We describe the design and fabrication of a lithographically patterned magnetic microcalorimeter. A paramagnetic AuEr film is sputter-deposited as the sensor, which is coupled to a low noise SQUID via a meander superconducting pickup loop used as an inductor. This inductor also provides the magnetic field bias to the sensor. The AuEr film is deposited over this meander such that the field created by a large current flowing in the loop magnetizes the sensor material. The use of thin film techniques in the fabrication of these magnetic sensors not only allows strong magnetic coupling between the sensor and the inductor, it also is scalable for array fabrication.      

自动量热仪测量结果不确定度评定

本文详细介绍了自动量热仪热值误差测量结果的不确定度评定方法。     

Fabrication of Metallic Magnetic Calorimeter for Radionuclide Analysis

We present a detailed report on the fabrication process of a metallic magnetic calorimeter (MMC). The MMC is configured in a planar geometry with a meander-shaped pickup coil covered with a Au:Er temperature sensor layer. The meander coil is used to apply a magnetic field to magnetize the erbium ions and to measure the magnetization change of the spin system. The MMC is designed to have a large area (1 mm \(^2\) ) and 3  \(\upmu \) m thickness Au:Er layer, which is suited for large metal absorbers with a few nJ/K heat capacity in radionuclide analysis applications. The completed devices are used in alpha and Q spectrometries.     

锥形量热仪确定聚合物材料导热系数的方法

通过对聚甲基丙烯酸甲酯聚合物材料在锥形量热仪实验条件下加热过程的分析和研究,建立了材料加热过程的数学模型。利用该模型来计算材料的平均导热系数,需要测量的物理量仅仅是物体表面或内部的温度,通过一次测试就可以得到不同温度范围内材料的平均导热系数,方法简单,可靠。利用文中的计算方法,得到PMMA在不同温度范围内的平均导热系数,结果表明,随温度范围的增加,材料平均导热系数值有增大的趋势。计算出的导热系数值在低温度范围与文献值比较接近。研究表明在高的温度范围内不能将传统测量的导热系数值用作火灾条件下材料的参数值。     

电磁热能表在中央空调计量系统中的应用

讲述了常用的几种中央空调计量方法和工作原理,给出了一种中央空调计量系统的架构;描述了电磁热能表的功能特点以及在中央空调计量系统中的应用,为中央空调计量系统提供一种实战解决方案,并说明了电磁热能表防止误计量的方法以及使用、调试的便利性。     

氧弹热量计热值误差测量结果的不确定度评定

本文通过对一定量的燃烧热标准物质苯甲酸在热量计的氧弹内燃烧放出的热量的测量结果,探讨了其不确定度的评定.