Instruments for detecting electric breakdowns in proportional drift chambers of the transition radiation tracker in the ATLAS experiment

The transition radiation tracker is a part of the ATLAS facility at the LHC accelerator at CERN and operates as a position detector and a detector of transient radiation. It consists of approximately 400000 proportional drift chambers (PDCs) filled with a mixture of Xe + CO₂ + O₂. During its operation, electric breakdowns may occur, which may result in a failure of the detecting element. To diagnose and find broken-down PDCs, an instrument has been developed that makes it possible, by analyzing signals from the anode, to detect defective PDCs and exclude them from the working detector.     

Methods for detecting structural changes in frames of video sequences when recording physical and chemical experiments

The possibility of applying the mean structural similarity, mean nonparametric structural similarity, and spectral criteria to detection of structural changes in the phase condition of an object of investigation is considered. Determination of cesium chloride phase transitions in the temperature range of 250–710°C is used as an example to demonstrate the experimental evidence of the efficiency of these criteria for solving the above-mentioned problems.     

Method for sealing nylon chambers for use at low temperatures

Two methods are described which were found to seal nylon to nylon for use at low temperatures.     

An installation for magnetron deposition of getter coatings in narrow-aperture chambers

An installation for magnetron sputtering of thin-film coatings has been designed to deposit getter films in extended vacuum structures with a complex aperture. A solenoid used in the installation (diameter, 600 mm; length, 6000 mm; and maximum field, 800 G) makes it possible to deposit materials by sputtering onto internal walls in any type of vacuum chambers employed in modern accelerators. Results of deposition of a TiZrV getter coating in narrow-aperture aluminum vacuum chambers that will be mounted in the damping sections of a PETRA III synchrotron radiation source by DESY (Hamburg, Germany) are presented. The atomic composition and the homogeneity of the film along its length have been investigated on a channel for SR-XRF analysis at the Budker Institute of Nuclear Physics.     

A system of multiwire drift chambers for wide-aperture spectrometers

A system of wide-aperture drift chambers with an operating area of 2.5×1.9 m² and 1.5×1.5 m² is described. The chamber, operating with two gas mixtures, is studied. The dependence of the chambers efficiency on the high voltages applied to the cathodes and potential wires, and the time distributions are presented. Using the system of drift chambers, a spatial distribution of ∼ 180 μm was achieved for straight tracks in a 8-mm drift gap. The chambers were included in the track systems of the VES and GAMS spectrometers at the Y-70 accelerator of the Institute for High-Energy Physics (Protvino).     

The use of a nitrogen laser for observation of space charge effects in drift chambers and development of high precision vertex chambers

A two-stage nitrogen laser has been built and is presently being used to investigate properties of drift chambers. In this paper we present the measured parameters of this laser, the results of a study of the double track separation in a drift chamber of jet design and a measurement of the saturation effects in this chamber as a function of total gain. An understanding of the saturation effects is important for drift chambers with multiple hit capability. The laser technique reported here represents a major improvement in the simplicity of investigation of the double track separation and saturation effects. In addition, we have demonstrated the usefulness of this kind of laser in the development of high precision drift chambers working in a resolution range of ∼ 20–30 μm.     

Large proportional chambers for muon detection in the CELLO experiment at petra

We describe the muon detector in the CELLO experiment. This detector is composed of one layer of proportional chambers placed after a total of 5 interaction lengths of matter. These chambers have cathode read-out, thus enabling the unambiguous determination of coordinates. A total of 32 chambers has been built in order to cover 95% of the total solid angle. The read-out electronics use the FILAS integrated chips made by EFCIS. Data concentration is done by a multiplexing system which addresses only those chambers which have some information. The precision is poor, but sufficient for muon detection: σ = ±6 mm.     

Study of resolution for a large array of drift chambers

Three drift chambers arranged to represent the cross section of the LEP L3 muon detector were used for track measurements. Displacing the middle chamber by 3.8 mm, corresponding to the sagitta of a 45 GeV muon in 5.1 kG, measurements with UV laser tracks 3 m long yield an equivalent momentum resolution of 1.5%.     

Eliminating the induction effect in grid ionization chambers

The influence of the grid shielding inefficiency on the total energy resolution of parallel-plate ionization chambers with electron collection is analyzed. The design of a chamber is proposed and investigated, in which the influence of the induction effect on the energy resolution is substantially suppressed and, at the same time, the grid manufacturing technology is simplified.     

复杂网络中的完全子图搜索算法研究

现实生活中,许多实际网络中通常包含由若干结点组成的完全子图,一些实际网络甚至是由一些完全子图通过公共节点链接而成的,如何搜索这类网络中的完全子图,是一件很有意义的事情.提出了一种搜索这类特殊复杂网络的完全子图的算法,编制了实现算法的程序,将算法程序应用于机械制造中的产品零部件关系网、中药方剂网等实际的复杂网络,取得了良好的效果.为深入研究这一类型的复杂网络提供了有力的工具.     

The capabilities of multielectrode heterogeneous ionization chambers for X-ray thickness measurements

An X-ray setup featuring automatic correction of the radiation spectrum and flux is developed for measuring the thickness of articles.     

空中手写笔笔迹检测系统

提出了一种基于微加速度传感器与微角速度传感器的空间笔迹检测系统,并对轨迹检测系统的算法进行了描述。手写动态采集系统使用安装于手写笔上的加速度传感器和角速度传感器采集手写笔的动态信息,通过A/D转换将得到的数据由串行通信接口传送至计算机进行处理。该系统可用于检测手写笔在三维空间的运动轨迹,并通过三维空间的姿态角变换矩阵将手写笔动态信息投影到二维坐标平面,经过一系列积分运算最终重现笔迹信息。介绍了手写笔运动过程中重力加速度对笔迹重现的影响以及从检测到的加速度中剔除重力加速度得到纯净运动加速度的方法,对传感器的标定进行了相应的说明。实验结果表明,该系统达到了预期的效果。     

准绝热开口氩三相点复现装置

氩三相点是ITS-90温标重要的低温固定点和我国国家温度基准固定点.氩三相点复现装置是实现氩三相点复现的基本实验装置.介绍了中国计量科学研究院最新研制的基于准绝热原理的用于长杆铂电阻温度计的开口氩三相点复现装置.该装置可以在降温过程中充入足够量的氩气,保证了足够量的氩气固化,确保了较长的温坪时间,解决了按恒定热流法设计带来的复现性较差、温坪持续时间短等问题.通过采用高精密电桥测量显示:新建氩三相点复现装置温坪持续时间26 h以上,复现性0.04mK,且16 h的温坪变化在0.2 mK以内;使用两支温度计多次测量结果标准偏差均在0.05 mK以内,标准不确定度大于0.2 mk.该装置的研制提高了我国氩三相点的复现水平,保障了国家基准量值的传递,为开展国际比对奠定了基础.     

矫直及探伤精整线

介绍北钢新五十万吨生产线矫直及探伤精整线工艺及设备配置。     

Hydrodynamic stabilization in the combustion chambers of liquid-propellant engines

Attention focuses on approaches to stabilization within the combustion chambers of liquid-propellant engines in which the structural and hydraulic features of the injectors and mixing heads are taken into account.     

A 32-channel CAMAC module for reading information from multiwire proportional chambers

An AA-32 32-channel CAMAC module is intended for reading information from the anode wires of multiwire proportional chambers. The amplifying part, signal delay module, and digital part for writing information into the computer are all placed on the same two-layer CAMAC board. ANODE-2-50M 8-channel microcircuits are used for amplifying signals. A two-port memory is used to delay (for up to hundreds of microseconds and more) the signals. The digital part of the system, including a two-port memory, is designed on Altera programmable gate arrays.     

A versatile controller for data acquisition from the coordinate detector streamer chambers

A 4-channel controller in the 16-bit ISA bus standard on the basis of programmable logic devices is described. The controller provides sequential data exchange with a personal computer at a speed up to 1 Mb/s in each channel. It comprises a 4-channel counter, a 4-bit majority coincidence circuit for trigger decision, and a 31-bit timer.     

Multichannel audio monitor for detecting electrical signals

The multichannel audio monitor (MUCAM) permits the simultaneous auditory monitoring of concurrent trains of electrical signals generated by as many as eight different sources. The basic working principle of this device is the modulation of the amplitude of a given pure tone by the incoming signals of each input channel. The MUCAM thus converts a complex, multichannel, temporal signal sequence into a musical melody suitable for instant, subliminal pattern analysis by the human ear. Neurophysiological experiments requiring multi-electrode recordings have provided one useful application of the MUCAM.