Tuning of the cosmic-ray test system of the BESⅢ drift chamber

The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the chamber.The noise performance,drift time and charge measurements,and the scanning of channels were examined specifically.The preliminary results of the test indicate that the whole system works well.     

Aging effect in the BESIII drift chamber

As the main tracking detector of BESIII, the drift chamber provides accurate measurements of the position and the momentum of the charged particles produced in e+e-collisions at BEPCII. After six years of operation, the drift chamber is suffering from aging problems due to huge beam-related background. The gains of the cells in the first ten layers show an obvious decrease, reaching a maximum decrease of about 29% for the first layer cells. Two calculation methods for the gain change(Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) give almost the same results. For the Malter effect encountered by the inner drift chamber in January 2012, about 0.2% water vapor was added to the MDC gas mixture to solve this cathode aging problem.These results provide an important reference for MDC operating high voltage settings and the upgrade of the inner drift chamber.     

Tuning of the cosmic-ray test system of the BESⅢ drift chamber

The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the chamber.The noise performance,drift time and charge measurements,and the scanning of channels were examined specifically.The preliminary results of the test indicate that the whole system works well.     

两个不同单元尺寸的小单元漂移室模型的性能研究

利用宇宙线分别测量了两个单元尺寸为14mm和16.4mm充He/C3H8(60/40)气体的小单元漂移室模型的性能，包括空间分辨，dE/dx分辨和单元效率. 测量结果表明两个漂移室模型的性能没有明显区别.     

Studies of dE/dx measurements with the BESⅢ

The Beijing Spectrometer Ⅲ(BESⅢ)is a general-purpose detector used for the study of τ-charm physics at the Beijing Electron-Positron Collider Ⅱ(BEPC Ⅱ).This paper presents our studies of the dE/dx measurement in the drift chamber of BESⅢ,which is important for the identification of charged particles.Corrections applied to the dE/dx measurement in data reconstruction are discussed.After our current dE/dx calibration,a resolution of about 6% has been obtained for minimum ionization particles,and a 3σ K/πseparation is obtained for momenta up to 760 MeV/c.These results meet the design goals of the BESⅢ drift chamber.     

噪声对漂移室性能影响的模拟研究

利用蒙特卡罗方法模拟了漂移室的随机噪声和对其性能的影响,分别考虑了击中丝和非击中丝的时间道和电荷道的噪声,给出了径迹效率和动量分辨随噪声水平和噪声分布的变化情况.     

Design and implementation of the detector control system for the BESⅢ drift chamber cosmic ray test

After the construction of the BESⅢ drift chamber,a long period of cosmic rays test is necessary to verify its performance.This also provides a good opportunity to integrate the detector readout electronics and Detector Control System (DCS) into a unified working system.The goal of the DCS is to guarantee reliable physics data quality and the safe operation of the detector.It monitors and controls the HV,gas,VME crates and the environmental variables.The upper-level system is mainly developed from LabVIEW and the lower-level system mainly uses MCU and PLC technology.The system is designed to be highly flexible and scalable so that it can be applied to other detectors with little or no change.In the immediate future,it will be integrated into the entire BESⅢ Slow Control System.     

A Flash-ADC data acquisition system developed for a drift chamber array and a digital filter algorithm for signal processing

A Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offline processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio (SNR) is increased and a better time and energy resolution can be obtained.     

Studies on the drift properties and spatial resolution using a microMEGAS-equipped time projection chamber

R&D studies on the performance as well as on the gas properties of the microMEGAS-based time projection chamber with standard readout were carried out in June 2005 using 4 GeV/c pion beam in a magnetic field from 0 to 1 T at the proton synchrotron beam line at KEK, Japan. Analysis of the electron drift velocity, diffusion constant and point resolution of padrow measurement for MicroMEGAS TPC filled with 95% argon and 5% isobutane gas are presented. The underlying physical mechanism which determines the optimal TPC performance are briefly discussed. Preliminary measurements of gas properties and spatial resolution in close agreement with the analytical calculation and MAGBOLTZ simulation are summarized and presented in this paper.      

监控漂移管宇宙线实验性能研究

利用宇宙线对ATLAS实验上的监控漂移管室进行了性能研究, 根据BEE室的测试标准及步骤简要的测量了漂移管的主要特性. 包括: 漏电流、噪声水平、漂移时间分布、电荷分布及探测效率. 测试结果表明都在ATLAS规范要求之内.     

The laser calibration system of the ALICE time projection chamber

A Large Ion Collider Experiment (ALICE) is the only experiment at the Large Hadron Collider (LHC) dedicated to the study of heavy ion collisions. The Time Projection Chamber (TPC) is the main tracking detector covering the pseudo rapidity range |η| < 0.9. It is designed for a maximum multiplicity dN/dy = 8000. The aim of the laser system is to simulate ionizing tracks at predifined positions throughout the drift volume in order to monitor the TPC response to a known source. In particular, the alignment of the read-out chambers will be performed, and variations of the drift velocity due to drift field imperfections can be measured and used as calibration data in the physics data analysis. In this paper we present the design of the pulsed UV laser and optical system, together with the control and monitoring systems. for the ALICE Collaboration Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”, Budapest, Hungary, 4–9 August 2005.     

Software alignment of the BESⅢ main drift chamber using the Kalman Filter method

Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.     

A fast energy‐dispersive multi‐element detector for X‐ray absorption spectroscopy

In this paper results are presented from fluorescence‐yield X‐ray absorption fine‐structure spectroscopy measurements with a new seven‐cell silicon drift detector (SDD) module. The complete module, including an integrated circuit for the detector readout, was developed and realised at DESY utilizing a monolithic seven‐cell SDD. The new detector module is optimized for applications like XAFS which require an energy resolution of ～250–300 eV (FWHM Mn Kα) at high count rates. Measurements during the commissioning phase proved the excellent performance for this type of application.     

Development of high granulated straw chambers of large sizes

We have developed the baseline design for the straw drift tube tracking detectors for high-rate environment application. The low-mass inner straw elements and the technology of the multianode straws assembly were devised and checked. The prototype chamber was constructed and studied. The granularity of similar chambers can be reduced to 1 cm². The text was submitted by the authors in English.     

一种新型陀螺动态漂移检测系统的设计

在分析传统陀螺动态漂移测量方法的基础上,介绍了一种新的高、低温陀螺动态漂移测量系统的原理和结构设计。该系统由计算机软件控制其检测全过程,系统的中心部件由CCD摄像机、图像采集卡和处理软件等构成。处理软件用VC开发而成,利用一种快速的目标跟踪算法,它能实时的跟踪目标并能画出其运动轨迹,计算出陀螺的动态漂移。实验证明了该系统的简单性和实用性,其分辨最小动态漂移角度的能力不低于1.8′。     

MINICOOL环境试验箱制冷系统设计

环境试验箱是一种提供高、低温环境的试验设备,主要用于机械、电子、电工、航空、航天及军事等领域的一些电子产品在高、低温环境下的性能测试、筛选及考核试验。试验箱制冷系统采用以R22/R23为工质的复叠制冷循环,以系统热负荷和试验箱性能指标为依据,计算出了系统各点的状态参数,以此为基础对压缩机进行了选型,对系统的其它制冷部件进行了设计。     

CONSTRUCTION AND PERFORMANCE OF TWO-DIMENSIONAL DRIFT CHAMBER

The two dimensional drift chamber was formed by gluing a delay-line in a MIT-Harvard type drift chamber. An average drift velocity about 3.34cm/μs was obtained when the chamber was operated at plateau region and filled with P-9 gas. Its average space resolution is 570μm. The output signal amplitude of the chamber being changed when alter the incident particle's (both β^－ and X-ray) position was observed.     

A 45° PROTOTYPE OF THE CENTRAL DRIFT CHAMBER FOR BES AND RESULTS OF COSMIC RAY TEST

It is described that the function,structure, amplitude characteristics and results of cosmic ray test of a prototype of the central drift chamber for Beijing Spectrometer (BES). It was found that if appropriate high voltage is applied on the field wires homogeneous signal amplitude from different Layer of the chamber can be obtained. The drift velocity deduced by track reconstruction is 5.3cm/μs. The spatial resolution is about 134μm.     

New high negative dispersion photonic crystal fiber

A new high negative dispersion photonic crystal fiber is proposed. It has double-core structure. The inner core has a circle germanium-doped region. The outer core is formed by removing the 3rd ring air-holes around the core. There are two ring air-holes between the two cores, Diameter of the 1st ring air holes is bigger than that of the 2nd ring air-holes, this can make mode coupling between inner mode and outer mode and showed that the high negative PCF is the result of this structure characteristics. There are honeycomb photonic lattice in the PCF's cladding. The influence of the structure parameters deviated from the design those on the chromatic dispersion are evaluated. When the structure parameters Λ=1.50 μm, d_core=2.10 μm, d₁=0.90 μm, d₂=0.44 μm and d₃=1.04 μm, the dispersion coefficient D is −1320 ps/(nm·km) at 1550 nm. This is a new kind of chromatic dispersion compensation PCF.     

带有实时温度补偿功能的微型光谱仪研制

解调飞机上变栅距光栅位移传感器的微型光谱仪在受到严重的高低温冲击后会出现温度漂移。针对航空领域中变栅距光栅位移传感器的解调系统研制了一种具有实时温度补偿功能的微型光纤光谱仪。为了实现实时温度补偿,分析了温度变化对微型光谱仪的影响,并对传统的交叉式Czerny-Turner光路进行了优化,用ZEMAX软件模拟得到：在相同的受热产生的变形条件下,优化的C-T光路光谱漂移量相比优化前的更小且整体漂移线性度更好。在此基础上提出了一种引入参考光来实现实时温度补偿的方法,并最终基于改进的C-T光路制作了一个体积为80 mm×70 mm×70 mm、工作波段在500～1 000 nm、积分时间为8 ms～1 000 ms、光学分辨率约为2 nm的微型光纤光谱仪,用实验验证了优化的C-T光路的光谱温度漂移情况及温度补偿方案的可行性。实验结果表明在近60 ℃范围内的温度冲击下,研制的微型光谱仪能够达到波长标准误差小于0.1 nm,波长最大误差小于传感器系统所要求的0.3 nm,满足初始的设计要求。该微型光谱仪的创新之处在于采用了优化的交叉式C-T光路作为色散系统且基于引入参考光的方法实现了实时温度补偿功能。