Performance studies of a full-length prototype for the CASTOR forward calorimeter at the CMS experiment

The Time-Of-Flight detector (TOF) of the ALICE experiment at the CERN LHC is based on Multi-gap Resistive Plate Chambers (MRPCs). The TOF detector consists of 152928 readout channels covering a total area of 141 m². In this paper the results of the calibration with cosmic-ray data collected during 2009 are presented.     

Design,development and performance study of six-gap glass MRPC detectors

The multigap resistive plate chambers (MRPCs) are gas ionization detectors with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV) is applied on the outer surfaces of outermost resistive plates only, while the interior plates are left electrically floating. The presence of multiple narrow sub-gaps with high electric field results in faster signals on the outer electrodes, thus improving the detector’s time resolution. Due to their excellent performance and relatively low cost, the MRPC detector has found potential application in time-of-flight (TOF) systems. Here we present the design, fabrication, optimization of the operating parameters such as the HV, the gas mixture composition, and, performance of six-gap glass MRPC detectors of area 27 cm \(\times \) 27 cm, which are developed in order to find application as trigger detectors, in TOF measurement etc. The design has been optimized with unique spacers and blockers to ensure a proper gas flow through the narrow sub-gaps, which are 250 \(\upmu \)m wide. The gas mixture consisting of R134A, Isobutane and SF\(_{6}\), and the fraction of each constituting gases has been optimized after studying the MRPC performance for a set of different concentrations. The counting efficiency of the MRPC is about 95% at 17.9 kV. At the same operating voltage, the time resolution, after correcting for the walk effect, is found to be about 219 ps.     

Test of the LHAASO electron detector prototype using cosmic rays

The LHAASO project is to be built in south-west China, using an array of 5137 electron detectors for the measurement of incident electrons arriving at the detector plane. For quality control of the large number of electron detectors, a cosmic ray hodoscope with two-dimensional spatial sensitivity and good time resolution has been developed. The first prototype of the electron detector has been tested with the hodoscope and the performance of the detector is found to be consistent with the design.     

Time stamp generator with digital correction for the T0 detector of the ALICE experiment

Time measurements in detecting particles from radioactive radiation sources are one of the main types of measurements in many branches of science and engineering: nuclear physics, space researches, nuclear medicine. The developed precise time stamp generator DWDC (Discriminator With Digital Correction) with a dead time of 25 ns is intended for applications in basic research of matter. It is planned to modernize the acquisition system of the T0 starting trigger detector using the DWDC module (ALICE experiment).     

用于CBM-TOF超级模块质量评估的SoC数据读出方法

在高压缩重子物质（Compressed Baryonic Matter,CBM）实验中,多气隙电阻板室（Multi-gap Resistive Plate Chamber,MRPC）探测器被用于构建飞行时间（Time of Flight,TOF）谱仪。根据CBM实验需求,TOF谱仪被设计成由6种不同类型的超级模块构成的探测器墙。每个模块最多包含5块MRPC探测器,能提供320路电子学通道,单个模块的数据率高达6 Gbps。为了评估CBM-TOF超级模块的性能,本文提出了一种基于TCP/IP千兆以太网技术的数据读出方法。考虑到TCP/IP协议的复杂性,该方法利用AlteraSoC FPGA从前端电子学接受数字化的时间数据,并通过千兆以太网并行地发送数据到DAQ软件。实验室测试结果表明,单个读出扣板全链路读出速率达到550 Mbps,能够用于CBM-TOF MRPC探测器质量评估。     

A moving microfoil conversion electron detector for selective excitation double Mössbauer experiments

A lightweight microfoil conversion electron detector has been built for use as a detector/analyser for selective excitation double Mössbauer experiments. The detector weighs approximately 40 g; it can be moved with constant acceleration by a conventional electromechanical drive, with peak velocities up to ±15 mm/s. Conversion electrons from resonant absorption events are collected from both sides of two 0.3 μm thick⁵⁷Fe-enriched stainless steel foils inside the detector. The detector's performance (signal to noise per unit time) has been compared with a potassium ferrocyanide absorber and proportional counter, and it is found to be about ten times better for a given source strength and sampling angle. The overall detector linewidth is 0.42 (2) mm/s, compared with 0.37 (1) mm/s for the PFC absorber.     

Measurement of through-going particle momentum by means of multiple scattering with the ICARUS T600 TPC

The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid argon time projection chambers is now mature. The study of rare events, not contemplated in the standard model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the ν_μ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrates that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the multiple Coulomb scattering along the particle’s path. Moreover, we show that momentum resolution can be improved by almost a factor two using an algorithm based on the Kalman filtering technique.PACS 29.40.Gx; 29.85.+c     

L0 trigger unit prototype for BM@N setup

The BM@N facility is a fixed target experiment based on heavy ion beams of the Nuclotron-M accelerator. The aim of the BM@N is to study nucleus – nucleus collisions at energies up to 4.5 GeV per nucleon. A level 0 trigger processor unit (Trigger L0 unit, T0U) for the BM@N deuterons and carbon ions at Run’2015 has been developed. The T0U is used to generate a BM@N zero level trigger and a TOF detector precise start.T0U generates trigger signal based on beam line and target area detector signals. This module also provides both control and monitoring of the detector front-end electronics power supplies. This article presents a concept, characteristics and test results of the T0U module during the Run 2015.     

Using a LaBr3:Ce scintillator for positron annihilation lifetime spectroscopy

A LaBr₃:Ce scintillator has a high light output (~60000 p.e/MeV) and a short decay constant (<25 ns), which makes it good for time spectrometry. Compared with a BaF₂ scintillator, it can bear a much higher count rate, and can be coupled to photomultipliers without using a quartz window. In this work, a positron annihilation lifetime spectrometer (PALS) consisting of two bulks of φ25 mm×25 mm LaBr₃:Ce scintillator coupled to two XP20D0 photomultipliers, respectively, was built. A time resolution of FWHM=206 ps was measured for the PALS with a ⁶⁰Co source at the energy window for ²²Na. With this spectrometer, a reasonable lifetime value τ=221±4 ps in a pure Si sample is obtained, which means that the utilization of LaBr₃:Ce as the detector for a PALS is feasible.     

A CW and pulse EPR spectrometer operating at 122 and 244 GHz using a quasi-optical bridge and a cryogen-free 12 T superconducting magnet

A high-field continuous-wave (CW) and pulse electron paramagnetic resonance spectrometer operating at 122 and 244 GHz is described. The instrument is based on a millimeter-wave bridge built from quasi-optical components. To improve the sensitivity, a cryo-cooled detector/mixer is used. The magnetic field is generated using a cryogen-free superconducting 12 T magnet (warm bore, 88 mm) equipped with a helium-flow cryostat for sample cooling. The advantages of this spectrometer are described and first results (obtained in CW mode) on different types of samples at 122 and 244 GHz are presented. The extensions to pulse operation as well as double resonance techniques (electron-electron and electron-nuclear) are briefly discussed.     

Pulse shapes from electron and photon induced events in segmented high-purity germanium detectors

Experiments built to search for neutrinoless double beta-decay are limited in their sensitivity not only by the exposure but also by the amount of background encountered. Radioactive isotopes in the surrounding of the detectors which emit gamma-radiation are expected to be a significant source of background in the GERmanium Detector Array, GERDA. Methods to select electron induced events and discriminate against photon induced events inside a germanium detector are presented in this paper. The methods are based on the analysis of the time structure of the detector response. Data were taken with a segmented GERDA prototype detector. It is shown that the analysis of the time response of the detector can be used to distinguish multiply scattered photons from electrons. PACS 23.40.-s; 14.60.Pq;29.40.-n     

ICARUS and its applications for studies of neutrino interactions and proton decay

The main physics issues of the ICARUS experiment are observations of solar, atmospheric, beam, and supernova neutrinos and possibly of proton decay, with its unique experimental features, in which both high visual resolution and accurate calorimetry are combined. The ICARUS project represents a new generation of detectors, providing three-dimensional views of ionizing events and particle identification, working also as a good homogeneous calorimeter. A first module (T600) has been built and was successfully tested in an external site in Pavia (Italy) during summer 2001. Large samples of cosmic muon tracks and cosmic showers have been collected with a spectacular richness of details. On the basis of the experience acquired in the realization of the T600 module, four additional modules will be built to reach a total mass of 3000 t. The detector will be placed in the underground laboratory in Gran Sasso (LNGS).     

基于可调谐激光的光谱辐射照度响应度定标

探测器的光谱辐射照(亮)度响应度是辐射定标中最重要的参数之一。传统的光谱辐射定标采用宽谱段光源和单色仪装置测量,新建的激光辐射测量装置采用激光和探测器测量,可以大大降低测量的不确定度。该装置首先将可调谐激光耦合进入积分球生成均匀的朗伯体单色光源,然后采用低温辐射计量传的标准陷阱探测器和面积已知的光阑,进行400～900 nm探测器的光谱辐射照度响应度标定。研究主要集中在四个方面：(1) 低温辐射计仅在某些分立激光波长定标标准探测器,其他激光波长下的光谱响应度必须进行插值,通过对比光谱响应度直接测量方法推导的陷阱探测器量子吸收效率,可以计算插值在其他波长带来的光谱响应度偏差,结果表明400～900 nm数据插值算法的总体偏差小于0.074%;(2) 实验采用电荷积分法测量标准探测器和被测探测器的电荷信号,并采用监视探测器消除激光功率起伏以降低激光功率稳定性的影响,测量重复性优于0.1%;(3) 针对标准探测器在向低温辐射计溯源和进行光谱辐射照度响应度量传时的激光功率差异,采用激光双光路叠加法测量探测器不同波长下的非线性系数,分析标准探测器光谱非线性带来的测量不确定度,在450,632.8和850 nm波长下,当探测器电流从0.2 mA变到3 nA时的非线性修正小于1.000 25;(4) 针对标准探测器定标时的功率模式和量传时的辐射照度模式差异,采用二维电控位移平台测量探测器的均匀性并进行修正,测量得到的标准探测器中心直径5 mm的非均匀性小于0.03%。最终采用可调谐激光辐射照度响应度测量装置,可以实现400～900 nm辐射照度响应度测量不确定度0.14%～0.074%(k=1)。实验对比了激光辐照度响应度装置和标准灯-单色仪装置两种方法测量的探测器的光谱辐射照度响应度。测量结果表明两种装置在400～900 nm的响应度标定近似等价,测量偏差全部位于标准灯-单色仪装置的测量不确定度范围内, 验证了激光辐照度响应度测量装置的实用性。     

红外探测器TPS434低温、磁场性能研究

以商用高灵敏度红外探测器TPS434为研究对象,测量了其灵敏度随温度(280～10 K)、辐射的调制频率、磁场变化(0～6 T)的相关信息。从实验结果得到：TPS434的灵敏度随着温度降低而降低,随辐射的调制频率增加而衰减,但是低温下的衰减速率变缓,说明探测器的弛豫时间变短;热电堆的温差电动势在低温下会随磁场发生线性变化,可以通过线性拟合扣除磁场对测量结果的影响。由实验所得数据估算等效噪声功率NEP以及最小可检测功率Pmin,对TPS434作为THz探测器的可行性进行了分析。     

Detector and readout performance goals for quantum well and strained layer superlattice focal plane arrays imaging under tactical and strategic backgrounds

Advancements in III–V semiconductor based, Quantum-well infrared photodetector (QWIP) and Type-II Strained-Layer Superlattice detector (T2SLS) technologies have yielded highly uniform, large-format long-wavelength infrared (LWIR) QWIP FPAs and high quantum efficiency (QE), small format, LWIR T2SLS FPAs. In this article, we have analyzed the QWIP and T2SLS detector level performance requirements and readout integrated circuit (ROIC) noise levels for several staring array long-wavelength infrared (LWIR) imaging applications at various background levels. As a result of lower absorption QE and less than unity photoconductive gain, QWIP FPAs are appropriate for high background tactical applications. However, if the application restricts the integration time, QWIP FPA performance may be limited by the read noise of the ROIC. Rapid progress in T2SLS detector material has already demonstrated LWIR detectors with sufficient performance for tactical applications and potential for strategic applications. However, significant research is needed to suppress surface leakage currents in order to reproduce performances at pixel levels of T2SLS FPAs.     

Experimental study on the aging process of the LR 115 cellulose nitrate radon detector

An experimental determination of the aging process of cellulose nitrate detector material was based on the examination of special properties of the LR 115 solid state nuclear track detectors (SSNTDs) of various ages up to 18 years. The examined relevant parameters are the bulk etching rate v_b and the track etching rate v_t. These parameters are responsible for the appearance, the size and the registration efficiency of tracks of -particles from radon gas in the detector. To find a correlation between these material parameters and the detector sensitivity an experimental calibration of indoor room and outdoor soil detector devices based on LR 115 took place at the Umweltforschungszentrum Leipzig-Halle (Germany). To avoid routine calibration work in external radon exposure facilities a correction of the age dependent calibration factors with the material parameters measured in one's own laboratory was targeted. In this study a general age dependence, however, was not found. The following statements for practical applications can be made. (i) the bulk etching rate v_b for detectors of the same batch has a depth dependence and this dependence is constant over 2 years (LR 115 September 1994). (ii) detectors of different batches older than 5 years and stored at room temperature show an odd v_b behaviour when v_b is used for describing track shapes. (iii) the calibration factor of detectors of different batches that were stored at about +4°C is constant over 5 years (LR 115 September 1994 and February 1999, Table 2).

The conclusion is that LR 115 detectors not older than 5 years and stored in a refrigerator at about +4°C should be preferred for radon measurements. Furthermore these detectors should be recalibrated every year and the microscope work of this calibrations should be performed by the same person who performs the measurements.

In addition, a phenomenon related to fundamental track formation mechanisms was found, that the time straggling of the time t_through when vertical tracks penetrate the 12 μm thick detector layer is independent of the age of the detectors and the energy of the -particle at the detector surface.     

High-speed electronics of the T0 detector for the ALICE experiment (CERN)

The design and special features of the main units of high-speed electronics for the trigger subsystem of the T0 detector of the ALICE experiment are considered. Its characteristic time resolution is 50 ps. The dead time does not exceed 25 ns.     

Search for heavy particles decaying into electron-positron pairs in pp collisions

We present results of searches for technirho (rho(T)), techniomega (omega(T)), and Z' particles, using the decay channels rho(T),omega(T),Z'-->e(+)e(-). The search is based on 124.8 pb(-1) of data collected by the D0 detector at the Fermilab Tevatron during 1992-1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes pp-->rho(T),omega(T),Z'-->e(+)e(-) as a function of the mass of the decaying particle. For certain model parameters, we exclude the existence of degenerate rho(T) and omega(T) states with masses below about 200 GeV. We exclude a Z' with mass below 670 GeV, assuming that it has the same couplings to fermions as the Z boson.     

Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensionai Vernier anode axe introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high- energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.     

使用曲面微通道板和感应电荷位置灵敏阳极的软X射线-极紫外光子计数成像探测器研究

本项目对我国空间探测的极紫外(EUV)波段大视场相机所需求的球面光子计数成像探测器的关键技术进行了研究。首先,建立了光阴极材料次级电子产出模型,利用该模型计算了软X射线-EUV波段常用的光电阴极材料—碱卤化物的次级电子产出,分析了微通道板(MCP)的次级电子产出。建立了测量MCP量子探测效率的装置,并推导出MCP量子探测效率的计算公式,测量了MCP在软X射线-EUV波段的量子效率以及MCP量子效率随掠入射角的变化。其次,建立了球面实芯微通道板的制备装置,利用高温热成型方法制备出曲率半径为150 mm球面MCP,利用光刻技术制备出有效直径为48 mm的楔条形感应电荷位置灵敏阳极,在此基础上集成了一套使用球面MCP和感应电荷位置灵敏阳极的两维光子计数成像探测器。再次,研制出包括快速前端模拟电路与后续数字电路的成像读出电路,编制了能矫正图像畸变的图像实时采集和处理软件。最后,建立了MCP探测器空间分辨率、图像线性的检测装置,对研制出的探测器性能进行了检测,检测结果表明:探测器的各项技术指标完全满足要求。