【作者】 刘小桦；

【导师】 安琪；

【作者基本信息】 中国科学技术大学 ， 物理电子学， 2008， 博士

【摘要】 兰州重离子加速器冷却储存环(HIRFL-CSR)工程的CSRm内靶实验将利用重离子束流进行强子物理研究,包含的探测器设备有:径迹探测器、飞行时间探测器、电磁量能器和强子量能器等。CSRm外靶实验将在核物质状态方程、放射性束物理和超核等方面开展物理研究,包含的探测器设备有:起始时间探测器,靶区γ探测器,大接收度二极磁铁,多丝漂移室径迹探测器,飞行时间墙和中子墙等。其中,多丝漂移室通过测量带电粒子的漂移时间得到粒子径迹信息,飞行时间墙和中子墙采用了快塑料闪烁体加光电倍增管的探测方案测量粒子飞行时间,要求读出电子学系统具有高精度时间电荷测量性能。本论文将研究多丝漂移室、飞行时间墙和中子墙的读出电子学方法,设计基于TOT(Time-over-Threshold)技术的读出电子学系统并进行详细测试。探测器读出电子学主要涉及两个方面的技术——电荷测量和时间测量。电荷测量技术包括电荷-电压转换、波形数字化和电荷-时间转换三种。基于TOT技术的电荷-时间转换具有电路简单、低成本和低功耗的特点。时间测量技术包括定时和时间-数字转换。前沿定时是粒子物理实验中最常用的定时方式。前沿定时结构简单,但需要进行“时间游动”修正,修正方法有波形数字化、幅度修正和电荷修正。定时后的信号送到时间数字化芯片(TDC)中进行量化。时幅变换TDC、Wilkingson型TDC、游标卡尺型TDC和计数器TDC都可以得到很高的时间测量精度。欧洲核子中心(CERN)开发的HPTDC是一种非常适合粒子物理实验的高性能数据驱动型TDC。SFE16是一款基于TOT技术的16通道集成芯片。每个通道由一个电荷灵敏前放、极零相消电路、两级滤波成形电路、主放大器、甄别器和输出驱动电路组成,输出脉冲的宽度与输入电荷量相关。多丝漂移室读出电子学系统采用了SFE16进行时间和电荷测量。前端处理模块的SFE16用于对探测器信号放大、成形和甄别。前端处理模块通过差分电缆连接到64通道时间测量模块。安装在PXI机箱内的64通道时间测量模块采用了HPTDC完成时间测量。测量数据通过PXI总线传输到计算机。飞行时间墙和中子墙都采用了快塑料闪烁体加光电倍增管的探测方案,其读出电子学系统也采用TOT技术。为了保证时间测量精度,信号先分成两路,其中一路送到前沿定时甄别器和HPTDC中进行时间测量,另一路送到SFE16和HPTDC进行电荷测量。电荷信息用来进行时间游动效应修正。8个通道的电路集成在一块3U尺寸的PXI模块上。测试数据通过PXI总线传输到计算机。读出电子学系统的测试包括时间性能和电荷性能两个方面,测试又可分为三个阶段:实验室环境下的电子学测试、读出电子学系统与探测器联合测试和现场测试。电子学测试主要是利用信号发生器的信号测试读出电子学系统的性能。联合测试是利用探测器和读出电子学系统搭建的测试平台,将探测器的信号送到读出电子学系统进行测试。现场测试得到整个系统在实际工作环境下的性能。更多还原

【Abstract】 CSRm internal target experiment facility consists of track detector, time of flight detector, electromagnetic calorimeter, hadronic calorimeter etc. CSRm external target experiment facility consists of start time detector, Multi-wire Drift Chamber, Time of Flight Wall, Neutron Wall, etc. Multi-wire Drift Chamber is used to measure the track of charged particles. Time of Flight Wall is used to measure the flight time of charge particle. Neutron Wall is used to measure the flight time of neutron. This thesis mainly discusses the readout electronics system of Multi-wire Drift Chamber (MWDC), Time of Flight Wall and Neutron Wall. An implement and test of the readout electronics based Time-over-Threshold technique is described in details.Charge measurement and time measurement are two important parts of readout electronics of detector. There are three methods of charge measurement that are charge-to-voltage conversion, wave sampling and charge-to-time conversion. Charge-to-time converter based Time-over-threshold technique has the characteristic of simple circuit, low price and low power. Time measurement includes time discrimination and time to digital converter (TDC). Leading end discriminator is easily realized and integrated. But it has time error because of time walk effect. The error can be corrected by charge measurement. Some types of TDC also are introduced, such as TAC+ADC method, Wilkinson TDC, vernier TDC and counter TDC. HPTDC developed by CERN is a counter TDC with very high resolution and is suitable for particle physics experiment.SFE16 is a 16-channel integrated ASIC based Time-over-Threshold technique. Each channel of SFE16 consists of a charge sensitive preamplifier, a pole-zero stage, two selectable filters, an amplifier, a discriminator and a "LVDS compatible" current driver. The output pulse width is a function of input charge.The readout electronics of MWDC uses SFE16 to implement time measurement and charge measurement. The front-end boards with SFE16, realizing the MWDC signal preamplification, shaping and discrimination, will be mounted on the detector. The front-end boards connected to 64-channel time measurement board through differential cables. 64-channel board adopts HPTDC and is installed in PXI crate. The measurement result is transferred to computer through PXI bus.Time of Flight Wall and Neutron Wall both use fast plastic scintillator detectors and phototubes. The readout electronics of them also use Time-over-Threshold technique. To improve time measurement resolution, signal is splitted into two ways, one is sent to leading end discriminator and HPTDC to get precise flight time. The other is sent to SFE16 chip and HPTDC to measure the charge of signal that is used to correct time-walk error. The 8-channel electronics are integrated in one PXI module of 3U size. The measurement result is transferred to computer through PXI bus.The test of readout electronics will give time and charge measurement performance. Test can be divided into three steps that are electronics test in lab, detector and readout electronics combined test, field test. Electronics test uses signal from signal generator to test the performance of readout electronics in lab. For combined test, detector and readout electronics is combined into a test platform. Signal from detector is used to test the performance of the platform. Field test gives the performance of the whole system under real work environment.更多还原