【作者】 杜中伟；

【导师】 苏弘； 安琪；

【作者基本信息】 中国科学技术大学 ， 物理电子学， 2014， 博士

【摘要】 核能具有资源丰富、清洁经济的优点,是未来的主要能源。ADS嬗变系统(Accelerator Driven Sub-critical System)是以核废料为原料,通过加速器加速质子打靶后产生的散裂中子来驱动次临界堆核裂变反应,其对解决核废料安全处置和核燃料稳定供给有着重要意义。在ADS系统中,对散裂反应和裂变反应中产生的中子流强度的探测是一个关键问题,探测精度直接决定了核反应的可控性能。中子探测器需要对中子和γ光子进行甄别。n-γ甄别有两种方法：一是通过粒子飞行时间和能量测量后计算出其质量来甄别；二是通过测量粒子脉冲形状来甄别。波形数字化技术是通过对中子探测器输出的电流脉冲进行波形数字化,由软件对波形数据进行处理来获得飞行时间、电荷量和衰减时间,有着高集成度和准确的n-γ甄别能力等优点。本课题的研究目标是高采样频率和高精度的波形数字化技术以及低延迟的触发判选技术。为此,开展了针对高速开关电容阵列芯片DRS4加高分辨率ADC的波形数字化技术的应用研究,基于该芯片设计了相应的前端插件和触发插件以及数据处理软件,建立了一套中子探测的最小读出电子学系统。该系统能实现5GSPS采样率的波形数字化,一路输入即可完成飞行时间、电荷和衰减时间三项目标的测试,有效的降低了系统的复杂度和成本。同时研究出了零随机延迟触发判选技术,使触发插件能为即时的波形采样提供小且固定的延迟的触发判选结果,以减少系统死时间。论文详细介绍了相应的硬件开发和软件开发,并通过实验验证了读出电子学系统的n-γ甄别能力和触发判选性能。更多还原

【Abstract】 Nuclear energy has the advantage of abundant resources and economy, and is the main energy source of the future. Accelerator Driven Sub-critical Systemcan transmutatethe nuclear waste as raw materia of nuclear energy. Soit has important significance to solve the safe disposal of nuclear waste and stable nuclear fuel supply stability. In the ADS system, detecting the intensity of the neutron which is producedby the spallation and fission reactions is a key issue. The accuracy of theneutrondetection directly determines the performance of nuclear reaction controlling. Neutron detectors need to discriminatethe neutron out ofthe y photons by measuring the time-of-flight and the pulse shape. For satisfying the physical requirements of high precision, high integration density and minimum cost, we have developed the waveform digitizing technology that acquires the data of electric charge, time-to-flight and pulse fall time in single read-out process. The waveform digitizing technology is based on high-speed switched capacitor array (SCA) chip named DRS4that allows sample an interested region of analog signal up to a rate of5GSPS. Together with the DRS4module, the front-end module and the trigger module are designed to build a waveform digitizing system. Beside, the zero-delay trigger technology is developed, which makes the trigger module can provide the trigger decision of a low and fixed latency for the instant waveform sampling.Thispaper introduces the hardware and software development of the waveform digitizing technology in detail, and the n-ydiscrimination ability and trigger performance aretested by the experiment.更多还原