基于电流放大芯片的Micromegas探测器高集成度读出电子学设计

Design of Highly Integrated Readout Electronics Based on Current Amplifier for Micromegas Detector

  • 摘要: 高分辨、大面积Micromegas探测器广泛应用于粒子物理实验、医学成像和工业检测等领域。针对Micromegas探测器多通道的读出需求,设计并实现了一种512通道的高集成度前端电子学(compact front-end electronics,Compact_FEC)。该电子学采用电流读出芯片ADAS1128,芯片集成128个电流放大器,可实现多通道电荷信息测量。电子学支持USB3.0和千兆以太网通信,可实现与上位机进行通讯交互。通过对电子学性能进行测试,在电子学线性动态范围为−77.97~0 fC的测试条件下,增益约213.6 Code/fC,积分非线性为2.7%,噪声小于0.7 fC。为验证读出电子学对Micromegas探测器阳极条信号的读出能力,利用55Fe放射源进行X射线能量分辨率测试,同时利用宇宙射线进行缪子击中位置重建位置分辨率测试。通过放射源测试可探测到X射线的全能峰与Ar逃逸峰;其中全能峰能量分辨率约20.23%@ 5.9 keV,全能峰与逃逸峰峰值比约2.09∶1。缪子击中位置测试结果表明,读出电子学测得Micromegas探测器x维度和y维度的位置分辨率分别为0.240 mm和0.243 mm。上述两项测试验证了Compact_FEC在单粒子测量模式下可用于读出Micromegas探测器。

     

    Abstract: Micromegas detector has the advantages of high spatial resolution, large area and easy processing. It is widely used in particle physics experiments, medical imaging and industrial inspection. As the demand for spatial resolution and detection areas in particle physics experiments grows, so does the field of Micromegas detectors. Advancements in etching and printed circuit board (PCB) manufacturing are leading to increasingly refined readout units and larger detection areas. The number of detector channels is also significantly increasing. A 512-channel highly integrated front-end electronics (compact front-end electronics, Compact_FEC) was designed and implemented for the multi-channel readout requirements of Micromegas detectors. The front-end electronics board mainly consists of a detector signal readout module, a data acquisition module and a power supply module. The detector signal readout module uses a current-based readout chip, ADAS1128. The chip consists of 128 current integral amplifiers, sample-and-hold circuits, two 24-bit resolution ADCs and a digital processing section, among others, which enables the measurement of multi-channel charge. The data acquisition module consists of an FPGA core board, USB 3.0 circuits, and Gigabit Ethernet. The main functions of the module include the configuration of the chip, chip data acquisition, and communication interaction with the host computer. The performance of the front-end electronics was first tested under floating input conditions. The gain of charge measurement is about 213.6 Code/fC in the dynamic range of −77.93-0 fC. The integration nonlinearity is 2.7%, and the noise is less than 0.7 fC. Furthermore, to validate the performance of the detector system, X-ray energy resolution tests were performed with the 55Fe radioactive source, and spatial resolution tests were performed with cosmic rays for track reconstruction. The X-ray full peak and Ar escape peak can be observed; the energy resolution of the full peak is about 20.23%@5.9 keV, and the ratio of the full energy peak and escape peak is about 2.09∶1. Since the charge center of gravity method is used in cosmic ray muon test to reconstruct the Muon hit bositions, the response of the cosmic ray muon energy deposited in Micromegas detector was first tested. The test results show that the spectrum of ionization energy deposited by Muon is well-matched to the Landau-Gaussian distribution. The muon hit bositions test results for the x-direction spatial resolution is 0.240 mm, and for the y-direction spatial resolution is 0.243 mm. In summary, Compact_FEC can detect signals from the Micromegas detector in single-particle measurement mode.

     

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