太阳γ射线谱仪的高能端电子学读出系统原型设计  

Prototype design of electronics readout system for solar gamma-ray spectrometer's high energy deposited

作　　者：陈伟[1,2,3] 郭建华[1,2] 汪慎 

机构地区：[1]中国科学院紫金山天文台,南京210008 [2]中国科学院暗物质与空间天文重点实验室,南京210008 [3]中国科学院大学,北京100049 [4]中国科学技术大学天文与空间科学学院,合肥230026

出　　处：《核技术》2018年第2期24-30,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.11273070;No.11622327);中国科学院青年创新促进会项目(No.2014275);中国科学院空间科学战略性先导科技专项空间科学任务概念研究项目(No.XDA15007114)资助~~

摘　　要：大面积太阳γ射线谱仪(Large Area Solar Gamma-ray Spectrometer,LASGA)是一台计划搭载在中国空间站上的高能辐射探测器,用于探测10 ke V-2.5 Ge V的太阳X/γ射线。LASGA的量能器由溴化镧闪烁晶体阵列构成,采用双端读出的方式扩大其动态测量范围;高增益端采用光电倍增管(Photomultiplier Tube,PMT)、低增益端采用光电二极管(Photodiode,PD)读出。由于PD对光电子没有放大能力,为了提高信噪比,LASGA的低增益端需要搭配低噪声的读出电子学系统。针对LASGA对前端电子学的要求,使用挪威IDEAS公司的电荷测量芯片VA140设计了多通道(128通道)、低噪声电子学原型系统,完成了其性能测试。测试表明,在室温下电子学系统的噪声水平为600e-@0 p F,在0-200 f C范围内有良好线性,保证单个溴化镧单元能够线性测量到250 Me V,满足项目要求。该电子学读出系统不仅适用于光电二极管等光电转换器件的读出,也可用于大面积的硅微条探测器。[Background] The large area solar gamma-ray spectrometer （LASGA） is a high-energy radiation detector that consists of anti-coincidence detectors and calorimeter. The calorimeter is composed of 5 orthogonal LaBr3 （lanthanum bromide） layers. Each layer includes fourteen 25 mm×25 mm×400 mm LaBr3 crystals. To achieve large dynamic range, each LaBr3 crystal matches with two independent readout elements with different gains. High gain readout uses a photomultiplier tube （PMT） while the low gain uses photodiode （PD）. Since PD has no amplification capability for photoelectrons, the LASGA readout system requires a low-noise readout electronics system to achieve a high signal-to-noise ratio （SNR）. [Purpose] This study aims to design an electronics prototype system with high dynamic range and low noise properties. [Methods] A 64-channel charge sensitive ASIC （VA140） produced by the IDEAS Inc. was used in front-end electronics board. And an Altera cyclone field-programmable gate array （FPGA） （EP3C25Q240C8） was employed to control the ASIC, analog to digital converter （ADC） and digital to analog converter （DAC） chips in data acquisition board. The digitalized detector signal was packaged in field-programmable gate array （FPGA） and sent to personal computer （PC） for processing. [Results] The performance of the electronics prototype was tested, while the minimum ionizing particles （MIPs） response of LaBr3 with cosmic ray muon was carried out as well. The test results showed that the noise level of the electronics system （@ 0 pF） and the detection system （connected with PD） at room temperature was about 600 e- and 1 800 e- respectively. And there was a good linearity in the range of 0-200 fC. The integral nonlinearity （1NL） of 126 channels in the range of 0-180 fC was better than 3%. [Conclusion] Single bromide lanthanum unit can measure the energy deposited linearly up to 250 MeV. The dynamic range and SNR of the prototype system could fully meet the project＇s

关 键 词：大面积太阳γ 射线谱仪 溴化镧 光电二极管 读出电子学 低噪声 

分 类 号：TL8[核科学技术—核技术及应用]