Environmental test of the BGO calorimeterfor DArk Matter Particle Explorer

DArk Matter Particle Explorer (DAMPE) is the first Chinese astronomical satellite, successfully launched on Dec. 17 2015. As the most important payload of DAMPE, the BGO calorimeter contains 308 bismuth germanate crystals, with 616 photomultiplier tubes, one coupled to each end of every crystal. Environmental tests have been carried out to explore the environmental adaptability of the flight model of the BGO calorimeter. In this work we report the results of the vibration tests. During the vibration tests, no visible damage occurred in the mechanical assembly. After random or sinusoidal vibrations, the change of the first order natural frequency of BGO calorimeter during the modal surveys is less than 5%. The shift ratio of Most Probable Value of MIPs changes in cosmic-ray tests are shown, the mean value of which is about -4%. The comparison of results of cosmic-ray tests before and after the vibration shows no significant change in the performance of the BGO calorimeter. All these results suggest that the calorimeter and its structure have passed through the environment tests successfully.     

重离子在半导体器件中引起的单粒子效应

重离子引起的单粒子效应是威胁航天器安全的重要因素之一 ,利用加速器进行地面模拟是研究单粒子效应的重要手段 .概述了单粒子效应研究的历史和现状,讨论了单粒子效应研究的基本方法 ,最后简要介绍了在兰州重离子加速器上已开展的单粒子效应研究工作. Single event effects (SEE ′s) have been observed in semiconductor device in space since 1975. It has been verified from many spaceflight tests that single event effect induced by cosmic ray is one of the important sources of anomalies and malfunctions of spacecraft. Initially, a brief outline of space radiation environment is given. The history and recent trends were described, and basic methods and necessary facilities for SEE testing were also discussed. Finally, the research ...     

国内典型地区地面大气中子能谱测量与仿真

基于多球能谱仪开展了广州、兰州和拉萨等地区的大气中子能谱和通量测量,获取了大气中子能谱的典型特征。测量结果表明：不同地区的大气中子通量受海拔高度的影响明显,地面大气中子通量随着海拔的增加而增加。此外,基于蒙特卡罗仿真工具也可以模拟初级宇宙射线粒子在地球大气层中的核反应过程,从而计算获取大气中子能谱。大气中子能谱测量数据与仿真数据吻合良好。     

用12C离子模拟质子引起的单粒子效应

在理论分析的基础上 ,提出了一种利用兰州重离子加速器提供的高能12C离子模拟质子引起单粒子效应的途径 .在保证核反应机制是引起单粒子效应主要机制的前提下,用高能12C离子可以模拟质子在功率金属 -氧化物 -半导体场效应晶体管中引起的单粒子烧毁以及单粒子栅极击穿 ,获得质子单粒子效应的饱和截面 ,定性研究质子单粒子效应的角度效应 ,还可以作为高能质子单粒子效应实验前的预备实验 .该方法拓展了兰州重离子加速器加速的轻的重离子在单粒子效应实验研究方面的应用 ,对现阶段国内开展质子单粒子效应实验研究具有重要意义. The mechanisms for proton and heavy ion induced single event effect (SEE) are discussed and a method to simulate proton induced SSEE (PSEE) with high energy 12 C is proposed in this paper. The experiments which can be done by using this method include single event burnout (SEB) and single event gate rupture in power MOSFET, single event upset (SEU) and single event transient (SET) in less sensitive device and angle effect. The experimets with high energy ...     

在羊八井设置KASCADE强子量能器研究宇宙线膝区成分

预期在高海拔测量宇宙线空气簇射（AS）轴心中的高能强子成分能提供对宇宙线膝区成分灵敏的一些新的AS观测量。 假定在羊八井ARGO阵列的中央设置一台类似于KASCADE所使用的强子量能器, 记录AS轴心区的高能强子, 模拟计算分析表明, 采用适当的事例选择条件, 能在有效运行1—2 a的观测数据中, 选出有合理大小的、 初能在膝区的、 由AS轴心区高能强子组成的事例样本, 并给出对膝区成分灵敏的许多新观测量的分布。 It is shown that measuring the high energy hadrons in air shower cores at high altitudes (like Yangbajing) can provide some new observables which are sensitive to the cosmic ray composition at the knee region. Assuming a hadron calorimeter (like KASCADE calorimeter) is set up at the center of ARGO array, the event selection conditions are studied for that the primary energies of the selected events range just around the knee. The sample has a reasonable size for 1—2 years’ exposure and a number of observables are shown to be sensitive to the composition.     

Positrons and electrons in primary cosmic rays as measured in the PAMELA experiment

The PAMELA experiment is being carried out on board the Russian satellite Resurs DK1 placed in the near-earth near-polar orbit on June 15, 2006. The apparatus comprising a silicon-strip magnetic spectrometer and an electromagnetic calorimeter allows measurement of electron and positron fluxes in cosmic rays in a wide energy interval from ～100 MeV to hundreds of GeV. The high-energy electron and positron separation technique is discussed and the data on positron-to-electron ratio in primary cosmic rays up to E ≈ 10 GeV from the 2006–2007 measurements are reported in this work.     

Proton spectrum of the 2005 January 20 solar flare

An extreme solar cosmic ray event broke out on 2005 January 20.Not only is it the most intensive solar energetic particle (SEP) event,with＞100 MeV particles measured by GOES satellite since 1986,but it has been the largest ground level enhancement (GLE) event recorded by the ground-based neutron monitors since 1956.This work presents the solar proton spectra for this event with data obtained by GOES in multiple energy cbannels.These spectra are well fitted by a modified power-law function.The spectral index of around -1 indicates that the January 20 event has a hard energy spectrum.Possible mechanisms for the acceleration of relativistic protons are discussed.     

Proton spectrum of the 2005 January 20 solar flare

An extreme solar cosmic ray event broke out on 2005 January 20. Not only is it the most intensive solar energetic particle (SEP) event, with >100MeV particles measured by GOES satellite since 1986, but it has been the largest ground level enhancement (GLE) event recorded by the ground-based neutron monitors since 1956. This work presents the solar proton spectra for this event with data obtained by GOES in multiple energy channels. These spectra are well fitted by a modified power-law function. The spectral index of around －1 indicates that the January 20 event has a hard energy spectrum. Possible mechanisms for the acceleration of relativistic protons are discussed.     

准单能中子单粒子效应研究现状

对国际上用于单粒子效应(SEE)研究的准单能中子源进行了相关调研,对产生准单能中子源的7Li(p, n)7Be核反应、装置布局以及表征中子场性质的中子注量率、中子能谱、中子束流轮廓及其均匀性、热中子本底等参数的理论计算及实验测量进行了系统的介绍。进行准单能中子SEE实验要求中子源有较高的中子注量率水平、较大的束流轮廓、较好的束流均匀性以及较低的热中子本底,并且能测量出精确的中子能谱。对准单能中子SEE实验过程以及三种中子SEE截面的尾部修正方法进行了介绍。     

用重离子实验数据推算质子翻转截面和轨道翻转率

空间单粒子辐射环境主要由重离子和高能质子构成,但在地面利用两种离子评估器件单粒子效应敏感度成本太高,因此利用重离子实验数据推算质子敏感参数成为一个非常活跃的研究课题.利用Barak经验公式,在重离子实验获得器件的σ LET值曲线的基础上,计算了几种典型器件在不同能量下的质子翻转截面以及典型轨道上质子引起的翻转率,并同FOM方法预示的质子翻转率进行了比较,其结果将对卫星电子系统抗辐射加固设计具有重要参考价值. The radiation environments concerned with single event upset mainly consist of heavy ions from cosmic ray and large flux proton from solar events and planetary radiation belts. The most reliable calculation for SEE rate induced by proton and henvy ions are the way to use the experimentally measured data rospectively. But it is too expensive to test devices with both heavy ions and protons. So it is necessary to derive models for predicting proton cross sections and rates from heavy ion test data....     

Energy correction for the BGO calorimeter of DAMPE using an electron beam

The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons,electrons and positrons originating from deep space.The electromagnetic calorimeter(ECAL),made of bismuth germinate(BGO),is one of the key sub-detectors of DAMPE,and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV.In this paper,methods for energy correction are discussed,in order to reconstruct the primary energy of the incident electrons.Different methods are chosen for the appropriate energy ranges.The correction results of Geant4 simulation and beam test data(at CERN) are presented.     

THE RESPONSE OF A 3×3 BGO DETECTOR ARRAY TO 0.5—21MeV PHOTONS

An array of 9 BGO crystals of 20×20×200mm³ equipped with photomultiplier readout was assembled and tested. Radioactive γ and neutron sources, (p,γ) reactions by low energy protons from Van de Graaff accelerator and (n,γ) reactions by thermal neutrons from nuclear reactor were employed to produce photons in the energy range from 0.5 to 21MeV. The energy response of the array is shown to be linear over the whole range. Data on the energy resolution follow an E^1/2 dependence at low energies, and deviate from it at 4.43MeV and higher energies. Results from the lateral energy deposition of showers were compared with the predictions of the Monte Carlo simulation and found to be in good agreement. Our study demonstrates the feasibility of calibration and monitoring of BGO electromagnetic calorimeter by means of radioactive sources and low energy (p,γ) reactions.     

Measurement of the high-energy electron and positron spectrum in the PAMELA experiment

The PAMELA magnetic spectrometer onboard the Resurs DK1 satellite no. 1 was put into (Earth) orbit on June 15, 2006; measurements continue at the present time. The scientific objective of the spectrometer is the study of antiproton, proton, positron, electron and light nucleus fluxes in cosmic rays. In this paper, we present the technique for measuring electron and positron spectra in the energy range from 20 to 800 GeV.     

Optimal gamma-ray selections for monochromatic line searches with DAMPE

The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray detector covering a wide energy band with a high energy resolution. One of the key scientific goals of DAMPE is to carry out indirect detection of dark matter by searching for high-energy gamma-ray line structure. To promote the sensitivity of gamma-ray line search with DAMPE, it is crucial to improve the acceptance and energy resolution of gamma-ray photons. In this paper, we quantitatively proved that the photon sample with the largest ratio of acceptance to energy resolution is optimal for line search. We therefore developed a line-search sample specifically optimized for the line-search. Meanwhile, in order to increase the statistics, we also selected the so-called BGO-only photons that convert into e⁺e^- pairs only in the BGO calorimeter. The standard, the line-search, and the BGO-only photon samples are then tested for line-search individually and collectively. The results show that a significantly improved limit could be obtained from an appropriate combination of the date sets, and the increase is about 20% for the highest case compared with using the standard sample only.     

微处理器80C86及其外围芯片协合效应实验研究

研究了总剂量辐照对微处理器 80C86及其外围芯片82C85单粒子效应敏感度的影响.252Cf轰击 80C86获得的单粒子效应截面在0-12 0Gy(Si)剂量范围内没有明显的变化 ;外围芯片 82C85中发生的单粒子脉冲可能引起系统故障. Total dose dependence of the single event effct (SEE) sensitivity for microprocessor 80C86 and its peripheral chip 82C85 are reported. In this study, 1 μCi 252 Cf was used as a heavy ion simulator and the samples were tested by a patent 8086 test system following exposure to 60 Co γ rays. It is found that SEE cross section of 80C86 does not show significant change with increasing total dose from 0-120 Gy(Si). SEE test also shows that single event transient (SET) in 82C85...     

Magnetic calorimeter for registration of small energy release

A scheme of magnetic calorimeter for registration of rare events characterized by small energy release (cosmic rays, WIMPs, solitary X-ray quanta) is proposed. The calorimeter is brought to operation by adiabatic demagnetization, and its magnetic response is measured by a quantum interferometer (SQUID, A. Barone and G. Paterno, Physics and applications of Josephson Effect). Special consideration is given to the specific features of calorimeter operation in the ferromagnetic transition region. The trigger registration of ultrasmall energy release by a ferromagnetic system in the metastable state is described.     

Monte Carlo predictions of proton SEE cross-sections from heavy ion test data

The limits of previous methods prompt us to design a new approach(named PRESTAGE) to predict proton single event effect(SEE) cross-sections using heavy-ion test data.To more realistically simulate the SEE mechanisms,we adopt Geant4 and a location-dependent strategy to describe the physics processes and the sensitivity of the device.Cross-sections predicted by PRESTAGE for over twenty devices are compared with the measured data.Evidence shows that PRESTAGE can calculate not only single event upsets induced by indirect proton ionization,but also direct ionization effects and single event latch-ups.Most of the PRESTAGE calculated results agree with the experimental data within a factor of 2-3.     

中国散裂中子源在大气中子单粒子效应研究中的应用评估

由于缺少可用的散裂中子源,多年来我国在大气中子单粒子效应方面主要依靠模拟仿真和单能中子试验的方式开展研究.随着中国散裂中子源(CSNS)通过国家验收,基于CSNS开展大气中子单粒子效应研究成为可能.本文利用CSNS反角白光中子源开展多款静态随机存取存储器器件的中子单粒子效应试验,并与早期开展的高原大气试验结果进行对比,对CSNS在大气中子单粒子效应研究中的应用进行评估.结果表明,相同器件在CSNS反角白光中子源测得的单粒子翻转截面小于大气试验的结果,且不同器件的翻转截面与特征尺寸没有明显的单调关系.分析得到前者由于CSNS反角白光中子谱偏软;后者由于特征尺寸降低导致的临界电荷变小和灵敏体积变小对截面的贡献是竞争关系.针对截面偏小的问题,根据能谱差异分析了中子能量阈值对器件翻转截面的影响,发现能量阈值取12MeV进行计算时,器件在CSNS反角白光中子源和高原大气中子环境中能够得到较一致的截面.研究结果表明CSNS反角白光中子源能够用于加速大气中子单粒子效应试验.考虑到CSNS的运行功率正在逐步提高,且多条规划中的白光中子束线与大气中子能谱更为接近,预期未来CSNS将能更好地应用于大气中子单粒子效应研究.     

不同偏置影响锗硅异质结双极晶体管单粒子效应的三维数值仿真研究

针对国产锗硅异质结双极晶体管(SiGe HBT),采用半导体器件三维计算机模拟工具,建立单粒子效应三维损伤模型,研究不同偏置状态对SiGe HBT单粒子效应的影响.分析比较不同偏置下重离子入射器件后,各端口电流瞬变峰值和电荷收集量随时间的变化关系,获得SiGe HBT单粒子效应与偏置的响应关系.结果表明:不同端口对单粒子效应响应的最劣偏置不同,同一端口电荷收集量和瞬变电流峰值的最劣偏置也有所差异.载流子输运方式变化和外加电场影响是造成这种现象的主要原因.     

一种二进制降能器设计方法

为提升在中国原子能科学研究院的100 MeV质子回旋加速器上进行多能点质子单粒子效应实验的效率,针对该加速器提供的100 MeV质子设计了一种二进制降能器.降能器包括6片铝降能片,厚度分别为0.5,1,2,4,8,16,32 mm,即后一片厚度均为前一片的2倍.提出相对厚度的概念,此概念也可用来表示产生的质子能点的次序以及降能器的状态或操作.降能器产生的9.69 MeV以上的61个质子能点间隔在0.84—4.09 MeV之间,且能量岐离均在10%以下,散射角半高宽均在45 mrad以下,基本可满足质子单粒子效应实验的要求.对加速器直接提供的质子的能量精度对降能器产生的质子能点的影响进行分析,发现经降能器产生的质子能量越低,其影响也就越大.此外,降能器对加速器直接能够提供的70—100 MeV能区的质子也是适用的,且可通过增加降能片数量的方式来获得更加连续化的质子能点.本文提出的降能器设计方法简单有效,具有较强的借鉴价值.