利用YBJ-ARGO实验研究太阳2005年1月16日—20日爆发期间宇宙线变化

分析了2005年1月15日至27日的YBJ-ARGO-SPT实验数据, 观测到了期间由太阳耀斑引起的宇宙线福布什下降, 与其他观测手段的观测结果一致. 根据次级粒子多重数的不同, 分能区进行了讨论, 发现在同一观测地点, 福布什下降幅度随能量升高而变小. 这是第一次在同一观测地点分能区对太阳活动期间宇宙线福布什下降的观测结果, 与理论预期相符合.     

近地雷暴电场与羊八井地面宇宙线关联的模拟研究

雷暴期间地面宇宙线强度变化的研究对理解大气电场加速宇宙线次级带电粒子的物理机理具有重要意义. 分析西藏羊八井ARGO实验中2012年大气电场的数据后发现, 近地雷暴电场的强度可达1000 V/cm甚至更高. 用Monte Carlo方法模拟研究了近地雷暴电场与羊八井地面宇宙线强度的关联. 当雷暴电场强度(取1500 V/cm)大于逃逸电场时, 宇宙线次级粒子中正、负电子的数目呈指数增长, 在大气深度约520 g/cm²处达到极大值, 与Gurevich等提出的相对论电子逃逸雪崩机理和Dwyer理论相符. 当雷暴电场强度小于逃逸电场时, 在所有负电场范围和大于600 V/cm的正电场范围, 总电子数目随电场强度的增大而增加; 当正电场小于400 V/cm时, 总电子数目均出现一定幅度的下降; 在电场为400–600 V/cm范围内, 总电子数目的变化与原初粒子的能量有关, 原初能量小于80 GeV时, 其次级粒子中总电子数目增加, 原初能量在80–120 GeV 范围内时, 总电子数目变化不明显, 原初能量大于120 GeV时, 总电子数目出现下降, 下降幅度约4%. 模拟结果可对羊八井ARGO实验的观测结果给予合理的解释.     

宇宙线对地球气候的影响

对宇宙线影响地球气候的一些观测结果和物理机制的研究进行了总结和概述,主要讨论了宇宙线对大气中化学反应、云形成过程等的影响,并给出了羊八井宇宙线观测站对宇宙线流强和大气参量日变化的初步观测结果．     

日影偏离度与太阳平均磁场的关联

利用西藏羊八井空气簇射阵列1990年6月至1996年8月间观测到的10TeV宇宙线的太阳阴影位置,以及相同期间的太阳表面平均磁场的数值,研究了太阳阴影的偏离度与太阳平均磁场的关系,并结合简单的理论模型对这种关系进行了计算和解释.     

10TeV宇宙线时间变化研究

利用羊八井ASγ二期阵列实验数据,分析研究了10TeV宇宙线时间变化,以10.4σ和9.6σ的显著性发现了10TeV宇宙线流强气象效应修正后的半太阳日和太阳日周期变化,没有发现有恒星日变化.同时发现10TeV宇宙线流强有7天左右周期变化的迹象.     

甚高能区宇宙线流强气象效应的分析

讨论了用中日合作西藏羊八井超高能宇宙线空气簇射阵列作甚高能区宇宙线强度监测的可能性;分析了空气簇射阵列触发计数率的气象效应;摸索出一套气压及环境温度效应的修正方法,并用于1992年1月至2月观测数据的修正.     

ARGO实验探测γ暴的灵敏度研究

西藏羊八井ARGO实验是对广延大气簇射事例进行观测研究的"全覆盖式"地面宇宙线观测实验, 其主要目的之一就是探测E>10GeV的γ暴. 通过Monte Carlo模拟, 估算了ARGO实验探测10GeV γ暴所具有的灵敏度.     

“西藏羊八井宇宙线国家野外科学观测研究站”和“国际科技合作基地”正式挂牌

2009年10月12日,中国科学院副院长詹文龙视察了位于海拔4300米的西藏羊八井国际宇宙线观测站,为国家科技部授予的“西藏羊八井宇宙线国家野外科学观测研究站”和“国际科技合作基地”举行了正式的挂牌仪式,并参加了国家天文台的中德合作亚毫米波望远镜的奠基仪式。陪同视察的有中科院高能物理研究所党委书记兼副所长王焕玉,     

利用羊八井中子监测器研究宇宙线的太阳日周期变化

通过对宇宙线周期变化研究可以得到宇宙线产生和传播区域的重要信息,是宇宙线长期研究的重要热点问题。利用位于西藏羊八井(地磁截止刚度:14.1 GeV) 的中子监测器2006 至2011年的观测数据,研究宇宙线的太阳日周期变化。在对中子监测器观测数据进行气压修正后,通过Lomb-Scargle 傅立叶变换法对修正后的数据进行周期分析,发现宇宙线计数率存在超过地球公转运动Compton-Getting 效应的太阳日周期变化,该周期变化可能是地球公转效应和宇宙线传播物理过程调制效应以及剩余气象效应的叠加。计算分析了1 日周期信号的振幅和初相位随时间的变化,发现1 日周期变化的初相位存在较为明显的年周期变化规律,这可能是地球公转和自转合成运动的结果;1 日周期变化幅度在2010 年后出现增大趋势。这些结果对宇宙线周期变化和各向异性的研究具有重要参考意义。With the study of the cosmic rays' solar diurnal variation we can get the important information about Cosmic Ray's production and propagation. It's important issues of cosmic rays' studies. We analyze the temporal variation of cosmic rays rate observed with the Yangbajing neutron monitor during 2006 to 2011, and nd semidiurnal and diurnal period signals included in the rates of cosmic rays with vertical rigidity equal to 14.1 GV. We have checked the time dependence of the phase and the amplitude of semidiurnal and diurnal anisotropy, and nd that the phase of diurnal signal varies yearly, it could be a synthetic movement of the earth's rotation and revolution. The amplitude before 2010 is obvious smaller than that after 2010. These results are of great reference value for studying the anisotropy and time variation of cosmic rays.     

无限风光在险峰——为羊八井宇宙线观测站建立五周年而作

 自1990年元月10日一期阵列建成并于同年六月开始正式运行以来,羊八井宇宙线观测站己经问世五周年了。五年,在已有的高山站中是个很小的数字（见表1）,然而羊八井已挤身国际超高能γ天文实验三大主力行列而名扬海外。是什么使得它如此神奇?扩大了四倍的羊八井二期阵列将会有什么表现?羊八井三期发展计划将会给地面宇宙线实验和γ天文学科形势带来怎样的变化?这些不仅是羊八井实验的参与者也是所有关心羊八井事业、想了解羊八井立足我国自然优势发展国际合作推动学科发展的经验的人们所感兴趣的事情。     

Cosmic Ray Flux Variation due to Solar Flares during January 16—20, 2005 with YBJ-ARGO Experiment

The YBJ-ARGO experiment is located in Tibet at 4300m a.s.l.. The data of this experiment under scalar mode can be used to study the solar modulation of cosmic ray flux at E>10GeV. The data during January 15—17, 2005 are analyzed, and a cosmic ray flux Forbush decrease after several X class solar flares has been observed. All detailed structures of the flux curves are similar to the results from neutron monitors. The maximum amplitudes of FD are about －6%, －6%, －4% and －3% with multiplicity greater than 1, 2, 3 and 4, respectively, i.e. the maximum amplitude of FD decreases as the energy of cosmic ray increases. These are the results about a FD measured at the same site (Yangbajing) with different cosmic ray energies for the first time.     

Forbush decreases recorded by the URAGAN muon hodoscope in 2006–2011

Variations in the cosmic ray muon flux on Earth’s surface during Forbush decreases (FD) recorded by the URAGAN muon hodoscope in 2006–2011 are investigated. The dependence of the rate of amplitude reduction on the primary particle energy in a range above 10 GeV at different phases of FD development is studied by analyzing the variations in the cosmic ray muon flux recorded with the hodoscope. Analytical data on the spatial and angular dynamics of the muon flux are used to estimate variations in the spatial anisotropy of the muon flux during FDs.     

Specific features of studying Forbush decreases in the muon flux

The variations in the cosmic ray (CR) muon flux during the Forbush decreases (FDs), registered by the DECOR muon detector and the URAGAN muon hodoscope during the periods of their operation from 2004 to 2006, are analyzed. The unified method for determining the parameters of variations in the CR flux during FDs has been developed, and the dependences of the FD characteristics on the rigidity of primary CRs and information about the spatial-angular dynamics of the muon flux during FDs have been obtained.     

Performances and long-term stability of the LHAASO-KM2A prototype array

A prototype array for the LHAASO-KM2A, which consists of 42 detector units and fully overlaps the ARGO-YBJ experiment, was set up at the Yangbajing cosmic ray observatory and has been in stable operation since Octoter 2010. The resulting performances of the KM2A electromagnetic particle detector prototypes fully meet the design requirements. Through hybrid observation of cosmic ray showers with the ARGO-YBJ experiment, the performances and long-term stability of the prototype array are tested and the results are consistent with expectation. The cosmic ray moon shadow observed by the prototype array is also presented.     

The role of cosmic rays in the Earth’s atmospheric processes

In this paper, we have provided an overview of cosmic ray effects on terrestrial processes such as electrical properties, global electric circuit, lightning, cloud formation, cloud coverage, atmospheric temperature, space weather phenomena, climate, etc. It is suggested that cosmic rays control short-term and long-term variations in climate. There are many basic phenomena which need further study and require new and long-term data set. Some of these have been pointed out.     

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.     

寻找超高能宇宙线源——西藏广延空气簇射实验

总结了１９９０年６月到１９９３年１０月期间西藏空气簇射阵列的观测结果。寻找了来自于蟹状星云、Ｘ射线双星、脉冲星、活动星系核和其它活动天体的能量为１０ＴｅＶγ射线连续发射，没有发现连续稳定发射的迹象，但给出了每个源的流强上限。在阵列所观测的天区寻找了１０ＴｅＶ的γ暴，结果没有发现能量１０ＴｅＶ的γ暴，最后也给出了发现此种γ暴的上限。应用该阵列，明显地观测到了能量为１０ＴｅＶ的宇宙线流强的太阳和月亮阴影。观测了朝向和远离太阳的行星际空间磁场对宇宙线阴影的影响，这是行星际磁场对阴影位移影响的第一次直接观测。研究并发现在实验期间，太阳阴影的位置每年都在变化。同时观测在此期间，朝向和远离方向的宇宙线阴影的不同变化。另外，应用该实验的数据，给出了所谓的“膝”区的原初宇宙线能谱。