Study of Ultra-High Energy Cosmic Rays at Tibetan highlands

青藏高原超高能宇宙线研究

• 批准号: 04044042
• 负责人: YUDA Toshinori
• 金额: $ 9.09万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04044042/
• 关键词: Tibet; Yangbajing; Air Shower Array; Interplanetary Magnetic Field; Solar Magnetic Field; Gamma-Ray; Cosmic Ray Origin; Crab Nebula; 太陽の影; 空気シャワー; 宇宙天体

The Tibet Air shower array at Yangbajing (4,300m, 90.5ﾟ E and 30.1ﾟ N) in Tibet has been operated continuously since January 1990, with Chinese scientists. The present array consists of 65 scintillation detectors which are placed in a lattice of 15m spacing. The mode energy of observed showers is estimated to be about 7 TeV for gamma rays. The angular resolution was well examined by observing the shadowing of cosmic rays by the moon. The moon shadow was observed with the significance of 7.1sigma and the angular resolution of the array is estimated to be 0.88ﾟ for showers with its mode energy 7 TeV and 0.52ﾟ for those with its mode energy 35 TeV.A small deflection of the shadow to the west by about 0.16ﾟ is comparable with that expected from the geomagnetic field effect.On the other hand, the sun shadow was observed in the direction away from the sun by 0.70ﾟ to the west and 0.40ﾟ to the south. This deflection is considered to be caused by the combined effect of the magnetic fields betw … More een the sun and the earth. Note that these data were taken when the sun was still in an active phase between 1990 and 1993. Such effect on the cosmic ray shadow is the first observation and is expected to bring us new information on the large scale structure of the solar and interplanetary magnetic field and its time variation.A search for steady emission of 10 TeV gamma rays has been made for various point sources including the Crab nebula, Cyg X-3 and Her X-1. For Cyg X-3, flux limits obtained at 10 TeV and 30 TeV for Cyg X-3 are far below the levels obtained by extrapolation of the Kiel flux. For the Crab nebula, the result obtained with no excess is inconsistent with the possitive results from the THEMISTOCLE experiment, while still being consistent with the Whipple new data. We also searched for gamma-ray emission from active galactic nuclei (AGNs) which have been reported to be poweful gamma-ray sources by EGRET on board the Compton GRO.In particular, the result for the nearest AGN,Markarian 421 at 10 TeV is interesting, and the further observation on this source will provide new information on the strength of infrared photon field in the universe. The present air shower array will be extended up to an effective area of 3.7 *10^4 m^2 in 1994. This array will consist of 221 scintilation detectors which are placed in a lattice of 15 m spacing. The trigger rate is taken to be about 250 Hz with a dead time less than 30 %. The mode energy for proton showers is estmated to be about 5 TeV.This new array will provide important information on the interplanetary magnetic field as well as acceleration of cosmic rays in the very near future. Less

位于西藏羊八井（4,300m，东经90.5°，北纬30.1°）的西藏风淋室阵列自1990年1月以来一直在中国科学家的帮助下持续运行。目前的阵列由 65 个闪烁探测器组成，这些探测器以 15m 间距排列。观测到的伽马射线流星雨的模式能量估计约为 7 TeV。通过观察月球对宇宙射线的阴影，可以很好地检验角分辨率。观测到的月影具有 7.1sigma 的显着性，对于模式能量为 7 TeV 的流星雨，阵列的角分辨率估计为 0.88ﾟ，对于模式能量为 35 TeV 的流星雨，阵列的角分辨率估计为 0.52ﾟ。阴影向西的小偏转约 0.16ﾟ 与地磁场效应的预期相当。另一方面，在远离太阳的方向上观测到太阳阴影太阳经过 向西 0.70ﾟ，向南 0.40ﾟ。这种偏转被认为是由太阳和地球之间的磁场的综合效应引起的。请注意，这些数据是在 1990 年至 1993 年间太阳仍处于活动阶段时获取的。这种对宇宙射线阴影的影响是首次观测到，预计将为我们带来有关太阳和行星际磁场的大尺度结构及其时间变化的新信息。已经对包括蟹状星云、Cyg X-3 和 Her X-1 在内的各种点源进行了 10 TeV 伽马射线稳定发射的搜索。对于 Cyg X-3，Cyg X-3 在 10 TeV 和 30 TeV 下获得的通量限制远低于通过基尔通量外推获得的水平。对于蟹状星云，无过量情况下得到的结果与THEMISTOCLE实验的阳性结果不一致，但仍与Whipple新数据一致。我们还搜索了来自活动星系核（AGN）的伽马射线发射，据康普顿 GRO 上的 EGRET 报道，活动星系核（AGN）是强大的伽马射线源。特别是，最近的活动星系核 Markarian 421 在 10 TeV 的结果很有趣，对该源的进一步观测将为宇宙中红外光子场的强度提供新的信息。目前的风淋室阵列将于1994年扩大到有效面积3.7 *10^4 m^2。该阵列将由221个闪烁探测器组成，这些探测器以15 m间距排列。触发频率约为 250 Hz，死区时间小于 30%。质子簇射的模式能量估计约为 5 TeV。这个新阵列将在不久的将来提供有关行星际磁场以及宇宙射线加速的重要信息。较少的

项目成果

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T.Saito、T.Yuda、K.Kasahara 等人：“初级宇宙射线“膝”能量处的质子强度。”

M.Amenomori et al.: "Cosmic ray deficits from the directions of the Moon and the Sun detected with the Tibet air shower array" Physical Review D. 47. 2675-2681 (1993)

M.Amenomori 等人：“西藏空气簇射阵列检测到的来自月球和太阳方向的宇宙射线缺陷”《物理评论》D. 47. 2675-2681 (1993)

M.Amenomori,Z.Cao,T.Yuda et al.20GB05:Search for steady emission of 10-TeV gamma-rays from the Crab Nebula,Cygnus X-3 and Hercules X-1 using the Tibet-air shower array: Physical Review Letters. 69. 2648-2471 (1992)

M.Amenomori,Z.Cao,T.Yuda 等人20GB05：利用西藏空气簇射阵寻找蟹状星云、天鹅座 X-3 和武仙座 X-1 的 10-TeV 伽马射线稳定发射：物理

M.Amenomori et al.: "Direct evidence of the interplanetray magnetic field effect on the cosmic ray shadow by the sun" The Astrophysical Journal. 415. L147-L150 (1993)

M.Amenomori 等人：“行星际磁场对太阳宇宙射线阴影影响的直接证据”《天体物理学杂志》。

M. AMENOMORI et al.: "Recent results of the Tibet AS-G experiment" AIP Conference Proceedings. (1992)

M. AMENOMORI 等人：“西藏 AS-G 实验的最新结果”AIP 会议记录。