Are protons still dominant at the knee of the cosmic-ray energy spectrum?

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	Are protons still dominant at the knee of the cosmic-ray energy spectrum?
	Tibet ASGamma Collaboration
刊名	PHYSICS LETTERS B
	2006
卷号	632 期号:1 页码:58-64
关键词	SHOCK ACCELERATION HYBRID-EXPERIMENT REGION HELIUM NUCLEI TIBET
通讯作者	Huang, Q (reprint author), Univ Tokyo, Inst Cosm Ray Res, Kashiwa, Chiba 2778582, Japan.
英文摘要	A hybrid experiment consisting of emulsion chambers, burst detectors and the Tibet-11 air-shower array was carried out at Yangbajing (4300 m a.s.l., 606 g/cm(2)) in Tibet to obtain the energy spectra of primary protons and heliums. From three-year operation, these energy spectra are deduced between 10(15) and 10(16) eV by triggering the air showers associated with a high energy core and using a neural network method in the primary mass separation. The proton spectrum can be expressed by a single power-law function with a differential index of -3.01 +/- 0.11 and -3.05 +/- 0.12 based on the QGSJET + HD and SIBYLL + HD models, respectively, which are steeper than that extrapolated from the direct observations of -2.74 +/- 0.01 in the energy range below 10 14 eV. The absolute fluxes of protons and heliums are derived within 30% systematic errors depending on the hadronic interaction models used in Monte Carlo simulation. The result of our experiment suggests that the main component responsible for the change of the power index of the all-particle spectrum around 3 x 1015 eV, so-called "knee", is composed of nuclei heavier than helium. This is the first measurement of the differential energy spectra of primary protons and heliums by selecting them event by event at the knee energy region. (c) 2005 Elsevier B.V. All rights reserved.
学科主题	Physics
类目[WOS]	Physics, Multidisciplinary
收录类别	SCI
语种	英语
WOS记录号	WOS:000234520500008
公开日期	2016-02-25
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/212634]
专题	高能物理研究所_粒子天体物理中心
作者单位	中国科学院高能物理研究所
推荐引用方式 GB/T 7714	Tibet ASGamma Collaboration. Are protons still dominant at the knee of the cosmic-ray energy spectrum?[J]. PHYSICS LETTERS B,2006,632(1):58-64.
APA	Tibet ASGamma Collaboration.(2006).Are protons still dominant at the knee of the cosmic-ray energy spectrum?.PHYSICS LETTERS B,632(1),58-64.
MLA	Tibet ASGamma Collaboration."Are protons still dominant at the knee of the cosmic-ray energy spectrum?".PHYSICS LETTERS B 632.1(2006):58-64.