Measurement of the radial density gradient of cosmic ray in the heliosphere by the GRAPES-3 experiment

被引：10

作者：

Kojima, H. ^{[1
,2
]}

Antia, H. M. ^{[2
,3
]}

Dugad, S. R. ^{[2
,3
]}

Gupta, S. K. ^{[2
,3
]}

Hayashi, Y. ^{[2
,4
]}

Jagadeesan, P. ^{[2
,3
]}

Jain, A. ^{[2
,3
]}

Kawakami, S. ^{[2
,4
]}

Mohanty, P. K. ^{[2
,3
]}

Nonaka, T. ^{[2
,4
]}

Oshima, A. ^{[2
,5
]}

Rao, B. S. ^{[2
,3
]}

Shibata, S. ^{[2
,5
]}

机构：

[1] Aichi Inst Technol, Fac Engn, Toyota 4700392, Japan

[2] GRAPES 3 Expt, Cosm Ray Lab, Ooty 643001, India

[3] Tata Inst Fundamental Res, Mumbai 400005, Maharashtra, India

[4] Osaka City Univ, Grad Sch Sci, Osaka 5588585, Japan

[5] Chubu Univ, Coll Engn, Kasugai, Aichi 4878501, Japan

来源：

ASTROPARTICLE PHYSICS | 2015年 / 62卷

关键词：

Cosmic rays; Heliosphere; Solar wind; Convection; Diffusion; ANISOTROPY; MODULATION; SIDEREAL; FIELD;

D O I：

10.1016/j.astropartphys.2014.07.003

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

A radial anisotropy in the flux of cosmic rays in heliosphere was theoretically predicted by Parker and others within the framework of the diffusion-convection mechanism. The solar wind is responsible for sweeping out the galactic cosmic rays, creating a radial density gradient within the heliosphere. This gradient coupled with the interplanetary magnetic field induces a flow of charged particles perpendicular to the ecliptic plane which was measured and correctly explained by Swinson, and is hereafter referred as 'Swinson flow'. The large area GRAPES-3 tracking muon telescope offers a powerful probe to measure the Swinson flow and the underlying radial density gradient of the galactic cosmic rays at a relatively high rigidity of 100 GV. The GRAPES-3 data collected over a period of six years (2000-2005) were analyzed and the amplitude of the Swinson flow was estimated to be (0.0644 +/- 0.0008)% of cosmic ray flux which was an similar to 80 sigma effect. The phase of the maximum flow was at a sidereal time of (17.70 +/- 0.05) h which was 18 min earlier than the expected value of 18 h. This small 18 min phase difference had a significance of similar to 6 sigma. indicating the inherent precision of the GRAPES-3 measurement. The radial density gradient of the galactic cosmic rays at a median rigidity of 77 GV was found to be 0.65% AU(-1). (C) 2014 Elsevier B.V. All rights reserved.

引用

页码：21 / 29

页数：9

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