Galactic Anisotropy of Cosmic Ray Intensity Observed by an Air Shower Experiment

Mahmud Bahmanabadi; Mehdi Khakian Ghomi; Farzaneh Sheidaei; Jalal Samimi

doi:10.1071/AS06015

RESEARCH ARTICLE

Previous Contents Vol 23(3)

Galactic Anisotropy of Cosmic Ray Intensity Observed by an Air Shower Experiment

Mahmud Bahmanabadi ^A ^B , Mehdi Khakian Ghomi ^A , Farzaneh Sheidaei ^A and Jalal Samimi ^A

+ Author Affiliations

- Author Affiliations

^A Physics Department, Sharif University of Technology, P.O. Box 11365-9161, Tehran, Iran.

^B Corresponding author. E-mail: bahmanabadi@sina.sharif.ac.ir

Publications of the Astronomical Society of Australia 23(3) 129-134 https://doi.org/10.1071/AS06015
Submitted: 25 May 2006 Accepted: 12 September 2006 Published: 24 November 2006

Abstract

We have monitored multi-TeV cosmic rays by a small air shower array in Tehran (35°43′ N, 51°20′ E, 1200 m = 890 g cm^–2). More than 1.1 × 10⁶ extensive air shower events were recorded. These observations enabled us to analyse sidereal variation of the galactic cosmic ray intensity. The observed sidereal daily variation is compared to the expected variation which includes the Compton–Getting effect due to the motion of the earth in the Galaxy. In addition to the Compton–Getting effect, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.

Keywords: cosmic rays

Acknowledgements

This research has been partly supported by Grant No. NRCI 1853 of the National Research Council of the Islamic Republic of Iran.

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