Anisotropy of cosmic radiation in the Galaxy

Gombosi, T. I.; Kóta, J.; Somogyi, A.; Varga, A.; Betev, B. L.; Katsarsky, L. M.; Kavlakov, S.; Khirov, I.

doi:10.1038/255687a0

Cited by 21 publications

(11 citation statements)

References 4 publications

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“…At E 0 ≈ 10 14 eV, the EAS-TOP 11 results (Aglietta et al 1996) demonstrated that the main features of the anisotropy (i.e., of cosmic-ray propagation) are similar to those measured at lower energies (10 11 -10 14 eV), both with respect to amplitude ((3-6) × 10 −4 ) and phase ((0-4) hr local sidereal time (LST)) (Gombosi et al 1975;Fenton et al 1975;Nagashima et al 1989;Alekseenko et al 1981;Andreev et al 1987;Ambrosio et al 2003;Munakata et al 1997;Amenomori et al 2005;Guillian et al 2007;Abdo et al 2008). At higher energies the limited statistics do not allow any firm conclusion to be drawn (Kifune et al 1984;Gherardy et al 1983;Antoni et al 2004;Amenomori et al 2006;Over et al 2007).…”

Section: Introductionmentioning

confidence: 66%

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV

Aglietta

Алексеенко

Alessandro

et al. 2009

ApJ

157

136

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The amplitude and phase of the cosmic-ray anisotropy are well established experimentally between 10 11 eV and 10 14 eV. The study of their evolution in the energy region 10 14-10 16 eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this Letter, we extend the EAS-TOP measurement performed at E 0 ≈ 10 14 eV to higher energies by using the full data set (eight years of data taking). Results derived at about 10 14 and 4 × 10 14 eV are compared and discussed. Hints of increasing amplitude and change of phase above 10 14 eV are reported. The significance of the observation for the understanding of cosmic-ray propagation is discussed.

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Section: Introductionmentioning

confidence: 66%

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV

Aglietta

Алексеенко

Alessandro

et al. 2009

ApJ

157

136

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“…This pattern is sphere [19,20]. However, it is difficult to ascribe the wave to a specific direction and/or "source", as for instance, the direction of galactic rotation or the direction of the local magnetic field [24].…”

Section: Resultsmentioning

confidence: 99%

“…A small offset between the monthly means has been introduced for clarity. ; inverted filled triangle = Poatina [13]; filled square = Matsushiro [14]; filled triangle = Utah [5]; asterisk = Hong Kong [15]; small filled circle = Baksan [16]; filled star = Tibet [17]; open cross = Baksan EAS [18]; open triangle = Kamioka [7]; open square = Norikura [19]; open diamond = Musala Peak [20]; open circle = EAS-TOP [21]; open star = Linsley [22].…”

Section: Figmentioning

confidence: 99%

Search for the sidereal and solar diurnal modulations in the total MACRO muon data set

Ambrosio¹,

Antolini²,

Baldini³

et al. 2003

Phys. Rev. D

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We have analyzed 44.3M single muons collected by MACRO from 1991 through 2000 in 2,145 live days of operation. We have searched for the solar diurnal, apparent sidereal, and pseudo-sidereal modulation of the underground muon rate by computing hourly deviations of the muon rate from 6 month averages. We find evidence for statistically significant modulations with the solar diurnal and the sidereal periods. The amplitudes of these modulations are < 0.1%, and are at the limit of the detector statistics. The pseudo-sidereal modulation is not statistically significant.The solar diurnal modulation is due to the daily atmospheric temperature variations at 20 km, the altitude of primary cosmic ray interactions with the atmosphere; MACRO is the deepest experiment to report this result. The sidereal modulation is in addition to the expected Compton-Getting modulation due to solar system motion relative to the Local Standard of Rest; it represents motion of the solar system with respect to the galactic cosmic rays toward the Perseus spiral arm.PACS numbers: 95.85. Ry, 98.70.Sa

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“…Current experimental results show that the main features of the anisotropy are similar in the energy range (10 11 ÷ 10 14 eV), both with respect to amplitude (10 −4 ÷ 10 −3 ) and phase ((0 ÷ 4) h LST) [1,2,3,4,5,6,7,8,9,10,11]. At higher energies, between 10 14 and 10 17 eV, the limited statistics do not allow any firm conclusion to be drawn [12,13,14,15,16], although the observation of a larger anisotropy amplitude with a different phase has been recently reported at ∼ 4 · 10 14 eV [17].…”

Section: Introductionmentioning

confidence: 90%

The East-West Method: An Exposure-Independent Method to Search for Large-Scale Anisotropies of Cosmic Rays

Bonino¹,

Алексеенко²,

Deligny³

et al. 2011

ApJ

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The measurement of large scale anisotropies in cosmic ray arrival directions at energies above 10 13 eV is performed through the detection of Extensive Air Showers produced by cosmic ray interactions in the atmosphere. The observed anisotropies are small, so accurate measurements require small statistical uncertainties, i.e. large datasets. These can be obtained by employing ground detector arrays with large extensions (from 10 4 to 10 9 m 2 ) and long operation time (up to 20 years). The control of such arrays is challenging and spurious variations in the counting rate due to instrumental effects (e.g. data taking interruptions or changes in the acceptance) and atmospheric effects (e.g. air temperature and pressure effects on EAS development) are usually present. These modulations must be corrected very precisely before performing standard anisotropy analyses, i.e. harmonic analysis of the counting rate versus local sidereal time. In this paper we discuss an alternative method to measure large scale anisotropies, the "East-West method", originally proposed by Nagashima in 1989. It is a differential method, as it is based on the analysis of the difference of the counting rates in the East and West directions. Besides explaining the principle, we present here its mathematical derivation, showing that the method is largely independent of experimental effects, that is, it does not require corrections for acceptance and/or for atmospheric effects. We explain the use of the method to derive the amplitude and phase of the anisotropy and we demonstrate its power under different conditions of detector operation.

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Anisotropy of cosmic radiation in the Galaxy

Cited by 21 publications

References 4 publications

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV

Search for the sidereal and solar diurnal modulations in the total MACRO muon data set

The East-West Method: An Exposure-Independent Method to Search for Large-Scale Anisotropies of Cosmic Rays

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Anisotropy of cosmic radiation in the Galaxy

Cited by 21 publications

References 4 publications

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 14 eV

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 14 eV

Search for the sidereal and solar diurnal modulations in the total MACRO muon data set

The East-West Method: An Exposure-Independent Method to Search for Large-Scale Anisotropies of Cosmic Rays

Contact Info

Product

Resources

About

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV

EVOLUTION OF THE COSMIC-RAY ANISOTROPY ABOVE 10 ¹⁴ eV