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Cosmic ray solar diurnal and sidereal variations


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Juwono, Alamsyah M 1997 , 'Cosmic ray solar diurnal and sidereal variations', Research Master thesis, University of Tasmania.

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Data from underground cosmic ray observatories at Cambridge and
Liapootah, Tasmania and Mawson, Antarctica, have been studied to
determine the amplitudes of Solar Diurnal Variations for period of 11 years,
1982-1992, for Cambridge and Mawson observatories, and for 1992-1993 for
Liapootah observatory. The amplitudes are estimated for either monthly
average or yearly average, for ground based and free space as well. The
monthly Solar Diurnal Variations have been shown to be contaminated by
Sidereal component, and by using method of the sinusoidal fittings, the
amplitudes of Solar Diurnal Variation and the Sidereal component of the
variation have been extracted. The results of extracting the monthly Solar
Diurnal Variations are (0.104 ± 0.004 %), (0.116 ± 0.006 %) for Cambridge,
(0.090 ± 0.004 %) for Mawson and (0.060 ± 0.008 %) for Liapootah. The
amplitudes of Sidereal component contaminating the Solar Diurnal Variations
also have been found. These sidereal amplitudes are (0.043 ± 0.006 %) and
(0.022 ± 0.008 %) for Cambridge, (0.019 ± 0.006 %) for Mawson and
(0.0067 ± 0.012 %) for Liapootah.
By using the Sidereal Variation component as detected in a deep
underground station at Poatina as reference, i.e. that it is assumed to be purely
galactic, the percentage of the Sidereal component detected by one of
Cambridge's telescope which is due to North-South Anisotropy has been
estimated. The result is that about 72% of total 0.043% Sidereal component
detected in that telescope is due to North-South Anisotropy, and the other
28% is of galactic origin.
Times of Maximum for monthly Solar Diurnal Variation detected by the
two observatories, Cambridge and Mawson, are also discussed. The results
show that in the ground-based observation Time of Maximum of Mawson
tends to be later than those of Cambridge. Free Space analysis shows that
there is good similarity among Times of Maximum of the monthly Solar
Diurnal Variations detected by the two telescopes at Cambridge and one at
Mawson, which in turn exhibits that cosmic ray particles which are detected
in polar regions may undergo different magnetic bending than those detected
in lower latitude regions. The free space analysis also gives the estimates of
free space amplitudes of the Solar Diurnal Variations for corresponding Solar
Diurnal Variation amplitudes as they observed in the ground.
Yearly Solar Diurnal Variations at Cambridge and Mawson have also been
studied. The wave-forms of the yearly plots during period of 1982-1993 show
that they are consistent with the long-term modulations, either 11-year or 22-
year modulation. In this case it is shown that the cosmic rays detected in those
two observatories during 1985/1986 underwent a minor depression, i.e. a
situation when 11-year and 22-year modulation waves are superposing with
one out of phase to the other.
The last part of this study concerns on North-South Asymmetry of the
sidereal variation. Data from vertical telescope at Liapootah are used for this purpose. The 1992-1993 data of Liapootah have been compared to data from
the vertical telescope at Matsushiro underground station. The result of the
Sidereal Variation of (0.040 ± 0.007 %) from Liapootah is significantly larger
than that found from Matsushiro which is (0.026 ± 0.008 %). This result
confirms what previously reported by Munakata et al. (1994). Sidereal
Variations from other telescope components of Liapootah station have also
been studied. They are plotted against the latitudes of viewing of
corresponding telescopes, to examine the presumption that there is NorthSouth
Asymmetry of Sidereal Variation. The result of the plotting supports
the presumption, and it exhibits that the line of symmetry may lie somewhere
between equator and 20C S.

Item Type: Thesis - Research Master
Authors/Creators:Juwono, Alamsyah M
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Examines the data for 1982-1992 from two underground cosmic ray observatories, Cambridge in Tasmania, and Mawson in Antarctica, and for 1992-1993 from Liapootah observatory in Tasmania to determine the amplitudes of solar diurnal variations. Thesis (M.Sc.)--University of Tasmania, 1997. Includes bibliographical references. Examines the data for 1982-1992 from two underground cosmic ray observatories, Cambridge in Tasmania, and Mawson in Antarctica, and for 1992-1993 from Liapootah observatory in Tasmania to determine the amplitudes of solar diurnal variations

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