Physics & Astronomy ETDs

Publication Date



The sidereal diurnal variation of cosmic rays has been measured using underground (40 m.w.e.) meson telescopes located near Albuquerque, New Mexico (35.20°N, 106.41°w) and at Chacaltaya, Bolivia (16.31°s, 68.15°w). Each ofthe two locations has telescopes which scan the vertical and four inclined directions.

Two and three complete years were used for the tele­scopes at the Bolivia and New Mexico locations respectively. The average solar diurnal variations were calculated for each telescope for each month. Based on these monthly averages, the sidereal diurnal variations were computed. A correction was made in the analysis for any yearly modulation of the solar diunal variation. If such a correction were not made in the calculation of the sidereal diurnal variation, then a statistically significant spurious result could possibly occur. The statistical significance of the results are discussed, based on the standard error statistic.

The amplitude and time of maximum of the sidereal diurnal variation for each of the ten telescopes were found. In general it was discovered that the amplitudes of the sidereal diurnal variations were large for telescopes with asymptotic latitudes far from the geographic equator and the amplitudes were small for telescopes with asymptotic latitudes close to the geographic equator.

The maxima of the sidereal diurnal variations were found to lie in the vicinity of 19hrs. and 6hrs. S.T. for telescopes with asymptotic directions in the Northern and Southern Hemispheres respectively.

A model, proposed by Swinson, is discussed which is based on considerations of the general streaming patterns of charged particles in the interplanetary medium and is independent of any net galactic anisotropy. This model predicts the observed sidereal variation for each type of sector structure of the interplanetary magnetic field.

The alternative predictions of a two-way, galactic aniso­tropy are compared and contrasted with this model. It is suggested that the observed sidereal variations of primaries of energies 100 GeV or smaller are due mainly to the con­ditions which exist in the inner solar system.

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Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Derek B. Swinson

Second Committee Member

Charles L. Hyden

Third Committee Member

Harjit Singh Ahluwalia



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