Variations with Sidereal Time in the Intensity of the Cosmic Ultra-Radiation

Abstract

PRELIMINARY results of measurements on the cosmic ultra-radiation, or the so-called highly penetrating radiation, as carried out by me using a Kolhörster ionisation chamber in Abisko in Northern Sweden (N. lat. 68° 21′, 388 metres above sea-level), have been reported in Lund Meddelanden, No. 121. The chamber is placed in an iron shield of 11 cm. floor-thickness and 6 cm. wall-thickness, and the opening upwards free. During the period Nov. 13, 1929–Jan. 13, 1930, the chamber was observed every second hour except during the nights between 24^h and 6^h M.E.T. approximately. Later on, a photographic recording cylinder was placed in front of the microscope of the chamber, and the observations have been performed day and night in connexion with—as before—meteorological, magnetic, and auroral routine work.