Mesotron Intensity as a Function of Altitude

Abstract

DURING July 1945, measurements of the intensity of mesotrons passing through 8 cm. of lead at various heights in the Himalayas up to an altitude of 16,800 ft. were made by me and Mela Ram¹. During November 1945, I extended these measurements up to 33,000 ft. above sea-level in an aeroplane flight over Lahore. The apparatus used in the flight was the same as that used in the hills. The duration of the flight between 17,000 ft. and 33,000 ft. was one hour and forty minutes. The results are shown in the figure in the form of a curve in which the number of triple coincidences per minute are plotted against the pressure in millibars.