Cosmic ray measurements on mountains are limited in general to altitudes below about 4000 meters. Above this height Regener has made successful use of small balloons carrying self-recording apparatus, and occasional flights have been made with manned balloons by Piccard, Cosyns, and by American workers. Balloon experiments are, however, hardly practicable in this country, so we decided to investigate cosmic rays, and in particular the production of showers, using an aeroplane. Facilities for flying to a height of about 10 km. Were generously provided by the Air Ministry. Apparatus Two independent sets of three tube counters were used in conjunction with the usual coincidence counting circuits. The counters could be arranged in a vertical line to record vertical penetrating particles, or in a triangle to record showers. The triple coincidences were recorded by telephone counters which were photographed at intervals together with a clock and aneroid barometer. The detailed design of the apparatus required some consideration since the aeroplane available (the Vickers Vespa machine used for high altitude experiments at the Royal Aircraft Establishment) had an open observer’s cockpit in which the counting set had to be installed.
Counting Hexagonal Patches and Independent Sets in Circle Graphs
