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Abstract
The thesis is divided into three sections each of which gives an account of a distinct piece of work. The first section is concerned with Cosmic Radiation and was done under the supervision of Dr L. Janossy during 1939 and 1940. In 1940 cosmic ray work was interrupted by the war and the other two sections deal with problems arising from the war effort which were investigated under the direction of Professor D.R. Hartree while in the employ of the Ministry of Supply. Part I. Cosmic Radiation Title: Meson Formation and the East-West Asymmetry and, Latitude effect at Sea Level Mesons, which form over 70% of the cosmic radiation at sea-level, are secondaries produced in the atmosphere (mainly near the top), by a primary radiation whose nature , is uncertain. Two main hypotheses of meson creation have been put forward - the proton hypothesis and the photon hypothesis. At sea-level the geomagnetic effects (the latitude and east-west asymmetry effects) are due almost entirely to mesons. Determination of the meson intensity as a function of latitude and zenith angle resulting at sea-level from the adoption of firstly the proton hypothesis and secondly the photon hypothesis, and comparison of the two sets of results with the observed geomagnetic effects at sea-level, affords evidence on the validity of these hypotheses. Part I of this thesis is mainly concerned with the determination of the geomagnetic effects shown by mesons at sea-level on flair two hypotheses. The proton hypothesis is first considered. The sea-level latitude effect allowing for decay and absorption in passing through the atmosphere, which would result if all mesons arose by a process of a particular multiplicity k, is worked out for a set of different k's. It is assumed that a proton has a probability ϕ(k) of producing k mesons simultaneously and the function ϕ(k) is determined empirically by superposing the results for particular k's so as to give the latitude effect which is actually observe) at sea-level. Using the ϕ(k) thus found, the asymmetry at sea-level at various latitudes and zenith angles is determined and compared with the corresponding experimental values. The photon hypothesis is next considered. The probability ϕ(k) of a photon producing k mesons simultaneously is again determined empirically by consideration of sea-level latitude effect. In this case the situation is complicated by the fact that the photons are themselves secondaries, arising by the cascade process from primary electrons. The hypothesis only becomes possible if the ratio of positive to negative electrons in the primary radiation is greater than unity; an upper limit to this ratio can be found by consideration of the observed asymmetry at the top of the atmosphere. Using the upper limit so determined, the asymmetry at sea level is calculated and again compared with experimental values at various latitude and zenith angles.
