Articles written in Proceedings – Section A
Volume 73 Issue 3 March 1971 pp 119-133
Observations on the nuclear interaction of cosmic ray pions and nucleons of energies ≳ 20 GeV - Part I. Experimental details and results relating to fluctuations in the angular distribution of the secondary particles produced in interactions in carbon
In this paper, which is the first of a series entitled ‘Observations on the Nuclear Interactions of Cosmic Ray Pions and Nucleons of Energy ≳ 20 GeV’, a description is given of the experimental arrangement, the types of data collected and the methods employed to analyse and classify the data. Results on the fluctuations in the angular distribution of the secondary particles produced in interactions in carbon are also presented and it is shown that these fluctuations are considerably larger in certain cases than what can be accounted for purely from statistical fluctuations in the isotropic and uncorrelated emission of secondaries in the c.m. system of the collision with a target nucleon and in others difficult to be understood on this basis if additional features of these interactions are also considered. It is suggested that ‘correlated emission’ of secondaries possibly due to final state inter-actions or multiparticle resonances with different ‘Q-values’ and other properties are perhaps the cause of the observed fluctuations; this is in contrast to the explanation in terms of simple motion of ‘fire balls’ in the c.m. system as has been generally discussed.
Volume 73 Issue 4 April 1971 pp 170-178
Detailed features of extremely collimated nuclear interactions induced by cosmic ray particles in carbon and brass (belonging to group I as classified in Part I of this series of papers) are presented. These extremely collimated nuclear interactions seem to be preferentially induced by pions rather than by nucleons; also the relative frequency of these seems to be less when brass is used as target compared to the case with carbon as target. The distribution of multiplicities of secondary particles emitted in the forward direction show certain regularities in the case of interactions induced by charged primaries. Observations on the γ-rays associated with these events give support to the interpretation that in these inelastic collisions pions are produced in pairs in the forward direction with low transverse momentum. It is suggested that such a low energy di-pion system could be the same as found in the so-called ABC effect.
Volume 73 Issue 5 May 1971 pp 213-222
Using a combined set-up of a multiplate cloud chamber, an air Cerenkov counter and a total absorption spectrometer, the ratio of pions to protons not associated with large air showers has been determined to be 0·50 ± ·07 in the energy region 20–40 GeV at an altitude of 800 gm/cm2. In the same energy region the ratio of neutral to charged particles is found to be 0·66 ± ·07. From the ratio of neutrons to protons deduced from these measurements (