• S C Tonwar

      Articles written in Proceedings – Section A

    • 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

      S Lal R Raghavan T N Rangaswamy B V Sreekantan A Subramanian S C Tonwar R H Vatcha

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      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.

    • Observations on the nuclear interactions of cosmic ray pions and nucleons at energies ≳ 20 GeV - Part II. The extremely collimated nuclear interactions

      S Lal R Raghavan T N Rangaswamy B V Sreekantan A Subramanian S D Verma S C Tonwar R H Vatcha

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      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.

    • Time structure of the hadronic component of extensive air showers

      S C Tonwar G T Murthy B V Sreekantan

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      A detailed study of the time structure of hadrons of energy > 5 GeV in extensive air showers has been carried out at Ootacamund (8·00 gm/cm2) using a total absorption spectrometer at the centre of the T.I.F.R. air shower array. A comparison of the experimental results with theoretical calculations shows that the experimentally observed spectra can be explained only on the basis of a rather large production (∼ 15%) of mucleon-antinucleon pairs among the secondaries of high energy interactions. Also it has been shown that an isobar-cum-pionisation type of model is preferred to a pure pionisation model in ultra high energy interactions. A small fraction of hadrons (∼0·5%) of energy > 20 GeV are found to arrive considerably delayed (> 25 ns) with respect to the shower front. While these are indicative of the presence of heavy mass particles (M ∼ 10 GeV/c2) among the hadrons in air showers it is concluded experiments of a more direct nature are essential for establishing the production of heavy mass particles.

      In this paper all the details regarding the experimental set up, the procedures for classification and analysis of data and the methods adopted for the evaluation of the errors in the measurement of energy and time delay are presented and the main conclusions from the experimental results summarised. Details of calculations of the time structure functions on the basis of different models of high energy interactions and a critical discussion of the comparison of the experimental results with theoretical predictions are presented elsewhere.


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