CHACALTAYA Emulsion Chamber Experiment

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This is a publication of results obtained by the collaboration experiment of the Brazil and Japan Emulsion Group over a period of nearly ten years since 1962. It is divided into five parts. I. Introduction gives a short description of the emulsion chambers exposed at Mt.Chacaltaya Laboratory (5200m), Bolivia, ranging from Camara No.1 of 0.4m^2 up to Camara No.15 of 44.2m^2, with a brief historical review of the collaboration experiment. Main part of the present results are obtained with Camara No.12 (6m^2) and No.13(9.8m^2), both of which have the producer layer for nuclear interactions in the chamber itself. II. Morphological Studies on Cosmic-ray Components give the results on frequency, energy spectrum and zenith angle distribution of the electromagnetic and the nuclear-active components at Chacaltaya. The vertical flux for the electromagnetic component is (2.66・10^<-9> / cm^2 sec sterad)・(E / 10^<12>eV)^<-β> with β=2.07±0.10, covering energy region of 2・10^<11>eV〜5・10^<13>eV. Ratio of a flux value of the electromagnetic component to that of the nuclear-active component of the same visible energy is 〜0.56, constant over the concerned energy region. III. Fire-ball Studies on C-jets give detailed analysis on 85 events of local nuclear interactions with ΣE_γ≥3TeV occurred in the producer layer. High energy γ-rays produced in the interaction are described in the integral form as N_γexp(-N_γE_γ / ΣE_γ) with N_γ=8±1. All of the results on energy spectrum, angular distribution, p_T distribution and p_T-θ_γ correlation show that those γ-rays are products of an isotropic intermediate state (a fire-ball) with momentum distribution, N_γexp(-p^*_γ / p_ο) (p^*_γ / p^2_ο)dp^*_γ with N_γ=8±1, p_ο=82±15 MeV in its rest system. A fire-ball analysis is made on individual 75 C-jets with the observed γ-ray multiplicity equal to or greater than 4. Seventy one events are found to show emission of a fire-ball. Their experimental mass spectrum has a peak at 〓_γ〜1.2GeV, giving the average value as <〓_γ>=1.28±0.35 GeV where 〓_γ is a part of the rest energy liberated into γ-rays. IV. Atmospheric Interactions be concernsed with analysis on 41 γ-ray families which are selected by the imposed criteria as representing directly the parent atmospheric interactions. The events are divided into two groups according to their value of a sum of transverse momenta of γ-rays as: (A) Σp_<Tγ>≲2.5GeV / c and (B) Σp_<Tγ>>2.5GeV / c. Fire-ball analysis on 28 events of the group (A) shows that they are emissions of a fire-ball of identical properties with that found in the C-jets. Whereas, 13 events of the group (B) are found to exhibit emission of a larger fire-ball, named as "super heavy quantum (SH quantum)". The experimental data give its mass as 〓_γ=8±2GeV and isotropic emission of γ-rays with average multiplicity <N_γ>=30±8. Its total rest energy will be 20〜25 GeV. The momentum distribution of γ-rays from the SH-quantum is not of a simple exponential form but has a less steep tail on the higher momentum regions. V. Conclusion gives a summary of the results and comparisons with other experiments. Emission of a small fire-ball with 〓_γ=1.31±0.28 GeV (average over 99 events) is confirmed in multiple production process over a wide energy region starting the accelerator region of 〜10 GeV up to cosmic-ray region of ΣE_γ〜100 TeV. Its total rest energy is estimated to be 2.2〜2.6 GeV. This is identified as "H-quantum" proposed by Hasegawa. Re-analysis of the Bristol-Bombay experiment of a balloon emulsion chamber confirmed the existence of the H- and SH-quanta. Fire-ball analysis on the Hexas Lone Star of the Bristol group shows a fire-ball of still larger mass, its 〓_γ being about 78±10 GeV. A large air shower event called Andromeda with ΣE_γ〜3・10^<16>eV suggests the existence of a large fire-ball of the same property. Thus, as a c
理論物理学刊行会の論文
1971-09-14

CHACALTAYA Emulsion Chamber Experiment

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