CHACALTAYA Emulsion Chamber Experiment (original) (raw)

1971, Supplement of the …

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 (5200 m), Bolivia, ranging from Camara No. 1 of 0.4 m 2 up to Camara No. 15 of 44.2 m 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 (9.8 m 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)-P with ,8=2.07±0.10, covering energy region of 2•10 11 eV~5•10" 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-l-all Studies on C-jets give detailed analysis on 85 events of local nuclear interactions with L:Er~3 TeV occurred in the producer layer. High energy 7-rays produced in the interaction are described in the integral form as Nrexp(-NrEr/L:Er) with Nr=8±1. All of the results on energy spectrum, angular distribution, PT distribution and PT-Or correlation show that those 7-rays are products of an isotropic intermediate state (a fire-ball) with momentum distribution, Nrexp(-p"t/po)(p1/pi)dp"t with Nr=8±1, po=82±15MeV in its rest system. A fire-ball analysis is made on individual 75 C-jets with the observed 7-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 IDlr~1.2 GeV, giving the average value as <IDlr)=1.28±0.35 GeV where Wlr is a part of the rest energy liberated into 7-rays. IV. Atmospheric Interactions be concemsed with analysis on 41 7-ray families which are * This number is obtained from a part of the chamber which was analyzed in INS (Tokyo), Campinas Univ. and CBPF of Rio de Janeiro. Once the energy measurement is made on all detected individual r-rays constituting the C-jet, one can apply the method of coupling of a pair of rrays into n°-meson in order to estimate a location of its production in the producer layer. Their average height is estimated as