CHACALTAYA Emulsion Chamber Experiment

Abstract

The photograph shows the air shower event called "Andromeda" recorded in the X-ray film under 4 cascade units of lead of Camara 14. The event is visually composed of the following three parts.A. Black nucleus at the center. A characteristic dimension of its lateral size is ~1 em. Estimation on the total energy is obtained as 16,000 TeV by photometry measurement on the opacity of the X-ray films and the integration over the lateral spread and the depth variation through the chamber.B. Very high energy r-rays in the black nucleus. With help of microscopic observation on the nucleus part in their nuclear emulsion plates, one recognizes the existence of a number of very high energy cascade showers in a stream of numerous shower tracks of the black nucleus. It shows the existence of 30 r-rays (or electrons) with energy ranging 5~100 TeV in the nuclear region. Most of them are interpreted as originated from an atmospheric nuclear interaction of L;E7~400 TeV occurred~600 m above the chamber.C. Associated particles of the electromagnetic and the nuclear-active component in the outer region. In the outer region of ;cz em, we observe about 240 particles of the electromagnetic component with energy E 7;c1 TeV, sum of their energy being :EE7~550TeV. Besides, we observe 16 events of Pb-jet with EP,;c2TeV, their energy sum being :EEP,~50TeV. The total number of particles of the N-component will be about three-times of the above value because of the finite thickness of the chamber. Lateral distribution of the both components can be represented as exp( -r/ro)rdr with ro=5±0.5 em. Integral energy spectrum of the electromagnetic component is expressed as E-P with ,8=1.6±0.3. at North Dakota State University on May 30, 2015 http://ptps.oxfordjournals.org/ Downloaded from 4 C. M. G. Lattes et al. and M. Akashi et al. AbstractThis 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 Componentsgive 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 ...

Revised production cross-section of γ-rays in p–p collisions with LHC data for the study of TeV γ-ray astronomy

“…and hereafter we omit angle brackets, · · · , in the left-hand side for the simplicity, as we are not interested in the azimuthal component. Remembering a well-known relation in π 0 -decay [33] α * ≈ m π 0 E * 1 E * 2 = m π 0 E * 1 (E * π 0 − E * 1 )…”

“…In Paper I, we assumed that the distributions of the energy and transverse momentum in the multiple meson production are both given by the exponential function, exp[−(E * γ /T 0 + p t /p 0 )] (E * γ : γ-ray energy, p t : its transverse momentum), which are expected from the fire-ball picture [12]. On the other hand in the QCD picture, the energy distribution is given by the algebraical function, (1 − x * ) m , expected from the quark dimensional counting approach [13], where x * is the light cone momentum fraction, and m relates to the number of quarks actively involved in the collision with m = 3 ∼ 6 practically.…”

“…Stecker [3] presented the production cross-section of π 0 , σ pp→π 0 (E 0 , E π 0 ) with E π 0 < ∼ 100 GeV (E 0 < ∼ 1 TeV) in the form of very useful parameterizations in 1973, and later one of the authors (T. S.) revised it in the previous paper [1] (hereafter Paper I), applicable for the higher energy region E 0 > ∼ 1 TeV. Nevertheless, the reliability is not always satisfactory, particularly in the forward region for E γ > ∼ 1 TeV (E 0 > ∼ 10 TeV) because of the limitation in the accelerator data, having no data on the energy spectra in the forward region, while Chacaltaya emulsion chamber (EC) group [20,33] have given them using CR-beams, but poor in data quality.…”

Fingerprints of disoriented chiral condensates in cosmic ray showers

“…Almost forty years ago exotic, apparently hybrid and unexpected events, dubbed Centauros, were observed in cosmic ray (CR) experiments in emulsion chambers in Chacaltaya by Lattes and collaborators [1]. Those events were very different from what is commonly observed in CRs, exhibiting a large number of hadrons and a small number of electrons and gammas, which suggests the presence of very few rapid-gamma-decaying hadrons.…”

Production cross sections of γ-rays, electrons, and positrons in p–p collisions

“…Previously, we have focused upon γ-ray production via π 0 instead of π ± , the energy determination of which is rather easy and reliable even in the highenergy region, > ∼ TeV, once a calorimeter is set well behind the vertex point of p-p interaction. In practice, cosmic-ray beam data is often obtained with an emulsion chamber (EC), covering E 0 = 10 ∼ 300 TeV [24,25]. The EC used in these references consists of approximately 2 m air-gap spacer between an artificial carbon target and the calorimeter, which is distant enough to separate each γ-ray core and measure simultaneously its shower energy using a nuclear emulsion plate.…”