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Characteristics of cosmic-ray hadronic interactions in the l00_1017 eV range are studied by observing a total of 429 cosmic-ray families of visible energy greater than 100 TeV found in emulsion chamber experiments at high mountain altitudes, Chacaltaya (5200 m above sea level) and the Pamirs (4300 m above sea level). Extensive comparisons were made with simulated families based on models so far proposed, concentrating on the relation between the observed family flux and the behaviour of high-energy showers in the families, hadronic and electromagnetic components. It is concluded that there must be global change in characteristics of hadronic interactions at around l0b~eV deviating from those known in the accelerator energy range, specially in the forwardmost angular region of the collision. A detailed study of a new shower phenomenon of small-pT particle emissions, PT being of the order of 10 MeV/c, is carried out and its relation to the origin of huge "halo" phenomena associated with extremely high energy families is discussed as one of the possibilities. General characteristics of such super-families are surveyed.

Microstructural attributes of steels affect hysteretic magnetic properties because the microstructure affects domain wall movement and pinning. Two important features are grain size and dislocation density. The consensus experimentally is that the coercivity tends to be linearly related to the inverse of the average grain diameter and to the square root of the dislocation density. In this article, these experimental tendencies are utilized in formulating the dependence of the hysteresis parameters of the Jiles–Atherton model as a function of grain size and dislocation density. The results are then used in computing the first and third harmonics of the magnetic induction as a function of grain size and dislocation density. This is done via an adaptation of a hysteresis model formulated by Jiles for higher excitation frequencies. The results indicate that the harmonic amplitudes decrease monotonically with inverse grain size and the square root of dislocation density. Since increasing inverse grain size and dislocation density are correlated with increasing tensile strength, the results are consistent with experimental results for the decrease of the harmonic amplitudes with increasing tensile strength in automotive steels. Also, the harmonic amplitudes decrease with increasing excitation frequency, consistent with experiment.

A number of observations of Cygnus X-3 have been made and evidence has been reported for emission of PeV and TeV gamma rays from this abject. The results given by the experimental data include the surprising fact that the number of muons involved in the showers induced by photons is not as small as expected. One way of explaining the observed excess of cosmic-ray muons in the y-ray induced showers i s to postulate the rapid growth of the photonuclear cross section at energies 10'GeV. We examine in some detail the development of proton and gamma showers with full account for the photoproduction cross section. Both the lower and upper limits for the number of muons in y-initiated showers with photoproduction are calculated. It is shown that for y-initiated showers the number of muons is comparable with that in r, showers if the rapid increase of the photoproduction cross section is assumed.

Here we present a summa~ of joint discussions on the results of three mountain experiments with large-scale emulsion chambers, at Pamir, Mt. Fuji and Chacahaya. Observations cover gamma quanta, hadrons and their clusters (called "families").The following topics are covered, concerning the characteristics of nuclear interactions the energy region 1014-1016 eV: (i) rapid dissipation seen in atmospheric diffusion of high-energy cosmic-rays; (i.i) multiplicity and Pt increase in produced pi-mesons in the fragmentation region; (iii) existence of large-P t jets, (iv) extremely hadron-rich family of the Ccntauro type: (v) exotic phenomena in the extremely high energy region beyond 1016 eV.