Simultaneous observation of families and accompanied air showers at Mt. Chacaltaya

Simultaneous observations of families and accompanied air showers with emulsion chambers and the air shower array of electronic equipment at Mt. Chacaltaya (5200 m, 540 g/${\mathrm{cm}}^2$) reveal that families bear the data of nuclear interactions generated deep in the atmosphere. 47 outstanding families with Σ${\mathit{E}}_{\gamma }$≥10 TeV are correlated with the accompanied air showers of the size ${10}^5$–${10}^8$. A scatter plot of the average family energy versus the size of the relative air shower requires further energy fractionizing process(es) in the propagation of high energy cosmic rays in the atmosphere, such as a larger dissipative mechanism in nuclear interaction, heavier chemical composition of the primary cosmic rays, etc. We reach the conclusion that nuclear interaction changes its features in the energy region ${\mathit{E}}_0$≳${10}^{16}$ eV, because the heavier composition, proposed so far, is not sufficient for the required dissipative process. A comparison with the data from the HADRON experiment at a similar altitude with a similar technique shows that no larger deviations are present between both experiments. © 1996 The American Physical Society.