A phenomenon of abnormally weak absorption of very-high-energy cosmic-ray hadrons in lead is discussed. This phenomenon was first observed in Tien-Shan high-altitude experiments in hadronic cores of extensive air showers and has encouraged to introduce the hypothesis of a so-called long-flying or penetrating cosmic-ray component. A similar effect was detected later with deep uniform lead X-ray emulsion chambers (XREC) at the Pamirs. Experiments, which are sensitive to the production of charmed hadrons in the forward kinematic region (x(Lab) greater than or similar to 0.1), have been carried out at the Tien-Shan and Pamirs with exposing two-storey XRECs with large air gaps to prove explanation of the experimental results with high charm production cross section sigma pp -> cc over bar similar to 8 at x(Lab) greater than or similar to 0.1 at ⟨E-Lab⟩ similar to 75 TeV. This sigma pp -> cc over bar value makes it possible to reproduce the experimental hadron-absorption curve observed with XRECs, including curve's bending at a depth of similar to 70 c.u.
展开▼
