Intense bundles of particles in cores of nuclear-electromagnetic cascades in the atmosphere with energies around 100 PeV (gamma-families with halo)

• Published in: Nuclear physics. Section B, Proceedings supplement Vol. 122; pp. 263 - 266
• Main Authors: Puchkov, V.S., Borisov, A.S., Guseva, Z.M., Denisova, V.G., Kempa, J., Kanevskaya, E.A., Maximenko, V.M., Mukhamedshin, R.A., Pyatovsky, S.E., Slavatinsky, S.A., Amineva, T.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2003
• ISSN: 0920-5632; 1873-3832
• DOI: 10.1016/S0920-5632(03)80394-8

An appreciable fraction of gamma-families are accompanied by a halo, a narrow bundle of high-energy particles (energy density > 20 TeV/mm 2) recorded in X-ray emulsion chambers as a diffuse dark spot in the central region of a gamma-family. Gamma-families in the experiment “Pamir” are compared with simulations by three different codes of quark-gluon string model (MQ, MCO and QGSJet) based on extrapolating accelerator data up to energy E o = 3 ∗ 10 18 eV and under various assumptions on mass composition of primary cosmic rays (PCR). The spectrum of halo area, S, is analyzed, especially at S > 100 mm 2. Simulations by different codes predict that at a PCR energy E o ∼ 10 18 eV the probability of initiating a halo with S ∼ 1000 mm 2 is 60% for primary protons and 40% for Fe nuclei. The fraction of protons in PCR composition at E 0 = 10 16 ÷ 10 17 eV is estimated.