Galactic sites of acceleration of cosmic rays to energies of order 1015 eV and higher, dubbed PeVatrons, reveal themselves by recently discovered gamma radiation of energies above 100 TeV. However, joint gamma-ray and neutrino production, which marks unambiguously cosmic-ray interactions with ambient matter and radiation, was not observed until now. In 2020 November, the IceCube neutrino observatory reported an ∼150 TeV neutrino event from the direction of one of the most promising Galactic PeVatrons, the Cygnus Cocoon. Here we report on the observation of a 3.1σ (post-trial) excess of atmospheric air showers from the same direction, observed by the Carpet–2 experiment and consistent with a few months flare in photons above 300 TeV, in temporal coincidence with the neutrino event. The fluence of the gamma-ray flare is of the same order as that expected from the neutrino observation, assuming the standard mechanism of neutrino production. This is the first evidence for the joint production of high-energy neutrinos and gamma-rays in a Galactic source.

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Based on a huge data set acquired with a unique recording system, multiplicity events <i>M </i>=4&ndash;50 on a neutron monitor have been analyzed in detail. The multiplicity events are recorded in detail for the first time, their structure being examined. The multiplicity processes in a neutron monitor have been numerically simulated by a toolkit GEANT4. Analysis of neutron monitor data with high temporal and spatial resolution reveals that most multiplicity events involving more than three adjacent counter tubes are due to local hadronic air showers with characteristic dimensions of size 1&ndash;3 m and duration of ~1 ms

Early results of the search for E γ > 1 PeV cosmic photons from point sources with the data of Carpet-2, an air-shower array equipped with a 175 m 2 muon detector, are presented. They include 95% CL upper limits on PeV photon fluxes from stacked directions of high-energy IceCube neutrino events and from four predefined sources, Crab, Cyg X-3, Mrk 421 and Mrk 501. An insignificant excess of events from Mrk 421 will be further monitored. Prospects of the use of the upgraded installation, Carpet-3 (410 m 2 muon detector), scheduled to start data taking in 2019, for searches of E γ > 100 TeV photons, are briefly

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