Search for Extensive Photon Cascades with the Cosmic-Ray Extremely Distributed Observatory

Abstract

Although the photon structure is most efficiently studied with the accelerator instruments, there is also
a scientifically complementary potential in investigations on photons produced in the outer space.
This potential is already being explored with gamma ray telescopes, ultra-high energy cosmic ray observatories
and, since very recently, by the Cosmic-Ray Extremely Distributed Observatory (CREDO).
Unlike the former instruments focused on detection of single photons, CREDO aims at the detection
of cascades (ensembles) of photons originating even at astrophysical distances.
If at least a part of such a cascade reaches Earth, it might produce a unique pattern
composed of a number of air showers observable by an appropriately dense array of standard detectors.
If the energies of air showers constituting the pattern are relatively low and if the typical
distances between the neighbors are large, the ensemble character of the whole phenomenon
might remain uncovered, unless the CREDO strategy is implemented.