Search for massive interacting particles near the cores of extensive air showers of energies of about 2×10¹⁴-10¹⁶ eV

Abstract

An experiment carried out at mountain altitude to study the time structure of hadrons in extensive air showers has revealed the existence of a special class of delayed high energy interacting particles at distances less than 20 m from the axes of showers of energy greater than 2*10¹⁴ eV. These particles having energies more than 20 GeV and delays more than 20 ns relative to the air shower front, constitute about 0.5% of the hadrons of similar energy. Detailed calculations predict the frequency of events with such delay-energy characteristics to be less than 10^-4 if they are due to known hadrons like nucleons and pions. The high energy large delay events however can be understood if there exist particles much heavier than nucleons (mass >10 GeV/c²) which are produced in ultrahigh energy interactions. Under certain circumstances the flux of such massive interacting particles has been deduced from the experimental data as approximately 10^-9 cm^-2 s^-1 sr^-1.