High energy cosmic ray neutrons

Abstract

A measurement of the sea level energy spectrum of cosmic ray neutrons in the energy range 50-1000 GeV has been performed. The neutrons interacted in a thick iron absorber, the burst subsequently produced being detected by a scintillation counter. The burst sizes were used to select events and to estimate the energy of the neutrons. The experimental results show a neutron spectrum that is steeper ( Y= 2.95 + 0.1) than might normally be expected. This has been discussed in terms of nucleon propagation in the atmosphere. One possible explanation would be a decrease in the nucleon attenuation length in the atmosphere. An alternative solution is in terras of the charge exchange probability for nucleon interactions. If, as has recently been postulated, the Aleph baryon is produced in high-energy (> 1000 GeV) nucleon collisions, this would lead to a deficit in the expected number of neutrons at sea level in the energy range covered by this experiment. A search for high energy magnetic monopoles has been made using the same apparatus. No events satisfying the selection requirements were observed and the upper limit to the flux at the 909s confidence level is < 9.5- 10(^-11) cm(^-2) sec(^-1) sterad(^-1). An investigation of the characteristics of long cylindrical proportional and sonic spark counters has also been carried out.