Study of the Absolute Flux and Energy Spectrum of Cosmic Ray Neutrons in the Atmosphere

摘要

A neutron detector has been constructed to measure the flux and energy spectrum of cosmic ray neutrons in the atmosphere over the energy range (thermal energy -20MeV). The latitude effect of the neutron flux was determined by comparing the counting rate of the detector during balloon launches at different geomagnetic latitudes. A counting-rate variation with altitude has also been observed due to a variation of the neutron energy spectrum with altitude. An improved version of the detector has been made. The results of balloon and rocket launches led to a determination of the neutron flux as a function of the atmospheric depth, from 300 to 0.1 gm/cm sq cm. Furthermore a high energy neutron detector has been made to measure the steady state solar neutron flux over the energy range 30-120MeV. Background estimation shows that a neutron flux from the sun of the order of 0.001/sqcm/sec can be detected. (Author)