CosmicRay Air Showers at Sea Level
Abstract
An investigation at sea level of cosmicray showers with sizes from 5×10^{5} to over 10^{9} particles is described. The core locations, arrival directions, and particle density distributions of several thousand showers whose cores landed within an area of 10^{5} m^{2} were determined by the techniques of fasttiming and density sampling. The most important results are as follows: (1) The existence of primary particles with energies greater than 10^{18} ev is established by the observation of one shower with more than 10^{9} particles. (2) The function f(r)=0.45(NR_{0}^{2})r^{0.7}(1+r)^{ 3.2}, where r=RR_{0} and R_{0}=79 m, describes the lateral distribution of particles at distances in the range 50 m<R<400 m and for showers with sizes in the range 5×10^{5}<N<10^{8}. (3) At distances greater than 50 m from the core the density fluctuations in individual showers have a Poisson distribution. (4) The size and zenith angle distribution can be represented by the formula s(N, x)=s_{0}(10^{6}N)^{Γ+1}exp[(x x_{0})Λ], where x=x_{0}θ, x_{0}=1040 g cm^{2}, s_{0}=(6.6+/1.0)×10^{8} cm^{2} sec^{1} sterad^{1}, Γ=1.9+/0.1, Λ=(113+/9) g cm^{2}, x_{0}<x<1.3x_{0}, and 7×10^{5}<N<7×10^{8}. (5) No evidence is found of anisotropy in the arrival directions or of a break in the energy spectrum of the primaries up to the largest energies observed. (6) Assuming a specific model for shower development and taking into account fluctuations in the depth of the first interaction, the integral energy spectrum of the primaries is J(E)=J_{0}(10^{15}E)^{γ}, where J_{0}=(8.1+/3.1)×10^{11} cm^{2} sec^{1} sterad^{1}, γ=2.17+/0.1, and 3×10^{15} ev<E<10^{18} ev.
 Publication:

Physical Review
 Pub Date:
 April 1961
 DOI:
 10.1103/PhysRev.122.637
 Bibcode:
 1961PhRv..122..637C