Cosmic-Ray Increase at High Altitude on February 23, 1956

A vertical telescope with a stopping power of 22 g/${\mathrm{cm}}^2$ was flown to an atmospheric depth of 10 g/${\mathrm{cm}}^2$ at Minneapolis seventeen hours after the beginning of the giant solar flare and cosmic ray increase of February 23, 1956. The cosmic-ray intensity was normal below 300 g/${\mathrm{cm}}^2$, but at 10 g/${\mathrm{cm}}^2$ was five times the normal intensity at Minneapolis. The particles apparently have energies less than one Bev, presumably originated near the sun and reached the earth by scattering from magnetic fields near the solar system.