The Primary Cosmic Radiation at High Latitudes

Various properties of the new group of low energy primary cosmic-ray particles ($E<\mathrm{}1.6\mathrm{}$ Bev for protons) which enter the top of the atmosphere at geomagnetic latitudes north of 52° were investigated during the summer of 1950. Measurements at both 52°N (Swarthmore, Pennsylvania) and 69°N (Fort Churchill, Manitoba) were obtained with the same quadruple-coincidence counter trains used previously, oriented either horizontally or vertically, and with pulsed ionization chambers biased to detect bursts exceeding 1.0 $\mathrm{P}\mathrm{o}-\alpha$.