FURTHER OBSERVATIONS ON THE NATURE OF THE CURRENT REDUCTION IN THE PRIMARY COSMIC-RAY INTENSITY

It has been established that a sharp cutoff mechanism has reduced the primary cosmic-ray intensity. Although the experimental results which led to this conclusion were entirely consistent with the possibility that the 1958 and 1950 magnetic rigidlty spectra differ only wlth respect to the lower limit, it was not possible to determine whether the form of the spectrum had also changed. Results of experiments with balloon-borne pulsed ionization chambers relating to the form of the spectrum and providing information on the flux of heavy nuclei are reported. (W.D.M.)