Short-Lived Intensity Increase of the Nuclear Component of Cosmic Rays as a Result of Solar Activity

Abstract

T SECOND cosmic rocket contained equipment described in Ref. 1 for investigating the nuclear component of cosmic rays. This equipment consisted of two independently operating devices. The two devices were Cherenkov counters provided for recording nuclei in cosmic radiation moving at relativistic velocities. More than 100 nuclei with Z ^ 15, more than 3000 nuclei with Z ^ 5, and approximately 30 thousand nuclei with Z ^ 2, were detected during flight. Magnitudes of the flux of various groups of nuclei derived from mean values of the rate of detection are given in Ref. 1. The rate of detection derived by averaging over longer periods of time remains practically constant during the whole flight period after the rocket passes the external radiation belt. The rate of detection during separate short time intervals, however, deviates considerably from the mean value. The most noticeable deviation was observed on Sept. 12, 1959, at 11 hr 27 min universal time; at that time, it was observed that the rate of detection increased in the two devices for a period of approximately 17 min. This case is shown in Fig. 1 which depicts the dependence of intensity of flux of different groups of nuclei on time. The axis of the abscissa is universal time; the ordinate axis is the counting rate in the channels for detecting nuclei with Z J> 2, Z ^ 5 and Z ^ 15. The counting rate is determined in accordance with the magnitude of the time intervals required for recording 96 nuclei with Z ^ 2, eight nuclei with Z ^ 5, and two nuclei with Z ^ 15. The dashed line represents mean values (for 12 hr) of the counting rate. During a period of 17 min after 11 hr 27 min, 512 counts of nuclei with Z ^ 2 were recorded; their average number during the same time interval equals 388. Considering that the device is equipped with a scaler with a scale of 32, it is assumed that the number of counts during 17 min, in any case, is not less than 480, and exceeds the mean value of counts at least by approximately the quadruple of the statistical error. The probability that the increment is a consequence of statistical fluctuations is less than 10 ~. The number of counts of nuclei with Z ^ 5 and Z ^ 15 increased at the same time. The number of counts in the channels for counting nuclei with Z ^ 2, Z ^ 5 and Z ^ 15 increased 1.3 ± 0.1, 1.5 ± 0.3, and 11.8 ± 3.7 times, respectively. The probability of the increment resulting from statistical fluctuations for nuclei with Z ^ 15 is smaller by several orders of magnitude than for the group with Z ^ 2. Simultaneous increase of the counting frequency in two independent counters definitely implies a variation of the nuclear component. It is pointed out that the increase in the number of counts