An instance of a temporary increase in the intensity of heavy nuclei during the flight of the third satellite

Abstract

To determine the cosmic ray nuclear component, a cerenkov integral-type counter was installed on the third artificial earth satellite similar to the counters used on cosmic rockets(1-3). This counter detected nuclei with 2 2. 5,Z z 12-14,Z ;3 31-34 and 2 > 34. In order to investigate the chemical composition of the nuclear component, brenkov differential-type counters@) were also installed. Each differential-type counter was associated with two groups of gas-discharge counters which formed a telescope with the geometric factor l? w 2.5 . lo4 cm2ster. The total energy of the detected nuclei exceeded 1+1*5 BeV. In this paper a description is given of a short increase in the intensity of the heavy nuclei, similar to that detected during the flight of the second cosmic rocket(*). To observe variations in the intensity of the nuclear component, the most favourable conditions occur in free space outside Earth’s magnetic field. Near Earth, owing to geomagnetic effects, the intensity varies widely in flight from the equator to high latitudes (the latitude effect>: Such variation hinders observation of temporary variations. Yet the intensity at a particular instant can be compared with the mean intensity on the corresponding geomagnetic latitude. High latitudes are the most convenient for which the mean intensity of the nuclear component should be independent of latitude. There are two reasons for the constancy of the mean intensity at high latitudes. Firstly, owing to the existence of a region of “highlatitude clipping” where the intensity is constant, low-energy nuclei do not enter into orbit round Earth. Secondly, owing to the energy threshold of Cerenkov counters, nuclei with total energy less than 1+1*5 BeV/nucleon are not recorded and this too must lead to constancy of the mean intensity at high latitudes. Figures 2 and 3 in another paper of this journal w show the dependence of nuclei with Z 2 2, Z 2 5 and Z 2 12-14 on latitude, as found during the flight of the third cosmic rocket. It is apparent from these diagrams that, beginning from latitudes 50-55*, intensity remains unchanged within the limits of statistical error. If the intensity of the nuclei increases notably for a short period of time during flight above this region, such an increase is to be regarded as a variation in the intensity of the nuclear component, provided of course that the increase is large enough and that it cannot be due to statistical fluctuations. While scrutinising the material obtained during the flight of the third satellite, just such an increase was noted as at 1 I.20 hr world time 1 December 1960 for 12 min. At this time the satellite was in the high latitude region. According to the integral-type counter, the intensity of nuclei with 2 > 12-14 increased by a factor of 2-8 f l-4 compared with the mean value for geomagnetic latitudes 50-70*. The increase in intensity for nuclei with z 2 5, as well as for 2 > 2 (according to the differential counter), was within the limits of statistical error throughout the period. In the shorter period from 11.20 to 11.26 hr, the