Japanese-American Cooperative Emulsion Experiment

The Japanese-American Cooperative Emulsion Experiment (JACEE) has been continued since 1979. The purpose of the project is to obtain the composition of cosmic particles and the energy distribution in the energy range from 1012 to 1016 eV. The first phase of experiment was made in the period between 1979 and 1982 by balloon flight. From this experiment, it was able to be said that the closed galaxy model for cosmic ray transport was not confirmed. The spectrum of Fe nuclei with the energy less than 100 GeV/n can be explained by the propagation effect in space. The test of various detection devices were also made in the first phase. In the second phase, the counting statistic quantity will be increased by a factor of 5. A counter system will be introduced in the detection system, and the overall detection area will be about 500 m2 . sr, hr. FThe third and the fourth phases of the project are designed to observe the energy range from 1015 to 1016 eV, and the detector will be carried on a space shuttle and on a space platform. (Kato, T.)