The average mass composition of cosmic rays with primary energies between 1017 and 1018eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases. © 2000 The American Physical Society.
Publication Source (Journal or Book title)
Physical Review Letters
Abu-Zayyad, T., Belov, K., Bird, D., Boyer, J., Cao, Z., Catanese, M., Chen, G., Clay, R., Covault, C., Cronin, J., Dai, H., Dawson, B., Elbert, J., Fick, B., Fortson, L., Fowler, J., Gibbs, K., Glasmacher, M., Green, K., Ho, Y., Haung, A., Jui, C., Kidd, M., Kieda, D., Knapp, B., Ko, S., Larsen, C., Lee, W., Loh, E., Mannel, E., Matthews, J., Matthews, J., & Newport, B. (2000). Evidence for Changing of Cosmic Ray Composition between 1017 and 1018 eV from Multicomponent Measurements. Physical Review Letters, 84 (19), 4276-4279. https://doi.org/10.1103/PhysRevLett.84.4276