Several possible methods to distinguish protons and pions in the cosmic radiation at energies of over 100 GeV are discussed. One of these methods based on multiple sampling of ionization losses in an array of gas proportional counters together with a measurement of energy in an ionization calorimeter or momentum in a magnet spectrograph is discussed in greater detail.Fluctuations in ionization losses (“Landau” fluctuations) make the method difficult but not impossible. Experimental results on Landau fluctuations with a variety of incident particles and energies are presented and it is shown that they are in better agreement with the theory of Blunck and Leisegang than with that of Landau.Artificial events in which the sampled ionization losses obeyed the Landau and Blunck and Leisegang distributions are generated on a computer by a Monte Carlo program. Based on an analysis of a sample of 20000 such events by likelihood ratio method the attainable proton-pion separation in the cosmic radiation at 100 GeV energy is presented.
- 1 - sciences appliquees, technologies et medecines ; 2 - sciences exactes et technologie ; 3 - terre, ocean, espace ; 4 - geophysique externe