Influence of the Nature of Ionizing Particles on the Specific Luminescence of Organic Scintillators

The relationship between the specific luminescence dS/dx of organic scintillators and characteristic quantities of the ionizing particle is investigated. Considering the existence of the two scintillation components and the effect of δ rays, it is shown that dS/dx depends on the specific energy loss dE/dx and on the charge number z of the incident particle: For a given differential energy loss, the ion having the greatest charge number gives rise to the highest light output; for a given particle with increasing dE/dx, the specific luminescence goes through a maximum. The theoretical conclusions are in agreement with experimental results obtained using α particles of 1 to 8 MeV, 3He ions in the energy range 1–3 MeV and protons from 0.3 to 3 MeV. An experimental device is described, which allows a direct measurement of the energy loss ΔE of particles passing through a thin organic scintillator, and of a quantity proportional to the number ΔS of emitted photons.