Particle penetration through frozen gases

The energy deposition of swift charged particles penetrating solids is accompanied by such processes as particle (electrons, atoms, photons …) production or phase transition along the particle track. The electron yield obtained with thin copper foils covered with solid CO2 (or Xe) and the erosion of frozen CO2 (or Xe) by transmission of protons (1 MeV) was measured quantitatively. The obtained CO2 (or Xe) thickness was related 1. to the yield of convoy electrons (Ee ≃ 540eV) being emitted along the beam direction (Θ=O°) with a vector velocity ve equal to the projectile vector velocity vp and 2. to the intensity of low energy “true” secondary electrons (Ee < 50eV). The adsorbate thickness dependence of both electron yields is found to be independent of their electron transport lengths 1(Ee.