Particle bombardment energy distributions

Fig. 11. Energy distribution of the positive, negative and neutral atoms backscat-tered from a stainless steel (304) surface for 10 keV D bombardment. The ion beam was at normal incidence and the backscattered particles had been observed at an angle of 45 deg. to the normal70 ...

The Be ( a) Li" reaction has been much used for exciting the states of Li and the 0.48 MeV and 4.62 MeV states have been seen with moderate bombarding energies and possibly the 7.65 MeV state with 14 MeV deuterons . The angular distribution for the ground state group is isotropic for deuterons of energy from 0.3 to 0.7 MeV , and the correlation between the alpha particles to the first excited and the subsequent radiation is isotropic . This confirms the spin J = for the first excited state of Li . The alpha particle spectrum in the bombardment of beryllium by deuterons includes a continuous distribution of particles from the three body process Be (< 2a) H . 

Deuteron pick-up and stripping and related reactions. Hadley and York undertook to investigate the angle and energy distribution of the charged particles emitted when 90 Mev neutrons bombarded targets of C, Cu, and Pb. 

The radiation-induced electrons are widely distributed over energies, from values lower than the ionization potential I of environmental molecules to values being equal to the initial energy of the bombarding particle. Such a distribution is due to the fact that the motion of fast primary electrons induces the creation of secondary electrons with an energy sufficient to cause further ionization. These in turn yield electrons of a third generation, and so on until the appearance of... 

Details of the deposition process and system geometry - e.g. the deposition process used, angle-of-incidence distribution of the depositing adatom flux, substrate temperature, deposition rate, gaseous contamination, concurrent energetic particle bombardment (flux, particle mass, energy). 

Let us consider first the low-energy fission of the lighter fissionable elements, in the neighborhood of Pb208. These elements (gold, thallium, lead, bismuth), when bombarded with particles such as 20-Mev deuterons, undergo symmetric fission, the distribution function of the products having a half width at half maximum of 8 to 15 mass-number units (20). 

In addition to thermal desorption, gas desorption has been found to result from electron, ion and photon bombardment of surfaces. Therefore, simultaneous particle and photon bombardments can be expected to alter desorption rates, as well as the nature and charge distribution of the desorbed species. Furthermore, simultaneous bombardment of a surface by neutrons and ions could affect diffusion processes, e.g., by radiation-induced segregation. In turn, desorption processes can be influenced by altering the diffusion of species from the bulk to the surface. The type, energy, and angular distribution of particles expected to strike neutral beam injector dump areas (such areas can represent 1/9 of total first wall area) can cause synergistic effects on gas desorption which can be quite different from those expected from the interaction of plasma radiations with the first wall. 

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