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We present a revised reaction set for low pressure high density CF 4 plasma modelling. A global model (volume averaged) was developed to study a CF 4 discharge that includes the neutral species CF 4 , CF 3 , CF 2 , CF, F 2 , F, and C, the metastable states CF(a 4 Σ − ) and CF 2 ( 3 B 1 ), the positive ions + CF 3 , + CF 2 , CF + , + F 2 , F + , and C + , the negative ions -CF 3 , -F 2 , and F − , and electrons. The main reactions that contribute to the production and loss of each species are pointed out with an emphasis on the radicals CF 2 , CF and F, the dominant positive ion + CF 3 , and the dominant negative ion F − . We find wall processes to have a significant influence on the discharge. The density of F 2 is high due to recombination of F atoms at the walls and the losses of the radicals F, CF, and CF 3 are mainly through wall recombination. As the pressure is increased, F − becomes the dominant negative charged species. The discharge is found to be weakly electronegative below ∼10 mTorr and the electronegativity decreases with increased absorbed power.

The decay of the compound nucleus is traditionally calculated using a sequential emission model, such as the Weisskopf-Ewing or Hauser-Feshbach ones, in which the compound nucleus decays through a series of residual nuclei by emitting one particle at a time until there is no longer sufficient energy for further emission. In the case of light compound nucleus, however, the excitation energy necessary to fully disintegrate the system is relatively easy to attain. In such cases, decay by simultaneuous emission of two or more particles becomes important. A model which takes into account these decays is the Fermi break-up model. Recently, the Fermi break-up model was shown to be equivalent to the statistical multifragmentation model used to describe the decay of highly excited fragments from heavy ion reactions when the residual nuclei have few excited states. Due the simplicity of the thermodynamic treatment used in the multifragmentation model, we have adapted it to the calculation of Fermi breakup of light nuclei in a general context. The ultimate goal of this study is to calculate the distribution of isotopes produced in proton-induced reactions on light nuclei of biological interest, such as C, O and Ca. Although most of their residual nuclei possess extremely short half-lives and thus represent little long-term danger, they tend to be neutron-deficient and to decay by positron emission, which allows the monitoring of proton radiotherapy by PET ('positron emission tomography').

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