Alpha particles resulting from

An alplia particle is an energetic helium nucleus. The alplia particle is released from a radioactive element witli a neutron to proton ratio tliat is loo low. Tire liclium nucleus consists of two protons and two neutrons. Tlie alpha particle differs from a helimn atom in that it is emitted witliout any electrons. The resulting daugliter product from tliis t) pe of transformation lias an atomic number tliat is two less tlian its parent and an atomic mass number tliat is four less. Below is an e. ample of alplia decay using polonium (Po) polonium has an atomic mass number of 210 (protons and neutrons) and atomic number of 84. 

Describe the nuclear model of the atom. How does this model explain the results of alpha-particle scattering from metal foils ... 

Americium toxicity results primarily from the damage done by the alpha particle emitted during radioactive decay. This alpha particle has very limited penetration in tissue, and hence, the cellular damage (including damage to genomic material) occurs only in the immediate vicinity of the sequestered americium. 

Dosimetric Studies. The main objective of Rn-d dosimetry is to enable the assessment of the observed dose from Rn-d deposited in the respiratory tract from measured Rn-d concentration in the atmosphere. As a consequence of an inhomogeneous Rn-d deposition within the lung, different dosimetric concepts have been developed to describe either regional mean dose values (e.g. for tracheobronchial or pulmonary region) or microdosimetric dose calculations (e.g. for the basal cell layer). Using Monte Carlo calculation methods it is also possible to account for the random nature of cellular hits by deposited alpha particles. The results of such dosimetric calculations should provide the following information needed for Rn-d risk assessment ... 

Edwards et al. (1980) used a Cm-242 source to irradiate externally a thin film of blood. The energy of 4 9 MeV of the alpha particles were almost entirely absorbed by the blood. The dicentrics yield was linear from 0.11 to 4 2 Gy. From this resulted a RBE of 17.9 with respect to Co-60 gamma rays. It was, however, only 6.0 at the initial slope. To explain this RBE, which was low compared to that expected from neutron experiments, a model is presented taking into account cell killing and mitotic delay. 

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