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Natural background radiation is mainly due to radon, but how much is in the air around us? A figure can be calculated by using a silicon detector to measure a particles emitted from the dust deposited on a filter through which air is drawn by a vacuum cleaner. The detector described here also allows measurement of very low macroscopic surface activities.

The scattering of protons emitted from the neck area of the fissioning nucleus by fission fragments has been computed by solving the time-independent part of the Schrodinger equation for the symmetric fission of 235U+n. The current density (j=(h/2 pi )/2mi)( psi *GRAD psi - Psi GRAD psi *) is calculated as a function of the final energy of the protons and the interfragment distance. It was found that the ratio of 'polar emission' to 'equatorial emission' decreases with the interfragment distance. The possibility of explaining the 'polar emission' and 'equatorial emission' phenomena as a scattering of protons by fission fragments is discussed.

Ternary fission is approximated by the time-dependent evolution of the alpha-particle wavepacket in the potential generated by two moving fission fragments from ternary fission of 235U+n. The time-dependent Schrodinger equation is solved numerically by a finite elements method on an axially symmetric spatial mesh. The time-dependent evolution of the wavepacket is presented. It is illustrated by contour maps of the absolute value of current density j=mod.((h/4im pi )( psi *grad psi - psi grad psi *)). The angular distribution computed using the wavepacket function psi is compared with the experimental data. The calculated ratio of 'polar emission' to 'equatorial emission' is in good agreement with experiment.