On the absorption and scattering of γ-rays

An account of an experimental determination of the comparative absorption of penetrating γ-rays by a wide range of elements has recently been given by one of us. It is the object of the present paper to consider the results somewhat more fully, especially those concerned with scattering, which was not previously discussed. The rays used were those from RaB + C after filtration through 1 cm. lead. The absorption was primarily measured in terms of aluminium, whose apparent absorption coefficient was measured directly. It was shown that the apparent atomic absorption, for the absorber in one particular position, could be represented with considerable accuracy by μa' = aZ + bZ4 (1) where Z is the atomic number.