The absorption of [[nuclear]] particles or [[photon|photons]] by the mass of material through which the energy must pass. In [[nuclear log|nuclear logging]], this refers to the loss of [[radiation]] caused by the collective mass of materials in the wellbore environment through which the radiation energy must pass before being detected. With respect to the natural [[radioactivity]] level of some rock [[formation|formations]], it is sometimes referred to as [[self absorption|self-absorption]].