The influence of the counter wall and the counter shape on the spectral energy deposition in small volumes by 60Co gamma-rays and 200 kV x-rays.

The spectral energy deposition in small volumes by 60Co gamma-rays and by 200 kV X-rays was measured with a walled spherical counter, a walled cylindrical counter and a wall-less cylindrical counter. The simulated volumes had dimensions of 0.1--3 mum. By comparing the spectra of the spherical and cylindrical walled counters the influence of the counter shape is derived. The wall effect is discussed by comparing the spectra and the mean lineal energy measured with the walled and the wall-less cylindrical counters. The influence of the counter size and of radiation quality on the energy deposition spectra is also analysed.