[en] An ionization chamber for analyzing inhomogeneities in a radiated beam from a particle accelerator system has two measuring chambers formed by three mutually parallel walls spaced apart by spacer rings. Two of the three walls have single electrodes arranged thereon whereas a third wall has several mutually insulated electrodes applied on a measuring chamber side of the wall. The mutually insulated electrodes include a central circular electrode and a group of electrode segments arranged in circular fashion around the central electrode. Inhomogeneities in the radiation intensity of a beam being analyzed are detected by unequal currents in the central electrode relative to surrounding electrode segments or in the electrode segments themselves relative to each other