Patent ID: 8779375

Claim:
A device for dosimetry monitoring of a hadron beam, comprising n successive ionization chambers i obtained by a stack of n+1 parallel detector plates separated from each other by a gas filled gap, the detector plates having a collecting part comprising a collecting side insulated from a bias voltage part comprising a bias voltage side and arranged in such a way that the collecting side is facing the bias voltage side of a subsequent detector plate or inversely, the detector plates comprising m layers L k of materials, the resulting assembly of these detector plates forming a plurality of ionization chamber cells, the thicknesses I k and the choice of the materials of layer L k constituting the detector plates as well as the gap of an ionization chamber cell i have been selected in order to satisfy the following equation for the ionization chambers i: l gi + [ ∑ k = 1 m ⁢ l k ] i ≈ [ ∑ k = 1 m ⁢ WET k ] i where I gi is the gas filled gap distance between two detector plates; I k is the thickness of the corresponding layer L k of a detector plate; WET k is the water equivalent thickness of the corresponding layer L k of a detector plate; and where the difference between l gi + [ ∑ k = 1 m ⁢ l k ] i ⁢ ⁢ and ⁢ [ ∑ k = 1 m ⁢ WET k ] i is less than or equal to 5%.