PROBLEM TO BE SOLVED: To provide an energy degrader capable of mitigating the reduction in the transmittance of low-energy charged particle beams, and a charged particle beam irradiation system equipped therewith.SOLUTION: The energy degrader includes a plurality of attenuation members 11A-11G with differing magnitudes of energy attenuation, and the low-energy-side attenuation member 11G with a high magnitude of energy attenuation is formed from material that has a transmittance exceeding that of the high-energy-side attenuation member 11A with a low magnitude of energy attenuation.COPYRIGHT: (C)2013,JPO&INPIT【課題】エネルギーが低い方の荷電粒子線の透過率の低下を緩和することが可能なエネルギーデグレーダ及びそれを備えた荷電粒子線照射システムを提供すること。【解決手段】エネルギーの減衰量が異なる複数の減衰部材11A~11Gを備え、エネルギー減衰量が大きい方の低エネルギー側減衰部材11Gを、エネルギー減衰量が小さい方の高エネルギー側減衰部材11Aよりも透過率が高い材質から形成する。【選択図】図2
