An object of the present invention is to speed up an operation of extracting an ion beam from an accelerator. An accelerator 100 includes an upper magnetic pole 8 and a lower magnetic pole 9 sandwiching an ion circulation space 10 in which ions circulate. At least one of the upper magnetic pole 8 and the lower magnetic pole 9 is formed such that a magnetic pole interval between the upper magnetic pole 8 and the lower magnetic pole 9 varies when the ion circulation space 10 is viewed along an ion beam trajectory. That is, a wide interval region 11 having a larger magnetic pole interval than a peripheral region is formed in a region closer to a center point of the ion circulation space 10 than a center point of the ion beam trajectory.

An object of the present invention is to speed up an operation of extracting an ion beam from an accelerator. An accelerator 100 includes an upper magnetic pole 8 and a lower magnetic pole 9 sandwiching an ion circulation space 10 in which ions circulate. At least one of the upper magnetic pole 8 and the lower magnetic pole 9 is formed such that a magnetic pole interval between the upper magnetic pole 8 and the lower magnetic pole 9 varies when the ion circulation space 10 is viewed along an ion beam trajectory. That is, a wide interval region 11 having a larger magnetic pole interval than a peripheral region is formed in a region closer to a center point of the ion circulation space 10 than a center point of the ion beam trajectory.

An irradiation method and system for irradiating a target volume, the method comprising: providing thermal neutron absorbing nuclides (such as in the form of a high neutron cross-section agent) at the target volume; and producing neutrons by irradiating nuclei in or adjacent to the target volume with a beam of particles consisting of any one or more of protons, deuterons, tritons and heavy ions, thereby prompting production of the neutrons through non-elastic collisions between the atoms in the path of the beam (including the target) and the particles. The neutron absorbing nuclides absorb neutrons produced in the non-elastic collisions, thereby producing capture products or fragments that irradiate the target volume.

An irradiation method and system for irradiating a target volume, the method comprising: providing thermal neutron absorbing nuclides (such as in the form of a high neutron cross-section agent) at the target volume; and producing neutrons by irradiating nuclei in or adjacent to the target volume with a beam of particles consisting of any one or more of protons, deuterons, tritons and heavy ions, thereby prompting production of the neutrons through non-elastic collisions between the atoms in the path of the beam (including the target) and the particles. The neutron absorbing nuclides absorb neutrons produced in the non-elastic collisions, thereby producing capture products or fragments that irradiate the target volume.

An accelerator capable of efficiently and satisfactorily extracting a beam is provided. A main magnet A101 applies a main magnetic field to a space between a plurality of main magnetic poles M202 arranged to face each other. An RF kicker M204 causes a beam circulating in a main magnetic field region to which the main magnetic field is applied to be displaced to outside of the main magnetic field region. An extraction channel magnetic field to extract the beam is generated. A canceling magnetic field generation device M214 is provided to be closer to an inner peripheral side than an extraction channel M207 and generates a canceling magnetic field with a polarity opposite to that of a disturbance magnetic field produced by an extraction channel.

An accelerator capable of efficiently and satisfactorily extracting a beam is provided. A main magnet A101 applies a main magnetic field to a space between a plurality of main magnetic poles M202 arranged to face each other. An RF kicker M204 causes a beam circulating in a main magnetic field region to which the main magnetic field is applied to be displaced to outside of the main magnetic field region. An extraction channel magnetic field to extract the beam is generated. A canceling magnetic field generation device M214 is provided to be closer to an inner peripheral side than an extraction channel M207 and generates a canceling magnetic field with a polarity opposite to that of a disturbance magnetic field produced by an extraction channel.

To provide a circular accelerator capable of detecting the position of a circulating charged particle beam and a particle beam therapy system including the circular accelerator. A circular accelerator (39) configured to apply a first radio frequency to a circling charged particle beam to accelerate the charged particle beam, the circular accelerator including: an electrode (12), (13) configured to apply the first radio frequency to the charged particle beam; and a beam position monitor (16) provided in the electrode and configured to detect a position of the charged particle beam.

To provide a circular accelerator capable of detecting the position of a circulating charged particle beam and a particle beam therapy system including the circular accelerator. A circular accelerator (39) configured to apply a first radio frequency to a circling charged particle beam to accelerate the charged particle beam, the circular accelerator including: an electrode (12), (13) configured to apply the first radio frequency to the charged particle beam; and a beam position monitor (16) provided in the electrode and configured to detect a position of the charged particle beam.