Patent Number: 
Section: claims

1. A laser-driven particle beam irradiation apparatus comprising:a particle beam generator irradiating a target with pulsed laser light to emit a laser-driven particle ray;a beam converging unit forming a transportation path which guides the emitted laser-driven particle ray to an object to be irradiated and spatially converging the laser-driven particle ray;an energy selector selecting an energy and an energy width of the laser-driven particle ray;an irradiation port causing the laser-driven particle ray to scan the object to be irradiated to adjust an irradiation position in the object; andan irradiation controller controlling operation of the particle beam generator, the beam converging unit, the energy selector, and the irradiation port, whereinthe beam converging unit generates a magnetic field on a trajectory of the laser-driven particle ray and converging the laser-driven particle ray by the magnetic field, the magnetic field forcing divergence components of the laser-driven particle ray that go away from a center of the trajectory back to the center of the trajectory, andthe beam converging unit is provided between the particle beam generator and the energy selector. 2. A laser-driven particle beam irradiation apparatus comprising:a particle beam generator irradiating a target with pulsed laser light to emit a laser-driven particle ray;a beam converging unit forming a transportation path which guides the emitted laser-driven particle ray to an object to be irradiated and spatially converging the laser-driven particle ray;an energy selector selecting an energy and an energy width of the laser-driven particle ray;an irradiation port causing the laser-driven particle ray to scan the object to be irradiated to adjust an irradiation position in the object;an irradiation controller controlling operation of the particle beam generator, the beam converging unit, the energy selector, and the irradiation port; andan energy distribution converging unit forming the transportation path of the laser-driven particle ray and converging an energy distribution of the laser-driven particle ray through the transportation path to provide a peak at a particular energy, whereinthe beam converging unit generates a magnetic field on a trajectory of the laser-driven particle ray and converging the laser-driven particle ray by the magnetic field, the magnetic field forcing divergence components of the laser-driven particle ray that go away from a center of the trajectory back to the center of the trajectory, andthe energy distribution converging unit includes a phase rotation cavity unit forming a transportation path of the laser-driven particle ray and, under application of a high-frequency voltage, generating in the transportation path a high-frequency electric field in which a state in which protons in a bunch are accelerated and a state in which protons in a bunch are decelerated appear to converge the energy distribution of the laser-driven proton ray to a particular energy, and wherein the irradiation controller adjusts the phase of the high-frequency voltage to be applied to the phase rotation cavity unit to adjust the position of the energy peak of the energy distribution of the laser-driven particle ray. 3. The laser-driven particle beam irradiation apparatus according to claim 2, wherein the phase rotation cavity unit of the energy distribution converging unit includes an outer cavity forming the transportation path of the laser-driven particle ray and a plurality of inner cavities which are spaced in a row in the outer cavity and to which a high-frequency voltage is applied, wherein a high-frequency electric field is formed in a gap between adjacent inner cavities to converge the energy distribution of a proton beam around the energy of protons that enter the gap at a timing of being synchronized with the phase of the high-frequency voltage applied to the inner cavities among the protons in a bunch in the outer cavity. 4. The laser-driven particle beam irradiation apparatus according to claim 3, wherein the irradiation controller applies a pulse width compressing voltage to the inner cavities of the energy distribution converging unit to generate a high-frequency electric field in the gap between adjacent inner cavities, the pulse width compressing voltage being defined as  V  >                              E          0                ⁢                  β          0          2                ⁢                  γ          0          2                    q        ·                            1          -                                    m              2                        ⁢                                          c                4                            /                              E                0                2                                                                                      1            -                                          m                2                            ⁢                                                c                  4                                /                                  E                  0                  2                                                                    +                  fL          /          c                    wherein f is the frequency of the high-frequency voltage to be applied to the inner cavities, L is the distance from a laser-driven particle ray emission point in the target to the gap between adjacent inner cavities, β0 and γ0 are Lorentz factors, E0 is the total energy of the laser-driven particle ray, c is the speed of light, m is the mass of the laser-driven-particle ray, and q is the charge of the laser-driven particle ray. 5. A laser-driven particle beam irradiation method, comprising:a particle beam generating step of irradiating a target with pulsed laser light to extract a laser-driven particle ray;a beam converging step of spatially converging the laser-driven particle ray;an energy selecting step of selecting an energy and an energy width of the laser-driven particle ray according to a depth of an irradiation position set in an object to be irradiated;an irradiation step of adjusting the irradiation position of the laser-driven particle ray in the object to be irradiated; anda pulse width compressing step of reducing the pulse width of the laser-driven particle ray,wherein, in the beam converging step, a magnetic field forcing divergence components of the laser-driven particle ray that go away from a center of the trajectory of the laser-driven particle ray back to the center of the trajectory is generated on the trajectory and the laser-driven particle ray is converged by the magnetic field. 6. The laser-driven particle beam irradiation method according to claim 5, wherein, in the pulse width compressing step, a high-frequency electric field induced by a pulse width compressing voltage is generated and the laser-driven particle ray is guided to and passed through the high-frequency electric field to reduce the pulse width of the laser-driven particle ray, the pulse width compressing voltage being defined as  V  >                              E          0                ⁢                  β          0          2                ⁢                  γ          0          2                    q        ·                            1          -                                    m              2                        ⁢                                          c                4                            /                              E                0                2                                                                                      1            -                                          m                2                            ⁢                                                c                  4                                /                                  E                  0                  2                                                                    +                  fL          /          c                    wherein f is the frequency of the high-frequency voltage, L is the distance from a laser-driven particle ray emission point, β0 and γ0 are Lorentz factors, E0 is the total energy of the laser-driven particle ray, c is the speed of light, m is the mass of the laser-driven-particle ray, and q is the charge of the laser-driven particle ray.