| 主权项 |
1. A method for adjusting the position of a main coil assembly in a cyclotron with respect to a reference plane, said method comprising the steps of:
a) providing a cyclotron designed for accelerating charged particles in a particle acceleration region of a median plane of the cyclotron, said cyclotron comprising a main coil assembly designed to generate a main magnetic field ({right arrow over (B)}) for bending a trajectory of the charged particles in the acceleration region and first positioning means which are adapted to adjust a position of said main coil assembly with respect to said median plane; b) applying power to the main coil assembly; c) determining a first position (P1), at a first azimuth in the median plane and outside the particle acceleration region, at which the magnitude (Bv) of an axial component ({right arrow over (Bv)}) of the main magnetic field perpendicular to the median plane is smaller than 25% of a maximum magnitude (Bv_max) of the axial component of the main magnetic field at said first azimuth; d) placing a magnetic field sensor at the first position (P1) and orienting it in order to detect a radial component ({right arrow over (Bh)}) of the main magnetic field parallel to the median plane; e) measuring the magnitude of said radial component of the main magnetic field with the magnetic field sensor, thereby yielding a first measured value Bh1; and f) adjusting the position of the main coil assembly with respect to the median plane by using the first positioning means so as to reduce the absolute value of Bh1. |
