A device operable to accelerate a particle beam to an energy for irradiating a target volume. The device includes a particle accelerator operable in a first working phase in which particles of the particle beam are accelerated to the energy and a second working phase in which the particles of the particle beam are provided and extracted for irradiating the target volume. The device further includes a control device operable to interrupt an irradiation of the target volume if the target volume assumes a predetermined state. The control device is also operable to control the particle accelerator as a function of a comparison between a residual particle number stored in the accelerator and a reference value.
