SPES Cyclotron

The Cyclotron of the SPES project is a circular accelerator operating at the LNL laboratories. It was installed and tested in the 2015-2017 three-year period and it has been in operation since 2018.

The cyclotron is able to accelerate H- ions, produced with energy of 40 keV from an external source, to final energies varying from 35 to 70 MeV. The H- ions confined inside the accelerator by a magnetic field of 1.5 tesla and accelerated by two RF cavities to a voltage of 70 kV, once the desired energy is reached, are extracted from the machine by means of the stripping process of the whole electrons. The protons are then transported to target stations by means of beam transport lines. The use of the stripping process in the extraction phase allows for several advantages: it is possible to extract a high amount of current i.e. a large number of charged particles per second, by keeping low the beam losses; it is possible to simultaneously extract the protons in different points of the accelerator and therefore have more beams of charged particles to be transported (two in the case of this cyclotron) and used to irradiate different targets.

The SPES Cyclotron accelerates H- ions up to a maximum average current of 500 µA (35 kW of power at 70 MeV of energy) which can be modulated and divided into two beams of protons extracted at the same energy by two opposite and separate gates. This peculiarity has made it possible to configure the SPES facility in such a way as to maximize the number of target stations that can be reached (up to 8) by the high power proton beams and therefore to be able to exploit the accelerator at the same time for both planned nuclear physics experiments in the SPES project and for applications of different types, including those in the medical field (see LARAMED project).

The Cyclotron service takes care of the development, design and construction of the systems related to the Cyclotron and the transport lines of the high current intensity proton beam; is responsible for the maintenance and management of the Cyclotron and its subsystems, of the transport lines, of the magnetic elements and of the related power supplies. The department pertaining to the service deals with the conduction of the cyclotron and the transport of the high current intensity proton beams.

Main machine parameters
TypeCyclotron with 4 sectors, resistive magnet
ParticlesProtons (H)
Energy30-70 MeV
Current intensity700 µA (range 1 µA – 700 µA)
Maximum magnetic field1.6 T (Bo = 1 T)
RF radio frequency system2 delta cavities; Harmonic mode = 4; fRF = 56 MHz; Peak voltage = 70 kV;
RF power = 50 kW (2 RF amplifiers)
Source of ionsIext =8mA; Vext=40 kV; axial injection
DimensionsΦ=4.5 m, h=2.0 m, mass = 190 tons