Department of Accelerators
The main research activities are focused on simulations of beam dynamic parameters during accelaration and extraction process and on the development and design of target systems for various type of irradiations and experiments. Department has a three accelerators: cyclotrons TR-24 and U120M, and Microtron MT-25, which is located in Prague, outside Řež area.
In 2015, after a successful installation, the new Cyclotron TR-24 of the Canadian company ACSI (Advanced Cyclotron Systems Inc.) was commissioned.
This cyclotron provides proton beams with energies from 18 MeV to 24 MeV. It is equipped with an axial injection system with an external ion source of the CUSP type, which significantly increases the reachable current of the accelerated beams (up to 300 μA).
The cyclotron is operated in the acceleration mode of the negative ions H─ which are converted to the protons and extracted by means of a thin carbon foil. The required extracted proton energy can be tuned by the radial position of the stripping foil over the full energy range. The accelerated beam can be extracted simultaneously to two irradiation sites. One output with three target positions is located directly on the cyclotron vacuum chamber. The second beam output is connected with an ionto-optical beamline that allows the transport, focusing, and beam diagnostics. At the end of the beam line, there is a switching magnet which can distribute the beam into the three separate target positions. This arrangement allows installation and flexible use of up to eight different targets. The vacuum system, which is permanently in operation, is formed besides necessary forvacuum aggregates by two turbomolecular pumps and two cryopumps.
The range of energies, high currents of accelerated particles and generation of secondary neutron fluxes opens up the possibility to perform a variety of physical experiments and applications including preparation of a wide range of radionuclides for radiopharmaceutical research.
Within the frame of the project CANAM OP the high power neutron converter via reaction p(24MeV) + Be is being developed. This generator will provide a neutron field density of 1012 n.cm−2.s−1.
In cooperation with Department of Radiopharmaceuticals, implementation of the new targets including high-power ones for production of novel medical radionuclides for diagnostics and therapy is carried out.
Parameters of cyclotron TR-24:
|TR 24 – Advanced Cyclotron System Inc. (Canada)|
|Protons energy range||18-24 MeV|
|Max. beam current||300 µA|
|Accelerating frequency||85 MHz|
|Accelerating voltage||50 kV|
|Power consumption||180 kW|
|Average magnetic field||1,4 T|
Isochronous cyclotron U-120M provides beams of accelerated ions (p, H─, D+ , D─, 3He2+, 4He2+). It was designed and manufactured at JINR Dubna (the former USSR) for operation in positive regimes only. It was commissioned in 1977 and since that time it has been successfully operated and systematically upgraded solely by specialists and technicians from Department of Accelerators. The key upgrade was its conversion into negative ion accelerator completed in the years 1996–1998 that resulted in increase of extracted beam currents by one order. Nowadays, the U-120M is a multipurpose multiparticle accelerator which can be tuned according to the type of particles and the use (internal/ external beam) in a wide range of energies (1–55 MeV). Accelerated beams with currents from a few nA up to tens of µA are extensively used for a wide range of experiments in basic and applied research. In connection with target stations developed at the Department of Nuclear Reactions the cyclotron is a unique and powerful source of high-intense fast neutron beams.
U-120M was originally designed as an accelerator of light positive ions (A/Z = 1–2.8) with the maximum energy up to tens of MeV (K = 40). Since the early 1990s, the cyclotron has undergone major upgrade in terms of acceleration of negative ions H−, D− in order to increase external beam intensities. An extensive modernization and replacement of almost all flooded cyclotron subsystems was realized after floods in 2002.
The cyclotron is routinely operated in positive and negative modes. Positive ions (H+, D+, 3He+2, 4He+2) are extracted from the cyclotron by means of three sections electrostatic deflection system with a magnetic kicker. Negative ions H-, D- are extracted by a stripping method using a thin carbon foil.
Parameters of accelerated and extracted beams are as follows:
|Ions||Energy [MeV]||Max. current [μA]|
|H+||Internal beam||1 - 37||> 200|
|H+||External beam||6 - 25||5|
|H−/H+||External beam||6 - 37||50 - 30|
|D+||Internal beam||2 - 20||> 80|
|D+||External beam||12 - 20||5|
|D-/D+||External beam||11 - 20||35 - 20|
|3He+2||Internal beam||3 - 55||20|
|3He+2||External beam||18 - 52||2|
|4He+2 (α)||Internal beam||4 - 40||40|
|4He+2 (α)||External beam||24 - 38||5|
The cyclotron is equipped with a beam line system for the transport of the accelerated and extracted ions to the experimental and target facilities. This system includes also short beam line for the ions extracted from negative regimes. As a research facility, the cyclotron serves for experiments in nuclear astrophysics (indirect metods), enables the detailed study of nuclear reactions and it is a data source for development of new international experimental facilities. Together with the unique target stations, the cyclotron is a powerful generator of fast neutron fluxes. Due to wide range of energies and variety of accelarated particles the cyclotron is effective tool for nuclear data measurements and production of radionuclides for research.
Moreover, accelerated ion beams can be adapted for other applications like irradiations of various samples and materials under vacuum or on the air after beam extraction through vacuum window (i.e. irradiation of biological samples, radiation rezistence tests of semicontrolled devices etc.).
The microtron is a cyclic accelerator of relativistic electron with a possibility of conversion primary electron beam to secondary photon beam and neutrons. Microtron MT-25 is located in Karlin Tunnel in Prague outside Řež area.
|Maximum energy||25 MeV|
|Energy range||6 - 25 MeV|
|Electron current||25 μA|
|High frequency source|
|Tunable magnetron||2 790 ± 5 MHz|
|Peak power||3 MW|
|Pulse lenght||3 μs|
|Repetition rate||425 s−1|
|Resonator freq.||2 796 MHz|
|Power supply freq.||50 Hz|