U400M accelerator complex – FLEROV LABORATORY of NUCLEAR REACTIONS

U400M isochronous cyclotron had been in operation since 1991. The cyclotron was designed for acceleration of Li to Bi ion beams with A/Z=3÷3.6 at energies of 34÷60 MeV/nucleon and the ones with A/Z=8÷10 at energies of 4.5÷9 MeV/nucleon.
U400M cyclotron delivered ¹¹B, ¹⁵N, ³²S beams to ACCULINNA-1,2 separators, ¹⁸O, ²²Ne to COMBAS setup and ⁴⁰Ar, ⁴⁸Ca to MASHA mass-spectrometer.

Modernization of U400M accelerator complex was started in July 2020 as part of the development of DRIBS-III accelerator complex. The main purpose was to replace the broken-down and obsolete equipment: replacing the main magnet excitation windings, updating the vacuum system, cooling water system and power supply system, creating a new control system and replacing the radiation safety system. High- energy beam extraction system and accelerated beam transportation channels were upgraded as well. Replacing the main magnet excitation coils of U400M cyclotron was the most labour-consuming part of the work.
Within 1 year the old windings were dismantled and a new pair of windings each of which consists of 11 sections was installed. The total mass of one winding is 55 tones.

On completing the installation of the main magnet windings and connecting them to the power source and water cooling system the magnetic measurements were performed.
The output system was also upgraded. A new focusing magnetic channel MK-1 was calculated and manufactured based on the results of magnetic measurements as well as on the results of the analysis of the old output system operation. The new magnetic channel significantly increases the radial beam focusing and also compensates for the vertical beam refocusing that existed previously.

After completing the magnetic measurements the reinstallation of the equipment started. The layout of the vacuum chamber equipment was changed as a part of the installation.

The axial injection system was also changed. DECRIS-2 ion source was replaced by DECRIS-2M. The new source has greater intensity. Accelerated beam transportation channels and experimental setups located in the accelerator hall were installed at the final stage.

The water cooling system was improved, new power supplies, forevacuum equipment, vacuum cryopump compressors, control servers were installed and RF power amplifiers were improved. New power and control cable lines, forevacuum and helium lines for the vacuum system, RF power feeder lines of transportation, water cooling and compressed air supply lines were also installed.

Control system was completely updated. FLNR specialists developed and implemented new control schemes. Software developed. The control system combined both old and new equipment. The system is fully operational and put into operation.

U400M accelerator complex new interlocking and alarm systems and also Automated control system for building 101 were installed, tested and put into operation during the modernization.

Early in May 2024 the accelerator systems were tested offline. Then complex commissioning works with the production of accelerated beams started. The first results were received. After a full range of tests U400M accelerator complex will be put into operation. First experiments are planned for the second half year 2024.