Nuclotron

The nuclotron is a superconducting synchrotron particle accelerator with 251.5 m circumference at the Joint Institute for Nuclear Research in Dubna.

History

In 1973 a first proposal for the construction of a superconducting 20 GeV synchrotron was argued that goal was the replacement of the Synchrophasotrons. In the following years, attempts have been made with different superconducting magnet. Due to a tight financial budget, the magnets were designed for a maximum proton energy of 6 GeV. The plan was approved in December 1986. As a test system for a synchrotron in the new design with superconducting magnet, a 1.5 GeV synchrotron with the name " SPIN " was built.

The nuclotron was built in the years 1987-1992 in a tunnel 3.7 m below the Synchrophasotrons. In March 1992, the nuclotron first went into operation, first physical experiments with a built- target were carried out in 1994. A common pre-accelerator supplied the synchrophasotron and nuclotron.

In 1999, the nuclotron was expanded with a beam extraction unit, so from March 2000 experiments outside of the ring were possible.

In order to increase the beam intensity by a factor of 10-15 since the year began in 1996 plans to build a booster.

The operation of the Nuclotrons is mainly limited by financial constraints.

Technology

In nuclotron are ions of the atomic number 1 to 36, so hydrogen and krypton has been accelerated. The highest energy in the internal beam of 4.2 GeV per nucleon, in the deflected beam 2.2 GeV per nucleon. The cross-section of the jet pipe is 110x55 mm.

The electromagnets of Nuclotrons have iron cores that are completely inside the cryostat. The coils are made of niobium-titanium wires. At the maximum flux density of the dipole of 2 Tesla flows through the series-connected, a current of 6300 amperes magnets. The inductance of the coil and thus the stored energy in the magnets is relatively low, whereby rapid changes in magnetic field of up to 4 T / s are possible. The relatively low field strength of the magnets facilitated their preparation.

The nuclotron itself uses superconducting magnets, but the magnets are attached to the transfer lines to the experimental stations normally conductive, they need about half of the energy needs of the plant. Therefore, there are considerations to replace these magnets by superconducting versions.

For cooling the superconductor, a cooling system is used with a closed helium circuit. In addition, however, larger amounts of liquid nitrogen are needed. To begin operation, continuous operation of the Nuclotrons was only possible as long as the stocks of liquid nitrogen ranged; were consumed between 12 and 15 tons of liquid nitrogen. Only after a reconstruction of the helium cooling systems of consumption could be lowered so that the production capacity of the Institute for continuous operation sufficient. The cooling of the Nuclotrons to be needed for the operation of the superconducting magnets temperature of 4.5 Kelvin takes about 100 hours.