Universal linear accelerator

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Original part (single resonator) of the 120 meter long UNILAC in the GSI showroom

UNILAC ( uni versal L inear Ac celerator ) is the name of an accelerator for heavy ions at the GSI for Heavy Ion Research in Darmstadt . The “universal” in the name indicates that the system can accelerate ions of any mass number , from hydrogen to uranium .

With the help of UNILAC, A. for the first time synthesized the elements Bohrium (Bh, 107), Hassium (Hs, 108), Meitnerium (Mt, 109), Darmstadtium (Ds, 110), Roentgenium (Rg, 111) and Copernicium (Cn, 112).

Original structure

The UNILAC went into operation in 1975. He had four different ion sources . The actual accelerator essentially consisted of four consecutive Wideröe accelerators, each 7 m long, which operated at the frequency of 27.12 megahertz (MHz). The beam also passed two Alvarez accelerators, each 12 m long, operated at four times this frequency, i.e. 108.408 MHz, and then followed by 20 individual resonators each with its own power . These can be used to set the desired final energy for beams of different ions. There are also reloading routes ( strippers ) between the individual accelerator parts . These bring the ions to higher states of charge by "stripping" further electrons, so that the amplitude of the subsequent acceleration voltage is better utilized.

Today's structure

After modernization, the UNILAC currently (2016) consists of two ion sources (PIG + MUCIS / MEVVA). This is followed by an RFQ acceleration structure , followed by two IH (Interdigital H-Mode) structures at 36 MHz. These ensure an acceleration to 1.4 MeV / u. A post stripper (which is shot into by the upload injector, also with an RFQ and an IH structure) and four Alvarez structures enable further acceleration to 11.4 MeV / u.

Aside from independent experiments, the UNILAC also serves as an injector for the Synchrotron SIS 12/18 operated at GSI .

literature

• K. Blasche, H. Prange, Die GSI in Darmstadt I, Physikalische Blätter, Volume 33, June 1977, pp. 249-261, online

Web links

• UNILAC, GSI

Individual evidence

1. ↑ HF systems. January 2, 2012, accessed January 17, 2020 .