Construction of a booster linac for the RIKEN heavy-ion linac

Abstract

A linac consisting of six rf cavities has been constructed as an energy booster of the RIKEN heavy-ion linac. Various heavy ion beams have been accelerated to 5.8MeV∕u with intensities of more than 1pμA (particle microampere) in the continuous-wave mode. The booster cavities are based on a quarter-wavelength resonator of a coaxial structure. The first two cavities are frequency-variable in a range from 36to76.4MHz, whereas the last four are operated at a fixed frequency of 75.5MHz. The design study started in 1997 and the booster was commissioned in 2001. The total voltage gain of the booster ever achieved is 11MV, which is 70% of the designed value of 16MV. The high-intensity beams from the booster have been successfully applied to a systematic study on the synthesis of superheavy elements. The beam energy from the ring cyclotron has also been increased, owing to the additional velocity gain provided by the booster.

Experiments on searching for the heaviest elements

“…Ion source used is a 18GHz ECR Ion Source [12]. [12], RFQ-Linac [14], Original Linac [13], Booster ?Linac CSM [15], and a gas-filled recoil ion separator GARIS are shown.…”

“…The accelerator consists of three Linac, a frequency tunable RFQ-Linac [14], the original heavy ion Linac [13], and a booster Linac (CSM) [15]. A gas-filled recoil ion separator GARIS is used as a recoil separator.…”

Facility upgrade for superheavy-element research at RIKEN

“…Element Nh was synthesized by bombarding a Bi target with a Zn beam having an intensity of 0.5 p A 2 and an energy of 352.6 MeV (5.04 MeV/ u ) [ 3 ]. The energy was increased from 2.9 MeV/ u to 5.5 MeV/ u by adding a booster linac called charge-state-multiplier (CSM) system [ 22 ] comprising six DTLs.…”

Charge-state distribution ofU238in nitrogen gas and carbon foil at 14 and15 MeV/nucleon

“…The experiments were performed at the RIKEN RIBF by accelerating the uranium beams through the RIKEN heavy ion linac (RILAC) [6], booster linac [7], and RIKEN ring cyclotron (RRC) [8,9], as shown schematically in Fig. 1.…”