Charge stripping ofU238ion beam by helium gas stripper

Abstract

Development of a nondestructive, efficient electric-charge-stripping method is a key requirement for next-generation high-intensity heavy-ion accelerators such as the RIKEN Radioactive-Isotope Beam Factory. A charge stripper employing a low-Z gas is an important candidate applicable to high-intensity uranium beams for replacing carbon-foil strippers. In this study, a high-beam-transmission chargestripping system employing helium gas for 238 U beams injected at 10:8 MeV=u was developed and demonstrated for the first time. The charge-state evolution measured using helium in a thickness range of 0:24-1:83 mg=cm 2 is compared with theoretical predictions. Energy attenuation and energy spread due to the helium stripper are also investigated.

Charge state distribution ofKr86in hydrogen and helium gas charge strippers at2.7 MeV/nucleo

“…11(a). It is known as the shell effect, first observed by Moak et al [45], and also observed in the case of uranium stripping [34]. This discrepancy is caused by the difficulty of ionizing from the L shell of the Kr ion.…”

“…We constructed a prototype of a windowless gas charge stripping system in a beam line based on the basic design of the differential pumping system [34,39,40]. Figures 3 and 4 show the overview of the beam line and its detailed diagram, respectively.…”

“…A datum of the equilibrium charge state of uranium (U) in He gas is indicated by the solid diamond at 10.8 MeV=nucleon in Fig. 2(b) [34]. The Q eq data of U in heavier gases with Z ≥ 7 are indicated by open diamonds [16,18,19,22,[35][36][37] along with the plot of the semi-empirical formula (long-dashed line) [36].…”

“…Recently, charge strippers using gases with small atomic numbers (low-Z) such as hydrogen (H 2 ) or helium (He) have been found to provide considerably higher charge states among gases [34,38]. A datum of the equilibrium charge state of uranium (U) in He gas is indicated by the solid diamond at 10.8 MeV=nucleon in Fig.…”

Total projectile electron loss cross sections ofU28+ions in collisions with gaseous targets ranging from hydrogen to krypton

“…Besides basic research, the investigation of these processes is also motivated by their paramount importance for many applications, such as ion stripping and beam transport in accelerators and storage rings [1][2][3] as well as ion-driven fusion devices [4][5][6]. Essential here is that interactions between projectile ions and constituents of the residual gas can lead to a change of the projectile charge state.…”