Direct injection of fully stripped carbon ions into a fast-cycling induction synchrotron and their capture by the barrier bucket

N Munemoto,M Wake,K Takayama,T Kawakubo,Taufik Taufik,S Takano,E Kadokura,T Adachi,K Okamura,M Ikeda,X Liu,T Yoshimoto

doi:10.1103/physrevaccelbeams.20.080101

Abstract

Fully stripped carbon ions generated in a laser-ablation ion source are directly injected into a small-scale induction synchrotron. Carbon-ion beams of ${\mathrm{C}}^{6+}$, ${\mathrm{C}}^{5+}$, and ${\mathrm{C}}^{4+}$ are trapped in the barrier bucket. Beam properties, such as the momentum spread and beam lifetime in the low-energy ring, are measured and discussed in relation to the essential characteristics required in a carbon driver for future carbon therapies.

Highlights

Energy sweep extraction in a single acceleration cycle from a fast-cycling synchrotron has been proposed [1], where a fast-cycling induction synchrotron requiring no large-scale injector is used as a driver and a beam is continuously extracted by a new beam-handling method to allow continuous beam-spill loss from the barrier bucket
A fully stripped carbon-ion beam produced by the laser-ablation ion source (LAIS) was directly injected into the fast-cycling induction synchrotron called the KEK Digital Accelerator (DA) and captured by the barrier bucket for its lifetime, which is determined by electron capture caused by the interaction with residual atoms and molecules
The laser irradiation chamber is embedded in the high-voltage platform (HVP) of the core body of the LAIS, which accommodated the electron cyclotron resonance ion source (ECRIS) until 2015

Summary

INTRODUCTION

Energy sweep extraction in a single acceleration cycle from a fast-cycling synchrotron has been proposed [1], where a fast-cycling induction synchrotron requiring no large-scale injector is used as a driver and a beam is continuously extracted by a new beam-handling method to allow continuous beam-spill loss from the barrier bucket. Okamura and colleagues produced a C6þ beam of several tens of milliamps in their LAIS driven by a medium-energy CO2 laser (4 J) [7] and attempted immediate acceleration of a carbon-ion beam by an RFQ without charge separation. Based on these studies, research has begun on practical application of these carbon-ion beams in particle cancer therapy at various institutes, including in the private sector [8]. Some beam properties of the injected C4þ, C5þ, and C6þ beams are determined

Outline

LAIS and carbon ions

KEK-DA

Free run

BEAM LIFETIME

SUMMARY AND FUTURE PROSPECTS