Compact hadron driver for cancer therapies using continuous energy sweep scanning

Abstract

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is presented. To realize a slow extraction technique in a fast-cycling synchrotron, which allows energy sweep beam scanning, a zero momentum-dispersion DðsÞ region and a high flat DðsÞ region are necessary. The proposed design meets both requirements. The lattice has two-fold symmetry with a circumference of 52.8 m, a 2-m dispersion-free straight section, and a 3-m-long large flat dispersion straight section. Assuming a 1.5-T bending magnet, the ring can deliver heavy ions (200 MeV=u) at 10 Hz. A beam fraction is dropped from the barrier bucket at the desired timing, and the increasing negative momentum deviation of this beam fraction becomes large enough for the fraction to fall in the electrostatic septum extraction gap, which is placed at the large DðsÞ region. The programmed energy sweep extraction enables scanning beam irradiation on a cancer site in depth without an energy degrader, avoiding the production of secondary particles and the degradation of emittance. Details of the lattice parameters and computer simulations for slow extraction are discussed. An example extraction scenario is presented. Qualities of the spilled beam such as emittance and momentum spread are discussed, as well as necessary functions and parameters required for the extraction system.

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

“…A fully stripped carbon-ion beam delivered from the LAIS and directly injected into the KEK-DA is captured by the barrier bucket, which is expected to be a crucial beamhandling tool for a hadron driver in future cancer therapy [1]. The beam intensity of C 6þ in the current LAIS is still insufficient; however, the momentum spread is extremely small and on the order of 10 −3 , retaining the original momentum spread generated in the LAIS.…”

“…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 ring lattice with a large flat dispersion function has been designed for this technique.…”

Longitudinal splitting of bunches with variable energies in synchrotron

“…Yoshimoto et al have studied rectangular pulse beam splitting operation [1]. In terms of multienergy fast extraction of synchrotrons, Leo Kwee Wah and Takumi Monma et al proposed a continuous energy sweep scanning method [2]. By moving the acceleration voltage, the particles there experience a shortage in the accelerating voltage.…”