Tanuja Dixit

All-ion accelerators: An injector-free synchrotron

A medium-energy synchrotron capable of accelerating all-ion species is proposed. The accelerator employs a strong focusing lattice for ion-beam guiding and induction acceleration for acceleration and longitudinal capture, which is driven by a switching power supply. All ions, including cluster ions in their possible and arbitrary charge state, are accelerated in a single accelerator. Since the switching power supply employing solid-state switching elements is energized by a trigger signal, which is generated from a bunch monitor signal produced by a circulating ion bunch, the induction acceleration always synchronizes with the bunch circulation. This feature enables the realization of an almost injector-free synchrotron.

A Compact Hadron Driver for Cancer Therapies with Continuous Energy Sweep Scanning

The compact hadron driver for future cancer therapies based on the induction synchrotron concept, which has been proposed recently, is discussed. This is a fast cycling synchrotron that allows the energy sweep beam scanning. Assuming a 1.5 T bending magnet, the ring can deliver heavy ions of 200 MeV/au 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 enough large for the fraction to fall in the electrostatic septum extraction gap, which is placed at the large D(s) region. The programmed energy sweeping extraction makes spot scanning beam irradiation on a cancer area in depth possible.

Adiabatic damping during acceleration in the Induction Synchrotron

It was observed that a bunch-length shrunk with acceleration in the Induction Synchrotron (IS) experiment, where a single proton-bunch injected from the 500 MeV Booster was accelerated to 6 GeV in the KEK-PS. A novel technique capable of quantitatively predicting the adiabatic phenomenon of bunch shortening has been developed, based on a hypothesis that the particle oscillation amplitude varies inversely proportional to the square root of its oscillation frequency. The experimental result and analytical prediction is in good agreement with each other.

Acceleration scheme of the AIA and its control system

Acceleration scheme of All Ion Accelerator (AIA), one of the active applications of Induction Synchrotron (IS) is proposed with its beam simulation analysis. The KEK 500 MeV booster is going to be modified to KEK-AIA. Trigger system of the accelerator is described. A new type of acceleration cell for KEK-AIA is described.

Status of the induction acceleration system

A single proton bunch confined by the barrier voltage was accelerated by the induction step-voltage from 500MeV to 6GeV at the KEK 12-GeV proton synchrotron in March 2006. Various technical issues in the induction acceleration system, which have been faced in actual operation, are summarized.

A modification plan of the KEK 500MEV booster to an all-ion accelerators (An injector-free synchrotron)

A medium-energy synchrotron capable of accelerating all ion species based on a novel technology of the induction synchrotron has been proposed as an all-ion accelerator (AIA). The AIA without any specific injector employs a strong focusing lattice for ion-beam guiding and induction acceleration cells for acceleration and longitudinal capture, which are driven by a novel switching power supply. All ions, including cluster ions in their possible and arbitrary charge state, are accelerated in a single accelerator. A plan to modify the existing KEK 500 MeV Booster synchrotron to the AIA is under consideration. Important aspects in a 200 kV ion source, and specific features in the orbit correction associated with the low-field injection and induction acceleration, are described.