Dr Suzie Sheehy

Abstract:

Fixed Field Alternating Gradient accelerators have been realised in recent decades thanks partly to computational power, enabling detailed design and simulation prior to construction. We review the specific challenges of these machines and the range of different codes used to model them including ZGOUBI, OPAL, SCODE and a number of inhouse codes from different institutes. The current status of benchmarking between codes is presented and compared to the results of recent characterisation experiments with a 150 MeV FFAG at KURRI in Japan. Finally, we outline plans toward ever more realistic simulations including space charge, material interactions and more detailed models of various components.

Abstract:

Experiments on EMMA have shown that with rapid acceleration a linear non-scaling FFAG can accelerate through several integer tunes without detrimental effects on the beam [1]. Proton and ion applications such as hadron therapy will necessarily have a slower acceleration rate, so their feasibility depends on how harmful resonance crossing is in this regime. A simple and useful tool to answer such fundamental questions is the Simulator of Particle Orbit Dynamics (S-POD) linear Paul trap (LPT) at Hiroshima University, which can be set up to simulate the dynamics of a beam in an FFAG. We report here results of experiments to explore different resonance crossing speeds, quantify beam loss and study nonlinear effects. We also discuss the implications of these experimental results in terms of limits on acceptable acceleration rates and alignment errors.

Abstract:

In a linear non-scaling FFAG the betatron tunes vary over a wide range during acceleration. This naturally leads to multiple resonance crossing including first order integer resonances. The S-POD (Simulator for Particle Orbit Dynamics) plasma trap apparatus at Hiroshima University represents a physically equivalent system to a charged particle beam travelling in a strong focusing accelerator lattice. The S-POD system can be used as an experimental simulation to investigate the effects of resonance crossing and its dependence on dipole errors, tune crossing speed and other factors. Recent developments and experiments are discussed. Copyright © 2013 by JACoW- cc Creative Commons Attribution 3.0 (CC-BY-3.0).

Abstract:

PIP, the Proton Isotope Production accelerator, is a low energy (6-10 MeV) proton nsFFAG design that uses a simple 4-cell lattice. Low energy reactions involving the creation of specific nuclear states can be used for neutron production and for the manufacture of various medical isotopes. Unfortunately a beam rapidly loses energy in a target and falls below the resonant energy. A recycling ring with a thin internal target enables the particles that did not interact to be re-accelerated and used for subsequent cycles. The increase in emittance due to scattering in the target is partially countered by the re-acceleration, and accommodated by the large acceptance of the nsFFAG. The ring is essentially isochronous, the fields provide strong focussing so that losses are small, the components are simple, and it could be built at low cost with existing technology.