Masamitsu Aiba

FFAGS for muon acceleration

Due to their finite lifetime, muons must be accelerated very rapidly. It is challenging to make the magnets ramp fast enough to accelerate in a synchrotron, and accelerating in a linac is very expensive. One can use a recirculating accelerator (like CEBAF), but one needs a different arc for each turn, and this limits the number of turns one can use to accelerate, and therefore requires significant amounts of RF to achieve the desired energy gain. An alternative method for muon acceleration is using a fixed field alternating gradient (FFAG) accelerator. Such an accelerator has a very large energy acceptance (a factor of two or three), allowing one to use the same arc with a magnetic field that is constant over time. Thus, one can in principle make as many turns as one can tolerate due to muon decay, therefore reducing the RF cost without increasing the arc cost. This paper reviews the current status of research into the design of FFAGs for muon acceleration. Several current designs are described and compared. General design considerations are also discussed

Recent beam studies of the PoP FFAG proton synchrotron

The PoP (Proof of Principle) FFAG accelerator, which was the world first FFAG proton synchrotron, was constructed at KEK. After the first proton beam acceleration of FFAG, we studied various aspects of the PoP FFAG. The observed beam orbit shift during the acceleration was consistent with the simulation result. It was confirmed that the beam intensity increased about five times with multi-bunch injection. The horizontal acceptance of the PoP FFAG was estimated at about 4000 /spl pi/ mm.mrad experimentally.

Status of 150MeV FFAG synchrotron

The 150 MeV proton FFAG (fixed field alternating gradient) synchrotron has been developed for aiming to investigate the possibilities of various applications such as proton beam therapy. The construction started in September 2002, and almost completed recently. In the proceedings, the overview of construction and status of commissioning is to be reviewed

Development of FFAG Accelerator at KEK

The 150MeV proton FFAG accelerator is constructed and a beam is extracted at the final energy. This is the prototype FFAG for various applications such as proton beam therapy. We are now in preparation for using an extracted beam in the practical applications.

Beam extraction of the PoP FFAG with a massless septum

We propose a new extraction scheme with a massless septum magnet in FFAG accelerator, with which the DC beam can be extracted. The system consists of a combination of massless and ordinary septa without kickers. After passing through the massless septum, the beam tail is stretched by the field gradient of the massless septum magnet, and that can be extracted with an ordinary septum. From the result of the tracking simulation, the principle of the extraction scheme is verified. The result of the performance test of the massless septum indicates that the magnet works well as designed, and this scheme is feasible.

Beam Dynamics of FFAG Accelerator

Beam dynamics of FFAG Accelerator is described, focusing on the non‐linearity. The tracking simulations were performed, in order to understand the non‐linear motion in the guiding field of FFAG accelerator.

Acceptance survey of FFAG accelerators for the neutrino factory

Abstract A study of the acceptance of FFAG accelerators was carried out for the FFAG-based neutrino factory. Through the study, the basic parameters of 1 GeV /c ring, which is the first ring cascaded to accelerate muon beam up to 20 GeV /c , was optimized to have the large transverse acceptance of an order of 10,000π mm mrad .