The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides work on the parameters of a 3-4 and 0.5 TeV center-of-mass (COM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (COM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from 1098-4402͞99͞2(8)͞081001(73)$15.00 © 1999 The American Physical Society 081001-1 PRST-AB 2 CHARLES M. ANKENBRANDT et al. 081001 (1999) a heavy-Z target and proceeding through the phase rotation and decay (p ! m n m ) channel, muon cooling, acceleration, storage in a collider ring, and the collider detector. We also present theoretical and experimental R&D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the research and development since the feasibility study of muon colliders presented at the Snowmass '96

The term beta-beam has been coined for the production of a pure beam of electron neutrinos or their antiparticles through the decay of radioactive ions circulating in a storage ring. This concept requires radioactive ions to be accelerated to a Lorentz gamma of 150 for 6 He and 60 for 18 Ne. The neutrino source itself consists of a storage ring for this energy range, with long straight sections in line with the experiment(s). Such a decay ring does not exist at CERN today, nor does a high-intensity proton source for the production of the radioactive ions. Nevertheless, the existing CERN accelerator infrastructure could be used as this would still represent an important saving for a betabeam facility. This paper outlines the first study, while some of the more speculative ideas will need further investigations.

We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end. We summarize the physics that can be done with neutrino factories as well as with intense cold beams of muons. The physics potential of muon colliders is reviewed, both as Higgs factories and compact highenergy lepton colliders. The status and time scale of our research and development effort is reviewed as well as the latest designs in cooling channels including the promise of ring coolers in achieving longitudinal and transverse cooling simultaneously. We detail the efforts being made to mount an international cooling experiment to demonstrate the ionization cooling of muons.

The recombination, transfer and injection of the four beams from the PS Booster to the PS Main Ring, have a high level of intricacy and are a subject of permanent concern for the operation of the PS Injector Complex. These tasks were thus selected as a test bench for the implementation of a prototype of an automatic beam steering system. The core of the system is based on a generic trajectory optimizer, robust enough to cope with imperfect observations. The algorithmic engine is connected to pickup monitors and corrector magnets and its decision can be validated by the operator through a graphics user interface. Automatic beam steering can only be ef®cient if the beam optics is fully con®rmed by experimental observations, a condition which forces the systematic elimination of errors both in hardware and software.

The CERN baseline scenario for a Neutrino Factory comprises accumulation and compression of the beam delivered by a 2.2 GeV kinetic energy H − linac, to provide the time structure needed on the target. Originally, accumulation and bunch compression in one single ring was envisaged. To limit the RF voltage necessary for bunch rotation, quasi-isochronous lattices were studied. The low transition energy together with the long circumference, either leads to large dispersion or necessitates the addition of bending magnets with negative deflection angle. Several solutions for quasi-isochronous lattices were investigated. Finally, the quasi-isochronous lattices were abandoned, and a solution has been chosen with two separate rings, one for accumulation and the other for bunch-compression, and conventional lattices working far below transition. CERN PS Division, 1211 Geneva 23, SwitzerlandAbstract. The CERN baseline scenario for a Neutrino Factory comprises accumulation and compression of the beam delivered by a 2.2 GeV kinetic energy H − linac, to provide the time structure needed on the target. Originally, accumulation and bunch compression in one single ring was envisaged. To limit the RF voltage necessary for bunch rotation, quasi-isochronous lattices were studied. The low transition energy together with the long circumference, either leads to large dispersion or necessitates the addition of bending magnets with negative deflection angle. Several solutions for quasi-isochronous lattices were investigated. Finally, the quasi-isochronous lattices were abandoned, and a solution has been chosen with two separate rings, one for accumulation and the other for bunch-compression, and conventional lattices working far below transition.