The lattice of a Fixed Field Alternating Gradient (FFAG) accelerator normally has high symmetry. The whole ring consists of many identical cells which can be a simple FODO, doublet or triplet focusing unit. There is, however, no real reason for an FFAG lattice to have high symmetry, except for a linear nonscaling design which relies on high symmetry to avoid betatron resonances. We propose an FFAG lattice design with a superperiod that makes it possible to have long straight sections for injection, extraction and rf cavities. We discuss how to introduce a superperiod structure. The impact on dynamic aperture as well as the advantage of having long straight sections is presented.
The next generation of lepton flavour violation experiments will use high intensity and high quality muon beams. Such beams can be produced by sending a short proton pulse to the pion production target, capturing pions and performing RF phase rotation on the resulting muon beam in an FFAG ring, which was proposed for the PRISM project. A PRISM task force was created to address the accelerator and detector issues that need to be solved in order to realise the PRISM experiment. The parameters of the initial proton beam required and the PRISM experiment are reviewed. Alternative designs of the PRISM FFAG ring are presented and compared with the reference design. The ring injection/extraction system, matching with the solenoid channel and progress on the ring’s main hardware systems like RF and kicker magnet are discussed. The progress and future directions of the study are presented in this paper.
We present the case of a 50-year-old man who developed a delayed progressive swelling over the medial aspect of his right thigh, six weeks following minimally invasive plate osteosynthesis (MIPO) of a supracondylar femur fracture. Angiography showed a false aneurysm of the superficial femoral artery, caused by progressive displacement of a butterfly fragment. Open vascular repair was performed and the sharp edge of the butterfly fragment was removed.