1. NEUTRINO DETECTORS Cutting-Edge Accelerator Research for a Neutrino Factory and Other Applications Ajit Kurup for the FETS and UKNF Collaborations Cutting-Edge Accelerator Research for a Neutrino Factory and Other Applications Ajit Kurup for the FETS and UKNF Collaborations The Front End Test Stand The Front End Test Stand (FETS) is designed to test the technology required for the first part of a high-power (about 4MW) proton driver. Current proton drivers have only been able to achieve a pulsed power of 0.16MW. Thus, producing a clean, pulsed, high-power beam is a significant challenge. The FETS consists of a high-current ion source, a magnetic solenoid transport channel, a radio frequency quadrupole (RFQ) and a beam chopper. ion source solenoids radio frequency quadrupole beam chopper The RFQ The continuous stream of ions produced by the ion source needs to be converted into a pulsed beam before it can be accelerated. A radio frequency quadrupole (RFQ) is used to first bunch the ion beam and then accelerate it, whilst keeping it focused throughout. The electromagnetic design of the FETS RFQ has been done by the author. A prototype section of this design is currently being manufactured. ++ -- PROTON DRIVER TARGET PHASE ROTATION COOLING LINEAR ACCELERATOR RECIRCULATING LINEAR ACCELERATOR 1 st STAGE FFAG 2 nd STAGE FFAG neutrinos pions muons Aerial photo of the Rutherford Appleton Laboratory overlaid with a schematic of a neutrino factory. Drawing of the Muon Ionisation Cooling Experiment (MICE). This experiment is currently being constructed at the Rutherford Appleton Laboratories, Photograph of the solid target experiments being done by the UKNF collaboration. UKNF Recent observations of neutrino oscillations have shown that neutrinos are not massless, as previously thought. The most promising way to investigate the properties of neutrinos is to build a neutrino factory (NF). An NF is designed to produce a high intensity beam of neutrinos by accelerating and storing a beam of muons, which then decay to neutrinos. The neutrino beam would then be aimed at a detector thousands of kilometres away on the other side of the planet to allow them to oscillate. The muons are produced by firing a high- intensity proton beam at a target. The NF is a very challenging project and it is believed that only one would be built in the world. The UKNF collaboration is playing a leading role in several experiments required to prove the technology needed to build an NF. What are FFAGs? Fixed Field Alternating Gradient (FFAG) particle accelerators were first invented in the 1950’s. However, the behaviour of FFAGs is very complex and understanding this required a lot more computing power than was available at the time. Thus, the FFAG was dropped in favour of the synchrotron which behaved in a much simpler way. So for the next 40 years synchrotrons were the only machines used for accelerating particles to high energies. It was only until physicists started thinking about accelerating muons (a particle that lives for a very short time) that FFAGs where resurrected. The problem with synchrotrons is that the magnetic fields have to be increased as the particle is accelerated but the fields cannot be ramped up quick enough to accelerate muons before they decay. In FFAGs the magnetic field is fixed so the acceleration can be very rapid. Cancer Therapy FFAGs are more compact and easier to operate than cyclotrons, which are the most common machines currently used for cancer therapy. This means that it would be possible to have local cancer therapy centres as opposed to just a few in the world. FFAGs can also be used for heavy ion therapy (which doesn’t damage surrounding tissue and skin like X-ray therapy does) and boron neutron capture therapy, which can be used to only target the tumour. The British Accelerator Science and Radiation Oncology Consortium (BASROC) was recently formed by people from the medical and physics communities. The aim of BASROC is to build an electron FFAG model (EMMA) and to study the behaviour of proton FFAGs. EMMA has just been awarded funding and will be built at the Daresbury Laboratory within the next three years. Phase Rotation The beam of muons produced from the target in a neutrino factory has a very large range of energies in a very short space of time. However, what we really require is for the beam to have a small range of energies. The phase rotation section is designed to exchange the large spread in energy and short spread in time for a large spread in time and a short spread in energy. The author has been investigating the possibility of using an FFAG for phase rotation in a neutrino factory instead of a using a linear channel. Engineering drawing of the prototype section of the RFQ Simulation result showing longitudinal phase rotation after seven turns round an FFAG ring. This was presented at the Eighth International Workshop on Neutrino Factories, Superbeams and Betabeams 2006 in UC Irvine, CA, USA. Photograph of the sections of the RFQ currently manufactured. Simulation result showing the surface current distribution. This was presented at the European Particle Accelerator Conference 2006 in Edinburgh. Proof of principle 1MeV proton FFAG built in Japan and first operated in 2000. EMMA The Electron Model for Many Applications (EMMA) FFAG will be built at the Daresbury Laboratory within the next three years. anti-neutrinos neutrinos