Neutrino Factory R & D
S M H Alsari, M Aslaninejad, P Dornan, K Long, A Kurup, J Pozimski, P Savage
The discovery that neutrinos change from one type to another as they travel through space (‘neutrino oscillations’) implies that neutrinos are massive, that the Standard Model is incomplete and makes the neutrino sector the only presently-accessible window on physics beyond the Standard Model. The small, but non-zero, neutrino mass has astrophysical consequences. In particular, the interactions of the neutrinos may underpin the mechanism by which antimatter was removed from the early universe. The far-reaching consequences of neutrino oscillations justify a dedicated experimental programme. The worldwide consensus is that a Neutrino Factory – an intense high-energy neutrino source derived from the decay of a stored muon beam – is the ultimate tool for the study of neutrino oscillations.
We have begun an ambitious programme of R&D aimed at developing a conceptual design for the Neutrino Factory. A schematic diagram of the facility is shown in figure 1. The neutrino-production process starts with the bombardment of a target with a high-power proton beam. The pions produced in the collisions are captured and allowed to decay to produce muons. To reach the required stored-muon intensity requires that the size and divergence of the muon beam be reduced or ‘cooled’ before the muons are accelerated and placed in a storage ring. Muon decays in the straight sections of the storage ring produce the intense, collimated neutrino beams that are required for the precision study of neutrino oscillations. The Neutrino Factory R&D programme at Imperial is focused on the front end of the high-power proton source, the proton driver, and the muon cooling system.
The proton driver front-end test stand
The Neutrino Factory proton driver must deliver ~4MW of proton-beam power onto a pion-production target. To accelerate and control such a high power beam requires that the beam injected into the proton driver is of the highest quality; placing stringent demands on the injection system. The proposed injection system is based on a linear accelerator that takes H- ions to an energy of 180MeV. The electrons are stripped from the ions at injection into the proton driver.
We are working closely with members of the ISIS Department at CCLRC’s Rutherford Appleton Laboratory (RAL) and to develop a test stand to demonstrate that a beam with the properties required for the Neutrino Factory can be produced. A layout of the test stand is shown in figure 2. H- ions are extracted from the ion source and focused in the low-energy-beam-transport (LEBT) system. The radio-frequency quadrupole (RFQ) accelerates, focuses and bunches the beam. The final section of the test stand before the diagnostics, is the chopper. The chopper is used to make ‘gaps’ in the bunch train. These gaps are required to allow ‘kicker’ magnets to be energised without disturbing the beam. The Imperial group is responsible for the design of the RFQ and the diagnostics for the test stand as well as for the overall layout in the experimental hall at RAL.
Neutrino factory R&D at Imperial
The Neutrino Factory project at Imperial offers many opportunities both in software development, analysis, beam optics and hardware development. For more information please contact Prof. Ken Long (K.Long@Imperial.AC.UK) or Dr. Juergen Pozimski (J.Pozimski@Imperial.AC.UK).
Further information on the Neutrino Factory can be obtained by following the following links:
The UK Neutrino Factory Collaboration
International Scoping Study Group
Beams for European Neutrino Experiments
Muon storage rings
The Japanese Neutrino Factory group page
The US Neutrino Factory and Muon Collider Collaboration
Further information on MICE, the international Muon Ionisation Cooling Experiment can be found at the following link: