Transverse emittance reduction in muon beams by ionization cooling

Accelerated muon beams have been considered for the next-generation studies of high-energy lepton-antilepton collisions and neutrino oscillations. However, high-brightness muon beams have not yet been produced. The main challenge for muon acceleration and storage stems from the large phase-space volume occupied by the beam, derived from the production mechanism of muons through the decay of pions. The phase-space volume of the muon beam can be decreased through ionization cooling. Here we show that ionization cooling leads to a reduction in the transverse emittance of muon beams that traverse lithium hydride or liquid hydrogen absorbers in the Muon Ionization Cooling Experiment. Our results represent a substantial advance towards the realization of muon-based facilities that could operate at the energy and intensity frontiers.

M. Bogomilov, R. Tsenov, G. Vankova-Kirilova, Y. P. Song, J. Y. Tang, Z. H. Li, R. Bertoni, M. Bonesini, F. Chignoli, R. Mazza, A. de Bari, D. Orestano, L. Tortora, Y. Kuno, H. Sakamoto, A. Sato, S. Ishimoto, M. Chung, C. K. Sung, F. Filthaut, M. Fedorov, D. Jokovic, D. Maletic, M. Savic, N. Jovancevic, J. Nikolov, M. Vretenar, S. Ramberger, R. Asfandiyarov, A. Blondel, F. Drielsma, Y. Karadzhov, S. Boyd, J. R. Greis, T. Lord, C. Pidcott, I. Taylor, G. Charnley, N. Collomb, K. Dumbell, A. Gallagher, A. Grant, S. Griffiths, T. Hartnett, B. Martlew, A. Moss, A. Muir, I. Mullacrane, A. Oates, P. Owens, G. Stokes, P. Warburton, C. White, D. Adams, V. Bayliss, J. Boehm, T. W. Bradshaw, C. Brown, M. Courthold, J. Govans, T. Hayler, M. Hills, J. B. Lagrange, C. Macwaters, A. Nichols, R. Preece, S. Ricciardi, C. Rogers, T. Stanley, J. Tarrant, M. Tucker, S. Watson, A. Wilson, R. Bayes, J. C. Nugent, F. J. P. Soler, G. T. Chatzitheodoridis, A. J. Dick, K. Ronald, C. G. Whyte, A. R. Young, R. Gamet, P. Cooke, V. J. Blackmore, D. Colling, A. Dobbs, P. Dornan, P. Franchini, C. Hunt, P. B. Jurj, A. Kurup, K. Long, J. Martyniak, S. Middleton, J. Pasternak, M. A. Uchida, J. H. Cobb, C. N. Booth, P. Hodgson, J. Langlands, E. Overton, V. Pec, P. J. Smith, S. Wilbur, M. Ellis, R. B. S. Gardener, P. Kyberd, J. J. Nebrensky, A. DeMello, S. Gourlay, A. Lambert, D. Li, T. Luo, S. Prestemon, S. Virostek, M. Palmer, H. Witte, D. Adey, A. D. Bross, D. Bowring, A. Liu, D. Neuffer, M. Popovic, P. Rubinov, B. Freemire, P. Hanlet, D. M. Kaplan, T. A. Mohayai, D. Rajaram, P. Snopok, Y. Torun, L. M. Cremaldi, D. A. Sanders, L. R. Coney, G. G. Hanson, C. Heidt