Currently I am involved in the ALPHA experiment at CERN which aims to perform detailed spectroscopic studies of the properties of antihydrogen atoms. It is hoped that comparisons with ordinary hydrogen will provide stringent tests of the CPT theorem. We have recently succeeded in trapping antihydrogen atoms in a magnetic field minimum for periods of 1000 seconds or more and have observed the first resonant quantum transition in the anti-atom. This is the first ever study of the spectroscopic properties off an atomic system made entirely of antimatter. At Swansea we are performing experiments aimed at elucidating the properties of positronium. To do this we use pulses of positrons from a compact accumulator. We have learnt how to rapidly compress positron clouds in this device to efficiently make a cloud of positronium for future study. I am also interested in positron interactions with gases, and in particular annihilation and transport.

Selected publications

ANTIHYDROGEN

Resonant quantum transitions in trapped antihydrogen atoms, C. Amole and M. Charlton and 41 others [Nature 483 (2012) 439]

Confinement of antihydrogen for 1,000 seconds, G.B. Andresen and M. Charlton and 38 others [Nature Phys. 7 (2011) 558]

Trapped antihydrogen, G.B. Andresen and M. Charlton and 40 others [Nature 468 (2010) 673]

Antihydrogen formation dynamics in a multipolar anti-atom trap, G.B. Andresen and M. Charlton and 34 others [Phys. Letts B 685 (2010) 141]

Temporally controlled modulation of antihydrogen production and the temperature scaling of antiproton-positron recombination, M.C. Fujiwara and M. Charlton and 33 others [Phys. Rev. Letts 101 (2008) 053401]

Production and detection of cold antihydrogen atoms, M. Amoretti and M. Charlton and 37 others [Nature 419 (2002) 456]

POSITRONS AND POSITRONIUM

Directed fluxes of positronium using pulsed travelling optical lattices, P.F. Barker and M. Charlton [New J. Phys. 14 (2012) 045005]

Compression of positron clouds in the independent particle regime, C.A. Isaac, C.J. Baker, T. Mortensen, D.P. van der Werf and M. Charlton [Phys. Rev. Letts 107 (2011) 033201]

Weakly bound positron-electron pairs in a strong magnetic field, C.J. Baker, D.P. van der Werf, D.C.S. Beddows, P.R. Watkeys, C.A. Isaac, S.J. Kerrigan, M. Charlton and H.H. Telle [J. Phys. B: At. Mol. Opt. Phys. 41 (2008) 245003]

Three-body effects in positron annihilation on molecules, M. Charlton, D.P. van der Werf, R.J. Lewis, P.R. Watkeys and S.J. Kerrigan [J. Phys. B: At. Mol. Opt. Phys. 39 (2006) L329]

New source of dense, cryogenic positron plasmas, L.V. Jørgensen and M. Charlton and 27 others [Phys. Rev. Letts 95 (2005) 025002]

Positron plasma diagnostics and temperature control for antihydrogen production, M. Amoretti and M. Charlton and 29 others [Phys. Rev. Letts 91 (2003) 055001]

REVIEW

The route to ultra-low energy antihydrogen, M.H. Holzscheiter, M. Charlton and M.M. Nieto [Phys. Rep. 402 (2004) 1]

BOOK

Positron Physics, M. Charlton and J.W. Humberston (2000) Cambridge University Press pp454

PEDAGOGICAL AND POPULAR

Antihydrogen on tap, M. Charlton [Physics Education 40 (2005) 229]

Probing the antiworld, M. Charlton and J.S. Hangst, [Physics World October 2005 22]