Progress with Antihydrogen and Positronium

Last updated September 12, 2017 by Alessandro Ferraro

Tuesday, September 19 2017, 04:00 PM, Room 0G/017, Maths and Physics Teaching Centre

Speaker: Mike Charlton (Swansea University)

It has been possible for some time to form antihydrogen atoms by mixing antiprotons and positrons held in arrangements of charged particle (Penning) traps [1,2]. More recently, magnetic minimum neutral atom traps have been used to allow a small quantity of the antihydrogen yield to be trapped [3-5].

These advances will be discussed, and we will also describe some of the first physics experiments performed on antihydrogen including the observation of the two-photon 1S-2S transition [6], investigation of the charge neutrality of the anti-atom [7,8] and studies of the ground state hyperfine splitting [9] and spectrum [10].  We will discuss the physics motivations for undertaking these experiments and describe some near-future initiatives.

Positronium (Ps) continues to be of interest, and this has been spurred recently by the experimental availability of the atom in a variety of quantum states (see, e.g., [11-13]). In particular, Ps reactions involving charge exchange can be used to produce antihydrogen and other atomic species at low energies, and we will discuss some recent work in this area (e.g., [14-16]).

1. M. Amoretti et al. (ATHENA Collaboration), Nature 419 (2002) 456
2. G. Gabrielse et al. (ATRAP Collaboration), Phys. Rev. Lett. 89 (2002) 213401
3. G.B. Andresen et al. (ALPHA Collaboration), Nature 468 (2010) 673
4. G.B. Andresen et al. (ALPHA Collaboration), Nature Phys. 7 (2011) 558
5. G. Gabrielse et al. (ATRAP Collaboration), Phys. Rev. Lett. 108 (2012) 113002
6. M. Ahmadi et al. (ALPHA Collaboration), Nature 541 (2017) 506
7. C. Amole et al. (ALPHA Collaboration), Nature Commun. 5 (2014) 3955
8.  M. Ahmadi et al. (ALPHA Collaboration), Nature 529 (2016) 373
9. C. Amole et al. (ALPHA Collaboration), Nature 483 (2012) 439
10. M. Ahmadi et al. (ALPHA Collaboration), Nature 548 (2017) 66
11. D.B. Cassidy et al., Phys. Rev. Lett. 108 (2012) 043401
12. A.C.L. Jones et al., Phys. Rev. A 90 (2014) 012503
13. A. Deller et al., J. Phys. B: At. Mol. Opt. Phys. 48 (2015) 175001
14. A.S. Kadyrov et al., Phys. Rev. Lett. 114 (2015) 183201
15. C.M. Rawlins et al., Phys. Rev. A 93 (2016) 012709
16. W.A. Bertsche et al., New J. Phys. 19 (2017) 053020


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