Since the first trapped antihydrogen in 2010 [1] and observing its long lifetime in the 0.5 K deep neutral atom trap [2], experiments have been performed on the anti-atom resulting in the observation of resonant transitions between the hyperfine states of the ground state [3], experimental limits on the ratio of the gravitational mass to the inertial mass of antimatter [4] and an experimental limit on the charge of antihydrogen [5,6]. Recently, we have been able to observe he 1S-2S transition in antihydrogen [7]. I will give an overview of the ALPHA experiment [8] and present some of the results originating from recent experiments on trapped antihydrogen.
[1] G. B. Andresen et al. (ALPHA collaboration), Nature 468 (2010) 673
[2] G. B. Andresen et al. (ALPHA collaboration), Nature Phys. 7 (2011) 558
[3] C. Amole et al. (ALPHA collaboration), Nature 483 (2012) 439
[4] C. Amole et al. (ALPHA collaboration), Nature Communications 4 (2013) 1785
[5] C. Amole et al. (ALPHA collaboration), Nature Communications 5 (2014) 3955
[6] M. Ahmadi et al. (ALPHA collaboration), Nature 529 (2016) 373
[7] M. Ahmadi et al. (ALPHA collaboration), Nature 541 (2017) 506
[8] C. Amole et al. (ALPHA collaboration), Nucl. Instr. and Meth. in Phys. Res. A 735 (2014) 319
ALPHA collaboration: http://alpha.web.cern.ch
