  How long antihydrogen atoms linger in the ALPHA magnetic trap is an important
characteristic of the ALPHA apparatus. The initial trapping experiments in 2010
[1] were conducted with 38 detected antiatoms confined for 172 ms and in 2011
[2] with seven for 1000 s. Long confinement times are necessary to perform
detailed frequency scans during spectroscopic measurements. An analysis carried
out, using machine learning methods, on more than 1000 antiatoms confined for
several hours in the ALPHA-2 magnetic trap, yields a preliminary lower limit to
the lifetime of 66 hours. Hence this observation suggests that the measured
confinement time of antihydrogen is extended by more than two orders of
magnitude.
  [1] Andresen, G. B. et al. (ALPHA collaboration), Nature 468, 673-676 (2010)
  [2] Andresen, G. B. et al. (ALPHA collaboration), Nature Phys. 7, 558-564
(2011)
