Precision spectroscopy of antihydrogen is a promising path to sensitive tests of CPT symmetry. The ALPHA Collaboration, in a series of experiments at the CERN Antiproton Decelerator, has combined antiprotons and positrons to create antihydrogen atoms in a magnetic minimum trap. Trapping times of 1000s have been achieved. Over 1000 antihydrogen atoms have been trapped and a series of initial physics studies has been performed. ALPHA has illuminated antihydrogen atoms with microwaves and measured the positron spin flip frequency to ~0.1%. A technique based on Fermi acceleration has recently been employed to set a bound on the charge neutrality of antihydrogen to ~< 10^-9 e. A very crude direct bound on the antihydrogen acceleration in the Earth’s gravitational field limits the gravitational-to-inertial mass ratio to |M_G/M| <~100. The talk will provide an overview of the techniques we used to trap antihydrogen, ALPHA’s physics results and plans for the future.

Argonne Physics Division Colloquium Schedule