Laser Cooling of Antihydrogen for Fundamental Symmetry Tests with ALPHA at CERN

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This RTI proposal will directly and substantively support the research program of the CERN-based ALPHA (Antihydrogen Laser Physics Apparatus) Collaboration. Specifically, it directly supports equipment for the entirely Canadian-led initiative on laser cooling of antihydrogen. ALPHA is an international project whose goal is to measure and compare certain properties of 'antihydrogen' - the simplest atomic form of neutral antimatter - with those of ordinary hydrogen. ALPHA will directly test and challenge fundamental theories with regard to the similarities and differences ('symmetries') between matter and antimatter, an issue that is arguably one of the greatest unsolved problems in physics. In recent years, ALPHA has achieved many significant and high profile milestones in its pursuit of its primary goal, including: stable (2010) and long term (2011) trapping of neutral antimatter, and proof of principle microwave studies of trapped antihydrogen (2012). Having achieved its milestones of antihydrogen trapping and the first spectroscopy, ALPHA has undergone a major upgrade. The new apparatus (ALPHA-2), constructed with significant Canadian contributions, provides laser access to trapped antihydrogen, as well as improved magnetic field homogeneity for precision spectroscopy. Cooling of antihydrogen atoms via the application of radiation pressure will provide a cold and dense sample of trapped antihydrogen, and is a necessary step for achieving the ultimate precision in antihydrogen spectroscopy. However, development of the laser source required for such process has been technically challenging. In the past few years, the laser group in ALPHA-Canada has developed an all solid state Lyman-alpha laser system, installed the system at CERN, and successfully generated Lyman-alpha light at 121.5 nm at the antihydrogen trap chamber. Building on these important technical milestones, this RTI grant will provide critical equipment to make laser cooling of antihydrogen finally possible, which has been a dream for those in the field for many years. This grant will support the purchase of a high-power, narrow-linewidth pump laser and optical components in order to increase the energy of the Lyman-alpha light. These instruments will help enable the world’s first laser cooling of antihydrogen, and pave the path towards the ambitious goal of precision symmetry tests between matter and antimatter.