Cold Antihydrogen for Precise Laser Spectroscopy

%AD-2 %title\\ \\The Antihydrogen TRAP Collaboration (ATRAP) seeks to do precise laser spectroscopy of antihydrogen. Comparisons of antihydrogen and hydrogen atoms should provide the most stringent test of CPT invariance involving baryons and leptons. ATRAP is an expansion of the TRAP collaboration that developed the techniques to take CERN antiprotons from an energy of 6 MeV (momentum 100 MeV/c) all the way down to thermal equilibrium at 4 K for storage. This storage energy is lower than realized previously by more than ten orders of magnitude. The TRAP techniques include slowing, capturing, electron cooling and stacking of antiprotons. ATRAP and other collaborations will use antiprotons from the Antiproton Decelerator (AD). This new facility makes sense for such experiments because we showed that antiprotons can be accumulated in a trap at much lower expense than was required in the earlier CERN AC-AA-LEAR complex. In the closest approach yet to the production of cold antihydrogen, collaboration members were able to confine cold antiprotons and positrons together for the first time, and to observe their interaction. ATRAP now includes members who have pioneered crucial techniques required for the study of cold antihydrogen such as the laser spectroscopy of hydrogen, the spectroscopy of trapped hydrogen, atom trapping and laser cooling. Very recently we have demonstrated the first continuous source of Lyman alpha radiation (developed to facilitate antihydrogen spectroscopy) and have demonstrated that the stripping of high Rydberg states of positronium is an efficient way to produce the cold positrons needed for antihydrogen production.\\ \\