Grant: Subatomic Physics Envelope - Project

ALPHA (Antihydrogen Laser Physics Apparatus) is an international project at CERN, whose primary aim is to test fundamental symmetries between matter and antimatter using trapped antihydrogen atoms, the simplest atomic form of neutral antimatter. Since its approval by CERN in 2005 and the first beam in 2006, ALPHA has made substantial progress, and the construction of the experiment is nearly complete. Canadian scientists, now some 30% of the Collaboration, have been able to make important contributions from the beginning. It is the purpose of this Project Grant application to request support that will allow us to fully exploit the ALPHA apparatus in our effort to trap antihydrogen atoms to perform spectroscopy.. Cold atoms of antihydrogen promise a unique opportunity to study the properties of atomic antimatter, and via comparisons with its well-studied matter-counterpart, the possibility to test fundamental symmetries of Nature such as CPT invariance. The anti-atoms previously produced at CERN, while nearly at rest, were not confined and soon annihilated on the walls of the apparatus. In order to probe matter-antimatter symmetry at the highest possible precision, it is essential that the anti-atoms be suspended in vacuum to allow for detailed interrogation via laser light or microwaves. Cold antihydrogen is produced in ALPHA by mixing antiprotons and positrons in a Penning trap. The antiprotons are obtained from CERN's Antiproton Decelerator, currently the world's only facility providing high quality antiproton beams, while the positrons are accumulated from a radioactive source. In order to magnetically trap neutral antihydrogen atoms, one needs a field minimum in the region of antihydrogen production. Important features of ALPHA in confronting the associated technical challenges include one of the world's most powerful cold positron traps, the novel use of a superconducting octupole magnet for anti-atom trapping, and the application of subatomic physics techniques e.g., sophisticated detectors and analysis software, that will unambiguously demonstrate trapping of antihydrogen.