Does antimatter fall up? The science-fictional idea of antigravity is now being taken seriously by a number of researchers around the world. At Illinois Tech, we are developing a novel experimental apparatus to measure the gravitational acceleration of antimatter.
Einstein’s General Relativity, the accepted theory of gravity, predicts no difference whatsoever between the gravitational behaviors of matter and antimatter. While well-established experimentally, General Relativity has never been tested with antimatter. If antimatter is found to fall up in the gravitational field of the Earth — or even if it falls down, but at a different rate from matter — it will fundamentally change our view not only of gravity but of the nature and evolution of the Universe.
Our objective is to develop a novel experimental apparatus to measure the gravitational acceleration of antimatter. The measurement will require a source of neutral antimatter atoms and a precision device to measure their motion under gravity. Our approach is to use muonium — a hydrogen-like atom composed of an antimuon bound to an electron. (Although the electron is matter, since the antimuon is 200 times heavier than the electron, muonium should act gravitationally like antimatter.) Muonium sources exist at a number of particle accelerator laboratories around the world. Since muonium decays on average in 2.2 microseconds, the measurement is challenging and requires extreme mechanical precision.
We will continue the development of a precision interferometer employing thin silicon-nitride gratings made at Argonne National Laboratory using nanotechnology fabrication techniques. This IPRO project started in the fall 2014 semester and has continued since then, with significant progress being made. We will build on that progress by (if possible) building gratings and characterizing their precision (and, if necessary, figure out how to improve it). We will also carry out further design and simulation studies, including finite-element analysis (FEA) of the gratings, the optical bench, and their mechanical systems, in order to understand and optimize the performance of the experiment as a whole. We will continue the design of the needed cryogenic and vacuum systems. We will also continue experimental studies of our infrared-laser picometer-alignment system.
Students from a variety of disciplines interested in gaining experience in designing, building and testing experimental devices and mechanisms will find that this IPRO project offers a creative, interesting and challenging experience. For example, this includes students from the natural sciences, computer science, applied mathematics, electrical and computer engineering, mechanical engineering, materials engineering, and information technology and management.
Students interested in this IPRO project are also encouraged to contact Prof Mancini to undertake a summer research project for his research team that will follow up with one or two semesters of the IPRO project. This will offer the opportunity to perform more extensive cleanroom activity, because Argonne will provide more training, support, and access at that level of commitment. Interested students could be given research credit for the summer, albeit not as a paid intern at this time.