Collaborative Research: Experimental and Theoretical Study of the Plasma Physics of Antihydrogen Generation and Trapping

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

This award is made in response to a proposal submitted to and reviewed under the NSF/DoE Partnership in Basic Plasma Science and Engineering joint solicitation NSF 08-589. The award provides funds to support undergraduate participation in the overall research effort, which is being funded separately by the DoE under contract UC Berkeley Renewal of Grant DE-FG02-06ER54904 . The ultimate goal of this collaborative research is to measure the relative spectra of hydrogen and antihydrogen. Differences in the spectra could only result from CPT violation. A second, more remote goal is to measure the relative effects of gravity on hydrogen and antihydrogen. Positive results from either measurement would completely change our understanding of fundamental particles and fields. This proposal is focused on the immediate plasma and atomic physics issues surrounding the trapping of antihydrogen. These issues will be studied with experiments at CERN, with classical trajectory Monte Carlo, molecular dynamics, and 3D PIC codes, and with analytic theory. Some of the questions that will be addressed include: how to confine positrons, antiprotons in an octupole at sufficiently cold temperatures; how do leptons interact with the background radiation field; how do antiproton-antiproton collisions relax nonthermal distributions; how to mix positrons and antiprotons so that the resultant antihydrogen can be held in a very shallow neutral trap; how do zerofrequency bounce resonances cause antiproton loss when the confining potentials are changed, and; how to predict the energy and state of the resultant antihydrogen under various mixing schemes. While the motivation for seeking answers to these questions comes from antihydrogen research, many of these questions raise novel and deep issues in plasma and atomic physics. The long-term goals of this research address the very basis of our understanding of the world around us. Potentially, it has deep implications on the nature of particle interactions, on the question of matter-antimatter symmetry, and on cosmology. At the same time, this research is uniquely visible because the study of antimatter is accessible and fascinating to the public. Antihydrogen experiments are sufficiently simple that they can be comprehended in their entirety by graduate students. Consequently, they offer students a broad education. Experimentalists learn beam and plasma physics, experimental planning and design, instrumentation, UHV practice, electronics, cryogenics, magnetics and software development. Along with theory development, theorists can make critical contributions to the design, operation, and analysis of the experiments. The relative accessibility of the material makes it easy to integrate undergraduate students into both the experimental and theoretical program. The proposed research includes significant participation by members of underrepresented groups in the physical sciences. The undergraduate participation adds a broader educational impact through the early-year training of students by introducing them to scientific research as a possible career path.