These processes are the main cause of loss of trapped ¯H Thus there is considerable interest in obtaining cross sections for them, in order to determine annihilation rates under Methods of extending this work to ¯H scattering by He and H2 are discussed. This includes a very recent preliminary calculation that we have carried out using the Kohn variational method. The theoretical work that has been carried out for H¯H is described. In this chapter, we consider some of the interesting theoretical problems that arise when ¯H in which a positron is bound to an antiproton, interacts with H, He and H2. , which is entitled ‘Antihydrogen production and precision experiments’ and has 54 authors from The size and extent of the collaboration on this projectĬan be seen from ref. Out these experiments by trapping ¯H at very low temperatures (< 1 K) in an inhomogeneous magnetic field. On Neutral Antimatter), which is to be used at CERN to carry out experiments on antihydrogen (¯H) to test the CPT invariance of Quantum Field Theory and also Einstein’s Principle of Equivalence. The measured positron lifetime is > 8 days in our room temperature vacuum of 10Ī large group of experimentalists is currently working on the preparation of the ATHENA (ApparaTus for High precision Experiments We estimate the number of trapped positrons from the volume of this column and from the annihilation radiation when the positrons are ejected from the trap. + ions, and places an upper limit of approximately 5 K on the positron temperature of motion parallel to the magnetic field. This indicates the positróns have the same rotation frequency and comparable density (4 × 10 + laser-induced fluorescence, we observe centrifugal separation of the 9Be+ ions and positrons, with the positrons coalescing into a column along the trap axis. Up to a few thousand positrons are trapped and lose energy through Coulomb collisions (sympathetic cooling) with laser-cooled 9Be Positrons from a 2 mCi 22Na source travel along the axis of a 6 T magnet and through the trap after which they strike a Cu reflection moderator crystal. We present results on trapping and cooling of positrons in a Penning trap. The final two sections treat a range of topics involving positron and positronium interactions with atoms and molecules. The second section discusses topics involving antihydrogen and many-body phenomena, including Bose condensation of positronium atoms and positron interactions with materials. This book is organized into four sections: The first section discusses potential new experimental capabilities and the uses and the progress that might be made with them. It is virtually assured that the new experimental capabilities in this area will lead to a rapid expansion of this list. There are presently an intriguing variety of phenomena that await theoretical explanation. On the theoretical side, the ability to model complex systems and complex processes has increased dramatically in recent years, due in part to progress in computational physics. New concepts for intense positron sources and the development of positron accumulators and trap-based positron beams provide qualitatively new experimental capabilities. The timeliness of this subject comes from several considerations. The emphasis is on positron and positronium interactions both with themselves and with ordinary matter. The aim of this book (similar in theme to the workshop) is to present an overview of new directions in antimatter physics and chemistry research. This volume is the outgrowth of a workshop held in October, 2000 at the Institute for Theoretical Atomic and Molecular Physics at the Harvard- Smithsonian Center for Astrophysics in Cambridge, MA.
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