Plasma and trap-based techniques for science with positrons

Abstract

In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 10 2 to less than 10 −3 eV. Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasi-monoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

Producing long-lived 23S positronium via 33P laser excitation in magnetic and electri

“…Briefly, positrons emitted by β + decay of a 22 Na source were slowed by a solid Ne moderator [30] to a kinetic energy of a few eV, trapped and cooled in a Surko-style trap through the use of buffer gas [31]. The measurements were run in two different moments by using two different source intensities of 9 mCi and 25 mCi, respectively.…”

Advances in Ps Manipulations and Laser Studies in the AEgIS Experiment

“…Positrons are first emitted from a 9 mCi 22 Na β + source. Then they get slowed down to kinetic energies of a few eV in a solid Ne moderator [9] to be trapped in a so-called Surko-trap using buffer gas cooling [10]. Subsequently, positrons are transferred to a cylindrical Penning trap in a 0.1 T magnetic field where several pulses from the trap are accumulated.…”

Positronium for Antihydrogen Production in the AEGIS Experiment

“…Positrons emitted by a 22 Na radioactive source (about 50 mCi) are slowed down by means of a solid Ne moderator [19], captured in a two-stage Surko buffer trap [20] and stored in an accumulator. Here bunches of some 10 7 e + are released with a longitudinal velocity corresponding to an energy of 300 eV, magnetically trans-ported in a 0.14 T field and injected into the PenningMalmberg trap in a 5 T magnetic field.…”