E. A. Hessels

Stacking of cold antiprotons

Abstract The stacking of cold antiprotons is currently the only way to accumulate the large numbers of the cold antiprotons that are needed for low energy experiments. Both the largest possible number and the lowest possible temperature are desired, especially for the production and study of cold antihydrogen. The antiprotons accumulated in our particle trap have an energy 10 10 times lower than the energy of those delivered by CERNs Antiprotons Decelerator (AD). The number accumulated (more than 0.4 million in this demonstration) is linear in the number of accepted high energy antiproton pulses (32 in this demonstration). Accumulation efficiencies and losses are measured and discussed.

Proton radius from electron-proton scattering and chiral perturbation theory

We determine the root-mean-square proton charge radius,

Evaluation of the strength of electron-proton scattering data for determining the proton charge radius

{R}_{p}

Electron-cooled accumulation of 4×10 9 positrons for production and storage of antihydrogen atoms

, from a fit to low-

Large numbers of cold positronium atoms created in laser-selected Rydberg states using resonant charge exchange

{Q}^{2}

Observations of cold antihydrogen

electron-proton elastic-scattering cross-section data with the higher moments fixed (within uncertainties) to the values predicted by chiral perturbation theory. We obtain

Interference between two resonant transitions with distinct initial and final states connected by radiative decay

{R}_{p}=0.855(11)

A semiconductor laser system for the production of antihydrogen

fm. This number falls between the value obtained from muonic hydrogen analyses and the CODATA value (based upon atomic hydrogen spectroscopy and electron-proton scattering determinations).

ATRAP — Progress Towards Trapped Antihydrogen

Precisely measured electron-proton elastic scattering cross sections [Phys. Rev. Lett. {\bf 105}, 242002 (2010)] are reanalyzed to evaluate their strength for determining the rms charge radius (

Cryogenic Particle Accumulation In ATRAP And The First Antihydrogen Production Within A Magnetic Gradient Trap For Neutral Antimatter

R_{\rm E}