Antihydrogen at Rest for Precision tests of CPT and WEP

Michael H. Holzscheiter

Los Alamos National Laboratory
For the ATHENA Collaboration

The study of CPT invariance with the highest achievable precision in all 
particle sectors is of fundamental importance for physics. 
Equally important is the question of the gravitational acceleration of antimatter. 

In recent years, impressive progress has been achieved at the Low Energy 
Antiproton Ring (LEAR) at CERN in capturing antiprotons in specially designed 
Penning traps, in cooling them to energies of a few milli-electron volts, and 
in storing them for many hours in a small volume of space. Positrons have been 
accumulated in large numbers in similar traps, and low energy positron or 
positronium beams have been generated. Finally, steady progress has been made 
in trapping and cooling neutral atoms. Thus the ingredients to form antihydrogen 
at rest are at hand, and several experimental collaborations have been formed 
with the goal to produce this system. 

In this talk I will describe the techniques available to produce, decelerate, 
and accumulate antiprotons at low energy, how to generate high density plasmas 
of low energy positrons, and how to combine these two species into antihydrogen. 
I will describe the lay-out of the ATHENA experiment at the Antiproton Decelerator 
(AD) at CERN and will describe the current status and future plans in some detail.