Biological effectiveness of antiproton annihilation

We describe an experiment designed to determine whether or not the densely ionizing particles emanating from the annihilation of antiprotons produce an increase in biological dose in the vicinity of the narrow Bragg peak for antiprotons compared to protons. This experiment is the first direct measurement of the biological effects of antiproton annihilation. The experiment has been approved by the CERN Research Board for running at the CERN Antiproton Decelerator (AD) as AD-4/ACE (Antiproton Cell Experiment) and has begun data taking in June of 2003. The background, description and the current status of the experiment are given. (C) 2004 Elsevier B.V. All rights reserved.12th International Workshop on Positron and Positronium Physics (POSITRON03), Jul 19-21, 2003, Aarhus Univ, Inst Phys and Astron, Sandbjerg, Denmar