Speaker
Summary
High-resolution X-ray spectroscopy of light pionic atoms gives access to the
pion-nucleon and pion-nucleus scattering lengths by of the energy shift
and broadening of the X-ray transitions (np-1s) to the atomic ground state.
The accuracy achieved is about 0.1% for the shift and 4% for the line
width for the case pionic hydrogen. The large uncertainty of the line
width is due to processes during the atomic de-excitation cascade, the
knowledge of which actually constitutes the limits of this experimental
technique. A further improvement may be obtained by constraints from
results from pionic deuterium or helium, the optimization of the experiment
for transitions with higher lying initial states with n=4 or 5, or an
improved understanding of the de-excitation cascade.
