Abstract
The hadronic shift ε ls and broadening Γ ls of the ground state in pionic hydrogen are measured with unprecedented precision. The expected accuracy is about 1% for broadening and 0.2% for shift. This is an improvement by an order of magnitude for broadening as compared to previous experiments and allows an accurate test of chiral perturbation theory. Pions are stopped after being focused with a cyclotron trap and captured in a hydrogen target. The resulting X-rays are Bragg-reflected by a spherically bent crystal and detected in an array consisting of 6 CCD (charge coupled devices). The response function of the crystal is determined with an ECR-source. Recent results are presented. They indicate a pressure dependency for the broadening, but none for the shift.