Measurement of the strong interaction width and shift of the ground state of pionic hydrogen

CHALLENGE:

• To measure the strong interaction width and shift of the ground state of pionic hydrogen with high precision: better than 1% for the shift and about 2% for the width.

SOLUTION:

• Use the PSI cyclotron trap to produce the pionic hydrogen atoms in controlled environment.
• Use crystal spectrometers and CCD detectors to measure the X-ray lines.
• Perform measurements at different hydrogen densities.
• Perform simultaneous measurements of the pionic and muonic hydrogen X-ray lines.
• Use the atomic cascade code to determine the Doppler broadening corrections to the widths of the X-ray lines.

RESULT:

• The pion-nucleon scattering lengths will be determined with the accuracy of about 1%.
• The pion-nucleon coupling constant will be calculated.
• The isospin breaking effects will be evaluated.