Latest changes:

2017 Line shape analysis of the Kβ transition in muonic hydrogen (arXiv atoms-ph)
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2016 Remarks on a Johann spectrometer for exotic-atom research and more (published Spectrochim. Acta B)
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2015 Pionic hydrogen and friends (EXA14 proceedings)
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22.12.14
Hadronic shift in pionic hydrogen (published EPJ A)
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Pionic Hydrogen
collaboration © 2007

Webmaster: D.Gotta

Design: M.Nekipelov

 

Pionic Hydrogen


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

"QCD Lamb shift"

Physics interest:

  • Precise determination of the pion-nucleon scattering lengths.
  • Extraction of the pion-nucleon coupling constant
    and the pion-nucleon σ-term.
  • The pionic deuterium level shift reveals isospin breaking effects by constraining the scattering lengths as obtained from pionic hydrogen.
  • The pionic deuterium ground state width is dominated by true absorption and directly related to pion production strength α at threshold.

Challenge:

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

Approach:

  • Use the PSI cyclotron trap to produce pionic atoms in a controlled environment.
  • Use crystal spectrometers and CCD detectors to measure precisely the X-ray energies and line shapes.
  • Perform measurements at different hydrogen densities.
  • Perform measurements for different transitions.
  • Perform measurements of muonic hydrogen to quantify the Doppler broadening of X-ray lines from Coulomb explosion.
  • Correlate cascade theory to the Doppler broadening corrections.

Atomic cascade in pionic hydrogen:

Cascade

Preliminary results

ε1s /meV Γ1s / meV α / μb
πH 823 ± 19 --- 2006

Final results

πH + 7086 ± 10 --- 2014
πD - 2356 ± 31 1171 +23/-49 251 +5/-11 2010

 

Related experiments:

  • Precise determination of the charged pion mass.
  • Fluorescence X-rays.



Last Modified: Monday November 13, 2017 08:19