Status of the muonic hydrogen Lamb-shift experiment

Nebel, T.; Amaro, F. D.; Antognini, A.; Biraben, F.; Cardoso, J. M. R.; Conde, C. A. N.; Dax, A.; Dhawan, S.; Fernandes, L. M. P.; Giesen, A.; Hänsch, T. W.; Indelicato, P.; Julien, L.; Knowles, Paul E.; Kottmann, F.; Le Bigot, E.; Liu, Y.-W.; Lopes, J. A. M.; Ludhova, Livia; Monteiro, C. M. B.; Mulhauser, Françoise; Nez, F.; Pohl, R.; Rabinowitz, P.; Santos, J. M. F. dos; Schaller, Lukas A.; Schuhmann, K.; Schwob, C.; Taqqu, D.; Veloso, J. F. C. A.

doi:10.1139/P07-018

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Journal article

Status of the muonic hydrogen Lamb-shift experiment

Nebel, T. Max-Planck-Institutfur Quantenoptik, Garching, Germany
Amaro, F. D. Departamento de Fisica, Universidade de Coimbra, Portugal
Antognini, A. Max-Planck-Institutfur Quantenoptik, Garching, Germany
Biraben, F. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Cardoso, J. M. R. Departamento de Fisica, Universidade de Coimbra, Portugal
Conde, C. A. N. Departamento de Fisica, Universidade de Coimbra, Portugal
Dax, A. Physics Department, Yale University,New Haven, USA
Dhawan, S. Physics Department, Yale University,New Haven, USA
Fernandes, L. M. P. Departamento de Fisica, Universidade de Coimbra, Portugal
Giesen, A. Institut fur Strahlwerkzeuge, Stuttgart, Germany
Hänsch, T. W. Max-Planck-Institutfur Quantenoptik, Garching, Germany
Indelicato, P. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Julien, L. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Knowles, Paul E. Département de Physique, Université de Fribourg, Switzerland
Kottmann, F. Institut fur Teilchenphysik, ETH Zurich, Switzerland
Le Bigot, E. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Liu, Y.-W. Physics Department, National Tsing Hua University, Hsinchu, Taiwan
Lopes, J. A. M. Departamento de Fisica, Universidade de Coimbra, Portugal
Ludhova, Livia Département de Physique, Université de Fribourg, Switzerland
Monteiro, C. M. B. Departamento de Fisica, Universidade de Coimbra, Portugal
Mulhauser, Françoise Département de Physique, Université de Fribourg, Switzerland
Nez, F. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Pohl, R. Max-Planck-Institutfur Quantenoptik, Garching, Germany
Rabinowitz, P. Department of Chemistry, Princeton University, Princeton, USA
Santos, J. M. F. dos Departamento de Fisica, Universidade de Coimbra, Portugal
Schaller, Lukas A. Département de Physique, Université de Fribourg, Switzerland
Schuhmann, K. Institut fur Strahlwerkzeuge, Stuttgart, Germany
Schwob, C. Laboratoire Kastler Brossel, ENS, UPMC, CNRS, Paris, France
Taqqu, D. Paul Scherrer Institute, Villigen-PSI, Switzerland
Veloso, J. F. C. A. Departamento de Fisica, Universidade de Coimbra, Portugal

14.05.2007

Published in:

Canadian Journal of Physics. - 2007, vol. 85, no. 5, p. 469-478

English The Lamb-shift experiment in muonic hydrogen (μ⁻ p) aims to measure the energy difference between the 2S^F=1_1/2-2P^F=2_3/2 atomic levels to a precision of 30 ppm. This would allow the r.m.s. proton charge radius r_p to be deduced to a precision of 10⁻³ and open a way to check bound-state quantum electrodynamics (QED) to a level of 10⁻⁷. The poor knowledge of the proton charge radius restricts tests of bound-state QED to the precision level of about 6 × 10⁻⁶, although the experimental data themselves (Lamb-shift in hydrogen) have reached a precision of × 10⁻⁶. Values for r_p not depending on bound-state QED results from electron scattering experiments have a surprisingly large uncertainty of 2%. In our Lamb-shift experiment, low-energy negative muons are stopped in low-density hydrogen gas, where, following the μ⁻ atomic capture and cascade, 1% of the muonic hydrogen atoms form the metastable 2S state with a lifetime of about 1 μs. A laser pulse at λ ≈ 6 μm is used to drive the 2S → 2P transition. Following the laser excitation, we observe the 1.9 keV X-ray being emitted during the subsequent de-excitation to the 1S state using large-area avalanche photodiodes. The resonance frequency and, hence, the Lamb shift and the proton charge radius are determined by measuring the intensity of the X-ray fluorescence as a function of the laser wavelength. The results of the run in December 2003 were negative but, nevertheless, promising. One by-product of the 2003 run was the first observation of the short-lived 2S component in muonic hydrogen. Currently, improvements in the laser-system, the experimental apparatus, and the data acquisition are being implemented.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

Language

English

Classification

Physics

License

License undefined

Identifiers

RERO DOC 8911
DOI 10.1139/P07-018

Persistent URL

https://folia.unifr.ch/unifr/documents/300658

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