May 24 – 28, 2021
America/Vancouver timezone

Laser spectroscopy of long-lived pionic helium at PSI

May 25, 2021, 5:30 AM
Parallel session talk Experiments: Precision techniques at low energy Experiments: Precision and Low Energy


Masaki Hori (Max-Planck Institute of Quantum Optics (DE))


The PiHe collaboration recently used the 590 MeV ring cyclotron facility of Paul Scherrer Institute to carry out laser spectroscopy of metastable pionic helium atoms [1,2]. This is a three-body atom consisting of a helium nucleus, a ground-state electron, and a negatively-charged pion occupying a Rydberg state of principal and orbital angular momentum quantum numbers of around n=17 and l=16. By using a sub-nanosecond infrared pulsed laser, the pion was resonantly deexcited from the state (17,16) to a short-lived state (17,15). In future experiments, we intend to increase the experimental precision and compare the results with three-body QED calculations. This would allow the negatively-charged pion mass to be determined with a higher precision than before.

[1] Nature 581, 37 (2020)
[2] Physical Review A 89, 042515 (2014)

Primary authors

Masaki Hori (Max-Planck Institute of Quantum Optics (DE)) Hossein Aghai Khozani (Max-Planck-Gesellschaft (DE)) Dr Anna Soter (ETH Zürich) Andreas Josef Dax (Department of Physics Particle Physics) Dr Daniel Barna (Wigner Research Centre for Physics)

Presentation materials