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Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Experimental evidence for spin-orbit interactions in positronium-Xe collisions
1Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1, Komaba, Tokyo, 153-8902, Japan. saitou@youshi.c.u-tokyo.ac.jp
Physical Review Letters
|February 7, 2007
Summary
Spin-orbit interaction in positronium (Ps) was experimentally confirmed in Xenon gas. Applying a magnetic field significantly shortened ortho-positronium lifetime, indicating spin conversion during collisions.
Area of Science:
- Atomic and Molecular Physics
- Quantum Mechanics
- Positron Spectroscopy
Background:
- Positronium (Ps) is a fundamental leptonic system composed of an electron and a positron.
- Theoretical predictions by Mitroy and Novikov (2003) suggested spin-orbit interaction in Ps.
- Experimental verification of this interaction has been lacking.
Purpose of the Study:
- To experimentally detect and confirm the spin-orbit interaction of positronium with surrounding atoms.
- To investigate the effect of magnetic fields on positronium lifetime in Xenon gas.
- To quantify the annihilation cross-section enhancement due to spin-orbit interaction.
Main Methods:
- Experiments conducted using positronium in 1 atm Xenon gas.
- Application of a 1.0 T magnetic field to observe changes in positronium lifetime.
- Measurement of the annihilation cross-section of ortho-positronium.
Main Results:
- A significant decrease in the lifetime of magnetically unperturbed ortho-positronium was observed.
- This lifetime reduction is attributed to Ps spin conversion induced by spin-orbit interaction during Ps-Xe collisions.
- The measured annihilation cross-section was found to be three times larger than theoretically predicted.
Conclusions:
- Experimental evidence confirms the existence of spin-orbit interaction in positronium.
- Spin-orbit interaction significantly influences positronium spin conversion and annihilation rates in Xenon.
- The findings necessitate a revision of theoretical models regarding positronium-atom interactions.
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