Study on Bose-Einstein condensation of positronium

Shu, Kenji; Murayoshi, T.; Fan, X.; Ishida, Akira; Yamazaki, T.; Namba, T.; Asai, S.; Yoshioka, Kosuke; Kuwata‐Gonokami, Makoto; Oshima, Nobuyuki; O’Rourke, Brian; Suzuki, Ryoichi

doi:10.1088/1742-6596/791/1/012007

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…Positronium, the bound state of an electron and a positron [1,2], has been extensively investigated in fundamental physics [3][4][5]. Positronium is also expected to be a unique probe for surface electronic states because the energy and momentum distributions of positronium formed at a solid surface reflect the surface band structure [6,7].…”

Section: Introductionmentioning

confidence: 99%

Positronium formation at 4H SiC(0001) surfaces

Kawasuso

Wada

Miyashita

et al. 2020

J. Phys.: Condens. Matter

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Positronium formation at 4H SiC(0001) surfaces were investigated upon the removal of natural oxide layers by hydrofluoric acid etching and heat treatment at 1000 K in ultra-high vacuum. Two types of positronium were observed in the positronium time-of-flight (PsTOF) measurements irrespective of conduction type and surface polarity. One type formed the major part of the PsTOF spectrum with a maximum energy of 4.7 ± 0.3 eV. This energy exceeded the theoretical value calculated with valence electrons. The PsTOF spectrum shape was different from those of metal surfaces, suggesting that the surface state electrons or conduction electrons need to be considered as the positronium source. Another positronium appeared at 1000 K in the tail of the PsTOF spectrum with a maximum energy of 0.2–0.5 eV. This thermally-assisted athermal positronium may be formed via the surface state positrons and electrons.

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Section: Introductionmentioning

confidence: 99%

Positronium formation at 4H SiC(0001) surfaces

Kawasuso

Wada

Miyashita

et al. 2020

J. Phys.: Condens. Matter

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“…Cooling this atom via collisions with cold surfaces is very inefficient due to its small mass and the little time available before it decays. Laser cooling on 1S-2P transition has been proposed in 1988 [29], but has not yet been realized because of the great challenge posed by the evanescent nature of this system [30]. For the 1S-2S transition of Ps, the first order Doppler shift, can be avoided using two counter propagating laser beams as done for hydrogen [31].…”

Section: Introductionmentioning

confidence: 99%

Excitation of positronium from 2S to 20P state

Heiss,

Wichmann,

Radics

et al. 2018

Preprint

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We report the observation of positronium excitation from the 2S to the 20P state. The Rydberg positronium atoms fly a distance of 40 mm before being field ionized and detected in a micro-channel plate. The time of flight can thus be measured and the velocity distribution of the atoms excited in the 2S state is reconstructed. This is used as an input to the model of the line-shape in order to properly take into account the second order Doppler shift which is the main systematic uncertainty in the 1S-2S measurements of positronium.

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“…Positronium, the bound state of an electron and a positron [1,2], has been extensively investigated in fundamental physics [3][4][5]. Recently, some new challenges, such as positronium Bose-Einstein condensation [6] and the development of positronium beams [7], are steadily being explored. In material physics, positronium spectroscopy plays an important role in probing spin-polarized surface electronic states [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Positronium emission from GaN(0001) and AlN(0001) surfaces

Kawasuso¹,

Maekawa²,

Miyashita³

et al. 2021

J. Phys. B: At. Mol. Opt. Phys.

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Positronium emission from wurtzite GaN(0001) and AlN(0001) surfaces was observed by positronium time-of-flight spectroscopy. The positronium energy spectra contained two positronium components distinguished by their energies. Through detailed analyses based on Monte Carlo simulations, these two components were attributed to positronium formed from valence and conduction electrons. The obtained results augment the previous arguments regarding the contribution of conduction electrons to positronium emission from 4H SiC(0001) and Si(111) surfaces.

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Study on Bose-Einstein condensation of positronium

Cited by 7 publications

References 5 publications

Positronium formation at 4H SiC(0001) surfaces

Positronium formation at 4H SiC(0001) surfaces

Excitation of positronium from 2S to 20P state

Positronium emission from GaN(0001) and AlN(0001) surfaces

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