First observation of positronium negative ions emitted from tungsten surfaces

Nagashima, Yasuyuki; Sakai, Takahiko

doi:10.1088/1367-2630/8/12/319

Cited by 47 publications

(25 citation statements)

References 23 publications

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“…In the last decade an improved method to produce Ps − ions was developed by Nagashima and co-workers in Tokyo [543][544][545]. This method is better suited to spectroscopic investigations since it is much more efficient, and the Ps ion producing surfaces are less delicate: it is unlikely that a few nm thick carbon foil would be able to survive repeated irradiation from intense laser pulses.…”

Section: Ps − Spectroscopymentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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Abstract. The field of experimental positronium physics has advanced significantly in the last few decades, with new areas of research driven by the development of techniques for trapping and manipulating positrons using Surko-type buffer gas traps. Large numbers of positrons (typically ≥10 6 ) accumulated in such a device may be ejected all at once, so as to generate an intense pulse. Standard bunching techniques can produce pulses with ns (mm) temporal (spatial) beam profiles. These pulses can be converted into a dilute Ps gas in vacuum with densities on the order of 10 7 cm −3 which can be probed by standard ns pulsed laser systems. This allows for the efficient production of excited Ps states, including long-lived Rydberg states, which in turn facilitates numerous experimental programs, such as precision optical and microwave spectroscopy of Ps, the application of Stark deceleration methods to guide, decelerate and focus Rydberg Ps beams, and studies of the interactions of such beams with other atomic and molecular species. These methods are also applicable to antihydrogen production and spectroscopic studies of energy levels and resonances in positronium ions and molecules. A summary of recent progress in this area will be given, with the objective of providing an overview of the field as it currently exists, and a brief discussion of some future directions.

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Section: Ps − Spectroscopymentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

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“…With the recent progress in microbeam fabrication, an increase in active positron research is expected. Positrons can be applied not only to the abovementioned probing techniques, but also to various unique fields: the measurement of absorbed molecules by positron-annihilationinduced ion desorption, 56 the study of positron diffusion by positron spin relaxation, 57 and more fundamental research topics, such as inner-shell ionization by positron impact, 58 positronium negative ion (Ps -) formation from a W surface, [59][60][61] and the production of antihydrogen atoms by combining antiprotons and positrons. 62 It is promising to obtain higher spatial resolutions and more precise data by utilizing positron microbeams.…”

Section: Discussionmentioning

confidence: 99%

Analytical Methods Using a Positron Microprobe

2009

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Positrons have been used for material analysis not only because of their novel characteristics, such as an ability to detect open-volume type defects in materials, but also because interactions with solids differ from those of electrons in such processes as scattering and diffraction. Monoenergetic positron beams and microbeams were developed in the 1980s, and positron experiments have made progress in material analyses. In this article we review the fundamental technique of microbeam fabrication, especially using a magnetically-guided positron beam, its extension to various analytical methods, and expectations for future research.

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“…Some of them diffuse back to the surface and contribute to the positron re-emission or Ps emission if energetically allowed. The energy required to emit Ps − from the surface, φ Ps − , can be written as [22,17] …”

Section: Ps − Formation Using Carbon Thin Filmmentioning

confidence: 99%

“…The values of φ Ps − , which are estimated to be negative for polycrystalline tungsten and W(100), show that the Ps − emission is energetically allowed. Figure 1 shows our experimental setup to observe Ps − emission [17]. Slow positrons with an energy of 0.1keV are incident onto the target, biased at −W , through an earthed grid.…”

Section: Ps − Formation Using Carbon Thin Filmmentioning

confidence: 99%