Lifetime Measurements with a Scanning Positron Microscope

David, Armin; Kögel, G.; Sperr, P.; Triftshäuser, W.

doi:10.1103/physrevlett.87.067402

Cited by 81 publications

(49 citation statements)

References 19 publications

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“…Because the re-emitted positrons have a much smaller energy spread than the incident ones, they can be refocused to a smaller spot size. The technique can be repeated several times to produce beams suitable for positron microscopy (David et al, 2001) or to create high positron densities. A gas-phase remoderator with an efficiency of 4% has also been developed (Loewe et al, 2008(Loewe et al, , 2010.…”

Section: Remoderation and Brightness Enhancementmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

233

222

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In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 10 2 to less than 10 −3 eV. Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasi-monoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

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Section: Remoderation and Brightness Enhancementmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

233

222

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“…They are a very sensitive probe of the presence of defects in materials [6]. The recent development of a scanning positron microscope [7] may lead to an increased use of positrons for quality control of materials, particularly in the semiconductor industry. In medicine, positron emission tomography, or PET, has become a standard means of medical imaging (see, e.g., [8]).…”

Section: Introductionmentioning

confidence: 99%

Many-body theory of positron-atom interactions

2004

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A many-body theory approach is developed for the problem of positron-atom scattering and annihilation. Strong electron-positron correlations are included non-perturbatively through the calculation of the electron-positron vertex function. It corresponds to the sum of an infinite series of ladder diagrams, and describes the physical effect of virtual positronium formation. The vertex function is used to calculate the positron-atom correlation potential and nonlocal corrections to the electron-positron annihilation vertex. Numerically, we make use of B-spline basis sets, which ensures rapid convergence of the sums over intermediate states. We have also devised an extrapolation procedure that allows one to achieve convergence with respect to the number of intermediate-state orbital angular momenta included in the calculations. As a test, the present formalism is applied to positron scattering and annihilation on hydrogen, where it is exact. Our results agree with those of accurate variational calculations. We also examine in detail the properties of the large correlation corrections to the annihilation vertex.

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“…Scanning positron microscopes (SPM) have been developed to apply PAS to very small samples or samples with small features of interest [3][4][5][6][7]. Slow positron beams of SPMs focus on samples where the beam spot size is less than a few tens of µm.…”

Section: Introductionmentioning

confidence: 99%

“…The advantage of such a SPM is that it can obtain two or three dimensional PAS images using the scanning lateral injection position (xy) and the implantation depth (z) of the focused beams, which allow the defect distributions to be visually evaluated. The AIST microbeam system [8] uses an electron linear accelerator (LINAC) to produce positrons [9,10], and consequently, its beam intensity (10 6 e + /s) is 10-100 times higher than those of the other SPMs [3][4][5][6], which use radioisotopes as the positron source. Therefore, the AIST microbeam system can obtain PAS images within a reasonable time (~10 3 pixels/hour) [11] and hence, SPM may be a practical tool.…”

Section: Introductionmentioning

confidence: 99%

Development of Positron Microbeam in AIST

Oshima

Suzuki

Ohdaira

et al. 2008

MSF

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Abstract. To improve the spatial resolution of positron annihilation spectroscopy (PAS), a system to produce an intense positron microbeam was developed in AIST. A slow positron beam, which was produced by an electron linear accelerator, was focused by a lens onto a remoderator to enhance its brightness. The brightness-enhanced beam with an intensity of ≈1 × 10 6 e + /s was extracted from the remoderator and focused onto the sample by a lens. The beam size at the sample was 25 µm, which is more than two and half orders of magnitude smaller than that in the magnetic transport system (≈10 mm). Hence, the spatial resolution of PAS with an AIST positron microbeam can be drastically improved relative to PAS using conventional methods.

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Lifetime Measurements with a Scanning Positron Microscope

Cited by 81 publications

References 19 publications

Plasma and trap-based techniques for science with positrons

Plasma and trap-based techniques for science with positrons

Many-body theory of positron-atom interactions

Development of Positron Microbeam in AIST

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