Low-Energy Positron Diffraction from a Cu(111) Surface

Rosenberg, I. J.; Weiss, A. H.; Canter, K. F.

doi:10.1103/physrevlett.44.1139

Cited by 98 publications

(31 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some examples include new measurements of the Ps ground state hyperfine interval that may solve the long-standing discrepancy between theory and experiment [81], the resolution of the (perhaps related) positronium "lifetime puzzle" [82,83], advances in positron scattering from atoms and molecules [84][85][86], antihydrogen research [87][88][89][90], positron beam [91][92][93] and trap [66,69] development, materials science [65,94], and surface physics [95] (including positron diffraction [96,97] and positron induced Auger emission [98,99]). These areas, and others, will not be discussed here.…”

Section: Introductionmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental progress in positronium laser physics

2018

View full text Add to dashboard Cite

show abstract

“…16 Since the positron's charge is opposite to that of the electron, the interactions of positrons with a surface are substantially different from those of electrons. Some of the advantages of LEPD over LEED are that the elastic mean free path of a positron is predicted to be 30% less than that of an electron at 50 eV, and 5% less by 100 eV, and that no exchange-correlation term arises in positron-electron scattering.…”

Section: ·2 Low-energy Positron Diffraction (Lepd)mentioning

confidence: 99%

“…Greif et al reduced the size of the 22 Na source to 0.3 mm in diameter by depositing the source onto a non-radioactive support; they achieved a beam size of 20 × 37 μm while utilizing SEM optics. 22,23 However, the brightness of a typical electron gun with a LaB6 cathode exceeds by a factor of 10 16 that of a positron beam emitted from the combination of a W moderator and a 1 GBq 22 Na source. 24 Therefore, a focusing method using several magnetic lenses is not effective for fabricating a positron microbeam.…”

Section: Positron Microbeam Formationmentioning

confidence: 99%

“…A W mesh or a parallel arrangement of W foils has often been used as the target, which is called a "moderator". 16 Solid neon has also been used as a moderator owing to its high conversion efficiency of ~10 -3 , but some epithermal positrons are involved. 17 The efficiency and the positron beam profile also play crucial roles in the development of a remoderator (see next section).…”

Section: Generation Of Monoenergetic Positron Beamsmentioning

confidence: 99%

See 1 more Smart Citation

Analytical Methods Using a Positron Microprobe

2009

View full text Add to dashboard Cite

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.

show abstract

“…Only two preliminary studies have been performed on low energy positron diffraction (30,31) and much work is needed in this area. The spatial dimensions of the positron beam are important to diffraction studies and brightness enhancement would be useful in developing this potentially useful technique.…”

Section: Proposed Experimentsmentioning

confidence: 99%

Intense Positron Beams and Possible Experiments

Lynn

Frieze

1984

Positron Scattering in Gases

View full text Add to dashboard Cite

INTRODUCTIONIn this paper, we will survey some of the ideas that have been propcsed regarding the production of intense beams of low energy positrons. Various facilities to produce beams of this type are already under design or construction and other methods beyond those in use have been previously discussed.(1) Moreover, a variety of potential experiments utilizing intense positron beams have been suggested. It is to be hoped that this paper can serve as a useful summary of some of the current ideas, as well as a stimulation for new ideas to be forthcoming at the workshop.We begin with a general description of the development of variable energy positron beams to date. A second section will emphasize the intense positron beams currently being bui^t. Particular advantages and disadvantages will be discussed for the methods to be used to produce positrons for these beams. Emphasis will be placed on the beam under construction at the High Flux Beam Reactor (HFBR) at Brookhaven. The third section of the paper will briefly sketch some of the new condensed matter experiments that will be possible in the future owing to the increased positron current. Some of these proposed experiments are feasible immediately, while others must await implementation of certain technological developments (such as brightness enhancement) (2) for their completion. PRESENT BEAMSWe make the distinction in this paper between laboratory based beans, which are completely self-contained and utilize a dedicated positron source, and facility based beams, which utilize an accelerator or reactor to provide an intense source of positrons. Slow positron experiments have thus far been done almost exclusively using laboratory based beams in which the number of particles varies from 10 to 5x10 per sec. This current of positrons is suitable for a large class of experiments as is demonstrated by the many measurements that have been done using them already (1,3). Some measurements however, do require higher positron rates and for these the new, intense beams are necessary.Operationally, we will define intense positron beams as those that will supply more positrons than any presently existing laboratory beam using standard radioactive isotope sources (i.e. Co , Band Na ). This definition is not strictly correct as sometimes facility based beams can have characteristics such as time bunching which can make them ideally suited for certain experiments even though the average current may be less than a standard laboratory beam.The beams presently in use can be classified based on the source of the positrons, the type of moderator employed, and the transport system used, i.e. magnetic or electrostatic. In this paper we will not discuss general moderator development. Suffice it to say that low defect density polycrystalline (4) or single crystal (5) W samples appear to yield the largest moderation efficiencies as of this writing. Some recent experiments at Brookhaven seem to indicate that Pt(100) + CO (6) may also be competitive with single crystal W.The type of ...

show abstract

Low-Energy Positron Diffraction from a Cu(111) Surface

Cited by 98 publications

References 10 publications

Experimental progress in positronium laser physics

Experimental progress in positronium laser physics

Analytical Methods Using a Positron Microprobe

Intense Positron Beams and Possible Experiments

Contact Info

Product

Resources

About