Energy-Resolved Positron Annihilation in Flight in Solid Targets

Weber, Marc H.; Hunt, A. W.; Golovchenko, Jene Andrew; Lynn, Kelvin G.

doi:10.1103/physrevlett.83.4658

Cited by 15 publications

(7 citation statements)

References 25 publications

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“…This data constitute the first observation of Doppler broadening due to these deep core electrons in a high Z material. In-flight two-photon annihilation with gold M-shell electrons has been detected for 70 keV positrons by recording the energy of both annihilation g rays, E T E 1 1 E 2 [18]. Since energy is conserved the binding energy of the M-shell electrons shifted the centroid in this sum energy spectrum.…”

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confidence: 99%

Doppler Broadening of In-Flight Positron Annihilation Radiation due to Electron Momentum

et al. 2001

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Doppler Broadening of In-Flight Positron Annihilation Radiation due to Electron Momentum

et al. 2001

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“…It is also evident that there is no linear Zeeman shift, since x does not appear linearly (Eqs. (27) and (28)). The dependence of the perturbed energy levels on the magnetic field are shown in Figure 4.…”

Section: Ps In Electric and Magnetic Fieldsmentioning

confidence: 99%

“…Realizing the limitations of this method, a more accurate technique was developed [23][24][25] which remains the standard method for precision hyperfine interval measurements. Deutsch later went on to perform positron annihilation in flight measurements [26] which also became antecedents of modern day measurements (e.g., [27,28]). …”

Section: Introductionmentioning

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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“…The pore size cannot be determined. Two variations of DBS involve using two germanium detectors simultaneously (coincidence-DBS) (19) or measuring the S-parameter as a function of annihilation time [age-momentum correlation (AMOC)] (20). The coincidence-DBS technique offers significantly better energy resolution, is capable of distinguishing chemical environments, and may be useful in probing the pore surface chemistry.…”

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confidence: 99%

Positron Annihilation as a Method to Characterize Porous Materials

Gidley

Peng

Vallery

2006

Annu. Rev. Mater. Res.

309

256

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Key Words porous films, pore size, low dielectric constant, positronium ■ Abstract Beam-based positron annihilation spectroscopy (PAS) is a powerful porosimetry technique with broad applicability in the characterization of nanoporous thin films, especially insulators. Pore sizes and distributions in the 0.3-30 nm range are nondestructively determined with only the implantation of low-energy positrons from a table-top beam. Depth-profiling with PAS has proven to be an ideal way to measure the interconnection length of pores, search for depth-dependent inhomogeneities or damage in the pore structure, and explore porosity hidden beneath dense layers or diffusion barriers. The capability of PAS is rapidly maturing as new intense positron beams around the globe spawn more accessible PAS facilities. After a short primer on the physics of positrons in insulators, the various probe techniques of PAS are briefly summarized, followed by a more detailed discussion of the wide range of nanoporous film parameters that PAS can characterize. 51and sensitivity to processing-induced changes. A unique strength associated with beam-based PAS is the capabilities to depth-profile by controlling the positron implantation energy and to resolve laterally by finely focusing the beam on a small spot on the target. The capability to nondestructively detect depth-dependent pore structural characteristics even when the pores are buried under barrier layers will be an increasingly attractive capability as nanoporous films and composites become more complex.

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Energy-Resolved Positron Annihilation in Flight in Solid Targets

Cited by 15 publications

References 25 publications

Doppler Broadening of In-Flight Positron Annihilation Radiation due to Electron Momentum

Doppler Broadening of In-Flight Positron Annihilation Radiation due to Electron Momentum

Experimental progress in positronium laser physics

Positron Annihilation as a Method to Characterize Porous Materials

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