Two-dimensional analysis of positron age-momentum correlation (AMOC) data

Siegle, A.; Stoll, Hermann; Castellaz, P.; Major, J.; Schneider, Hendrik; Seeger, A.

doi:10.1016/s0169-4332(96)01043-4

Cited by 11 publications

(8 citation statements)

References 8 publications

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“…The characteristic trajectory followed by the positrons in (k, τ) space, along with the dependence of the γ spectra on the positron momentum, leads to a characteristic AMOC spectrum, i.e., the number of γ raysÑ γ (per unit positron) detected per unit time and Doppler-shifted energy. It can be measured in experiments [7,8,9,10,11,34] and calculated as…”

Section: Calculation Of the Time-varing γ Spectramentioning

confidence: 99%

“…Figure 6 shows the calculated time-varying annihilation rateZ eff (τ) [Eqn. (9), plotted using column 1 and column 3 (i.e., depletion due to annihilation included) of the output file 'zefft.coll'], and Fig. 7 the fraction of positrons surviving at time-density τ (plotted using the data in the 'ann data.coll' output file).…”

Section: Post Processingmentioning

confidence: 99%

“…Their usefulness as a probe relies on the strong positron-momentum dependence of the annihilation rate and γ spectra: epithermal annihilation manifests in a distinct 'shoulder' of the positron lifetime spectrum and of the related time-varying annihilation rate [4,5,6], and an associated distinct 'knee' in the AMOC (Age MOmentum Correlation') spectra [7,8,9,10,11,12], where the positron 'age' (i.e., lifetime from source to annihilation) is measured in coincidence with the emitted γ rays.…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, given user supplied scattering phase shifts, annihilation rates and annihilation γ spectra for the positron-atom system of interest, ANTICOOL enables the calculation of the time evolution of the positron momentum distribution f (k, t), the fraction of positrons annihilating in a given time (lifetime spectrum), and the time-varying annihilation rate and γ spectra for positrons cooling in a thermal atomic gas 2 . These quantities can be measured in positron lifetime [4,5] or AMOC experiments [7,8,9,10,11].…”

Section: Introductionmentioning

confidence: 99%

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ANTICOOL: Simulating positron cooling and annihilation in atomic gases

Green

2018

Computer Physics Communications

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The Fortran program ANTICOOL, developed to simulate positron cooling and annihilation in atomic gases below the positronium-formation threshold, is presented. Given positron-atom elastic scattering phase shifts, normalised annihilation rates Z eff , and γ spectra as a function of momentum k, ANTICOOL enables the calculation of the positron momentum distribution f (k, t) as a function of time t, the time-varying normalised annihilation rateZ eff (t), the lifetime spectrum and time-varying annihilation γ spectra. The capability and functionality of the program is demonstrated via a tutorial-style example for positron cooling and annihilation in room temperature helium gas, using accurate scattering and annihilation cross sections and γ spectra calculated using many-body theory as input. PROGRAM SUMMARYProgram Title: ANTICOOL Program Files doi: http://dx.doi.org/10.17632/kjstc6xskg.1 Licensing provisions: GPLv3 Programming language: Fortran 90 Nature of problem: Calculation of dynamics of antiparticle cooling and annihilating in atomic gases. Developed for positron cooling and annihilation in atomic gases, but easily modifiable and applicable to other binary elastic-collision cooling processes governed by quantum-mechanical cross sections. Solution method: Monte Carlo simulation. Restrictions: Elastic scattering and annihilation only: positron energies must be below the positroniumformation threshold. It is a single particle program, i.e., positron-positron interactions are not included and binary collisions with the gas atoms are assumed. $ The associated computer program and corresponding manual will be made available from the CPC library * Corresponding author. Tel: +44 (0)28 9097 1935.

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Section: Calculation Of the Time-varing γ Spectramentioning

confidence: 99%

Section: Post Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

ANTICOOL: Simulating positron cooling and annihilation in atomic gases

Green

2018

Computer Physics Communications

View full text Add to dashboard Cite

show abstract

“…The characteristic trajectory followed by the positrons in (k, τ) space, along with the dependence of the γ spectra on the positron momentum, leads to a characteristic AMOC spectrum i.e., the number of γ raysÑ γ (per unit positron) detected per unit time and Doppler-shifted energy. It can be measured in experiments [6][7][8][9][10]12] and calculated as…”

mentioning

confidence: 99%

Probing Positron Cooling in Noble Gases via Annihilation γ Spectra

Green

2017

Phys. Rev. Lett.

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γ spectra for positron annihilation in noble-gas atoms are calculated using many-body theory for positron momenta up to the positronium-formation threshold. These data are used, together with time-evolving positron-momentum distributions determined in the preceding Letter [Phys. Rev. Lett. 119, 203403 (2017)PRLTAO0031-9007], to calculate the time-varying γ spectra produced during positron cooling in noble gases. The γ spectra and their S[over ¯] and W[over ¯] shape parameters are shown to be sensitive probes of the time evolution of the positron momentum distribution and thus provide a means of studying positron cooling that is complementary to positron lifetime spectroscopy.

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Positron Spectroscopy

Coleman

2009

Digital Encyclopedia of Applied Physics

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An overview of the historical development of positron spectroscopy as a probe of condensed matter on the atomic and nano‐scale is followed by an introduction to the fundamentals of positron annihilation and interactions with condensed matter. The experimental techniques of positron lifetime and Doppler broadening spectroscopies, angular correlation of annihilation radiation, and their derivatives, are presented. The development of positron beams of controllable energy for the study of surfaces, interfaces and thin films and layers is described. Finally, examples are given which illustrate how the application of positron annihilation spectroscopy to probe the electronic structure of materials–in the bulk or at or near the surface–yields information not only of a fundamental nature, but also on technologically‐important structural, chemical and electronic properties such as open‐volume defects, nano‐structures, free volumes and phase changes.

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Two-dimensional analysis of positron age-momentum correlation (AMOC) data

Cited by 11 publications

References 8 publications

ANTICOOL: Simulating positron cooling and annihilation in atomic gases

ANTICOOL: Simulating positron cooling and annihilation in atomic gases

Probing Positron Cooling in Noble Gases via Annihilation γ Spectra

Positron Spectroscopy

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