Progress of the EPOS project: Gamma‐induced Positron Spectroscopy (GiPS)

Krause‐Rehberg, R.; Anwand, W.; Bräuer, G.; Butterling, Maik; Cowan, T. E.; Hartmann, Andreas; Jungmann, Marco; Krille, Arnold; Schwengner, R.; Wagner, A.

doi:10.1002/pssc.200982076

Cited by 9 publications

(6 citation statements)

References 5 publications

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“…Henceforth, it is implied that positron trapping or annihilation at dislocation means annihilation at vacancies associated with dislocations. Present lifetime value is in consistent with reported experimental value of 158 ps for deformed Fe 32 . This lifetime remains constant till 523 K and starts decreasing sharply beyond 673 K. The decrease in lifetime between 523 and 823 K can be understood as annealing of dislocations along with associated vacancies.…”

Section: Resultssupporting

confidence: 92%

Dislocation Driven Chromium Precipitation in Fe-9Cr Binary Alloy: A Positron Lifetime Study

Babu,

Rajaraman,

Amarendra

et al. 2011

Preprint

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The influence of initial heat treatment on anomalous Cr precipitation within high temperature solubility region in Fe-9Cr alloy has been investigated using positron lifetime studies. Air-quenched samples with pre-existing dislocations exhibited a distinct annealing stage in positron lifetime between 800 and 1100 K corresponding to Cr-precipitation. During this stage, Transmission Electron Microscopy showed fine precipitates of average size 4 nm, dispersed throughout the sample and from EDS analysis they are found to be Cr-enriched. The existence of dislocations is found to be responsible for Cr precipitation.

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Section: Resultssupporting

confidence: 92%

Dislocation Driven Chromium Precipitation in Fe-9Cr Binary Alloy: A Positron Lifetime Study

Babu,

Rajaraman,

Amarendra

et al. 2011

Preprint

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“…(iii) It was demonstrated that bremsstrahlung can be used to produce positrons directly in the sample [74]. Hence the master clock of the linac, which produces intense bursts of γ radiation, can serve to trigger the time measurement [75].…”

Section: Pulsed Beamsmentioning

confidence: 99%

Positrons in surface physics

Hugenschmidt¹

2016

Surface Science Reports

127

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Within the last decade powerful methods have been developed to study surfaces using bright low-energy positron beams. These novel analysis tools exploit the unique properties of positron interaction with surfaces, which comprise the absence of exchange interaction, repulsive crystal potential and positron trapping in delocalized surface states at low energies. By applying reflection highenergy positron diffraction (RHEPD) one can benefit from the phenomenon of total reflection below a critical angle that is not present in electron surface diffraction. Therefore, RHEPD allows the determination of the atom positions of (reconstructed) surfaces with outstanding accuracy. The main advantages of positron annihilation induced Auger-electron spectroscopy (PAES) are the missing secondary electron background in the energy region of Auger-transitions and its topmost layer sensitivity for elemental analysis. In order to enable the investigation of the electron polarization at surfaces low-energy spin-polarized positrons are used to probe the outermost electrons of the surface. Furthermore, in fundamental research the preparation of well defined surfaces tailored for the production of bound leptonic systems plays an outstanding role. In this report, it is envisaged to cover both, the fundamental aspects of positron surface interaction and the present status of surface studies using modern positron beam techniques.

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“…Such a measurement is difficult using a slow (∼keV) positron beam. In recent years, PAS for bulk materials via Gamma-induced Positron Spectroscopy (GiPS) has been developed [5][6][7][8][9][10][11][12][13][14]. In GiPS, a high energy photon is implanted into the sample and positron generation and annihilation occurs inside the sample directly.…”

Section: Introductionmentioning

confidence: 99%

Gamma-induced positron spectroscopy for bulk materials using a MeV energy LCS gamma-ray beam

Sugita¹,

Miyamoto

Terasawa

et al. 2023

JJAP Conf. Proc.

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We have developed a Doppler broadening measurement Gamma-induced Positron Spectroscopy (GiPS) system, and performed a demonstration measurement for cm size Zr based amorphous and crystallized alloys using a laser Compton scattering (LCS) gamma-ray beam with a maximum energy of 16.9 MeV at the NewSUBARU synchrotron radiation facility, Hyogo, Japan. This method makes use of positrons generated inside the sample by implantation of highly energetic gamma-ray photons. GiPS can be a non-destructive measurement for bulk size material in air. In this study, the result of the Doppler broadening measurement is in good agreement with the density change caused by crystallization.

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Progress of the EPOS project: Gamma‐induced Positron Spectroscopy (GiPS)

Cited by 9 publications

References 5 publications

Dislocation Driven Chromium Precipitation in Fe-9Cr Binary Alloy: A Positron Lifetime Study

Dislocation Driven Chromium Precipitation in Fe-9Cr Binary Alloy: A Positron Lifetime Study

Positrons in surface physics

Gamma-induced positron spectroscopy for bulk materials using a MeV energy LCS gamma-ray beam

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