Profiles and absorption coefficients of positrons implanted in solids from radioactive sources

Mourino, Manuel; Löbl, H.; Paulin, R.

doi:10.1016/0375-9601(79)90890-9

Cited by 46 publications

(29 citation statements)

References 4 publications

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“…It is well visible that the positron implantation range depends not only on the density of implanted material. Mourino et al [10] proposed to include into the empirical relation also the atomic number of implanted material. One should note that the proposed description of our experimental data is only a crude approximation.…”

Section: The Positron Distributionmentioning

confidence: 99%

Detection of Positron Implantation Profile in Different Materials

Dryzek

2005

Acta Phys. Pol. A

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The objective of this paper is experimental studies of the linear absorption coefficient, or mean penetration depth of positrons emitted from 22 Na isotope in different materials. For this purpose we constructed a new experimental setup which allows us to scan the depth implantation profile of positrons. For the studied metals: Mg, Al, the obtained values of mean penetration depth coincide well with those which can be calculated using the mathematical formula commonly used but for Si and S the discrepancy has been observed similarly like for polymers.

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Section: The Positron Distributionmentioning

confidence: 99%

Detection of Positron Implantation Profile in Different Materials

Dryzek

2005

Acta Phys. Pol. A

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“…2 The values of the mass absorption coefficient (solid circles) versus the atomic number for selected materials. The dashed lines represent the dependencies proposed by Mourino et al [2]. The solid lines represent the equations (3) and (4) being the best least square fit to the experimental points.…”

Section: Discussionmentioning

confidence: 96%

“…Mourino et al [2] found a weak dependence of the mass absorption coefficient on the atomic number, Z, of the absorber. Sucha [3] and others authors pointed out that the exponential decay law is valid only below a critical depth, the role of the backscattered positrons in the formation of the profile were also established.…”

Section: Introduction Positrons Emitted In a βmentioning

confidence: 98%

Experimental studies of beta positron implantation profiles in condensed matter

Dryzek

2007

Phys. Status Solidi (c)

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PACS 78.70.BjThe results of the new measurements of the linear absorption coefficient for positrons emitted from 22 Na and 68 Ge\68 Ga sources are presented. As a result, improvements were made to the well-known Gleason et al. (G. I. Gleason et al., Nucleonics 8, 12 (1951) [1]) formula giving the value of the mass absorption coefficient. It was shown that this coefficient depended not only on the maximum energy of emitted positrons but also on the atomic number the implanted absorber and exhibited an oscillatory dependence on atomic number for heavy absorbers. Introduction Positrons emitted in a β+ decay have energies from almost zero up to a definite maximum. Except for very high energy (greater than several MeV) the main slowing-down interaction is with the electrons of the matter through which the particle passes. In matter, due to its small mass, the positron makes fewer collisions in a given distance, travels a large distance, is deflected easily and so does not travel in straight lines. The combination of the tortuous trajectory and continuous distribution of energy indicates that the positrons do not show a definite range but are absorbed approximately exponentially as a function of the penetration depth. It is common knowledge that the penetration depth profile is characterized by only one physical parameter -the linear absorption coefficient -α + . Such conclusions were established over fifty years ago supported by a transmission experiment, where positrons passed thought thin foils of different thickness. From this experiment Gleason et al. [1] proposed that the linear absorption coefficient depends only on the maximum energy of implanted positrons and density of the matter as follows:

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“…Figure 1 shows the calculated implantation profile for our 200 µm thick tungsten samples using the formula from Mourino, et al [14]. At a depth of 58.7 µm, 95% of 22 Na positrons annihilate in our tungsten samples, and less than 0.004% of positrons survive at a depth of 200 µm.…”

Section: Analysis Techniques 221 Doppler-broadening Positron Annihmentioning

confidence: 99%

“…Consequently, the mean energy of this energy spectrum is often used to calculate the penetration depth in samples. We have chosen the method by Mourino et al to calculate positron penetration depth [13], which takes into account material density, atomic number, and the positron mean energy [14].…”

Section: Analysis Techniques 221 Doppler-broadening Positron Annihmentioning

confidence: 99%

Development of positron annihilation spectroscopy for characterizing neutron irradiated tungsten

et al. 2014

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Tungsten samples (6 mm diameter, 0.2 mm thick) were irradiated to 0.025 and 0.3 dpa with neutrons in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory as part of the US/Japan TITAN collaboration. Samples were then exposed to deuterium plasma in the Tritium Plasma Experiment (TPE) at 100, 200 and 500ºC to a total fluence of 1 x 10 26 m -2 . Nuclear reaction analysis (NRA) and Doppler broadening positron annihilation spectroscopy (DB-PAS) were performed at various stages to characterize radiation damage and retention. We present first results of neutron irradiated tungsten characterized by DB-PAS in order to study defect concentration. Two positron sources, 22 Na and 68 Ge, probe ~58 µm and through the entire 200 µm thick samples, respectively. DB-PAS results reveal clear differences between the various irradiated samples. These results, and a correlation between DB-PAS and NRA data are presented.

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Profiles and absorption coefficients of positrons implanted in solids from radioactive sources

Cited by 46 publications

References 4 publications

Detection of Positron Implantation Profile in Different Materials

Detection of Positron Implantation Profile in Different Materials

Experimental studies of beta positron implantation profiles in condensed matter

Development of positron annihilation spectroscopy for characterizing neutron irradiated tungsten

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