Relationship between Enhanced Positronium Formation and Enhanced Positron Trapping in Polymers at Low Temperature

• Authors: J. Kansy , T. Suzuki
• Languages of publication: EN

Abstracts

EN

Positron annihilation lifetime spectroscopy is used for investigation of low-density polyethylene and ethylene-methyl methacrylate copolymers of 1.45, 3.0, and 5.4 mole% of methyl methacrylate. The lifetime spectra are collected at 30 K, one by one, as a function of elapsed time. In the computer analysis a new theoretical model is developed, which enables separating the annihilation from positron free state, its trapped state and bound state in positronium. The positron trapping rateμ and the enhanced positronium formation rateκ are determined. The calculated values of μ andκ turned out to be linearly correlated. This correlation presumably originates from an influence of trapped electrons on the trapping of positrons. The dependences ofκ on measurement time are determined for low-density polyethylene and ethylene-methyl methacrylate of different methyl methacrylate content. A theoretical model describing quantitatively the dependences is proposed. The model considers the processes of electron-ion recombination, electron trapping, and electron scavenging by dipolar carbonyl groups supplied by methyl methacrylate additives.

Keywords

EN

78.70.Bj; 71.60.+z; 61.80.Fe

Discipline

• 71.60.+z: Positron states(for positron annihilation, see 78.70.Bj)
• 78.70.Bj: Positron annihilation(for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
• 61.80.Fe: Electron and positron radiation effects

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2006
• Volume: 110
• Issue: 5
• Pages: 593-604

Dates

published

2006-11

received

2006-06-05

Contributors

author

J. Kansy

• Institute of Material Science, Silesian University, Bankowa 12, 40-007 Katowice, Poland

author

T. Suzuki

• High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan

References

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Identifiers

DOI

10.12693/APhysPolA.110.593