Positronium decay and formation in paraffin wax from polarized and unpolarized positrons |
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Authors: | N Gambara |
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Institution: | (1) Dipartimento di Fisica del Politecnico, 20133 Milano, Italy |
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Abstract: | Summary Ps formation and decay in heterogeneousn-alkane samples (paraffin waxes) have been studied both in the solid and in the liquid phase; then, in the solid phase, the
positron's residual degree of polarization was measured at the instant of Ps formation. Differently from what is already known
in homogeneousn-alkane samples, Ps shows, many degrees below the melting point, a mean lifetime longer than that typical of the liquid phase;
furthermore, the mean lifetime's values pertaining to the transition between solid and liquid do not show a sharp variation
across the melting temperature but gradually decrease over a range of temperatures of several degrees. Positronium decay in
static magnetic fields indicates that o-Ps magnetic quenching in liquid phase is regular, and corresponds to a contact density
value α=|ψ(0)|2/|ψ(0)|vac
2=0.79±0.07; instead, in the solid phase, o-Ps magnetic quenching shows anomalous behaviour for fields weaker than 7kG. Positrons'
residual polarization measurements do not reveal the presence of depolarization effects during the whole slowing-down process
until Ps is formed. |
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Keywords: | Positron states |
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