THE ENERGY-DEPENDENCE OF THE POSITRONIUM FORMATION CROSS-SECTION IN HELIUM

被引：52

作者：

OVERTON, N

MILLS, RJ

COLEMAN, PG

机构：

来源：

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS | 1993年 / 26卷 / 21期

关键词：

D O I：

10.1088/0953-4075/26/21/027

中图分类号：

O43 [光学];

学科分类号：

070207 ; 0803 ;

摘要：

The total cross section for positronium formation in helium for positrons of energies E from threshold (17.8 eV) to 250 eV has been measured using a gas cell transmission method. The results indicate that the cross section above E = 60 eV is satisfactorily described by 0.5e(-0.02E)pia0(2), tending to zero at energies close to 200 eV. The approximate description of the cross section at intermediate energies, falling as E-2.5, is consistent with a number of recent theoretical predictions but is in conflict with earlier experiments, which show an E-1 behaviour. The implications of these measurements are discussed, with particular reference to the observed merging of the total cross sections for positron- and electron-helium scattering at intermediate energies.

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页码：3951 / 3957

页数：7

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