Nuclear Instruments and Methods 199 (1982) 371 371 North-Holland Publishing Company ELECTRON MOMENTUM DISTRIBUTION IN AMORPHOUS METALS INVESTIGATED BY POSITRON ANNIHILATION K. KRISTIAKOVA and J. KRISTIAK Institute of Physics SA Sc, 89930 Bratislava, Czechoslovakia P. GALAN Institute of Preventive Medicine, Bratislava, Czechoslovakia Abstract Electron momentum distribution in amorphous metals and the crystalline form of NixFe80_xB20 (x = 10, 20, 30, 40) were investigated by positron annihilation. The samples were 30 mm thick ribbons, produced by rapid quenching of liquid metal on a rotating Cu wheel. The positron source was 22Na on mylar or blotting paper between two samples in sandwich arrangement. The 3,-radiation was detected by a Ge(Li) detector which has a resolution at 511.9 keV (l°6Ru) of 1.6 keV. An unfolding method based on Bayes principle was applied to calculate the Doppler-broadening; S-parameter values were also determined. The calculated momenturfi distributions revealed a difference for the Ni30FesoB20 sample. THE SURFACE BORON CONCENTRATION OF NixFeso_xB2o SAMPLES K. KRISTIAKOVA and J. KRISTIAK Institute of Physics SA Se, 89930 Bratislava, Czechoslovakia J. KVITEK * and J. CERVENA Institute of Nuclear Physics, 2506 Rez near Prague, Czechoslovakia Abstract The boron concentration of Ni,Fes0_xB2o (x = 10, 20, 30, 40) metallic glasses was measured using the nuclear reaction l°B(nth, 4He)VLi. The samples used were 30 mm thick ribbons prepared by rapid quenching of liquid metal on a rotating Cu wheel. Irradiation was performed by the thermal beam of the INP reactor, (flux 5 × 108 n/cm2s, time of irradiation 10 min). The a-particles were detected by a Si semiconductor detector with a surface barrier. The resolution of the system was 20 keV. The boron concentration was determined from the spectrum of o~-particles (E,, = 1471 keV). The amount of boron up to 0.4 mm was found to be constant with no concentration profile. Differences in B concentration were found, viz. there were more B atoms at the surface. 0167-5087/82/0000-0000/$02.75 © 1982 North-Holland vI. STRUCTURAL PROBLEMS

Electron momentum distribution in amorphous metals investigated by positron annihilation

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Nuclear Instruments and Methods 199 (1982) 371 371 North-Holland Publishing Company

E L E C T R O N M O M E N T U M D I S T R I B U T I O N IN A M O R P H O U S METALS INVESTIGATED BY P O S I T R O N A N N I H I L A T I O N

K. K R I S T I A K O V A and J. K R I S T I A K Institute of Physics SA Sc, 89930 Bratislava, Czechoslovakia

P. G A L A N Institute of Preventive Medicine, Bratislava, Czechoslovakia

Abstract

Electron momentum distribution in amorphous metals and the crystalline form of NixFe80_xB20 (x = 10, 20, 30, 40) were investigated by positron annihilation. The samples were 30 mm thick ribbons, produced by rapid quenching of liquid metal on a rotating Cu wheel. The positron source was 22Na on mylar or blotting paper between two samples in sandwich arrangement. The 3,-radiation was detected by a Ge(Li) detector which has a resolution at 511.9 keV (l°6Ru) of 1.6 keV.

An unfolding method based on Bayes principle was applied to calculate the Doppler-broadening; S-parameter values were also determined.

The calculated momenturfi distributions revealed a difference for the Ni30FesoB20 sample.

THE SURFACE BORON CONCENTRATION OF NixFeso_xB2o SAMPLES

K. K R I S T I A K O V A and J. K R I S T I A K Institute of Physics SA Se, 89930 Bratislava, Czechoslovakia

J. KVITEK * and J. CERVENA Institute of Nuclear Physics, 2506 Rez near Prague, Czechoslovakia

Abstract

The boron concentration of Ni,Fes0_xB2o (x = 10, 20, 30, 40) metallic glasses was measured using the nuclear reaction l°B(nth, 4He)VLi. The samples used were 30 mm thick ribbons prepared by rapid quenching of liquid metal on a rotating Cu wheel. Irradiation was performed by the thermal beam of the INP reactor, (flux 5 × 108 n/cm2s, time of irradiation 10 min). The a-particles were detected by a Si semiconductor detector with a surface barrier. The resolution of the system was 20 keV. The boron concentration was determined from the spectrum of o~-particles (E,, = 1471 keV). The amount of boron up to 0.4 mm was found to be constant with no concentration profile. Differences in B concentration were found, viz. there were more B atoms at the surface.