Theory of coherent neutron scattering by hydrogen-bonded ferroelectrics at low temperatures. I. General expression for inelastic coherent scattering of slow neutrons and effective thermal factors

1972 ◽  
Vol 9 (5-6) ◽  
pp. 475-483 ◽  
Author(s):  
S. Stamenković
Keyword(s):  
Neutron Scattering ◽  
General Expression ◽  
Low Temperatures ◽  
Coherent Scattering ◽  
Slow Neutrons ◽  
Hydrogen Bonded

Amplituden für kohärente Neutronen-Streuung gemessen an chemischen Verbindungen / Coherent Neutron Scattering Amplitudes Obtained from Chemical Compounds

1972 ◽  
Vol 27 (6) ◽  
pp. 901-905 ◽  
Author(s):  
L. Koester ◽  
K. Knopf
Keyword(s):  
Scattering Amplitudes ◽  
Neutron Scattering ◽  
Small Angle ◽  
Good Accuracy ◽  
Chemical Compounds ◽  
Coherent Scattering ◽  
Small Angle Scattering ◽  
Angle Scattering ◽  
Slow Neutrons

Abstract Coherent Neutron Scattering Amplitudes Obtained from Chemical Compounds Utilizing the small angle scattering of slow neutrons by Christiansen-filters we could determine with a good accuracy the scattering amplitudes of powders by comparing with wellknown liquids. Investigations on powders of halides and sulfates yielded coherent scattering amplitudes of the bound atoms (in 10-13 cm) : a (Na) = 3.63 ±0.02; a(K) =3.71 ±0.02; a (Rb) =7.08 ± 0.02; a (Cs) = 5.42 ± 0.02; a(Tl) =8.89 ±0.02; a (Br) =6.77 ±0.02; and a (I) =5.28 ±0.02. The scattering amplitudes of the liquids and the elements as standards are based on directly determined amplitudes from gravity-mirror measurements.

Lattice frequency spectra of Pb and Pb40Tl60 by neutron spectrometry

1970 ◽  
Vol 48 (15) ◽  
pp. 1781-1788 ◽  
Author(s):  
A. P. Roy ◽  
B. N. Brockhouse
Keyword(s):  
Force Constant ◽  
Direct Evidence ◽  
Coherent Scattering ◽  
Neutron Spectrometry ◽  
Frequency Spectra ◽  
Polycrystalline Specimen ◽  
Lattice Frequency ◽  
Slow Neutrons

Lattice frequency spectra of Pb and Pb40Tl60 have been measured at 90 °K by inelastic coherent scattering of slow neutrons from a polycrystalline specimen. The results compare favorably with the tunneling measurements of Rowell, McMillan, and Feldman. In Pb40Tl60 we see direct evidence of energy smearing arising from the finite lifetimes of the phonons caused by force-constant disorder in the alloy.

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