Kohn Anomaly and Coherent Scattering of Slow Neutrons in Liquid Metals

1965 ◽  
Vol 15 (17) ◽  
pp. 693-694
Author(s):  
K. S. Singwi ◽  
Lars-Erik Andersson
1970 ◽  
Vol 48 (15) ◽  
pp. 1781-1788 ◽  
Author(s):  
A. P. Roy ◽  
B. N. Brockhouse

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.


The neutron velocity selector of the Cavendish Laboratory has been used to measure the scattering cross-sections of ortho- and para -hydrogen for slow neutrons. The triplet and singlet scattering amplitudes of the neutron-proton interaction may be deduced from these cross-sections. The values obtained are a t = (0·537 ± 0·004) x 10 -12 cm, a s = -(2·373 ±0·007) x 10 -12 cm, where a t and a s are the triplet and singlet scattering amplitudes respectively. The values of the coherent scattering amplitude ƒ = 2(3/4 a +1/4 a ), and of the free proton cross-section σ ƒ = 4π(3/4 a 2 t + 1/4 a 2 s given by the above values of a t and a s , are ƒ = -(0·380 ± 0·005) x 10 -12 cm, σ ƒ = (20·41 ± 0·14) x 10 -24 cm 2 .


1972 ◽  
Vol 27 (6) ◽  
pp. 901-905 ◽  
Author(s):  
L. Koester ◽  
K. Knopf

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.


Physica ◽  
1965 ◽  
Vol 31 (8) ◽  
pp. 1257-1285 ◽  
Author(s):  
K.S. Singwi

1964 ◽  
Vol 136 (4A) ◽  
pp. A969-A980 ◽  
Author(s):  
K. S. Singwi

1977 ◽  
Vol 10 (24) ◽  
pp. 4901-4907
Author(s):  
R Bansal ◽  
J Naghizadeh

Sign in / Sign up

Export Citation Format

Share Document