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  • Author: F. Kienzle x
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The scintillation response of anthracene crystals has been investigated with 7.0 MeV a particles within the temperature range 1.5°K < T < 300°K and with 46 MeV α particles and 24 MeV deuterons within the temperature range 11°K < T < 300°K. With decreasing crystal temperature the scintillation light yield increases towards a temperature independent but still angularly dependent limiting value reached at about 4 CK.

The angular dependence of the scintillation light yield shows a so far unknown sharp peak at particle impact directions nearly paralel to the (a, b) plane. The peak changes with crystal temperature and ionization density in a complicated manner and disappears below 10°K.

For 0.6 MeV β particles the scintillation light yield has been investigated within the temperature range 11°K < T < 300°K. It increases with decreasing temperature less steeply than the α-light yield, i. e. the α/β yield ratio increases as the crystal temperature decreases. From this it is concluded that the quenching of excitations within an ionization column is a function of the crystal temperature. Similar results have been obtained with single crystals of naphthalene.

A possible relation between the scintillation anisotropy and the anisotropy of the lattice thermal conductivity has been examined.

Abstract

Neutron reflectometry (NR) is a powerful technique for probing the structure of lipid bilayer membranes and membrane-associated proteins. Measurements of the specular neutron reflectivity as a function of momentum transfer can be performed in aqueous environments, and inversion of the resulting reflectivity data yields structural profiles along the membrane normal with a spatial resolution approaching a fraction of a nanometer. With the inherent ability of the neutron to penetrate macroscopic distances through surrounding material, neutron reflectivity measurements provide unique structural information on biomimetic, fully hydrated model membranes and associated proteins under physiological conditions. A particular strength of NR is in the characterization of structurally and conformationally flexible peripheral membrane proteins. The unique ability of neutron scattering to differentiate protium from selectively substituted deuterium enables the resolution of individual constituents of membrane-bound protein-protein complexes. Integrative modeling strategies that supplement the low-resolution reflectometry data with complementary experimental and computational information yield high-resolution threedimensional models of membrane-bound protein structures.

Structure and Dynamics
Series: De Gruyter STEM