Polarized neutron reflectometry at the IBR-2 pulsed reactor
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ODS AND INSTRUMENTS OF NEUTRON EXPERIMENTS
Polarized Neutron Reflectometry at the IBR-2 Pulsed Reactor V. L. Aksenova, b and Yu. V. Nikitenkob a
Russian Research Centre “Kurchatov Institute,” pl. Akademika Kurchatova 1, Moscow, 123182 Russia b Joint Institute for Nuclear Research, ul. Zholio Kyuri 6, Dubna, Moscow oblast, 141980 Russia e-mail: [email protected] Received November 20, 2006
Abstract—Polarized neutron reflectometry as a method for investigating layered nanostructures and its implementation at the IBR-2 pulsed reactor (Dubna, Russia) are described. The experimental data illustrating the studies of magnetic layered nanostructures and the development of the method of polarized neutron reflectometry on the polarized neutron spectrometer are presented. The directions of further development of the method of polarized neutron reflectometry are analyzed. PACS numbers: 61.12.-q DOI: 10.1134/S1063774507030376
1. INTRODUCTION
2. POLARIZED NEUTRON REFLECTOMETRY
In 1946, Fermi [1] discovered the specular neutron reflection from materials. Already in 1951, Hughes and Burgy used a magnetic mirror to produce polarized neutrons [2]. However, only in 1981 did there appear the first publications concerned with the application of the method based on specular neutron reflection for investigating surfaces and interfaces in solids [3, 4]. At the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research (Dubna, Russia), Korneev and colleagues [5] were the first to use neutron reflection in measurements of the transmission of mirror magnetic neutron guides at the IBR-30 reactor. Research on neutron reflectometry with polarized neutrons (polarized neutron reflectometry) was continued in 1986 shortly after the IBR-2 high-flux pulsed reactor was put into operation at the Laboratory of Neutron Physics of the Joint Institute for Nuclear Research. The investigations were carried out on a polarized neutron spectrometer that was designed for depolarization studies of ferromagnets with the use of the polarization equipment modern at that time, such as the polarizer and polarization analyzer with an FeCo/TiGd bilayer and the Korneev spin flipper with an extended working area [6].
Over a period of twenty years, considerable progress has been made in the development of neutron reflectometry on the IBR-2 pulsed neutron source. Measurements have been performed with an improved broadbandness, an increased luminosity, a higher sensitivity, and a better accuracy in the determination of parameters of magnetic structures. There have appeared new possibilities for studying imperfections and inhomogeneities of nanostructures. New reflectometers intended for performing investigations with an angstrom resolution and determining vibrational spectra of “soft” layered structured have been designed. 2.1. Measurement Scheme The scheme designed for measuring magnetically noncollinear layered structures has become conven-
The experiments performed in 1989 on the determination of the depth of penetration of a magnetic field into
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