Construction and testing of the instrument for neutron holographic study at the Budapest Research Reactor

Abstract

Neutron scattering device dedicated to neutron holography experiments is described. The device is operating at a constant wavelength prepared by a double focusing monochromator. It is equipped by highly efficient shielding, proper collimator, Eulerian cradle, monitor detector, gamma-ray, and neutron detectors as well. Relevant software serves as control for the measurement and data collection. The harmonized application of the components enumerated above makes our device extremely efficient and unparalleled. Two atomic resolution neutron holographic experiments carried out illustrate the efficiency and power of the instrument.

Imaging local magnetic structure by polarized neutron holography

“…The magnetic moments in the z = c/2 plane are also reconstructible and produce clear spots in the reconstructed image. The image of the magnetic moments of Cr 3+ ions in planes at c = z/8 and z = 3c/8 was blurry, because the intensity of these atoms is suppressed by a factor of 2 due to the holographic symmetry [37] and the distance between two neighbouring atoms is only 1.5 Å, thus the side oscillations of the peaks overlap. The magnetic form factor of Cr 3+ is considerably narrower than the magnetic form factor of Cu 2+ which also encumber the reconstruction of Cr 3+ ions.…”

Application of neutron holography to polycrystalline samples

“…( 8). In some particular applications it is enough to observe some of the closest neighbors [8,16]. In most cases the determination of interstitial site occupied by an impurity atom can be made using the first neighbors, and the lattice distortions are also decreasing rapidly with increasing distance from the impurity atom.…”