Towards a Modelling of USANSPOL Intensities from Magnetic Ribbons

AbstractAmorphous magnetic ribbons represent both novel technologically relevant complex samples which are currently in the process of material development for use as magnetic sensors and actuators due to their exceptional magnetostriction properties as well as illustrative examples for developing the technique of ultra-small-angle polarised neutron scattering (USANSPOL) for the study of magnetic microstructure. We present the formalism on which the USANSPOL technique is based and highlight a potential route on which USANSPOL data analysis may be performed. Experimentally obtained scattering patterns are the results of a variety of parameters like material composition and production conditions as well as various environmental conditions, including zero-field environment, the influence of external magnetic field, mechan- ically induced stress, or a combination of both effects, and in magnetically saturated state. In the case of non-isotropic structures a two-dimensional record of the scattered neutron intensity is essential and more complexity is added by the special features of magnetic neutron scattering and the USANSPOL technique itself. In this work we concentrate on these peculiarities and describe the current experimental status which is driven by the underlying USANSPOL scat- tering formalism. Recent experimental results are presented to illustrate the phenomenological correspondence to our modelling

Wavelength-selected Neutron Pulses Formed by a Spatial Magnetic Neutron Spin Resonator

AbstractWe present a novel type of spatial magnetic neutron spin resonator whose time and wavelength resolution can be de- coupled from each other by means of a travelling wave mode of operation. Combined with a pair of highly efficient polarisers such a device could act simultaneously as monochromator and chopper, able to produce short neutron pulses, whose wavelength, spectral width and duration could be varied almost instantaneously by purely electronic means with- out any mechanical modification of the experimental setup. To demonstrate the practical feasibility of this technique we have designed and built a first prototype resonator consisting of ten individually switchable modules which allows to produce neutron pulses in the microsecond regime. It was installed at a polarised 2.6Å neutron beamline at the 250kW TRIGA research reactor of the Vienna University of Technology where it could deliver pulses of 55μs duration, which is about three times less than the passage time of the neutrons through the resonator itself. In order to further improve the achievable wavelength resolution to about 3% a second prototype resonator, consisting of 48 individual modules with optimised field homogeneity and enlarged beam cross-section of 6 × 6cm2 was developed. We present the results of first measurements which demonstrate the successful operation of this device

A deceleration system at the Heidelberg EBIT providing very slow highly charged ions for surface nanostructuring

Recently, it has been demonstrated that each single-impact of a slow (typically 1–2 keV/u) highly charged ion (HCI) creates truly topographic and non-erasable nanostructures on CaF2 surfaces. To further explore the possibility of nanostructuring various surfaces, using mainly the potential energy stored in such HCIs, projectiles with kinetic energies as low as possible are required. For this purpose a new apparatus, capable of focusing and decelerating an incoming ion beam onto a solid or gaseous target, has been installed at the Heidelberg electron beam ion trap (EBIT). An X-ray detector and a position-sensitive particle detector are utilized to analyze the beam and collision products. First experiments have already succeeded in lowering the kinetic energy of HCIs from 10 keV/q, down to not, vert, similar30 eV/q, and in focusing the decelerated beam to spot sizes of less than 1 mm2, while maintaining the kinetic energy spread below not, vert, similar20 eV/q

Potential energy - induced nanostructuring of insulator surfaces by impact of slow, very highly charged ions

We have recently shown that the impact of individual slow highly charged ions is able to induce permanent nano-sized hillocks on the surface of a CaF2 single crystal. The experimentally observed threshold of the projectile ion potential energy necessary for hillock formation could be linked to a solid-liquid phase transition (nano-melting). In this contribution we report on similar nano-sized surface modifications as a result of the potential energy of impacting highly charged ions for other surfaces

A deceleration system at the Heidelberg EBIT providing very slow highly charged ions for surface nanostructuring

Recently, it has been demonstrated that each single-impact of a slow (typically 1–2 keV/u) highly charged ion (HCI) creates truly topographic and non-erasable nanostructures on CaF2 surfaces. To further explore the possibility of nanostructuring various surfaces, using mainly the potential energy stored in such HCIs, projectiles with kinetic energies as low as possible are required. For this purpose a new apparatus, capable of focusing and decelerating an incoming ion beam onto a solid or gaseous target, has been installed at the Heidelberg electron beam ion trap (EBIT). An X-ray detector and a position-sensitive particle detector are utilized to analyze the beam and collision products. First experiments have already succeeded in lowering the kinetic energy of HCIs from 10 keV/q, down to ~30 eV/q, and in focusing the decelerated beam to spot sizes of less than 1 mm2, while maintaining the kinetic energy spread below ~20 eV/q