[en] This report does not only contain the new but also older - at least more unusual - applications of process computer technology. Therefore data on the economy of some systems could be given. The active interruption into the process via video display in some of the latest system is the main topic. The application of the process computer as optimization means is commom to all examples. Man is still responsible for process control. (orig.)

[en] We present a new approach for dynamic monochromatization of neutrons suitable for time-of-flight experiments at spallation neutron sources. The method requires polarized neutrons and is based on the Drabkin energy filter. In its initial application, this magnetic resonator device, consisting of a polarizer/analyzer system and a wavelength-dependent spin flipper, was proposed for extracting a narrow bandwidth from a broad bandwidth polarized neutron beam. At a spallation neutron source, wavelength is determined by time-of-flight (TOF) from the source to the detector. However, at each instant a spread of wavelengths is recorded due to the non-zero emission time of the source/moderator system. Particularly, high-intensity moderators for cold neutrons produce long ''tails'' in the intensity/time distribution for all wavelengths, degrading the resolution of the experiments. The Drabkin energy filter can be used to cut the neutron tails for all wavelengths, by drifting the resonance condition in synchronization with the TOF. Calculations show that the method is viable, and that substantial resolution gains are obtained by application to a TOF neutron reflectometer

[en] Polarized neutron reflectometry (PNR) has recently been applied to study lateral magnetic structures such as regular micron-sized magnetic arrays on a surface. To date, however, there is a lack of detailed accounts of the features observed in the scattered intensity map in the special case of time-of-flight (TOF) PNR. We present here preliminary measurement results on lithographically produced arrays of micron-sized rectangular permalloy magnetic bars. The measurements demonstrate the potential of the method to provide detailed structural information on a laterally patterned sample, as well as on its magnetic characteristics. The information can be obtained by analyzing the specular reflection along with three off-specular Bragg sheets. Most of the features seen experimentally can be interpreted by using simple heuristic arguments. In addition, we also present results of a study of lateral magnetic domains in an exchange-biased Co/CoO bilayer film to illustrate the capability of TOF PNR in the study of large lateral magnetic domains in the case when almost no off-specular scattering is detected

[en] The 20 MW_th OPAL research reactor has five neutron beam assemblies. These provide cold and thermal neutrons to various neutron guides and associated neutron beam instruments. In 2010 a project was initiated to install a new cold neutron guide, CG2, in one of the assemblies. This installation would allow up to four new neutron beam instruments to be built, significantly expanding the reactor's capabilities. The project concluded in December 2012 with the successful installation of CG2. Each neutron beam assembly has an in-pile plug, a primary shutter and a front cover. Together these constitute the neutron guide's in-pile components, with a total mass of over 12 tonnes. The CG2 installation required the complete replacement of the existing components. This replacement was scheduled to coincide with OPAL's first major shutdown. With a budget of $2.3 million and an expected dose of 50 man.mSv, the CG2 installation was a large and complex task. Work during the shutdown involved over 40 ANSTO personnel and radiation fields approached 1 Sv/h in some areas. Despite this, the installation team received a collective dose of only 10 man.mSv, and the project was completed to budget and within schedule. This paper will outline the details of the project, focusing on lessons learned and recommended practices. Each OPAL in-pile plug has a design life of 10 years at full power operation, and similar replacements will be performed regularly as the reactor ages. It is hoped that this information will be useful for other research reactors planning large capital engineering projects

[en] We show that the magnetic coupling of a [26 AFe/15 ANb]^*18 multilayer is changed from antiferro- to ferromagnetic in a continuous and reversible way by introducing hydrogen into the sample. The magnetic structure and its change during hydrogen charging (and the following decharging) of the Nb layers is measured in situ by neutron reflectivity. (orig.)

[en] Magnetic properties of a series of Gd/W multilayers with constant W-layer thickness (18 A) and variable Gd-layer thickness have been studied by polarized neutron reflectometry and SQUID magnetometry. Our results are not consistent with enhanced Gd moments and/or strong ferromagnetic spin polarizations in the W layers as claimed by Heys et al. [1]. As an unexpected and remarkable feature we have observed for the multilayers with thin Gd films of 14 and 19 A strong unusual peaks in the reflectivity spectra which depend on the external magnetic field and on the cooling process. These peaks depend on the magnetic structure of the layer system and do not occur in multilayers with thicker Gd films. (orig.)

[en] Fe/Nb multilayers are studied by neutron small-angle reflectivity measurements. It is shown that for small thicknesses of the Nb spacer layers (t_Nb<24 A) an oscillating behaviour of the indirect exchange coupling is present. For larger Nb thicknesses the strength of this RKKY-like interaction decays rapidly and merges into a non-oscillatory antiferromagnetic background presumably resulting from a dipole contribution to the coupling energy. (orig.)

[en] The polarization of a narrow, highly collimated polychromatic neutron beam is tested by a neutron spin splitter that permits the simultaneous measurement of both spin states. The device consists of a Si-Co_0.11 Fe_0.89 supermirror, which totally reflects one spin state up to a momentum transfer q=0.04 angstrom ^-1, whilst transmits neutrons of the opposite spin state. The supermirror is sandwitched between two thick silicon wafers and is magnetically saturated by a magnetic field of 400 Oe parallel to its surface. The neutron beam enters through the edge of one of the two silicon wavers, its spin components are split by the supermirror and exit from the opposite edges of the two silicon wafers and are recorded at different channels of a position-sensitive detector. The device is shown to have excellent efficiency over a broad range of wavelengths

[en] The new research reactor at ANSTO (OPAL) is operating with seven neutron beam instruments in the user programme and three more under construction. The reactor design provides for expansion of the facility to eighteen instruments, and much of the basic infrastructure is already in place. However, an expansion of the neutron guide system is needed for further beam instruments. For this purpose, several possibilities are under consideration, such as insertion of multi-channel neutron benders in the existing cold guides or the construction of a new elliptic cold guide. In this work Monte Carlo (MC) simulations have been used to evaluate performance of these guide configurations. Results show that these configurations can be competitive with the best instruments in the world.

[en] Fe/CeH_2-δ multilayers exhibit at room temperature evidence of interlayer exchange coupling. Subsequent Fe layers are either parallel or antiparallel to each other, depending on the Fe and CeH_2-δ layer thickness. However, when both layers have thickness larger than ∼15 A, the antiferromagnetic structure becomes fragmented into domains laterally limited to a few microns, and the magnetic structures become very fragile. Small magnetic fields of a few Oersteds acting on the samples during growth induce helimagnetic configurations which coexist with antiferromagnetic coupling. The magnetic structures can be permanently destroyed by applying magnetic fields larger than 150 Oe