Two-axis Goniometer Research Articles

Two-axis goniometer for single-crystal nuclear magnetic resonance measurements.

We report the design and construction of a two-axis goniometer capable of any sample orientation with respect to the external magnetic field. The advantage of this design is that it allows free rotations around a single axis independent of the other which minimizes rotational error without reduction of the angle range. Goniometer is capable of operating with high precision at both low and high temperatures and in high magnetic fields. To test its performance, it was mounted on the custom made nuclear magnetic resonance probe for use in an Oxford Instruments wide-bore variable field superconducting magnet.

Design of a multifunctional sample probe for transport measurements

We describe a multifunctional sample probe for transport measurements, equipped with a two-axis goniometer providing computer controlled 360${^\circ}$ out of plane and manual 360${^\circ}$ in-plane rotation. The multifunctional sample probe has been successfully implemented to a host dewar and electromagnet system. The developed probe is capable of performing transport measurements and device characterizations with high flexibility of controlling magnetic and electrical fields, angle, temperature and current/voltage parameters in a wide range. The design of the multifunctional sample probe allows easy connection of other external devices and easy installation into other dewar and magnet systems. A software interface based on NI Labview visual programming language has been developed to control the system. The setup has been tested in the hysteresis loop measurements of perpendicularly magnetized Co/Pt/CoO ultra-thin films with anomalous Hall effect (AHE) method. We have also performed temperature dependent exchange bias measurements of the samples. The developed probe revealed much better resolution in the case of perpendicularly magnetized ultra-thin Co/Pt/CoO films compared to a standard vibrating sample magnetometry system.

SENJU: a new time-of-flight single-crystal neutron diffractometer at J-PARC.

SENJU is a new single-crystal time-of-flight neutron diffractometer installed at BL18 at the Materials and Life Science Experimental Facility of the Japan Accelerator Research Complex (J-PARC). The diffractometer was designed for precise crystal and magnetic structure analyses under multiple extreme sample environments such as low temperature, high pressure and high magnetic field, and for diffraction measurements of small single crystals down to 0.1 mm3 in volume. SENJU comprises three choppers, an elliptical shape straight supermirror guide, a vacuum sample chamber and 37 scintillator area detectors. The moderator-to-sample distance is 34.8 m, and the sample-to-detector distance is 800 mm. The wavelength of incident neutrons is 0.4-4.4 Å (first frame). Because short-wavelength neutrons are available and the large solid angle around the sample position is covered by the area detectors, a large reciprocal space can be simultaneously measured. Furthermore, the vacuum sample chamber and collimator have been designed to produce a very low background level. Thus, the measurement of a small single crystal is possible. As sample environment devices, a newly developed cryostat with a two-axis (ω and φ axes) goniometer and some extreme environment devices, e.g. a vertical-field magnet, high-temperature furnace and high-pressure cell, are available. The structure analysis of a sub-millimetre size (0.1 mm3) single organic crystal, taurine, and a magnetic structure analysis of the antiferromagnetic phase of MnF2 have been performed. These results demonstrate that SENJU can be a powerful tool to promote materials science research.

Low temperature and high magnetic field spectroscopic ellipsometry system.

We report on the design and implementation of a spectral ellipsometer at near-infrared wavelength (700-1000 nm) for samples placed in high magnetic fields (up to 14 T) at low temperatures (~4.2 K). The main optical components are integrated in a probe, which can be inserted into a conventional long-neck He dewar and has a very long free-space optical path (~1.8 m×2). A polarizer-sample-(quarter-wave plate)-rotating analyzer configuration was employed. Two dielectric mirrors, one before and one after the sample in the optical path, helped to reflect the light back to the analyzer and a two-axis piezo-driven goniometer under the sample holder was used to control the direction of the reflected light. Functional test results performed on an intrinsic GaAs wafer and analysis on the random error of the system are shown. We obtained both amplitude and phase ellipsometric spectra simultaneously and observed helicity transformation at energies near the GaAs exciton transitions in the phase spectra. Significant shifts of them induced by magnetic fields were observed and fitted with a simple model. This system will allow us to study the collective magneto-optical response of materials and spatial dispersive exciton-polariton related problems in high external magnetic fields at low temperatures.

A two-axis goniometer for low-temperature nuclear magnetic resonance measurements on single crystals

We report on the construction of a two-axis goniometer intended for low-temperature, single-crystal nuclear magnetic resonance (NMR) measurements. With the use of home-made and commercially available parts, our simple probe-head design achieves good sensitivity, while maintaining a high angular precision and the ability to orient samples also when cooled to liquid helium temperatures. The probe with the goniometer is adapted to be inserted into a commercial (4)He-flow cryostat, which fits into a wide-bore superconducting solenoid magnet. Selected examples of NMR measurements illustrate the operation of the device.

Two-axis Magnetic Field Orientation Dependence of Critical Current in Full-Width REBCO Coated Conductors

Abstract Considerable progress has been made with the development of YBa2Cu3O7-δ and related rare-earth (REBCO) coated conductors in recent years. The introduction of BaZrO3 (BZO) nanoparticles has resulted in enhanced critical current density ( Jc ) for magnetic field orientations away from the intrinsic ab peak, with the absolute Jc and the degree of anisotropy depending on the geometry and orientation distribution of the nanoparticles; and REBCO coated conductors with a variety of substitutions and additions (Gd, Sm, Ba, Zr, Sn) are becoming commercially available in kilometre lengths. It is therefore increasingly important to characterise the magnetic field orientation dependence of critical current ( Ic ) in full-width coated conductors without destructive sample preparation, both for fundamental pinning studies and the design of large-scale applications. A two-axis goniometer has been developed, allowing the critical current to be measured as a function of both the magnitude and orientation of the applied magnetic field, Ic(B,θ,ϕ) , on full-width samples. Measurements of Ic(B,θ,ϕ) at 77 K are reported for four REBCO tapes made by metal organic chemical vapour deposition (MOCVD) with different rare earth content and the results interpreted in relation to rare earth substitution and pinning centre populations. The implications of the field orientation dependence for low and intermediate field applications are discussed.

Reliability of goniometric measurements in children with cerebral palsy: A comparative analysis of universal goniometer and electronic inclinometer. A pilot study

BackgroundEven though technological progress has provided us with more and more sophisticated equipment for making goniometric measurements, the most commonly used clinical tools are still the universal goniometer and, to a lesser extent, the inclinometer. There is, however, no published study so far that uses an inclinometer for measurements in children with cerebral palsy (CP). The objective of this study was two-fold: to independently assess the intra and inter-examiner reliability for measuring the hip abduction range of motion in children with CP using two different instruments, the universal two-axis goniometer and electronic inclinometer. A pool of 5 examiners with different levels of experience as paediatric physiotherapists participated. The study did not compare both instruments because the measurement procedure and the hip position were different for each.MethodsA prospective, observational study of goniometery was carried out with 14 lower extremities of 7 children with spastic CP. The inclinometer study was carried out with 8 lower extremities of 4 children with spastic CP. This study was divided into two independent parts: a study of the reliability of the hip abduction range of motion measured with a universal goniometer (hip at 0° flexion) and with an electronic inclinometer (hip at 90° flexion). The Intraclass Correlation Coefficient (ICC) was calculated to analyse intra and inter-examiner agreement for each instrument.ResultsFor the goniometer, the intra-examiner reliability was excellent (>0.80), while the inter-examiner reliability was low (0.375 and 0.475). For the inclinometer, both the intra-examiner (0.850-0.975) and inter-examiner reliability were excellent (0.965 and 0.979).ConclusionsThe inter-examiner reliability for goniometric measurement of hip abduction in children with CP was low, in keeping with other results found in previous publications. The inclinometer has proved to be a highly reliable tool for measuring the hip abduction range of motion in children with CP, which opens up new possibilities in this field, despite having some measurement limitations.

Phase function measurements on nonspherical scatterers using a two-axis goniometer

We present a two-axis goniometer for measuring the phase function of scattering media with an angular resolution of about 0.2 deg having 12 decades of dynamic range and covering almost the full solid angle. The setup is evaluated with polystyrene spheres and with perpendicularly and obliquely illuminated thin glass cylinders. The scattering pattern and its intensity distribution are in excellent agreement with analytical theory. A multiple scattering configuration composed of two parallel cylinders is also examined. Finally, the phase function of dentin slabs is measured and its dependence on the dental microstructure is discussed.

High-pressure protein crystallography (HPPX): instrumentation, methodology and results on lysozyme crystals.

A new set-up and associated methodology for the collection of angle-dispersive diffraction data from protein crystals submitted to high hydrostastic pressure have been developed on beamline ID30 at the ESRF. The instrument makes use of intense X-rays of ultra-short wavelength emitted by two collinear undulators, and combines a membrane-driven diamond-anvil cell mounted on a two-axis goniometer and an imaging-plate scanner. Sharp and clean diffraction pictures from tetragonal crystals of hen egg-white lysozyme (tHEWL) and orthorhombic crystals of bovine erythrocyte Cu, Zn superoxide dismutase (SOD) were recorded at room temperature and pressures up to 0.915 and 1.00 GPa, respectively. The compressibility of tHEWL was determined from unit-cell parameters determined at 24 different pressures up to 0.915 GPa. High-pressure diffraction data sets from several crystals of tHEWL were collected and analyzed. Merging of data recorded on different crystals at 0.30 and 0.58 GPa produced two sets of structure amplitudes with good resolution, completeness, redundancy and R(sym) values. A third set at 0.69 GPa was of a similar quality except a lower completeness. The three structures have been refined. The pressure-induced loss of crystalline order in a tHEWL crystal beyond 0.82 GPa was captured through a series of diffraction pictures.

Automated angle-scanning photoemission end-station with molecular beam epitaxy at KEK-PF BL-1C

In order to satisfy demands to study the electronic structure of quantum nanostructures, a VUV beamline and a high-resolution and high-throughput photoemission end-station combined with a molecular beam epitaxy (MBE) system have been constructed at the BL-1C of the Photon Factory. An angle-resolved photoemission spectrometer, having high energy- and angular-resolutions; VG Microtech ARUPS10, was installed. The total energy resolution of 31 meV at the 60 eV of photon energy is achieved. For the automated angle-scanning photoemission, the electron spectrometer mounted on a two-axis goniometer can be rotated in vacuum by the computer-controlled stepping motors. Another distinctive feature of this end-station is a connection to a MBE chamber in ultahigh vacuum (UHV). In this system, MBE-grown samples can be transferred into the photoemission chamber without breaking UHV. Photoemission spectra of MBE-grown GaAs(0 0 1) surfaces were measured with high-resolution and bulk and surface components are clearly resolved.

New rubidium zinc hydrogen phosphate, Rb2Zn2(HPO4)3: synthesis, crystal structure, and 31P single-crystal NMR.

A new rubidium zinc hydrogen phosphate, Rb2Zn2(HPO4)3, is prepared by an unusual method utilizing long nucleation times. This material is crystallized from a gel with an initial composition of 1.0 ZnO/0.94 P2O5/0.96 Rb2O/0.04 Li2O/41 H2O, while the phosphate concentration equals 1.6 M and pH = 3.5. The gel is placed in a sealed Pyrex flask at 52 degrees C, and after 4.5 months crystallization of Rb2Zn2(HPO4)3 is noticed. This new crystalline compound has a three-dimensional framework structure built from spiral chains of alternating PO4 and ZnO4 tetrahedra connected pairwise and assembled by other PO4 tetrahedra, rubidium ions, and hydrogen bonds. The two rubidium ions, Rb(1) and Rb(2), have an exceptionally low number of oxygen contacts in the first coordination sphere, five and seven, respectively. Crystal data: monoclinic, P2(1)/c (no. 14), a = 12.5880(4), b = 12.7170(8), c = 7.5827(8) A, beta = 96.100(1) degrees, Z = 4. A single-crystal 31P NMR investigation of Rb2Zn2(HPO4)3 was performed employing a two-axis goniometer probe and reveals the presence of three chemically and six magnetically nonequivalent phosphorus sites, in accordance with the crystal structure. 31P chemical shielding anisotropies and isotropic chemical shifts (-3.3(3), -2.6(3), and 2.0(3) ppm) have been determined for the three phosphorus sites.

A two-axis goniometer for sensitivity enhancement in single-crystal nuclear magnetic resonance spectroscopy

The construction of a single-crystal nuclear magnetic resonance (NMR) probe with a new two-axis geometry for the goniometer has improved the sensitivity of the NMR response from small crystals. This allows studies of the smallest crystals used so far in single-crystal NMR. The goniometer of the probe uses only two different mountings of the crystal, and the rotation axis of the goniometer is tilted 45° with respect to the direction of the magnetic field. By moving the goniometer outside the radio frequency coil, the filling factor and the probe sensitivity increase. The improved sensitivity for the probe is illustrated by the P-{H1}31 cross-polarization spectrum of a 0.088 mm3 crystal of (NH4)2HPO4 and a Rb87 single-pulse spectrum of a 0.048 mm3 crystal of RbZn2(HPO4)PO4. Moreover, the capability to determine precise parameters for the solid-state NMR interactions using the new probe is demonstrated by Na23 and Rb87 single-crystal studies of NaNO3 and RbClO4.

Feasibility study of high energy channeling experiments at the debrecen cyclotron

Channeling investigations have been performed on the 20 MeV MGC cyclotron of the Institute of Nuclear Research of the Hungarian Academy of Sciences. A two-axis goniometer has been installed on a large scattering chamber. The beam quality was ensured and tested for the channeling purposes. Silicon single crystals cut perpendicular to ⟨100⟩ axis were used as test targets for the high energy irradiations. The 4He2+ beam was used at low beam current (<10 nA) for the systematic study. The theoretical and semi-empirical predictions on the energy dependence of the fundamental channeling parameters were tested and compared with the theory and the literature.

Surface Science

Omicron Associates has launched the AR 65 MCD angle-resolved electron spectrometer. The magnetic circular dichroism analyser could be used for both synchrotron and laboratory applications. The spectrometer is a 180° hemispherical instrument with a radius of 65 mm. The analyser has a typical angular acceptance of ±° over the complete retard ratio range and has an analysis area with a diameter of 1 mm. A compact design allows a 14° approach angle to be used. The AR 65 MCD is available as a base component mounted on a single-axis rotary stage, a two-axis goniometer stage with an angular resolution of 0.1°, or as part of a complete surface analysis system.

97/03225 Two-axis goniometer for use in the mixing chamber of a dilution refrigerator

97/03225 Two-axis goniometer for use in the mixing chamber of a dilution refrigerator

Two-axis goniometer for use in the mixing chamber of a dilution refrigerator

We have constructed a goniometer to rotate a sample around two independent axes in the mixing chamber of a dilution refrigerator. Two small computer-controlled stepper motors wound with superconducting wire rotate the sample around the axes with an angular range of 360 °. The goniometer was designed to investigate the angular dependence of the magnetic de Haas-van Alphen effect of heavy electron materials in a magnetic field of up to 14.5 T.

X-ray spectroscopic diagnostics of core ion confinement in large (JET) and medium size (COMPASS) tokamaks

Sophisticated X-ray spectroscopic instruments have been developed and used for confinement studies in tokamaks at JET and Culham Laboratory. The Bragg rotor survey spectrometer, when programmed to operate in monochromatic or limited spectral range (LSR) modes, has been used to derive transport coefficients from the transient spectral signature of injected, non-recycling, test ions. The coefficients appropriate to specific confinement regimes have been investigated with respect to ion charge state and tokamak machine parameters. The LSR mode allows discrimination against background X-:ray light, a particularly serious problem at high electron density, n e ≈ 10 20 m−3, in H mode where there is evidence, in COMPASS-D, for modest accumulation of impurities. Impurity ion accumulation is observed most clearly in passive spectroscopic studies of the 1s 2 − 1s2p line emission from intrinsic impurity ions such as CI(XVI) using a high resolution Johann configuration crystal spectrometer. Line shapes and line ratios within the limited spectral range 4.45-4.50 Å are interpreted in terms of ion and electron temperature and ion fluid velocity. In particular, the ‘q’/‘w’ line intensity ratios are interpreted in terms of the relative abundance of the CI(XV)/CI(XVI) ions which are modelled in terms of ion transport. These continuous, passive measurements of ion confinement are compared with results from the transient injection method. Absolute levels of the X-ray continuum, adjacent to the Cl(XVI) lines, are used to derive Z eff. Both the Bragg and Johann X-ray spectrometers have been calibrated for absolute photon sensitivity. The efficiencies of the diffractors in these instruments can be measured using a newly developed, two-axis goniometer.

Algorithm for crystal alignment with a two-axis goniometer

An algorithm for determining the necessary angular corrections to bring a selected direction in a crystal into alignment using a two-axis goniometer is presented. The procedure requires the measurement of the specimen-to-film distance, the x and y (or polar) coordinates of the reflection of interest, and the recording of the values of the rotation and oscillation axis settings used to make the back-reflection photograph. A solution in closed form may then be calculated and checked for feasibility, given the physical oscillation limits of the goniometer.

Triple ion beam irradiation facility

A unique ion irradiation facility consisting of three accelerators is described. The accelerators can be operated concurrently to deliver three ion beams on one target sample as large as 100 mm 2 in area. The energy ranges of the ions are 50 to 400 keV, 200 keV to 2.5 MeV and 1.0 to 5.0 MeV, which allows three different ions in the appropriate mass range to be simultaneously implanted to the same depth in a target specimen. Typical depth ranges are 0.1 to 1.0 μm. The X- Y profiles of all three ion beams are measured by a system of miniature Faraday cups. The ion beam energy of the low voltage accelerator can be ramped periodically during the implantation. Three different types of target chambers are in use at this facility. A triple-beam high vacuum chamber can hold nine TEM specimens at controlled temperatures in the range 400–800 °C during an irradiation by the three simultaneous beams. A second high vacuum chamber on the medium voltage accelerator beam line houses a low- and high-temperature translator and a two-axis goniometer for ion channeling measurements. The third chamber on the high energy beam line can be gas-filled for special stressed specimen irradiations. Applications of this facility to surface modification of materials are described.

A note on obtaining symmetrical angular yield curves in MeV ion channeling

Planar channeling effects can distort the angular yield (dip) curve measured about an axial channeling direction. Two methods for minimizing distortion due to planar channeling are discussed: 1) varying the angles θ and φ of a two-axis goniometer together during the angular scan, and 2) remounting the sample so that a scan of only θ produces an undistorted symmetric dip curve. In practice, remounting the sample is preferred in order to minimize effects due to the mechanical limitations of the goniometer.