Thermal Triple-axis Spectrometer Research Articles

Endurance – Modernisation of the instrumentation suite at the Institut Laue-Langevin

Endurance encompasses more than 30 new or upgraded instrument and infrastructure projects, rolled out over 8 years between 2016 and 2023. Many new or upgraded instruments have already been deployed and are in user-operation including: the fission-fragment gamma ray spectrometer, FIPPS; the upgraded cold-neutron TOF spectrometer IN5; new thermal TOF spectrometer PANTHER; and a second protein crystallography station, DALI. The D3 hot-neutron diffractometer and IN20 thermal triple-axis spectrometer have been upgraded while new and additional detectors for the SANS instruments D11 and D22 have been installed. The D16 cold-neutron diffractometer has been fully modernised and new coldneutron imaging instrument, NeXT, has been installed. Delivering a full suite of modernised instrumentation is dependent on the renewed in-pile beam extraction, H1-H2, new H24 (thermal) and H15 (cold) neutron guides and the in-house development and manufacture of critical technologies such as neutron detectors, monochromator optics and polarisation components. The new H24 guide provides dedicated endof-guide positions to the upgraded D10+ single crystal diffractometer, IN13 backscattering instrument and the new XtremeD powder and single-crystal diffractometer. H15 will accommodate a substantially upgraded D(00)7 polarised diffuse scattering and spectroscopy instrument while D11 will be rebuilt and relocated with an optically cleaner collimation. Two additional end-of-guide positions are available for new instrumentation: The SHARP+ cold-neutron TOF spectrometer and a 4th SANS instrument, SAM. The success of Endurance will provide users with a fully modernised suite of world-class instruments.

New design of a magnetic device for wide-angle XYZ polarization analysis PASTIS-3, from the concept to first tests with thermal neutrons

We present the new concept and neutron test results of the third generation PASTIS device for XYZ wide-angle polarization analysis for thermal neutrons. PASTIS-3 uses two polarized 3He Neutron Spin filter Cells (NSF) for polarizing and analyzing neutrons spins, flipping the incident neutron beam polarization by reversing the 3He spin state of the polarizing entrance cell. We detail a new coil design for high spatial homogeneity of the magnetic field in any field direction, and the calculation method employed to optimize the geometry and to characterize the field gradients. Various components of the apparatus are described with particular attention to their performance and impact on the relaxation time of the NSF cells. Finally, we present test results of the new device tested on the thermal triple-axis spectrometer IN20 at the ILL.

Evolution of Boson peak with Li-salt concentration in superionic xLi2SO4·(1−x)LiPO3 glasses

Inelastic neutron spectroscopy has been performed on two members of the family of superionic glasses: xLi2SO4·(1−x)LiPO3, x = 0.05 and 0.3. Measurements were performed on the thermal triple-axis spectrometer (Triax) at the University of Missouri Research Reactor covering 0.7Å−1<Q<4.5Å−1 and −2meV<E<25meV. A clear signature of a Boson peak is present for both the x = 0.05 and x = 0.3 samples. The Boson peak associated with the x = 0.3 sample is found to be enhanced and broadened to the high energy side of the peak compared to that of the x = 0.05 sample, indicating that the presence of more Li-salt results in modified dynamics of the underlying structural framework. Such dynamics are expected to influence the ionic conduction properties of these materials that are important as possible electrolyte materials in all solid-state Li-ion batteries.

PASTIS2 and CROCODILE: XYZ-wide angle polarisation analysis for thermal neutrons

We present a wide-angle device for inelastic neutron scattering with XYZ-polarisation analysis (PASTIS2). PASTIS2 employs a banana-shaped Si-walled 3He-filter for the polarisation analysis and allows pillar-free neutron scattering for horizontal scattering angles 0–100◦. The guide field direction at the sample can be chosen vertical or with 45◦ incremental steps in the horizontal scattering plane. When PASTIS2 is implemented on a polarised neutron beam, the incident neutron spin can be flipped with an easy-to-optimise broad-band adiabatic resonant flipper (CROCODILE) independent of the guide field direction at the sample position. We have tested the performance of this new device on the polarised thermal triple-axis spectrometer IN20 at the Institut Laue-Langevin, equipped with Heusler monochromator and the FlatCone multi-analyser, and discuss its potential for future instruments.

The beryllium-filter spectrometer option on TAIPAN

A high-throughput low-energy band-pass filter spectrometer is a recent addition to the thermal triple-axis spectrometer, TAIPAN [1] at ANSTO. The so-called Be-filter spectrometer option is a near-f...

Crystal field excitations in CeCu2Ge2: Revisited employing a single crystal and inelastic neutron scattering

The intermetallic compound, CeCu2Ge2, is the counterpart of the heavy-fermion superconductor CeCu2Si2. CeCu2Ge2 is a magnetically ordering (TN = 4.1K) Kondo lattice with a moderate Sommerfeld coefficient of 140 mJ/ molK2. Earlier inelastic neutron measurements on a polycrystalline sample revealed a doublet ground state and a quasi-quartet excited state at 16.5 meV, although a splitting of the 4f1 (J = 5/2) ground state multiplet into 3 doublets is expected from the point symmetry of the Ce3+ ions. We performed detailed inelastic neutron scattering experiments on a single crystal at the thermal triple-axis spectrometer PUMA at FRM II for different crystallographic directions. From our results we infer that the quasi-quartet, in fact, consists of two doublets at 17.0 and 18.3 meV which exhibit a strong directional dependence of their transition matrix elements to the ground state doublet. Finally, we will present a new set of crystal field parameters.

TAIPAN: First Results from the Thermal Triple-axis Spectrometer at OPAL Research Reactor

The thermal triple-axis spectrometer TAIPAN is the first instrument for inelastic neutron scattering at the new Australian research reactor OPAL. TAIPAN started operation in February 2009 and is in full user service since November 2010. Conceptually, it is similar to the triple-axis spectrometers IN8 (ILL) and PANDA (FRM-II) with variable incident and final energies and a secondary spectrometer with a single detector. The instrument can be operated either in a high flux mode with a double-focusing monochromator and analyser, or with Soller collimators - gaining resolution at the expense of intensity. Presently the PG (002) double-focusing monochromator and analyser are in use. The incident energy range on the TAIPAN TAS is from ∼5 meV up to ∼100 meV with neutron flux at sample position of 2.4≤107 n/cm2/s at incident energy of 14.8 meV. First experiments were performed with superionic conductor Cu2−δSe. The measurements reveal the presence of a soft mode related to ordering of Cu atoms followed by α - β phase transition at a lower temperature. The evolution of the magnetic structure with temperature in a magnetically modulated FePt3 thin film was investigated in the diffraction mode of TAIPAN. The results show that the film fabricated by modulation of the chemical order parameter consists of a magnetic FM/AFM superlattice in single-crystalline FePt3. The spin wave and phonon dispersion was recently investigated in TbVO3 single crystal. The acoustic and optical magnon branches were observed in the same energy range. This indicates that the 'orbital Peiers state' also exists in TbVO3.

Neutron Larmor Diffraction study of the BaM2(XO4)2 (M = Co, Ni; X = As, P) compounds

Neutron Larmor Diffraction is a relatively new concept in neutron scattering which allows high resolution studies of subtle structural features in condensed matter. Several setups exist in various neutron facilities around the world. One of them is the Zero-field spin-Echo for Triple-Axis option (ZETA), available on the thermal triple-axis spectrometer IN22 (CEA-CRG beamline at Institut Laue Langevin). We have used ZETA to study thermal evolution of lattice constants in serveral systems of physical interest. Among them, the BaM2(XO4)2 family is a serie of compounds which have been intensively studied for three decades, mainly because of their fundamental though puzzling magnetic properties. In this paper, we aim to shed a new light on the physical understanding of those systems by investigating the link between structural and magnetic ordering. The magnetoelastic effect is found to be weak but can be resolved thanks to the high resolution provided by NLD.

Double-Focusing Thermal Triple-Axis Spectrometer at the NCNR.

The new thermal triple-axis spectrometer at the NIST Center for Neutron Research (NCNR) is located at the BT-7 beam port. The 165 mm diameter reactor beam is equipped with a selection of Söller collimators, beam-limiters, and a pyrolytic graphite (PG) filter to tailor the beam for the dual 20×20 cm2 double-focusing monochromator system that provides monochromatic fluxes exceeding 108 n/cm2/s onto the sample. The two monochromators installed are PG(002) and Cu(220), which provide incident energies from 5 meV to above 500 meV. The computer controlled analyzer system offers six standard modes of operation, including a diffraction detector, a position-sensitive detector (PSD) in diffraction mode, horizontal energy focusing analyzer with detector, a Q-E mode employing a flat analyzer and PSD, a constant-E mode with the analyzer crystal system and PSD, and a conventional mode with a selection of Söller collimators and detector. Additional configurations for specific measurement needs are also available. This paper discusses the capabilities and performance for this new state-of-the-art neutron spectrometer.

TAIPAN: Thermal Triple-Axis Spectrometer

The thermal triple-axis spectrometer TAIPAN [1, 2] is the first instrument for inelastic neutron scattering at the new Australian research reactor OPAL. It is currently in the final stages of commissioning. Conceptually, it is similar to the triple-axis spectrometers (TAS) IN8 (ILL) and PANDA (FRM-II) with variable incident and final energies and a secondary spectrometer with a single detector. The instrument can be operated either in a high flux mode with a double-focusing monochromator and analyser, or with Søller collimators-gaining resolution at the expense of intensity.

3He spin filters for a thermal neutron triple axis spectrometer

We have tested two 3He neutron spin filters (NSF), one for the polarizer and one for the analyzer, in conjunction with a doubly focusing pyrolytic graphite (PG) monochromator on the state-of-the-art BT-7 thermal triple axis spectrometer (TAS) at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). This system will provide significantly better neutronic performance for polarization analysis over a conventional TAS with Heusler crystals. We discuss the scheme for employing NSFs on the TAS instrument, including the 3He cell design, spin-exchange optical pumping (SEOP) of these large 3He cells, and the holding fields on the spectrometer. Using Rb/K hybrid SEOP, we have produced 75% 3He polarization for the 11 cm diameter cells for TAS in less than two days.

The Swiss spallation neutron source SINQ—developments and upgrades for optimized user service

The Swiss spallation neutron source SINQ at the Paul Scherrer Institute (PSI) is a popular user facility for neutron scattering and neutron imaging serving user groups from a widespread international community, see also http://sinq.web.psi.ch/. Beyond reliable routine operation, PSI seeks to play a leading role in the development of facilities, instrumentation, sample environment, and user programs. On the side of neutron instrumentation, three instruments are currently being built up in the SINQ hall: a cold neutron radiography station (ICON), a thermal triple-axis spectrometer (EIGER) and a backscattering spectrometer (MARS).

Inelastic neutron scattering facilities at the Budapest Neutron Center

Two Triple Axis spectrometers are commissioned now at the Budapest Neutron Center. The Thermal Triple Axis Spectrometer (TAST) is installed on the 8-th beam (60 mm diameter) and supplied with a 120 mm-long sapphire crystal placed inside the channel (2 m far from monochromator) to filter fast neutrons. The Eulerian cradle can be placed at the sample position to carry out holographic measurements. Otherwise a normal goniometer (carrying up to 100 kg weight for orientation, e.g. Cryostat/magnet/heavy sample) is used. This spectrometer's resolution was modeled by VITESS program package. The second (cold) neutron spectrometer (ATHOS) on a curved (4200m) neutron guide is mounted at the 19m-position from the cold source. The neutron guide 1.5Θc, made of boron glass, is coated with NiTi multilayer. This instrument, developed into the RITA-type spectrometer, is supplied with a 190 × 190 mm2 position sensitive detector and a polarization option (stacked polarizer). In addition it has the optional COMPACT Neutron Spin Echo setup, based on Larmor precession, for energy analysis with the resolution of 10 µeV. The test measurements are presented. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The new thermal triple-axis spectrometer PUMA at the Munich neutron-source

The instrumentation of the new German neutron-source FRM II is currently making great progress. In this contribution we present the main and unique features of the new thermal triple-axis spectrometer PUMA, which is under construction now and is expected to be operational by the end of 2001.