Neutrons & Xrays

TASP Neutron Spectrometer, PSI Switzerland

TASP, the triple-axis spectrometer with cold neutrons, located at the end of the 1RNR14 neutron guide of the SINQ spallation source. TASP is operated as a collaboration between the Laboratory for Neutron Scattering (LNS) of PSI and the group of Prof. Henrik M. Rønnow; the Laboratory for Quantum Magnetism (LQM) of École Polytechnique Fedérale de Lausanne (EPFL).

TASP provides incident neutrons with a wide range of wavevectors and allows for large momentum transfers. It offers the option of polarised neutron experiments with either longitudinal or XYZ polarization analysis and neutron spherical polarimetry. For these experiments TASP has the option of a Mu-metal Polarization Analysis Device, MuPAD. A broad range of problems in condensed matter can be explored with TASP, such as the study of magnetic and structural phase transitions and their associated fluctuations, superlattice reflections and critical exponents. It is well suited for the study of low-energy collective excitations with high energy and momentum resolution and due to the very high sensitivity of the polarized neutrons techniques, it is an excellent tool to investigate complex magnetic structures. In addition, using diffuse scattering at TASP one can investigate various effects of disorder. TASP employs standard SINQ sample environments allowing for measurements in wide ranges of temperature, magnetic field and pressure.

CAMEA-PSI Neutron Spectrometer at PSI, Switzerland

As joint venture with the Laboratory for Neutron Scattering of Prof. C. Rüegg at PSI, construction of the new spectrometer CAMEA (Continuous Angle Multiple Energy Analyzer) has started, which will be installed as option at the current RITA-2 instrument at SINQ at PSI. This new spectrometer will be particularly suited for parametric studies under extreme conditions requiring restrictive sample environments such as high magnetic field magnets or pressure cells, and for experiments on small samples of novel materials. The novelty of the CAMEA design is that it employs a series of several upward-scattering analyzer arcs.  This design allows each analyzer to collect neutrons over different energy ranges and a large solid angle that are measured simultaneously by position sensitive detectors. In a single data acquisition an entire constant-energy line in the horizontal scattering plane is recorded for a quasi-continuous angular coverage with tremendous gains in data collection rates. The project is financed by the R’Equip program of the Swiss National Science Foundation, PSI and EPF Lausanne.

CAMEA-ESS Neutron Spectrometer at ESS Sweden

The 5 MW European Spallation Source (ESS) will be Europe’s next neutrons source, and there is currently a selection process underway for the 22 neutron instruments to be built. We are working on CAMEA a Swiss-Danish instrument project for the ESS, and wish to carry out a simple short survey (bold sections) of potential users for performing inelastic neutron scattering. A brief outline of the instrument is provided below.

CAMEA, the Continuous Angle Multi-Energy Analysis spectrometer, is an indirect geometry time-of-flight spectrometer that is designed to maximize the count rate within the horizontal plane for rapid mapping of excitations. The instrument uses concentric arcs of analysers sat behind each other to analyse the neutrons scattered off the sample to different final neutron energies, with the analysers scattering the neutrons vertically.  The instrument is optimized for cold neutron spectroscopy with an energy resolution that matches the energy resolution of cold triple axis spectrometers, but CAMEA will have an extended energy range to 60 meV energy transfer.
Large neutron count rates are achieved on CAMEA by using the full 5 MW pulse width, using a wide band of incident neutron energies, and the large solid angle coverage of each individual analyser, while the use of collimation with a well-defined neutron flight path achieves a low background count rate. The scattering geometry of CAMEA matches the restricted geometry of extreme environments including large split coil magnets and Paris-Edinburgh type pressure cells, and a small sample option will be included for the studies in nominal and extreme environments.
If you wish to know more about CAMEA, or want to provide us with your feedback, please feel free to contact us.

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