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T-REX is set to take its place as a world-class ESS spectrometer, used to measure wide energy transfer with good wave vector resolution, using polarized or non-polarized neutrons and Polarization Analysis. In particular, polarized neutrons will enable the separation of the magnetic spectra from nuclear scattering, the analysis of polarization and eigenvectors of magnetic excitations and permit the separation of coherent and nuclear spin incoherent scattering, which is of particular importance for hydrogen-containing samples in energy research, soft matter and life sciences.

T-REX-1Layout of T-REX in the Experimental Hall of the ESS.
Copyright: Forschungszentrum Jülich

The scientific mission of T-REX is mainly the study of dynamics in single crystals showing magnetic properties, which require the exploration of the energy range from several tenths of μeV, for the determination of small energy gaps, to several hundreds of meV, for studies of, for example, excitations in the parent compounds of high Tc superconductors or excitations into the Stoner continuum. Therefore, the range of incident neutron energy is selectable from 2 meV to 160 meV thanks to the extraction of neutrons generated at the thermal moderator of the ESS, whilst making use of a removable cold neutrons extraction system that includes a polarizing bender for cold neutrons.

The design of T-REX features XYZ neutron spin polarization analysis. Thermal neutron polarization is achieved with the SEOP setup [1]. Neutron spin analysis in XYZ is performed with the magic PASTIS setup [2], already manufactured for the TOPAS project. Specific investigations of high quality 3He cells are required [3], to achieve a long decay time of the polarization of the gas, which is a crucial for experimental investigations.

The chopper system [4] has been specifically designed to achieve a highly efficient poly-chromatic illumination of the sample. It enables variable acquisition time frames, by means of a specially developed chopper (the FAN chopper) that suppresses selectively the sub-pulses generated by the resolution defining choppers. The energy resolution can be adapted in the range from 1% to 3% at 3meV and from 3% to 6% at 100 meV, thus providing flexible trading of resolution for flux, by increasing up to 5 times the flux at the sample. By limiting the beam collimation, the Q resolution can be tailored to experimental needs [5].

The secondary spectrometer features a vacuum path of 3 m from sample to detector, which will cover 2.2 sr when reaching full scope. With the angles covered by design, it will yield a dynamic range that extends from 0.05 Å-1 < Q < 10 Å-1, thus exploring a wide range of the reciprocal space.

T-REXThe experimental area of T-REX.
Copyright: Forschungszentrum Jülich

T-REX Team

Forschungszentrum Jülich (DE): Nicolò Violini, Hans Kämmerling, Achim Heynen, Jörg Voigt, Thomas Brückel
Università degli Studi di Perugia (IT): Andrea Orecchini, Pietro Tozzi, Alessandro Paciaroni, Francesco Sacchetti
Consiglio Nazionale delle Ricerche (IT): Andrea Orecchini, Pietro Tozzi

References and Links

[1] E. Babcock, Z. Salhi, T. Theisselmann, D. Starostin, J. Schmeissner, A. Feoktystov, S. Mattauch, P. Pistel, A. Ioffe, J. of Phys / Conf. Series 711, 012008 (2016)

[2] E. Babcock, Z. Salhi, P. Pistel, A. Ioffe, G. Simeoni, J. of Phys / Conf. Series 528, 012018 (2014)

[3] Z. Salhi, E. Babcock, A. Ioffe, P. Pistel, J. of Phys / Conf. Series 528, 012015 (2014)

[4] J. Voigt, N. Violini, T. Brückel, NIMA 741, 26 - 32 (2014)

[5] N. Violini, J. Voigt, S. Pasini, T. Brückel, NIMA 736, 31 - 39 (2014)

ESS Instrument suite

Jülich and the ESS

Contact Information

Nicolò Violini
Jörg Voigt