报告题目： Inelastic Neutron Scattering: from Triple-Axis to Time-Of-Flight Spectrometers

报告人： 邓国初

时间： 1月13日，上午10：30

地点： 散裂园区A1-104

主持人： 王芳卫

报告简介：

Inelastic neutron scattering is one of the most important neutron scattering techniques, especially, in the fields of hard condensed matter and material sciences. Triple-axis spectrometers (TASs) and time-of-flight (TOF) spectrometers are the two types of most-widely used inelastic neutron scattering instruments. Instrumentations of both these two types of inelastic instruments were significantly improved in the last decades.

Since the first TAS built by B. N. Brockhouse, various novel designs and techniques were introduced in TAS instrumentation in order to improve instrument resolutions, data acquisition efficiency, etc. As a conventional TAS equipped with the double-focusing monochromator and analyzer, TAIPAN, taking the advantage of its high flux, still works as the workhorse at ASNTO.[1] It has been successfully used in studying superconductors,[2] multiferroic materials,[3] thin film magnetism,[4,5] quantum spin-liquid systems [6] and so on. Adopting the advanced multiplexing analyzer, SIKA at ANSTO is a very flexible and versatile cold-neutron triple-axis spectrometer with potential high data-acquisition efficiency.[7] Numerous successful studies conducted on SIKA demonstrate its capabilities: the spin-glass system (Ni0.40Mn0.60)TiO3,[8] the low-dimensional magnetism in SrCa13Cu24O41[9], the iron-based superconductor FeSe,[10] and the frustrated magnet YbZnGaO4[11], etc. Newly developed multi-analyzer TASs such as MultiFLEXX[12] and CAMEA[13] significantly increase the data acquisition rate by using both multiple detectors and multiple Ef. This design, taking both advantages of the continuous neutron beam of TASs and the wide scattering angle range of TOF spectrometers, becomes a new trend of inelastic neutron instrumentation.

Direct-geometry TOF spectrometers become mainstream inelastic instruments for pulsed spallation neutron sources with the advantages of wide coverage of both scattering angle and scattered neutron energy. Supermirror technique substantially increases neutron flux of TOF spectrometers with long guides. Repetition rate multiplication (RRM) is a newly developed technique to effectively improve utilization of every single neutron pulse.[14] A state-of-the-art concept design for a cold TOF spectrometer with RRM technique is proposed for CSNS.