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Instrument 17

For more information, contact Instrument Scientist: Garrett Granroth, granrothge@ornl.gov, 865.576.0900 Instrument Scientist: Sasha Kolesnikov, kolesnikovai@ornl.gov, 865.576.9145 Scientific Associate: Todd Sherline, sherlinete@ornl.gov, 865.773.3157 http://neutrons.ornl.gov/instruments/SNS/SEQUOIA 06-G00806E/gim SEQUOIA is optimized to provide a high neutron flux at the sample and fine en- ergy resolution. The spectrometer can select neutrons with incident energies from a few hundredths of an electron volt to a couple of electron volts and thus can study excitations over this wide energy scale. An elliptically shaped supermir- ror guide in the incident flight path boosts the performance at the lower end of this range. The sample and detector vacuum chambers provide a window-free final flight path and incorporate a large gate valve to al- low rapid sample changeout. A new T0 neutron chopper will not only block the prompt radia- tion from the source but also eliminate unwanted neutrons from the incident beam line. SEQUOIA is a collaboration between Oak Ridge National Laboratory and the Canadian Institute for Neutron Scattering.

Applications With its capability to acquire data quickly and relate them to three-dimensional momentum transfers, SEQUOIA allows new studies of single crystals and novel systems such as the following: High-temperature superconductivity: spin dynamics in superconductors and precursor compounds and incommensurate spin fluctuations at varying doping levels Model magnetic systems, such as one-dimensional spin chains and spin ladders, and crossover effects from one- to three-dimensional magnetism Excitations in quantum fluids, quantum critical phenomena, and non-Fermi liquid systems High-resolution crystal field spectroscopy reaching into the 1-eV range Coupling of electronic and spin systems in correlated-electron materials Colossal magnetoresistive materials Specifications Moderator Decoupled ambient water Source- to-Fermi chopper distance 18 m Chopper- to-sample distance 2.0 m Sample- to-detector distance 5.5 6.3 m cylindrical geometry Incident en- ergy range 10 2000 meV Resolution (elastic) 1 5% Ei Vertical detector coverage -30 30 Horizontal detector coverage -30 60 Minimum detector angle 3 March 2010 Status: Operational

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