Low temperature closed cycle refrigerator for neutron and x-ray scattering

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This proposal seeks to fund a low temperature closed cycle refrigerator appropriate for neutron and x-ray scattering studies of novel materials. It will provide sophisticated sample environment for single crystal and polycrystal samples over the temperature range from 300 K to 1.7 K and be able to stabilize temperature to the 0.005 K level for extended periods of time. One of this apparatus' defining features is that it will be mountable in both an Eulerian cradle of the McMaster Alignment Diffractometer at the McMaster Nuclear Reactor, and within a four-circle x-ray diffractometer at McMaster University, such that complementary neutron and x-ray diffraction studies can be carried out on the same material. It will be the only such low temperature sample environment apparatus in Canada so equipped, and it will enable sophisticated studies of magnetic and chemical structure and phase diagrams in new materials. Its temperature control will also allow sophisticated critical scattering studies to be carried out. This apparatus will also be incorporated into training and courses for graduate and senior undergraduate students at at least two universities.