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Oak Ridge National Laboratory

CDAC Contacts:
Tim Jenkins
Jian Xu

The Spallation Neutrons and Pressure (SNAP) beam line in the upcoming Spallation Neutron Source (SNS), at the Oakridge National Laboratory, is significant advance for high pressure neutron research. It is a project funded by DOE-BES to Oak Ridge National Laboratory. SNAP will be a unique world-class high pressure neutron instrument consisting of diffractometers and detectors integrated with a suite of next generation high-pressure devices. In completed form, the instrument will allow pressures of ~5 times the current pressure for neutron experiments and ~200 times the neutron beam intensity. Principle instrument design has been finalized and is shown in below.


Instrument construction has also begun and the instrument will come online before 2008. The Carnegie Institution of Washington is principally responsible design, fabrication, assembly, and testing of several pressure cells, both panoramic and Beijing-Washington type (Figs. 1, 2, and 3). These cells will be delivered to instrument at the SNS prior to the first beam. In addition to cell design and construction, CDAC was involved in the overall instrument design, allowing for several different experiment designs to be accommodated. These efforts are being carried out in coordination with neutron instrument development at the SNS and development of a different pressure device, a Paris-Edinburgh cell, at the State University of New York, Stony Brook.



Panoramic moissanite anvil cells, similar to ones in production for SNAP, have been used in neutron diffraction experiments successfully at several major neutron facilities. Single-crystal neutron diffraction experiments at high pressure have been performed on the Vivaldi instrument at ILL (Institut Laue-Lagevin, Grenoble, France) as shown in Fig. 4. High pressure neutron powder diffraction experiments have also been performed on the HIPPO at LANSCE, Los Alamos National Laboratory, as shown in Fig. 5. Neutron experimentation has helped to refine and improve cell design.





For larger load experiments, a 30 ton Beijing-Washington cell (BW-30) has been designed, fabricated and tested. This cell allows for increased sample volumes over the panoramic cell. The design of this cell has been shown above in Fig. 3 and a pictorial representation shown above in Fig. 4.