Optimisation and fabrication of a composite pyrolytic graphite monochromator for the Pelican instrument at the ANSTO OPAL Reactor
No Thumbnail Available
Date
2011-04-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
The triple monochromator for the TOF neutron spectrometer Pelican at ANSTO has been fully optimised in terms of overall performance, including the determination of the thickness of the pyrolytic graphite crystals. A total of 24 composite crystals were designed and fabricated. The calculated optimum thickness of 1.3 mm and the length of 15 cm of the monochromator crystals, that are not available commercially, were obtained by cleaving and soldering with indium. An extensive characterisation of the crystals using X-ray and neutron diffraction was conducted before and after the cleaving and bonding processes. The results proved that no damage was introduced during fabrication and showed that the design goals were fully met. The measured peak reflectivity and rocking curve widths were indeed in an excellent agreement with theory. In addition to the superior efficiency of the triple monochromator achieved by this novel approach, the amount of the crystal material required could be reduced by 1/3. (C) 2010 Elsevier B.V.
Description
Keywords
Neutrons, Graphite, Optics, Crystals, OPAL Reactor, Fabrication
Citation
Freund, A. K., & Yu, D.H. (2011). Optimisation and fabrication of a composite pyrolytic graphite monochromator for the Pelican instrument at the ANSTO OPAL Reactor. Paper presented to the International Workshop on Neutron Optics NOP 2010, 17-19 March 2010, Alpe d'Huez, France. In Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 634(1, Supplement), S75-S80. doi:10.1016/j.nima.2010.05.052