1. Department of Mechanical Engineering, University of Bristol, BS8 1TR UK
2. Institut Laue-Langevin (ILL), Grenoble, France
3. College of Engineering, Mathematics and Physical Sciences, University of Exeter, EX4 4QF, UK
4. ISIS Neutron Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK
5. Department of Physics, University of Bath, Bath BA2 7AY, UK