1. Department
of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, U.K.
2. AWE, Aldermaston,
Reading, Berkshire RG7
4PR, U.K.
3. The UK National
Nuclear Laboratory, The Central Laboratory, Sellafield,
Seascale, Cumbria CA20
1PG, U.K.