[1] YALE UNIV,DEPT PHYS,NEW HAVEN,CT 06520
[2] YALE UNIV,WRIGHT NUCL STRUCT LAB,NEW HAVEN,CT 06520
[3] UNIV COPENHAGEN,NIELS BOHR INST,DK-2100 COPENHAGEN O,DENMARK
[4] SRC,DARESBURY LAB,SCI RES COUNCIL,WARRINGTON WA4 4AD,LANCASHIRE,ENGLAND
[5] MCMASTER UNIV,DEPT PHYS,HAMILTON L8S 4M1,ONTARIO,CANADA
[6] UNIV FRANKFURT,INST THEORET PHYS,D-6000 FRANKFURT 70,FED REP GER