EG+G ORTEC , 100 Midland Road, Oak Ridge, Tenn. 37830, USA .

Canberra Industries, Inc ., 45 Gracey Ave., Meriden, Conn .

Digital Equipment Corporation （DEC） , Maynard, Mass. 01754, USA .

Lccroy, Inc . , 700 S. Main St ., Spring Valley , N. Y., 10977, USA .

Kinetic Systems Corp . , 11, Maryknoll Drive, Lockport, 111 . 60441 .

Digital Engineering, Inc ., 630 Bercut Drive, Sacrament, CA 95814 .

Tektronix, Inc . , PO box 4828 , Portland, Ore . 97208 .

Nuclear Data, Inc ., Schaumberg, 111, 60196, USA .

R. Anholt et al . , Zeit. Physik, A 1982 , to be published.

H. T. King et al . , Phys. Rev ., B25 , 1497 （ 1982 ）.