Measurement of the /sup 27/Al(n,2n)/sup 26/Al reaction cross section for fusion-reactor applications

The /sup 27/Al(n,2n)/sup 26/Al reaction is of considerable interest to the fusion reactor program. Aluminum is an attractive material for many structural applications, and the (n,2n) reaction is the major source of long-lived activity (/sup 26/Al, g.s. T/sub 1/2/ = 7.34 x 10/sup 3/ g). The threshold for this reaction falls within the spread of neutron energies generated by a D-T plasma. Its cross section is therefore a steeply rising function of energy for the primary fusion neutrons. This special feature makes it possible to use this reaction to measure plasma ion temperatures as well as neutron yields and neutron spectral shapes. The /sup 27/Al(n,2n)/sup 26/Al reaction is one of the major sources of displacement damage in Al-metal alloys and other aluminum containing fusion materials, thus the cross section near threshold will strongly affect the amount of displacement damage in these materials as well as the long-lived radioactivity