抄録
For optimal design of a Sc filter to get 2 keV neutrons from a reactor beam port, neutron total cross section of Sc has been measured near the 2 keV cross section minimum using the standard time-of-flight method. The result is given by a polynomial σt(E)= 18.00-4.51E+56.810E2-44.351E3+20.674E4-5.2389E5+0.5572E6 b (E in keV, 0.25<E<3), least square-fitted to the experiment. The minimum value of the cross section obtained is 0.21±0.03 b. This value markedly differs from 0.71+0.03 b, which is the recently reported value measured by similar kind of experiment, and close to 0.27+0.07 b measured by a different kind of experiment. The lower value of present measurement indicates that one may design more thicker filter than usually used. Analysis with the Breit-Wigner multi-level formula shows that the lower value may not be any obstacle for the interpretation of dominant contribution of spin-antiparallel interaction with thermal neutrons.
