 One isotope of cadmium , <unk> , absorbs neutrons with high selectivity : With very high probability , neutrons with energy below the cadmium cut @-@ off will be absorbed ; those higher than the cut @-@ off will be transmitted . The cadmium cut @-@ off is about 0 @.@ 5 <unk> , and neutrons below that level are deemed slow neutrons , distinct from intermediate and fast neutrons . 
