Previous SANS measurements at 5,500 ppm done by Heuser et. al have shown that on average, 2.6 hydrogen atoms are trapped per Angstrom of dislocation line. This measured cross section at Q = 0.02 {angstrom}{sup {minus}1} is (d{Sigma}/d{Omega}) = 0.02 1/cm/steradian. The results obtained in this research are consistent with SANS measurements at a binding energy of 0.3 eV, three different core radii and number of sites in the core. The curves illustrate the total number of hydrogen atoms trapped as a function of bulk concentration. At 5,500 ppm, all curves pass through Heusers et. al. 2.6H/{angstrom} experimental value. The ratio of the cross sections between 5,500 and 1,000 ppm is 3, and between 5,500 and 100 ppm is 5. Based on these theoretical results, the cross sections at these low concentrations should be measurable. The experiments at low concentrations will determine the number of sites and core radius when compared with the theoretical calculations. At low temperature (77 K) the deuterium atoms trapped per unit length of dislocation line increase by a factor of 10, which means that the SANS cross section can measure by a factor of one hundred as it is directly proportional to the square ofmore » deuterium density. With the decrease in temperature, the number of hydrogen atoms trapped increases. The hydrogen atoms become trapped even in the low strain field region. At 5,500 ppm for 77 K, 22 hydrogen atoms per Angstrom trapped compared with 2.6 hydrogen atoms per Angstrom at 300 K. At 77 K, the core contribution is independent of the binding energy and number of sites. Furthermore, the amount of hydrogen atoms in the bulk of the sample is negligible compared with the number of hydrogen atoms at the dislocation. At room temperature, about 30% of the total hydrogen concentration goes to the dislocation. The temperature effect is dominant in the modified Fermi-Dirac equation.« less