Im working with the problem 4.4 in Krane's introductory nuclear physics.

Im working with the problem 4.4 in Krane's introductory nuclear physics. The question is "What fraction of the time do the neutron and the proton in the deuteron spend beyond the range of their nuclear force?" There is a solution on this site, called "pset4sol", BUT in the solution, the author does not mention how to determine the constants A and C. The author instantly jumps from the calculations of the wave numbers, to the final answer of the probability. How do I determine the constants?