Using analytical methods, a new evaluation has been made of $\frac{R_s}{R_n}$, the ratio of nuclear spin-lattice relaxation rate in the superconducting phase to that in the normal phase, from expressions previously derived by Hebel and Slichter using the Bardeen-Cooper-Schrieffer theory of superconductivity. The results are given for several values of the effective breadth of the Bardeen-Cooper-Schrieffer energy levels.

• Received 13 May 1959

DOI:https://doi.org/10.1103/PhysRev.116.79