We extend low-temperature series for the second moment of the correlation function in $d=3$ simple-cubic Ising model from $u^{ 15}$ to $u^{ 26}$ using finite-lattice method, and combining with the series for the susceptibility we obtain the low-temperature series for the second-moment correlation length to $u^{ 23}$. An analysis of the obtained series by inhomogeneous differential approximants gives critical exponents $ 2\nu^{ \prime} + \gamma^{ \prime} \approx 2.55 $ and $ 2\nu^{ \prime} \approx 1.27 $.
Categories: hep-lat