Background: Nuclear reactions involving alpha particles play an important role in various astrophysical processes such as the γ-process of heavy element nucleosynthesis. The poorly known low-energy α-nucleus optical potential is a key parameter to estimate the rates of these reactions. Purpose:The α-nucleus optical potential can be tested by measuring the cross section of α-scattering as well as α-induced reactions. Low energy elastic α-scattering on 144 Sm has recently been measured with high precision. The aim of the present work was to complement that work by measuring the (α,n) cross sections on 144 Sm at low energies. The experimental data shall be used to constrain the α-nucleus optical model potential. From this potential the 144 Sm(α,γ) 148 Gd reaction rate can be derived with reduced uncertainties.Method: The 144 Sm(α,n) 147 Gd reaction was studied by bombarding Sm targets with α-beams provided by the cyclotron accelerator of Atomki. The cross section was determined using the activation method. The γ-radiation following the decay of the 147 Gd reaction product was measured with a HPGe detector. The experimental data are analyzed within the statistical model. Results:The cross section was measured in the α-energy range between 13 and 20 MeV in 1 MeV steps, i.e., from close above the (α,n) threshold. The results were compared with statistical model calculations using various approaches and parametrizations for the α-nucleus optical potential, and excellent agreement was obtained for two recent potentials. However, these potentials cannot reproduce literature data for the 144 Sm(α,γ) 148 Gd reaction with the same accuracy.Conclusions: Constraints for the α-nucleus potential were derived from an analysis of the new 144 Sm(α,n) 147 Gd data and literature data for 144 Sm(α,γ) 148 Gd. These constraints enable a determination of the reaction rate of the 144 Sm(α,γ) 148 Gd reaction with significantly reduced uncertainties of less than a factor of two.