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Abstract. The dd → 4 He η reaction has been investigated near threshold using the ANKE facility at COSY-Jülich. Both total and differential cross sections have been measured at two excess energies, Q = 2.6 MeV and 7.7 MeV, with a subthreshold measurement being undertaken at Q = −2.6 MeV to study the physical background. While consistent with isotropy at the lower energy, the angular distribution reveals a pronounced anisotropy at the higher one, indicating the presence of higher partial waves. Options for the decomposition into partial amplitudes and their consequences for determination of the s-wave η-α scattering length are discussed.PACS. 13.60.Le meson production -25.10.+s nuclear reaction involving few-nucleons systems -25.45.-z 2 H induced reactions -11.80.Et partial-wave analysis