A 12C+4He→ 16O+γ is regarded as the very important reaction to know the evolution of heavy stars. The cross section is, however, still unknown in spite of more than 40 years experiment in the world because of an existence of a resonance state of 16O at sub-threshold region. A cross section measurement with the direct detection of the produced 16O from Ecm= 2.4 downto 0.7 MeV have been planned at Kyushu University Tandem Laboratory(KUTL). Detection of the 16O is the most possible method at low energy, since a detection efficiency of the 16O is very high. The new windowless blow-in gas target was developed to achieve the pressure of 24 Torr. Many movable slit were installed in a recoil mass separator, so that the backgrounds generated by the 12C beam was eliminated effectively. The results of recent experiments at Ecm=2.4 and 1.5MeV are reported.