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Recently, there appears lots of papers on the possibility of light DarkMatter (DM) in MeV and sub-GeV scale. Until now, only INTEGRAL and COMPTELprovided experimental data of 511keV of galactic center, and two spectra ofGalactic Diffuse MeV gammas (GDMG), and COMPTEL provided the Cosmic BackgroundMeV gammas (CBMG) for wide sky for indirect detection of light DMs. Howeverexcept 511keV, those spectra for diffuse gammas included large statistical andsystematic errors in spite of 10 years observation, since both two instrumentssuffered from severe background radiation in space. In 2018 April, we(SMILE-project in Comic-ray Group of Kyoto University) have observed MeV gammarays for whole southern sky by Electron Tracking Compton Camera (ETCC) usingJAXA balloon at Australia during one-day. (SMILE2+ Project) By measuring allparameters of Compton scattering in every gamma, ETCC has achieved for thefirst time to obtain the complete direction of MeV gammas as same as opticaltelescopes, and also to distinguish signal gammas from huge background gammasin space clearly. In this observation, ETCC with a large Field of View of 3srobserved MeV gammas from 3/5 of all sky including galactic centre, a half disk,crab, and most of CBMG By reconstructing the Compton process, we successfullyobtained pure comic gammas by reducing background by more 2 orders, which isclearly certificated by the clear enhancement of detected gamma flux with ~30%during galactic center passing through the Field of View, which is consistentwith the ratio of CBMG and GDMG. Now 511keV gammas GDMG are preliminarilydetected with ~5 and >10 sigma respectively around Galactic Centre. Also wehave obtained near 105events of CBMG in with quite low background of only a few10% in total CBMG events. Thus we obtained good data for both with highstatistics and very low systematics even one day observation.

MeV Gamma-ray imaging spectroscopic observation for Galactic Center and Cosmic Background MeV gammas by SMILE-2+ Balloon Experiment