Apel, W. D.W. D.ApelArteaga-Velázquez, J. C.J. C.Arteaga-VelázquezBekk, K.K.BekkBertaina, M.M.BertainaBlümer, J.J.BlümerBozdog, H.H.BozdogBrancus, I. M.I. M.BrancusCantoni, E.E.CantoniChiavassa, A.A.ChiavassaCossavella, F.F.CossavellaDaumiller, K.K.Daumillerde Souza, V.V.de SouzaDi Pierro, F.F.Di PierroDoll, P.P.DollEngel, R.R.EngelFeng, Z.Z.FengFuhrmann, D.D.FuhrmannGherghel-Lascu, A.A.Gherghel-LascuGils, H. J.H. J.GilsGlasstetter, R.R.GlasstetterGrupen, C.C.GrupenHaungs, A.A.HaungsHeck, D.D.HeckHörandel, J. R.J. R.HörandelHuege, T.T.HuegeKampert, K. -H.K. -H.KampertKang, D.D.KangKlages, H. O.H. O.KlagesLink, K.K.LinkŁuczak, P.P.ŁuczakMathes, H. J.H. J.MathesMayer, H. J.H. J.MayerMilke, J.J.MilkeMitrica, B.B.MitricaMorello, C.C.MorelloOehlschläger, J.J.OehlschlägerOstapchenko, S.S.OstapchenkoPierog, T.T.PierogRebel, H.H.RebelRoth, M.M.RothSchieler, H.H.SchielerSchoo, S.S.SchooSchröder, F. G.F. G.SchröderSima, O.O.SimaToma, G.G.TomaTRINCHERO, GIAN CARLOGIAN CARLOTRINCHEROUlrich, H.H.UlrichWeindl, A.A.WeindlWochele, J.J.WocheleZabierowski, J.J.ZabierowskiKASCADE-Grande Collaboration2021-02-022021-02-0220170004-637Xhttp://hdl.handle.net/20.500.12386/30177KASCADE and KASCADE-Grande were multi-detector installations to measure individual air showers of cosmic rays at ultra-high energy. Based on data sets measured by KASCADE and KASCADE-Grande, 90% C.L. upper limits to the flux of gamma-rays in the primary cosmic ray flux are determined in an energy range of {10}<SUP>14</SUP>{--}{10}<SUP>18</SUP> eV. The analysis is performed by selecting air showers with a low muon content as expected for gamma-ray-induced showers compared to air showers induced by energetic nuclei. The best upper limit of the fraction of gamma-rays to the total cosmic ray flux is obtained at 3.7× {10}<SUP>15</SUP> eV with 1.1× {10}<SUP>-5</SUP>. Translated to an absolute gamma-ray flux this sets constraints on some fundamental astrophysical models, such as the distance of sources for at least one of the IceCube neutrino excess models.STAMPAenArticle10.3847/1538-4357/aa8bb72-s2.0-85031926882000412397800001https://iopscience.iop.org/article/10.3847/1538-4357/aa8bb72017ApJ...848....1AFIS/05 - ASTRONOMIA E ASTROFISICA