(* Input *)
(*kin = 20.;*)
mass= 936.;

sps={{Dashing[None],RGBColor[0,0,0]}, {Dashing[None],RGBColor[1,0,0]},{Dashing[None],RGBColor[0,0,1]},{Dashing[None],RGBColor[0,1,0]},{Dashing[None],RGBColor[0,1,1]}};

kIn[e_] := ((Sqrt[2*mass*e])/197.327)

kOut[e_,U0_] := ((Sqrt[2 mass (e- U0)])/197.327)

δ[e_,r_,u0_]:= ArcTan[((-kIn[e]Sin[kOut[e,u0]r]Cos[kIn[e]r] +kOut[e,u0]Cos[kOut[e,u0]r]Sin[kIn[e]r] )/(-kOut[e,u0] Cos[kOut[e,u0]r]Cos[kIn[e]r] - kIn[e]Sin[kIn[e]r]Sin[kOut[e,u0]r]))]

Plot[{δ[e,3,-2],δ[e,3,-5],δ[e,3,-6.5],δ[e,3,-6.8]},{e,0,5},PlotRange->All,PlotStyle->sps]

CS[e_,u0_]:=((4 π )/(2mass e 100)) (((Sin[δ[e,3,u0]]))^2)

Plot[{CS[ee,-2],CS[ee,-5],CS[ee,-6.5],CS[ee,-6.8]},{ee,0,1},PlotRange->All,PlotStyle->sps]