['The', 'probability', 'Pc', 'in', 'the', 'latter', 'case', 'is', 'given', 'to', 'a', 'very', 'good', 'accuracy', 'by', 'the', 'formula', 'for', 'the', 'linear', 'profile', ',', 'with', 'an', 'appropriate', 'gradient', 'taken', 'along', 'the', 'neutrino', 'trajectory', ',', '(', '12)Pc≃Θ(A−Δ)e−γ(cos2θrel+1)/2', ',', 'where', 'Θ(x', ')', 'is', 'the', 'step', 'function', ',', 'Θ(x)=1', 'for', 'x>0', 'and', 'Θ(x)=0', 'otherwise', '.']