def _sigma_pi_midE(self, Tp):
        """
        Geant 4.10.0 model for 2 GeV < Tp < 5 GeV
        """
        m_p = self._m_p
        Qp = (Tp - self._Tth) / m_p
        multip = -6e-3 + 0.237 * Qp - 0.023 * Qp ** 2
        return self._sigma_inel(Tp) * multip