in [
                &#39;front_window&#39;, &#39;rear_window&#39;, &#39;dem&#39;, &#39;mli&#39;,
                &#39;calibration_foil&#39;, &#39;dead_layer&#39;
            ]
        ]

        #if energies is None:
        energies = energies * u.keV
        #    self.energies = [ENERGY_CHANNELS[i].e_lower for i in range(1, 32)] * u.keV

        if attenuator:
            base_comps.append(self.components[&#39;attenuator&#39;])

        base = Compound(base_comps)
        base_trans = base.transmission(e