/**
  * Returns the photoionization mass attenuation coefficient.
  *
  * @param energy energy of the attenuated photons in keV.
  * @param z atomic number of the attenuating atoms.
  * @return the photoionization mass attenuation coefficient in cm²/g
  */
 public static double getPhoto(double energy, int z) {
   return Xraylib.CS_Photo(z, energy);
 }
  /**
   * Returns the mass attenuation coefficient.
   *
   * @param energy energy of the attenuated photons in keV.
   * @param z atomic number of the attenuating atoms.
   * @return the mass attenuation coefficient in cm²/g
   */
  public static double get(double energy, int z) {

    // return (new XCOMElement(z)).getAttenuation(energy*1e-3, "total");
    return Xraylib.CS_Total(z, energy);
  }