/**
  * Override setSector to automatically set the sector the particles are in as well as the system.
  * This is done automatically when adding it to a sector so normally should be modified.
  *
  * @param sector
  */
 public void setSector(E3DSector sector) {
   super.setSector(sector);
   if (particleList != null) {
     for (int i = 0;
         i < particleList.size();
         i++) // update all particles to have this sector... Particles could also point to the
       // parent for the getter??
       ((E3DParticle) particleList.get(i)).setSector(sector);
   }
 }