Circular accelerator for neutral particles
Scientists from the Fritz Haber Institute in Berlin succeeded in accelerating and focusing electrically neutral particles in a synchrotron for the first time.
Cynthia Heiner's research group generated a beam of ammonia molecules three millimeters in diameter within this circular particle accelerator, which was only 25 centimeters in size. A specially formed alternating electrical field controls the movement of the particle bundle, which moves at a speed of almost 90 meters per second on a circular path about 80 centimeters long. The hotter molecules have a stronger vertical velocity component and gradually leave the jet. What remains are extremely cold ammonia molecules with a temperature of 0.5 millikelvin, which are of particular interest for molecular physics and chemistry.
Ordinary synchrotrons work with electrically charged particles that are accelerated and guided by electric and magnetic fields. The idea of a neutral synchrotron is not new, but was never implemented due to technical challenges. In principle, all molecules with an electric dipole can be accelerated by high-frequency electric fields. Conceivable applications would be collisions between molecules moving in opposite directions to study their physical and chemical properties. Just as the development of the classic accelerators once helped particle physics achieve a breakthrough, the "molecular synchrotron" could serve as the basis for a completely new field of research. (vs)