Atoms Stopped by Magnetic Field Atom Coilgun

Physicists at the University of Texas at Austin (UTA) report in the Institute of Physics' New Journal of Physics that they have found a way to slow down, stop and trap atoms for the purpose of exploring them.

Physicists have been working on ways to stop and trap atoms for several decades. Progress was made when, in 1997, physicists Steve Chu, Claude Cohen-Tannoudji, and William D. Phillips jointly won the Nobel Prize for Physics for cooling and stopping an atom with laser, laser cooling.

Laser cooling uses laser light to cool gases and keep atoms floating or captured in "atom traps," which are magnetostatic devices that exert magnetic fields that influence atoms' energy in relation to their own magnetic (or Zeeman) energy. The atoms in increasing-energy states, which are low-fieldseekers, can be trapped in specialized magnetic field configurations.

This breakthrough is limited in use as it is only applicable to the specialized category of "closed two-level transition" atoms. This feature of laser cooling atom trapping eliminates many important atoms from study such as hydrogen, iron, nickel and cobalt.

UTA's Center tor Electromechanics developed a new design for a coilgun, which is a device constructed with coils through which an electric charge can be generated. When a charge flows in a coil, the coil generates a magnetic field in which the direction of energy flux emerges from the north pole of the coilgun and terminates on the south pole. The magnetic field and magnetic flux lines form closed magnetic loops around the coilgun.

This design for a coilgun inspired Physics professor Dr. Mark Raizen and his colleagues to aid their research into atom stopping by designing an "atomic coilgun." Their design slows and gradually stops atoms with sequenced magnetic field pulses. Their magnetic field atom coilgun will permit a much wider range of atom exploration as this methodology is not restricted to the species of closed two-level atoms.

The aspiration of Raizen's team of researchers is to use the atom coilgun to trap a hydrogen atom. The hydrogen atom is said by Raizen to be the Rosetta Stone of physics, as once hydrogen is explored and understood--hydrogen being the simplest atom on Earth--the keys to unlocking the mysteries of other atoms will be in hand (the Rosetta Stone had parallel inscriptions in Greek, Demotic and Egyptian hieroglyphics so clues to finally deciphering hieroglyphics were provided).

The atomic coilgun will have very broad applicability because nearly all elements are affected by magnetic or paramagnetic forces, which means that they too could be trapped at some time and explored.

Professor Raizen said, "Of particular importance are the doors being opened for our understanding of hydrogen. Precision spectroscopy of hydrogen's isotopes, deuterium and tritium, continues to be of great interest to both atomic and nuclear physics."

Joseph Winters, "Stopping atoms," Institute of Physics.