Stopping atoms in their tracks

Atomic trapping has become an essential tool in many areas of physics but has, until now, been limited to certain atoms. Now a group of physicists in the US have developed an “atomic coilgun” which opens up the possibility of trapping any atom irrespective of their size.

Hydrogen plays a vital role in powering stars through proton-proton reaction nuclear fusion. NGC 604 is an H II region inside the Triangulum Galaxy. It was discovered by William Herschel on September 11, 1784.

In 1997, three scientists won the Nobel Prize in Physics for conceiving the fundamental new idea of slowing atoms by laser cooling. Since then, atomic trapping and cooling have been at the forefront of science. However, the main drawback of current methods is that important atoms such as hydrogen are excluded as they do not have a “closed two-level atomic transition”.

Dr Mark Raizen and his colleagues who headed the research at the University of Texas realised that almost all atoms and many molecules are paramagnetic and can be manipulated by a magnetic field. The atomic coilgun slows and gradually stops atoms with an array of pulsed magnetic fields and was inspired by a coilgun devised in the University's Center for Electromechanics.

Dr 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.  Further study of tritium, as the simplest radioactive element, also serves as an ideal system for the study of Beta decay. "

The prototype atomic coilgun uses an 18-coil set up to slow a supersonic beam of metastable neon atoms. Dr Raizen’s team is now expanding to a 64-coil device which they hope to use to slow and stop the most basic element – hydrogen.

By Leila Sattary