Accelerated neutral atoms achieved using lasers and collisions

Ars Technica : Neutral particles are much harder to accelerate than charged particles for the very reason that researchers want to accelerate themâmdash;they don’t respond to electric and magnetic fields. A team of researchers led by R. Rajeev of the Tata Institute of Fundamental Research in Mumbai, India, has adapted laser plasma acceleration for use with neutral particles. Rajeev’s team began by using high-energy laser pulses to accelerate atoms and strip off their electrons, which left behind a plasma of positively charged ions moving in coherent waves. The researchers then created a slow-moving beam of so-called Rydberg atoms, whose outer electrons are loosely bound to their nuclei. Next, the team introduced the Rydberg atoms into the already-accelerated beam of fast-moving ions. When the two types of particles collided, the Rydberg atoms transferred their electrons to the ions. Separating out any residual ions left the researchers with a beam of neutral atoms with MeV energies, a billion times greater than had been achieved by previous neutral-particle accelerators. The atom accelerator is much less powerful than ion accelerators, but being only desktop-sized, it has a wider range of potential applications such as in nanolithography and further studies of plasma behaviors.