# Synopsis: Turning from Nuclei to Electrons for Dark-Matter Detection

A new analysis shows that it is possible to look for dark-matter particles with mass far below 1 giga-electron-volt by using atomic ionization.

Direct detection experiments of dark matter generally look for products of the interaction of the dark-matter particles with the nuclei of the detector. However, such nuclear recoil signals cannot typically be produced with sufficient strength by dark-matter particles of masses less than about 1 giga-electron-volt ($\text{GeV}$). Recently, Rouven Essig of Stony Brook University, New York, and colleagues suggested that in events in which such low mass dark-matter particles interact with the atomic electrons of the target, rather than off the nuclei, they could ionize the atoms, and this could produce an observable signal.

Now, these theorists, working with two members of the XENON10 Collaboration, have tested this idea by re-examining data previously used by the collaboration to obtain limits on dark-matter particles in the few-$\text{GeV}$ region. Where the previous analysis had been looking for nuclear recoils, the new analysis, reported in Physical Review Letters, instead looks for electrons as evidence of ionization, and is able to set limits on dark-matter particles with masses far below $1\phantom{\rule{0.333em}{0ex}}\text{GeV}$, the first direct-detection limits in this mass range.

These results are significant in themselves, but perhaps more important is the demonstration of the potential of this technique. Future experiments specifically designed to take advantage of this technique should be able to probe significant new regions in dark-matter parameter space. – Stanley Brown

More Features »

### Announcements

More Announcements »

## Previous Synopsis

Atomic and Molecular Physics

Read More »

Superfluidity

Read More »

## Related Articles

Astrophysics

### Focus: Hard and Soft Bounces Explain Asteroid’s Surface Structure

Experiments and computer simulations show that the segregation of small and large rocks on an asteroid’s surface can arise from the way particles hitting the surface collide with the rocks already present. Read More »

Particles and Fields

### Viewpoint: Spinning Gluons in the Proton

Computer simulations indicate that about 50% of the proton’s spin comes from the spin of the gluons that bind its quark constituents. Read More »

Astrophysics

### Synopsis: Neutrino Flashes from Exploding Stars

Calculations indicate that neutrino emission from a supernova could be detected on Earth, possibly revealing how the star explodes. Read More »