Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

The Sciences

Nothin’ But Neutrons

Physicists report evidence of a new atom.

By Shannon PalusDecember 19, 2016 6:00 AM
Physicists saw evidence that they’d produced an atom made up only of four neutrons, as illustrated here. | APS/Alan Stonebraker


Sign up for our email newsletter for the latest science news

In February, physicists revealed evidence of an atom made only of neutrons — something many thought impossible. Because matter is classified by how many protons it has, this is “element zero,” jokes Tomohiro Uesaka, who led the work at the Radioactive Isotope Beam Factory in Japan.

Since the ’60s, scientists have debated whether such a strange atom might exist. To find out, physicists produced helium atoms (normally two protons and two neutrons strong) with four extra neutrons, and fired a beam of the atoms at a target of liquid helium. They measured what came flying out the other side and calculated that groups of four neutrons had clustered together for a fraction of a second.

Currently, Uesaka’s team is designing experiments to solidify these strange atoms’ existence and better understand what holds them together. The unknown forces that briefly bound them could explain a larger mystery of the universe: how neutron stars, the incredibly dense remains of certain large stars, can pack matter together so tightly.

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%


Already a subscriber? Register or Log In