Particle physicists at Fermilab outside Chicago say they've found a new particle, a heavy relative of the neutron, and dubbed it the neutral Xi-sub-b.

The particle, whose existence was predicted by the Standard Model of physics, contains three quarks -- a strange quark, an up quark and a bottom quark -- a Fermilab release said Thursday.

The neutral Xi-sub-b is the latest entry in the periodic table of baryons, particles formed of three quarks -- the most common examples being the proton, with two up quarks and a down quark, and the neutron, with two down quarks and an up quark.

Fermilab's Tevatron particle collider, with its sophisticated particle detectors and trillions of proton-antiproton collisions, has been involved in the discovery and study of almost all the so-called bottom baryons.

Once produced in particle collision, researchers say, the neutral Xi-sub-b travels just a fraction of a millimeter before it decays into lighter particles that then decay again into even lighter particles.

Physicists study this "cascade" of decay to identify the initial particle.

Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy.