Nuclear pudding—to go

Detectors at a giant particle collider have recorded apparent evidence for an exotic form of nuclear matter that scientists compare to a slab of pudding moving at nearly the speed of light.

Motes of that extraordinary stuff may have formed briefly at Brookhaven National Laboratory in Upton, N.Y., where scientists propel nuclei to enormous velocities in the Relativistic Heavy-Ion Collider (RHIC).

Last month at the Quark Matter 2004 conference in Oakland, Calif., RHIC scientists described new hints of what’s known in physics-speak as a color glass condensate.

According to relativity theory, normally spherical nuclei flatten at the speeds they attain within RHIC because matter contracts along its direction of motion. Some theorists have predicted that under such conditions, gluons, which are particles known to suddenly emerge and disappear within nuclei, would proliferate wildly. This added bulk of flattened gluon pudding, 50 to 1,000 times as dense as ordinary nuclear matter, would dominate each speeding nucleus.

Last year, nuclei of heavy hydrogen and of gold were slammed against each other at RHIC. Now, scientists report that fewer particles than expected exited at right angles from those smash ups, an indication that the colliding bodies are not acting like tiny billiard balls. Instead, the pattern of particles emerging from the collisions is what would be expected from puddinglike slabs of color glass condensate slapping together, says Brookhaven theoretical physicist Larry McLerran.

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