Their transition to ground state takes place by collision with cold helium atoms.

Death by collisions with man-made structures and objects can be serious local issue.

One might be by atomic/molecular collisions, which we associate with heat transfer.

Given the option 1, it is invisible and unaffected by collisions.

The image is a reminder of another killing by collision, also in New York, two centuries later.

Any Soviet pilot who chose to stop in mid-air risked death by collision.

The high mountain ranges produced by continental collisions are immediately subjected to the forces of erosion.

Mansell's hopes of record 10th win dashed by collision.

The Alps have a complex geology, but the general structure is the same as for other mountain ranges formed by continental collision.

These pumps work on the principle that gas molecules can be given momentum in a desired direction by repeated collision with a moving solid surface.