Light Helium

NOV 01, 1948

Alfred O. C. Nier

The natural occurrence of a helium isotope of atomic weight 3 was observed in the Berkeley cyclotron in 1939 by Alvarez and Cornog, who showed that its abundance was very low compared with that of the normal helium atom of atomic weight 4.

This article is only available in PDF format

Physics Today is looking for a Senior Editor. Apply Now.

Related content

News

Article

Data reanalysis throws existence of an ocean on Titan into question

The finding that the Saturnian moon may host layers of icy slush instead of a global ocean could change how planetary scientists think about other icy moons as well.

February 02, 2026 10:10 AM

News

Article

Crossword: February 2026

January 30, 2026 09:09 AM

News

Article

Q&A: Trity Pourbahrami helps scientists communicate their work

After a foray into international health and social welfare, she returned to the physical sciences. She is currently at the Moore Foundation.

January 29, 2026 01:35 PM

News

Article

The new math of network optimization, courtesy of string theory

Modeling the shapes of tree branches, neurons, and blood vessels is a thorny problem, but researchers have just discovered that much of the math has already been done.

January 29, 2026 12:52 PM

This Content Appeared In