Closer to absolute zero

Previous attempts at very low temperatures reached 1/50,000 of a degree above absolute zero. Now, using helium isotopes helium-4 and helium-3 which separate at temperatures below 0.8° and additional nuclear magnetic properties, temperatures of one millionth of a degree were reached.
 Heinz London England 1962 Closer to absolute zero

Previous attempts at very low temperatures reached 1/50,000 of a degree above absolute zero. Now, using helium isotopes helium-4 and helium-3 which separate at temperatures below 0.8° and additional nuclear magnetic properties, temperatures of one millionth of a degree were reached.