Search for superconductivity in neptunium and plutonium using a liquid helium-3 cryostat

✍ Scribed by G.T. Meaden; T. Shigi

• Publisher: Elsevier Science
• Year: 1964
• Tongue: English
• Weight: 259 KB
• Volume: 4
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(64)90007-4

✦ Synopsis

Two of the actinide metals have been known for many years to be superconductors. They are thorium and uranium, which have low transition temperatures of approximately 1.4 ° K 1-4 and 0.8 ° K, 4-7 respectively. We have now carried out a search for superconductivity to below 0.5 ° K in the remaining two actinides which were available to us, namely neptunium and plutonium. It was hoped to include protactinium also but we were not able to obtain it in elemental form.

Previously4, 8 we have reported on experiments performed in a cryostat in which 0-75 ° K was obtained. However, in the present cryostat, which is a helium-3 one utilizing 600 cm 3 of gas at n.t.p., it was possible to reach 0-38° K and perhaps less. The experiments were complicated by the very high toxicity of both neptunium and plutonium, and precautions had to be taken to ensure that the cryostat did not become contaminated by the or-radioactivity.

The cryostat