The specific heat of liquid helium from 1.5°K down to 0.4°K

✍ Scribed by W.H. Keesom; W.K. Westmijze

• Publisher: Elsevier Science
• Year: 1941
• Weight: 28 KB
• Volume: 8
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(41)80010-x

✦ Synopsis

LETTER TO THE EDITOR

The specific heat of liquid helium from 1.5°K down to 0.4°K.

We measured the specific heat of liquid helium under its saturated vapour pressure from 1.5 clown to 0.4°K. The temperatures below I. I°K were obtained by adiabatic demagnetization of iron ammonium alum. In this way a temperature of 0. I°K could be reached, but up to 0.4°K the heat capacity of the helium is so small compared with that of the salt that it could not be measured.

We found that from 1.5°K down to 0.6°K the specific heat can be roughly represented by the formula c = 0.023 T 6 cal/g, deg. Though below this temperature the results are not yet very certain, they make it probable that from about 0.6°K downwards the power of 7" decreases somewhat. Our figures are considerably smaller than P i c k a r d and Simon's*).

Below I°K we used the magnetic temperature scale of our sample of iron ammonium alum. Measurements are in progress to establish the thermodynamic temperature scale in this region.

~r.H. KEESOM.