Measurement of the SOC state specific heat in He-4

A. R. Chatto, R. A. A. Lee, Robert Duncan, P. K. Day, D. L. Goodstein

Research output: Chapter in Book/Report/Conference proceedingChapter


When a heat flux Q is applied downward through a sample of liquid He-4 near the lambda transition, the helium self organizes such that the gradient in temperature matches the gravity induced gradient in T-lambda. All the helium in the sample is then at the same reduced temperature t(SOC) = TSOC-T lambda/T lambda and the helium is said to be in the Self-Organized Critical (SOC) state. We have made preliminary measurements of the He-4 SOC state specific heat, C-del T(T(Q)). Despite having a cell height of 2.54 cm, our results show no difference between C-del T and the zero-gravity He-4 specific heat results of the Lambda Point Experiment (LPE) [J.A. Lipa et al., Phys. Rev. B, 68, 174518 (2003)] over the range 250 to 450 nK below the transition. There is no gravity rounding because the entire sample is at the same reduced temperature t(SOC)(Q). Closer to T-lambda, the SOC specific heat falls slightly below LPE, reaching a maximum at approximately 50 nK below T-lambda, in agreement with t
Original languageEnglish
Title of host publicationMeasurement of the SOC state specific heat in He-4
StatePublished - 2006


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