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Demonstration of an Ultra-Stable Cryogenic Platform with 25 pK/root-Hz StabilityExisting paramagnetic susceptibility thermometers used in fundamental physics experiments near 2.2 K are capable of measuring temperature changes with a precision of about 100 pK in a one-hertz measurement bandwidth, with a demonstrated drift stability of about a nK per day. Commercial electrical heater controllers are only able to control power dissipation to a precision of about ten parts per million (ppm), with an open loop drift of about 50 ppm per day. We have developed an ultra-stable temperature platform with a demonstrated noise of 25 pK in a one-hertz bandwidth, and we have identified the physical source of this residual noise. We used an array of RF-biased Josephson junctions to precisely control the electrical power dissipation in a heater resistor mounted on this thermally isolated cryogenic platform to well beyond our ability to measure, which we estimate is stable to better than a part in 10(exp 12). This Josephson heater controller may be used in a new synchronous demodulation circuit to maintain absolute temperature stability of the stage to about the same level as the demonstrated noise, provided that the He-4 superfluid transition temperature is fundamentally stable at this level. This work may provide a blackbody temperature reference for use in space radiometry applications that is considerably more stable than the temperature of the cosmic background radiation itself. This new technology may enable critical heat capacity measurements in He-4 within a weightless laboratory to a reduced temperature of about 10(exp -11), where the critical fluctuation lengths would be about a cm, and the fluctuation rates would be measurable within the bandwidth of the thermometry.
Document ID
20060014056
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
Authors
Green, Colin J.
(New Mexico Univ. NM, United States)
Sergatskov, Dmitri A.
(New Mexico Univ. NM, United States)
Duncan, R. V.
(New Mexico Univ. NM, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2004
Publication Information
Publication: Proceedings of the 2004 NASA/JPL Workshop on Physics for Planetary Exploration
Subject Category
Physics (General)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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