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Author Hemmerich, J. L. ♦ Loos, J. ♦ Miller, A. ♦ Milverton, P.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS ♦ TEMPERATURE CONTROL ♦ SPECIFIC HEAT ♦ CALORIMETRY ♦ CALORIMETERS ♦ THERMOCOUPLES ♦ PERFORMANCE ♦ DESIGN ♦ URANIUM ♦ TRITIUM ♦ EPOXIDES
Abstract Temperature stabilization by inertial feedback control has proven a powerful tool to create the ultrastable environment essential for high resolution calorimetry. A thermally insulated mass, connected to a base through Seebeck effect sensors (thermopiles) is used as a reference to control the base temperature. The thermopile signal is proportional to both the heat capacity of the reference mass and the derivative {dot {Theta}} of the base temperature {Theta}. Using vacuum insulation and bismuth telluride thermopiles, we designed and tested temperature derivative sensors (TDSs) with sensitivities up to 3300 VsK{sup {minus}1}. Standard industrial controllers with approximately {plus_minus}1 {mu}V input noise and stability, permit control of temperature derivatives to {plus_minus}3{times}10{sup {minus}10} Ks{sup {minus}1}. Single-cup thermoelectric calorimeters coupled to the TDS-controlled base permitted measurement of heat flow from samples in a power range from 3 {mu}W to 10 W with high accuracy ({plus_minus}100 ppm), resolution ({plus_minus}0.2 {mu}W), and reproducibility ({plus_minus}1 {mu}W). The design of two instruments is described in detail. Their performance is demonstrated on a variety of measurements, e.g., the determination of sample heat capacities with temperature ramp rates {dot {Theta}}={plus_minus}5{times}10{sup {minus}6} Ks{sup {minus}1}, the half-life of a 3 g tritium sample in a uranium getter bed, the decay heat of depleted uranium, and the heat evolution of epoxy resin. {copyright} {ital 1996 American Institute of Physics.}
ISSN 00346748
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-11-01
Publisher Place United States
Journal Review of Scientific Instruments
Volume Number 67
Issue Number 11


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