Thermal gradient-induced forces on geodetic reference masses for LISA - General Relativity and Quantum CosmologyReport as inadecuate




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Abstract: The low frequency sensitivity of space-borne gravitational wave observatorieswill depend critically on the geodetic purity of the trajectories of orbitingtest masses. Fluctuations in the temperature difference across the enclosuresurrounding the free-falling test mass can produce noisy forces through severalprocesses, including the radiometric effect, radiation pressure, andoutgassing. We present here a detailed experimental investigation of thermalgradient-induced forces for the LISA gravitational wave mission and the LISAPathfinder, employing high resolution torsion pendulum measurements of thetorque on a LISA-like test mass suspended inside a prototype of the LISAgravitational reference sensor that will surround the test mass in orbit. Themeasurement campaign, accompanied by numerical simulations of the radiometricand radiation pressure effects, allows a more accurate and representativecharacterization of thermal-gradient forces in the specific geometry andenvironment relevant to LISA free-fall. The pressure dependence of the measuredtorques allows clear identification of the radiometric effect, in quantitativeagreement with the model developed. In the limit of zero gas pressure, themeasurements are most likely dominated by outgassing, but at a low level thatdoes not threaten the LISA sensitivity goals.



Author: L. Carbone, A. Cavalleri, G. Ciani, R. Dolesi, M. Hueller, D. Tombolato, S. Vitale, W. J. Weber

Source: https://arxiv.org/







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