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Test mass metrology for tests of the equivalence principle

Shiomi, Sachie (2002)
Ph.D. thesis, University of Birmingham.

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Abstract

The Equivalence Principle is accepted as one of the most fundamental principles in modern Physics. However, theories towards the unification of the four forces typically predict violations of this principle. Testing it at a high sensitivity is expected to make a breakthrough in the current understanding of Physics. A space-based project, STEP (Satellite Test of the Equivalence Principle), aims at testing the principle to the level of 10\(^{−18}\). This corresponds to an improvement of the current limits, established by ground-based experiments, by approximately five orders of magnitudes. To achieve the sensitivity, imperfections in STEP test masses, such as density inhomogeneity and thermal distortion, could be a problem. This thesis presents preliminary work on the verification of STEP test masses. We have measured density inhomogeneities in materials intended to be used as STEP test masses (beryllium and niobium). In addition, we have developed a device to measure differential thermal expansion of samples that cannot be machined, by using a capacitive sensing method. It is shown that the device has a precision of approximately 0.3 % in the differential thermal expansion of beryllium. This device could in principle be applied for the measurements of the real STEP test masses in the final shape. Our analysis based on the results of our measurements and literature survey shows that it is feasible to obtain materials that satisfy STEP requirements.

Type of Work:Ph.D. thesis.
Supervisor(s):Speake, Clive C.
School/Faculty:Schools (1998 to 2008) > School of Physics & Astronomy
Department:School of Physics and Astronomy, Birmingham Gravitation Group
Subjects:QB Astronomy
Institution:University of Birmingham
Library Catalogue:Check for printed version of this thesis
ID Code:96
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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