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Neutron Phase Contrast Imaging of PbWO4 Crystals for G Experiment Test Masses Using a Talbot-Lau Neutron Interferometer



Daniel S. Hussey, Vincent Lee, w snow, Kofi Assumin-Gyimah, Dipangkar Dutta


The use of transparent test/source masses can bene t future measurements of Newton's gravi- tational constant G. Such transparent test mass materials can enable nondestructive, quantitative internal density gradient measurements using optical interferometry and allow in-situ optical metrol- ogy methods to be realized for the critical distance measurements often needed in a G apparatus. To con rm the sensitivity of such optical interferometry measurements to internal density gradients it is desirable to conduct a check with a totally independent technique. We present an upper bound on possible internal density gradients in a lead tungstate (PbWO4) crystal using the NG-6 neutron phase contrast imaging station at NIST. We measured a fractional density gradient in two PbWO4 test crystals of (1=N)dN=dx = 1:0 106 cm1. This value is about two orders of magnitude smaller than required for future G measurements. We discuss the implications of this result and of other nondestructive methods for characterization of internal density inhomogeneties which can be applied to test masses in future G experiments.
Classical and Quantum Gravity


gravity, precision measurement, neutron phase imaging, dimensional metrology, mass metrology


Hussey, D. , Lee, V. , snow, W. , Assumin-Gyimah, K. and Dutta, D. (2022), Neutron Phase Contrast Imaging of PbWO4 Crystals for G Experiment Test Masses Using a Talbot-Lau Neutron Interferometer, Classical and Quantum Gravity, [online], (Accessed May 26, 2024)


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Created November 25, 2022, Updated November 29, 2022