title: The attracting masses in measurements of G: an overview of physical characteristics and performance.
abstract: Simple spheres and cylinders have been the geometries employed most frequently, but not uniquely, for the attracting masses used historically in measurements of the Newtonian gravitational constant G. We present a brief overview of the range of sizes, materials and configurations of the attracting masses found in several representative experimental arrangements. As one particular case in point, we present details of the large tungsten spheres designed originally by Beams, which have been incorporated into several different apparatuses for measuring G over the past 50 years. We also consider the question of possible systematic dependence of the results and their precision on the size of the large masses/mass systems that have been employed to date. We close with some considerations for possible future work.
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Virginia, 122 Engineer's Way, Charlottesville, VA 22904-4746, USA gtg@virginia.edu.
authors.forename: G T
authors.initials: GT
authors.lastname: Gillies
authors.affiliation: Department of High Energy Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India.
authors.forename: C S
authors.initials: CS
authors.lastname: Unnikrishnan
keywords: Newton's constant; attracting masses; gravitational constant; source masses; torsion balance; torsion pendulum