scholarly journals Toward a better system for short range precision force measurements

2020 ◽  
Vol 35 (03) ◽  
pp. 2040002
Author(s):  
Thomas Bsaibes ◽  
Luís Pires ◽  
David Czaplewski ◽  
Daniel López ◽  
Ricardo S. Decca
Keyword(s):  
Short Range ◽  
Spherical Surface ◽  
Angular Deviation ◽  
Force Measurements ◽  
Mechanical Oscillator ◽  
Capacitance Measurements ◽  
Force Sensitivity ◽  
Planar Source ◽  
Two Bodies ◽  
Long Cylinder

Many precision experiments have been done in the Casimir regime and in short range gravity when the separation between the interacting bodies is in the sub-micron range. Experimental complexity is minimized when one of the bodies is a sphere and the other one is a plate, making the alignment between the two bodies ubiquitous. Our group has produced the most precise Casimir measurements, and the best limits on predicted Yukawa-like potentials by measuring a force between a [Formula: see text] sphere attached to a [Formula: see text] micro-mechanical oscillator and a planar source mass. By replacing the spherical surface with a fraction of a [Formula: see text] long cylinder with [Formula: see text]m, the force sensitivity can be greatly enhanced. Here, it is paramount to know the angular deviation between the long axis of the cylinder and both the axis of rotation of the oscillator and the plate. Tests between a cylinder and a structure etched into a silicon wafer show that deviations of [Formula: see text]rad are readily accessible. Additionally, a scaled up experiment is used to investigate if capacitance measurements can determine the orientation of the cylinder with respect to a plane with the required precision.

scholarly journals CAPACITANCE MEASUREMENTS AND ELECTROSTATIC CALIBRATIONS IN EXPERIMENTS MEASURING THE CASIMIR FORCE

2011 ◽  
Vol 03 ◽  
pp. 527-540 ◽  
Author(s):  
R. S. DECCA ◽  
E. FISCHBACH ◽  
G. L. KLIMCHITSKAYA ◽  
D. E. KRAUSE ◽  
D. LÓPEZ ◽  
...  
Keyword(s):  
Casimir Force ◽  
Spherical Surface ◽  
Scaling Law ◽  
Anomalous Scaling ◽  
Capacitance Measurements ◽  
Spherical Surfaces ◽  
Theoretical Predictions ◽  
Coated Surfaces ◽  
Micrometer Size

We discuss the possibility of determining the properties and quality of spherical surfaces used in precise experiments with the help of capacitance measurements. The results of this kind measurements for the lens-plane and sphere-plane, Au coated surfaces are compared with theoretical predictions from various models of perfect and broken sphericity. It is shown that capacitance measurements are incapable of discriminating between models of perfect and modified centimeter-size spherical surfaces in an experiment demonstrating the anomalous scaling law for the electric force. Claims to the contrary in the recent literature are explained by the use of improper comparison. The data from capacitance measurements in an experiment measuring the Casimir force by means of a micromechanical torsional oscillator employing micrometer-size spheres are shown to be in excellent agreement with theoretical predictions using the model of a perfect spherical surface.

scholarly journals Self-Assembled Structures of Colloidal Dimers and Disks on a Spherical Surface

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 585
Author(s):  
Nkosinathi Dlamini ◽  
Santi Prestipino ◽  
Giuseppe Pellicane
Keyword(s):  
Computer Simulation ◽  
Monte Carlo ◽  
Binary Mixture ◽  
Self Assembly ◽  
Short Range ◽  
Spherical Surface ◽  
Hard Core ◽  
Attractive Potential ◽  
Curved Surfaces ◽  
Colloidal Aggregation

We study self-assembly on a spherical surface of a model for a binary mixture of amphiphilic dimers in the presence of guest particles via Monte Carlo (MC) computer simulation. All particles had a hard core, but one monomer of the dimer also interacted with the guest particle by means of a short-range attractive potential. We observed the formation of aggregates of various shapes as a function of the composition of the mixture and of the size of guest particles. Our MC simulations are a further step towards a microscopic understanding of experiments on colloidal aggregation over curved surfaces, such as oil droplets.

Complementary spherical surface screens

Antennas ◽  
2021 ◽  
Author(s):  
I. P. Kovalyov ◽  
N. I. Kuzikova
Keyword(s):  
Spherical Surface ◽  
Scattering Matrix ◽  
The Other ◽  
Numerical Verification ◽  
Conducting Plane ◽  
Conducting Sphere ◽  
The One ◽  
Relationship Of ◽  
The Relationship ◽  
Two Bodies

Ideally conducting spherical screens (SS) are investigated in this work. Boundary conditions on the surface of the field inside the sphere and outside it give relations connecting the elements of the scattering matrix (SM) of SS. These relations make it possible to express 4 submatrices of the SS SM in terms of one submatrix. The problem of the relationship between the characteristics of additional SS is considered. This problem is an analogue of Babinet's problem on additional flat screens. Combining additional flat screens forms a perfectly conducting plane, and combining additional SS gives a perfectly conducting sphere. When establishing the relationship of the characteristics of additional SS, they are considered, on the one hand, as a system of two bodies. On the other hand, this system forms a perfectly conducting sphere, the SM of which is diagonal. Equating the SM of the system with the SM of an ideally conducting sphere gives the sought relationship between the SMs of additional SS. The results of numerical verification of the relationships for the SM of additional SS are presented. In numerical calculations, the dimensions of the SS SM, which are infinite in the general case, have to be limited, this leads to an error. It is shown that with an increase in the SM dimension, the error decreases, and the elements of the resulting matrix approach those of the SM of an ideally conducting sphere. This confirms the validity of the relations for the SM of additional SS. The interrelation of characteristics of additional SS obtained in this work is analogous to the Babinet principle for additional flat screens. We believe that it will turn out to be just as popular and useful in calculating spherical screens and antennas, as Babinet's principle for flat screens and flat antennas.

Design of Piezoresistive Cantilevers for Low Force Electrical Contact Measurements

2000 ◽  
Author(s):  
Beth Pruitt ◽  
Aaron Partridge ◽  
Michael Bartsch ◽  
Yiching Liang ◽  
Thomas Kenny ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Electrical Contact ◽  
Electrical Contacts ◽  
Force Measurements ◽  
Force Sensitivity ◽  
Sensitivity Range ◽  
Output Force ◽  
Piezoresistive Cantilevers ◽  
Force Resolution ◽  
Processing Techniques

Abstract Micromachined piezoresistive cantilevers were fabricated to measure contact resistance and force for low force and small area electrical contacts. The intended application is the evaluation of contact tip geometries and metal films manufactured using standard semiconductor processing techniques. Prototype cantilevers are evaluated for force sensitivity, range, and noise as well as for feasibility of 4 wire contact resistance measurements at the end of the cantilever. The piezoresistors have a gage factor of about 35 and noise of about 1mV/Hz at 1Hz (the lowest frequency of intended measurements). Initial measurements of one cantilever design tested indicate sensitivity of 0.24mV/μN and force resolution of about 0.41mN for a piezoresistor drive voltage of about 9V and 100X gain on the bridge output. Force measurements are noise limited at the 5 Hz sampling rates used. 4-wire contact resistance measurements were made synchronously with piezoresistor bridge output voltage measurements.

scholarly journals CAPACITANCE MEASUREMENTS AND ELECTROSTATIC CALIBRATIONS IN EXPERIMENTS MEASURING THE CASIMIR FORCE

2011 ◽  
Vol 26 (22) ◽  
pp. 3930-3943 ◽  
Author(s):  
R. S. DECCA ◽  
E. FISCHBACH ◽  
G. L. KLIMCHITSKAYA ◽  
D. E. KRAUSE ◽  
D. LÓPEZ ◽  
...  
Keyword(s):  
Casimir Force ◽  
Spherical Surface ◽  
Scaling Law ◽  
Anomalous Scaling ◽  
Capacitance Measurements ◽  
Spherical Surfaces ◽  
Theoretical Predictions ◽  
Coated Surfaces ◽  
Micrometer Size

We discuss the possibility of determining the properties and quality of spherical surfaces used in precise experiments with the help of capacitance measurements. The results of this kind measurements for the lens-plane and sphere-plane, Au coated surfaces are compared with theoretical predictions from various models of perfect and broken sphericity. It is shown that capacitance measurements are incapable of discriminating between models of perfect and modified centimeter-size spherical surfaces in an experiment demonstrating the anomalous scaling law for the electric force. Claims to the contrary in the recent literature are explained by the use of improper comparison. The data from capacitance measurements in an experiment measuring the Casimir force by means of a micromechanical torsional oscillator employing micrometer-size spheres are shown to be in excellent agreement with theoretical predictions using the model of a perfect spherical surface.

Applications of AFM and STM: Solvation forces in liquids and inelastic photon excitation

1992 ◽  
Vol 50 (2) ◽  
pp. 1156-1157
Author(s):  
M. E. Welland ◽  
S. O'Shea ◽  
A. W. McKinnon ◽  
T. M. H. Wong
Keyword(s):  
Short Range ◽  
Photon Emission ◽  
Local Variation ◽  
Force Sensitivity ◽  
Photon Excitation ◽  
Scanned Probe Microscopy ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Solvation Forces ◽  
Tunnelling Current

We describe here non-standard applications of scanned probe microscopy; one application making use of the force sensitivity of the AFM to measure solvation forces at the liquid-solid interface and the other application based on the STM where the tunnelling current is used to excite photon emission from a surface.An interesting aspect of the solid-liquid interface is the molecular order induced in the liquid by the solid surface. This order can give rise to observable changes in the short range forces acting between two solids in a liquid medium; so called “solvation” or “structural” forces. As a first investigation of the local variation of short range forces in liquids we have used an AFM to observe solvation forces near a graphite surface. The AFM is ideal for this work as it can typically measure very small forces (∼10-10N) with high lateral (∼0.3nm) and vertical resolution (∼0.03nm). In this study, an optical deflection type AFM is used in which the movement of a small cantilever is sensed by measuring the deflection of a laser beam focussed on the back of the lever.

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

Ordering in Ni4Mo by TEM and APFIM

1987 ◽  
Vol 45 ◽  
pp. 214-215
Author(s):  
E.A. Kenik ◽  
T.A. Zagula ◽  
M.K. Miller ◽  
J. Bentley
Keyword(s):  
Electron Irradiation ◽  
Low Temperatures ◽  
Short Range ◽  
Atom Probe ◽  
Range Order ◽  
Considerable Time ◽  
Probe Field ◽  
Disordered Phase ◽  
Transmission Electron ◽  
Diffraction Patterns

The state of long-range order (LRO) and short-range order (SRO) in Ni4Mo has been a topic of interest for a considerable time (see Brooks et al.). The SRO is often referred to as 1½0 order from the apparent position of the diffuse maxima in diffraction patterns, which differs from the positions of the LRO (D1a) structure. Various studies have shown that a fully disordered state cannot be retained by quenching, as the atomic arrangements responsible for the 1½0 maxima are present at temperatures above the critical ordering temperature for LRO. Over 20 studies have attempted to identify the atomic arrangements associated with this state of order. A variety of models have been proposed, but no consensus has been reached. It has also been shown that 1 MeV electron irradiation at low temperatures (∼100 K) can produce the disordered phase in Ni4Mo. Transmission electron microscopy (TEM), atom probe field ion microscopy (APFIM), and electron irradiation disordering have been applied in the current study to further the understanding of the ordering processes in Ni4Mo.

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