Showing papers by "Ephraim Fischbach published in 2003"

Measurement of the Casimir Force between Dissimilar Metals

Abstract: The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator and an Au layer deposited on an ${\mathrm{A}\mathrm{l}}_{2}{\mathrm{O}}_{3}$ sphere, was measured dynamically with a noise level of $6\text{ }\text{ }\mathrm{f}\mathrm{N}/\sqrt{\mathrm{H}\mathrm{z}}$. Measurements were performed for separations in the $0.2--2\text{ }\ensuremath{\mu}\mathrm{m}$ range. The results agree to better than $1%$ in the $0.2--0.5\text{ }\ensuremath{\mu}\mathrm{m}$ range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment.

Improved tests of extra dimensional physics and thermal quantum field theory from new Casimir force measurements

Abstract: We report new constraints on extra-dimensional models and other physics beyond the standard model based on measurements of the Casimir force between two dissimilar metals for separations in the range $0.2--1.2\ensuremath{\mu}\mathrm{m}.$ The Casimir force between a Au-coated sphere and a Cu-coated plate of a microelectromechanical torsional oscillator was measured statically with an absolute error of 0.3 pN. In addition, the Casimir pressure between two parallel plates was determined dynamically with an absolute error of $\ensuremath{\approx}0.6\mathrm{mPa}.$ Within the limits of experimental and theoretical errors, the results are in agreement with a theory that takes into account the finite conductivity and roughness of the two metals. The level of agreement between experiment and theory was then used to set limits on the predictions of extra-dimensional physics and thermal quantum field theory. It is shown that two theoretical approaches to the thermal Casimir force which predict effects linear in temperature are ruled out by these experiments. Finally, constraints on Yukawa corrections to Newton's law of gravity are strengthened by more than an order of magnitude in the range 56--330 nm.

Constraining the couplings of massive pseudoscalars using gravity and optical experiments

Abstract: The simultaneous exchange of two pseudoscalars between fermions leads to a spin-independent force between macroscopic objects. Previous work has demonstrated that one can combine this interaction with tests of the weak equivalence principle, gravitational inverse square law, and studies of laser beam propagation in magnetic fields, to set significant new constraints on the Yukawa couplings of massless pseudoscalars to nucleons. Here we extend these results to massive pseudoscalars, and derive new constraints which relate the strengths of these couplings to the pseudoscalar mass.

Geometric random inner products: A family of tests for random number generators

Abstract: We present a computational scheme, GRIP (geometric random inner products), for testing the quality of random number generators. The GRIP formalism utilizes geometric probability techniques to calculate the average scalar products of random vectors distributed in geometric objects, such as circles and spheres. We show that these average scalar products define a family of geometric constants which can be used to evaluate the quality of random number generators. We explicitly apply the GRIP tests to several random number generators frequently used in Monte Carlo simulations, and demonstrate a statistical property for good random number generators.

Non-Transitive Quantum Games

Abstract: Non-transitivity can arise in games with three or more strategies $A,B,C$, when $A$ beats $B$, $B$ beats $C$, and $C$ beats $A$, ($A>B>C>A$). An example is the children's game \textquotedblleft rock, scissors, paper" ($R,S,P$) where $R>S>P>R$. We discuss the conditions under which quantum versions of $R,S,P$ retain the non-transitive characteristics of the corresponding classical game. Some physical implications of non-transitivity in quantum game theory are also considered.

Accelerator search for cosmic SIMPs

Abstract: We give limits on the contribution to the cosmic dark matter density of neutral, stable, strongly interacting massive particles (SIMPs). The limits are inferred from an accelerator mass spectrometry (AMS) experiment at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). The experiment accelerated nuclei of both gold and iron. The “SIMP signal” would be discovery of nuclei of these elements with anomalous masses. Since no such signal was observed for SIMP masses up to over 1 TeV, cosmic SIMP density limits may be given. Determining the minimum time of exposure to SIMPs trapped in the galaxy is a crucial element in the analysis of each sample.