arXiv subjects

S. Schlamminger

Publications and source records attributed to S. Schlamminger.

17 recordsLinked to original sources

arXiv2025

Ultralow loss torsion micropendula for chipscale gravimetry

We explore a new class of chipscale torsion pendula formed by Si$_3$N$_4$ nanoribbon suspensions. Owing to their unique hierarchy of gravitational, tensile, and elastic stiffness, the devices exhibit damping rates of $\sim 10\;μ$Hz and parametric gravity sensitivities near that of an ideal pendulum. The suspension nonlinearity can also be used to cancel the pendulum nonlinearity, paving the way towards fully isochronous, high $Q$ pendulum gravimeters. As a demonstration, we study a 0.1 mg, 32 Hz micropendulum with a damping rate of $16\;μ$Hz, a thermal acceleration sensitivity of $2\;\text{n}g/\sqrt{\text{Hz}}$, and a parametric gravity sensitivity of $5$ Hz/$g_0$. We record Allan deviations as low as 2.5 $μ$Hz at 100 seconds, corresponding to a bias stability of $5\times 10^{-7}g_0$. We also demonstrate a 100-fold cancellation of the pendulum nonlinearity. In addition to inertial sensing, our devices are well suited to proposed searches for new physics exploiting low-loss micro- to milligram-scale mechanical oscillators.

physics.app-ph↗

arXiv2024

Microscale torsion resonators for short-range gravity experiments

Measuring gravitational interactions on sub-100-$μ$m length scales offers a window into physics beyond the Standard Model. However, short-range gravity experiments are limited by the ability to position sufficiently massive objects to within small separation distances. Here we propose mass-loaded silicon nitride ribbons as a platform for testing the gravitational inverse square law at separations currently inaccessible with traditional torsion balances. These microscale torsion resonators benefit from low thermal noise due to strain-induced dissipation dilution while maintaining compact size (<100$\,μ$g) to allow close approach. Considering an experiment combining a 40$\,μ$g torsion resonator with a source mass of comparable size (130$\,μ$g) at separations down to 25$\,μ$m, and including limits from thermomechanical noise and systematic uncertainty, we predict these devices can set novel constraints on Yukawa interactions within the 1-100$\,μ$m range.

gr-qc↗

arXiv2017

Measurement of the Planck constant at the National Institute of Standards and Technology from 2015 to 2017

Researchers at the National Institute of Standards and Technology(NIST) have measured the value of the Planck constant to be $h =6.626\,069\,934(89)\times 10^{-34}\,$J$\,$s (relative standard uncertainty $13\times 10^{-9}$). The result is based on over 10$\,$000 weighings of masses with nominal values ranging from 0.5$\,$kg to 2$\,$kg with the Kibble balance NIST-4. The uncertainty has been reduced by more than twofold relative to a previous determination because of three factors: (1) a much larger data set than previously available, allowing a more realistic, and smaller, Type A evaluation; (2) a more comprehensive measurement of the back action of the weighing current on the magnet by weighing masses up to 2$\,$kg, decreasing the uncertainty associated with magnet non-linearity; (3) a rigorous investigation of the dependence of the geometric factor on the coil velocity reducing the uncertainty assigned to time-dependent leakage of current in the coil.

physics.ins-det↗

arXiv2015

A LEGO Watt Balance: An apparatus to determine a mass based on the new SI

A global effort to redefine our International System of Units (SI) is underway and the change to the new system is expected to occur in 2018. Within the newly redefined SI, the present base units will still exist but be derived from fixed numerical values of seven reference constants. More specifically, the unit of mass, the kilogram, will be realized through a fixed value of the Planck constant $h$. For instance, a watt balance can be used to realize the kilogram unit of mass within a few parts in $10^8$. Such a balance has been designed and constructed at the National Institute of Standards and Technology. For educational outreach and to demonstrate the principle, we have constructed a LEGO tabletop watt balance capable of measuring a gram size mass to 1 % relative uncertainty. This article presents the design, construction, and performance of the LEGO watt balance and its ability to determine $h$

physics.ins-det↗

arXiv2015

Recent measurements of the gravitational constant as a function of time

A recent publication (J.D. Anderson et. al., EPL 110, 1002) presented a strong correlation between the measured values of the gravitational constant $G$ and the 5.9-year oscillation of the length of day. Here, we provide a compilation of all published measurements of $G$ taken over the last 35 years. A least squares regression to a sine with a period of 5.9 years still yields a better fit than a straight line. However, our additions and corrections to the G data reported by Anderson {\it et al.} significantly weaken the correlation.

gr-qc↗

arXiv2015

First measurements of the flux integral with the NIST-4 watt balance

In early 2014, construction of a new watt balance, named NIST-4, has started at the National Institute of Standards and Technology (NIST). In a watt balance, the gravitational force of an unknown mass is compensated by an electromagnetic force produced by a coil in a magnet system. The electromagnetic force depends on the current in the coil and the magnetic flux integral. Most watt balances feature an additional calibration mode, referred to as velocity mode, which allows one to measure the magnetic flux integral to high precision. In this article we describe first measurements of the flux integral in the new watt balance. We introduce measurement and data analysis techniques to assess the quality of the measurements and the adverse effects of vibrations on the instrument.

physics.ins-det↗

arXiv2015

A summary of the Planck constant measurements using a watt balance with a superconducting solenoid at NIST

Researchers at the National Institute of Standards and Technology have been using a watt balance, NIST-3, to measure the Planck constant $h$ for over ten years. Two recently published values disagree by more than one standard uncertainty. The motivation for the present manuscript is twofold. First, we correct the latest published number to take into account a recently discovered systematic error in mass dissemination at the Bureau International des Poids et Mesures (BIPM). Second, we provide guidance on how to combine the two numbers into one final result. In order to adequately reflect the discrepancy, we added an additional systematic uncertainty to the published uncertainty budgets. The final value of $h$ measured with NIST-3 is $h = 6.626\,069\,36(37)\times 10^{-34}\,\mbox{J\,s}$. This result is $77(57) \times 10^{-9}$ fractionally higher than $h_{\mathrm{90}}$. Each number in parentheses gives the value of the standard uncertainty in the last two digits of the respective value and $h_{\mathrm{90}}$ is the conventional value of the Planck constant given by $h_{\mathrm{90}}\equiv 4 /( K_{\mathrm{J-90}}^2 R_{\mathrm{K-90}})$, where $K_{\mathrm{J-90}}$ and $R_{\mathrm{K-90}}$ denote the conventional values of the Josephson and von Klitzing constants, respectively.

physics.ins-det↗

arXiv2014

A determination of the local acceleration of gravity for the NIST-4 watt balance

A new watt balance is being constructed at the National Institute of Standards and Technology (NIST) in preparation for the redefinition of the International System of Units and the realization of mass through an exact value of the Planck constant. The total relative uncertainty goal for this instrument of a few parts in $10^{8}$ requires that the local acceleration due to gravity be known at the location of a test mass with a relative uncertainty on the order of only a few parts in $10^{9}$. To make this determination, both the horizontal and vertical gradients of gravity must be known such that gravity may be tied from an absolute reference in the laboratory to the precise mass location. We describe the procedures used to model and measure gravity variations throughout the laboratory and give our results.

physics.ins-det↗

arXiv2014

Reflections on a Measurement of the Gravitational Constant Using a Beam Balance and 13 Tons of Mercury

In 2006, a final result of a measurement of the gravitational constant $G$ performed by researchers at the University of Zürich was published. A value of $G=6.674\,252(122)\times 10^{-11}\,\mbox{m}^3\,\mbox{kg}^{-1}\,\mbox{s}^{-2}$ was obtained after an experimental effort that lasted over one decade. Here, we briefly summarize the measurement and discuss the strengths and weaknesses of this approach.

physics.ins-det↗

arXiv2013

A reference-beam autocollimator with nanoradian sensitivity from mHz to kHz and dynamic range of 10^7

We describe an autocollimating optical angle sensor with a dynamic range of 9 mrad and nrad/sqrt(Hz) sensitivity at frequencies from 5 mHz to 3 kHz. This work improves the standard multi-slit autocollimator design by adding two optical components, a reference mirror and a condensing lens. This autocollimator makes a differential measurement between a reference mirror and a target mirror, suppressing common-mode noise sources. The condensing lens reduces optical aberrations, increases intensity, and improves image quality. To further improve the stability of the device at low frequencies the body of the autocollimator is designed to reduce temperature variations and their effects. A new data processing technique was developed in order to suppress the effects of imperfections in the CCD.

physics.ins-det↗

arXiv2012

Torsion-balance tests of the weak equivalence principle

We briefly summarize motivations for testing the weak equivalence principle and then review recent torsion-balance results that compare the differential accelerations of beryllium-aluminum and beryllium-titanium test body pairs with precisions at the part in $10^{13}$ level. We discuss some implications of these results for the gravitational properties of antimatter and dark matter, and speculate about the prospects for further improvements in experimental sensitivity.

gr-qc↗

arXiv2011

Brownian force noise from molecular collisions and the sensitivity of advanced gravitational wave observatories

We present an analysis of Brownian force noise from residual gas damping of reference test masses as a fundamental sensitivity limit in small force experiments. The resulting acceleration noise increases significantly when the distance of the test mass to the surrounding experimental apparatus is smaller than the dimension of the test mass itself. For the Advanced LIGO interferometric gravitational wave observatory, where the relevant test mass is a suspended 340 mm diameter cylindrical end mirror, the force noise power is increased by roughly a factor 40 by the presence of a similarly shaped reaction mass at a nominal separation of 5 mm. The force noise, of order 20 fN\rthz\ for $2 \times 10^{-6}$ Pa of residual H$_2$ gas, rivals quantum optical fluctuations as the dominant noise source between 10 and 30 Hz. We present here a numerical and analytical analysis for the gas damping force noise for Advanced LIGO, backed up by experimental evidence from several recent measurements. Finally, we discuss the impact of residual gas damping on the gravitational wave sensitivity and possible mitigation strategies.

gr-qc↗

arXiv2009

Charge Management for Gravitational Wave Observatories using UV LEDs

Accumulation of electrical charge on the end mirrors of gravitational wave observatories, such as the space-based LISA mission and ground-based LIGO detectors, can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable Au-coated Cu plate brought near a Au-coated Si plate pendulum suspended from a non-conducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of $\sim$$10^5 e/\mathrm{s}$, as well as spectral measurements of the pendulum charge resulting in a white noise level equivalent to $3\times10^5 e/\sqrt{Hz}$.

gr-qc↗

arXiv2008

Preferred-Frame and CP-Violation Tests with Polarized Electrons

We used a torsion pendulum containing $\approx 10^{23}$ polarized electrons to search new interactions that couple to electron spin. We limit CP-violating interactions between the pendulum's electrons and unpolarized matter in the earth or the sun, test for rotation and boost-dependent preferred-frame effects using the earth's rotation and velocity with respect to the entire cosmos, and search for exotic velocity-dependent potentials between polarized electrons and unpolarized matter in the sun and moon. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in $10^{21}$ from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in Sm$ $Co$_5$ was measured to be $(4.19\pm 0.19)\times 10^{22} {\rm cm}^{-3}$ at a field of 9.6 kG.

hep-ex↗

arXiv2007

Test of the Equivalence Principle Using a Rotating Torsion Balance

We used a continuously rotating torsion balance instrument to measure the acceleration difference of beryllium and titanium test bodies towards sources at a variety of distances. Our result Delta a=(0.6+/-3.1)x10^-15 m/s^2 improves limits on equivalence-principle violations with ranges from 1 m to infinity by an order of magnitude. The Eoetvoes parameter is eta=(0.3+/-1.8)x10^-13. By analyzing our data for accelerations towards the center of the Milky Way we find equal attractions of Be and Ti towards galactic dark matter, yielding eta=(-4 +/- 7)x10^-5. Space-fixed differential accelerations in any direction are limited to less than 8.8x10^-15 m/s^2 with 95% confidence.

gr-qc↗

arXiv2007

High Sensitivity Torsion Balance Tests for LISA Proof Mass Modeling

We have built a highly sensitive torsion balance to investigate small forces between closely spaced gold coated surfaces. Such forces will occur between the LISA proof mass and its housing. These forces are not well understood and experimental investigations are imperative. We describe our torsion balance and present the noise of the system. A significant contribution to the LISA noise budget at low frequencies is the fluctuation in the surface potential difference between the proof mass and its housing. We present first results of these measurements with our apparatus.

gr-qc↗

arXiv2006

New CP-violation and preferred-frame tests with polarized electrons

We used a torsion pendulum containing $\sim 9 \times 10^{22}$ polarized electrons to search for CP-violating interactions between the pendulum's electrons and unpolarized matter in the laboratory's surroundings or the sun, and to test for preferred-frame effects that would precess the electrons about a direction fixed in inertial space. We find $|g_{\rm P}^e g_{\rm S}^N|/(\hbar c)< 1.7 \times 10^{-36}$ and $|g_{\rm A}^e g_{\rm V}^N|/(\hbar c) < 4.8 \times 10^{-56}$ for $λ> 1$AU. Our preferred-frame constraints, interpreted in the Kostelecký framework, set an upper limit on the parameter $|\bm{\tilde {b}}^e| \leq 5.0 \times 10^{-21}$ eV that should be compared to the benchmark value $m_e^2/M_{\rm Planck}= 2 \times 10^{-17}$ eV.

hep-ph↗