John Winterflood

Test of Lorentz Invariance in Electrodynamics Using Rotating Cryogenic Sapphire Microwave Oscillators

We present the first results from a rotating Michelson-Morley experiment that uses two orthogonally orientated cryogenic sapphire resonator oscillators operating in whispering gallery modes near 10 GHz. The experiment is used to test for violations of Lorentz invariance in the framework of the photon sector of the standard model extension (SME), as well as the isotropy term of the Robertson-Mansouri-Sexl (RMS) framework. In the SME we set a new bound on the previously unmeasured kappa(ZZ)(e-) component of 2.1(5.7) x 10(-14), and set more stringent bounds by up to a factor of 7 on seven other components. In the RMS a more stringent bound of -0.9(2.0) x 10(-10) on the isotropy parameter, P(MM) = delta-beta + 1 / 2 is set, which is more than a factor of 7 improvement.

High Performance Vibration Isolation Using Springs in Euler Column Buckling Mode.

A new vertical suspension technique utilising the remarkable properties of column springs in Euler buckling mode allows the mass of suspension springs to be reduced towards their ultimate minimum, greatly increasing the resonant frequency of internal modes, and allowing near ideal vibration isolation to substantially higher frequencies than achievable conventionally.

An inverted pendulum preisolator stage for the VIRGO suspension system

The design of a new preisolator stage for the VIRGO superattenuator is presented. The device is essentially a 6 m high inverted pendulum with horizontal resonant frequency of 30 mHz. An isolation of 65 dB at 1 Hz has been achieved. Very low forces are needed to move the whole superattenuator acting on the inverted pendulum. For this reason, the system is a suitable platform for the active control of the mirror suspension.

Using Euler Buckling Springs for Vibration Isolation.

Difficulties in obtaining ideal vertical vibration isolation with mechanical springs are identified as being due to the mass of the elastic element which is in turn due to its energy storage requirement. A new technique to minimize this energy is presented—being an Euler column undergoing elastic buckling. The design of a high performance vertical vibration isolation stage based on this technique is presented together with its measured performance.

Mathematical Analysis of an Euler Spring Vibration Isolator.

Abstract A new suspension technique uses flat springs in Euler buckling mode. This numerical analysis of the basic lever constrained configuration identifies the effect of the main geometrical parameters, and suitable values for obtaining the most useful force–displacement characteristic. The theory is shown to agree well with experimental measurements.

A long-period conical pendulum for vibration isolation

Abstract A practical design for a long-period conical pendulum based on the Scott-Russel linkage is presented together with proof-of-concept measurements on a simple prototype showing good stability for periods in excess of 20 seconds. The design is intended as a vibration isolation component for gravitational wave detection.

Transfer function of an ultralow frequency vibration isolation system

We have measured the transfer function of the recently proposed folded pendulum which has a resonant period up to 66 s. Results confirm that the dynamic behavior of the folded pendulum closely approximates that of a simple pendulum of the same period. The system can provide a simple one‐dimensional seismic isolation stage for laser interferometer gravitational wave antennas, as well as having application to very low frequency seismometers.

Passive vibration isolation using a Roberts linkage

The article present an ultralow frequency passive vibration isolation device as part of the preisolation stage for the Australian International Gravitational Observatory (AIGO). This isolator is based on the Roberts linkage and simulates a very long radius conical pendulum to provide two-dimensional isolation. It is designed as the second horizontal isolation component of the preisolator and it will support the remaining four isolation stages of the AIGO vibration isolator chain. A description of the device together with a theoretical model and its measured isolation performance are presented. With the current setup, we obtained 32 dB of isolation at 1 Hz.

Tilt sensor and servo control system for gravitational wave detection

This paper describes the design of a novel double-flexure two-axis tilt sensor with a tilt readout based on an optical walk-off sensor. The performance of the device has been investigated theoretically and experimentally. The walk-off sensor has demonstrated a sensitivity of 10−11 rad Hz−1/2 at 1 Hz. The tilt sensor has measured seismic noise ~10−9–10−10 rad Hz−1/2 for frequency in the 2–10 Hz range.

A LONG-PERIOD VERTICAL VIBRATION ISOLATOR FOR GRAVITATIONAL WAVE DETECTION

Abstract A novel design for a long-period passive vertical suspension system based on a torsion crank linkage is presented together with proof-of-concept measurements. A working range of centimetres and periods in excess of 20 s were obtained in agreement with theory. The design is cascadable with a horizontal isolator for 3D isolation.