Effect of heat treatment and aging on the mechanical loss and strength of hydroxide catalysis bonds between fused silica samples

Hydroxide catalysis bonds are used in the aLIGO gravitational wave detectors and are an essential technology within the mirror suspensions which allowed for detector sensitivities to be reached that enabled the first direct detections of gravitational waves. Methods aimed at further improving hydroxide catalysis bonds for future upgrades to these detectors, in order to increase detection rates and the number of detectable sources, are explored. Also, the effect on the bonds of an aLIGO suspension construction procedure involving heat, the fibre welding process, is investigated. Here we show that thermal treatments can be beneficial to improving some of the bond properties important to the mirror suspensions in interferometric gravitational wave detectors. It was found that heat treating bonds at 150\,^\circC increases bond strength by a factor of approximately 1.5 and a combination of bond ageing and heat treatment of the optics at 150\,\circC reduces the mechanical loss of a bond from 0.10 to 0.05. It is also shown that current construction procedures do not reduce bond strength

Absorption spectroscopy of complex rare earth ion doped hybrid materials over a broad wavelength range

In the present work we applied a measurement setup to determine several relevant properties of rare-earth doped nanoparticles dispersed in polymer slab waveguides in a single absorption measurement: background absorption of the polymer host material, water absorption, polymer composition (overtones), rare earth concentration, and ligand contribution (increase of exponential loss trend in the UV). Furthermore, nanoparticle size and concentration in case of a refractive index mismatch (1//spl lambda//sup 4/ and r/sup 6/ dependence of Rayleigh scattering losses in the UV) could be extracted

Erbium doped LaF3 nanoparticles incorporated in silicondioxide thin films for active integrated optical applications

We report on the low-cost processing of erbium doped lanthanum trifluoride (LaF3:Er) nanoparticles dispersed in silicondioxide (SiO2) films prepared through the sol-gel method. The influence of particle concentration and annealing temperature on the optical properties and its implications on scattering in the visible wavelength range will be discussed. Uniform, crackfree and low loss films have been obtained by spincoating multiple layers followed by several annealing steps. The lanthanum trifluoride host shields the erbium from the OH-groups present in the silicondioxide, resulting in a higher excited state lifetime of the erbium due to the reduced OH-quenching

The effect of crystal orientation on the cryogenic strength of hydroxide catalysis bonded sapphire

Hydroxide catalysis bonding has been used in gravitational wave detectors to precisely and securely join components of quasi-monolithic silica suspensions. Plans to operate future detectors at cryogenic temperatures has created the need for a change in the test mass and suspension material. Mono-crystalline sapphire is one candidate material for use at cryogenic temperatures and is being investigated for use in the KAGRA detector. The crystalline structure of sapphire may influence the properties of the hydroxide catalysis bond formed. Here, results are presented of studies of the potential influence of the crystal orientation of sapphire on the shear strength of the hydroxide catalysis bonds formed between sapphire samples. The strength was tested at approximately 8 K; this is the first measurement of the strength of such bonds between sapphire at such reduced temperatures. Our results suggest that all orientation combinations investigated produce bonds of sufficient strength for use in typical mirror suspension designs, with average strengths >23 MPa

A novel photodefinable polymer containing rare-earth doped nanoparticles for optical amplification

We report on neodymium doped LaF3 nanoparticles dispersed in a photo definable polymer. Standard spin coating is used to deposit uniform thin films on a silicondioxide buffer layer, which can be photocured and developed to produce monomode active optical waveguides. Optical properties of the film are obtained using a prism coupling setup, showing low losses of the photosensitive polymer host material in both the visible and infrared. In addition, the absorption and emission due to the neodymium doped LaF3 nanoparticles have been determined for a range of particle concentrations

Eten van waarde : peiling consument en voedsel

This report provides a description of a scientifically-funded instrument that measures and explains the perceptions (or 'thoughts') and behaviours (or 'actions') of consumers with regards to food quality values. A description of its application is presented to generate insights into how modern Dutch consumers think about food, what Dutch consumers actually buy and the relationship between perceptions and behaviours

Invited Article: CO_2 laser production of fused silica fibers for use in interferometric gravitational wave detector mirror suspensions

In 2000 the first mirror suspensions to use a quasi-monolithic final stage were installed at the GEO600 detector site outside Hannover, pioneering the use of fused silica suspension fibers in long baseline interferometric detectors to reduce suspension thermal noise. Since that time, development of the production methods of fused silica fibers has continued. We present here a review of a novel CO_2 laser-based fiber pulling machine developed for the production of fused silica suspensions for the next generation of interferometric gravitational wave detectors and for use in experiments requiring low thermal noise suspensions. We discuss tolerances, strengths, and thermal noise performance requirements for the next generation of gravitational wave detectors. Measurements made on fibers produced using this machine show a 0.8% variation in vertical stiffness and 0.05% tolerance on length, with average strengths exceeding 4 GPa, and mechanical dissipation which meets the requirements for Advanced LIGO thermal noise performance

Self-assembled monolayers on gold for the fabrication of radioactive stents

An innovative and easily applicable method for the fabrication of radioactive stents, to be used for the treatment of restenosis, is presented. By incorporating the b-emitting radioisotopes 186Re, 188Re, 90Y, or 32P into sulfur-containing adsorbates, it becomes possible to cover a gold surface with a radioactive self-assembled monolayer (SAM). Two methods have been investigated. In the first, SAMs consisting of potentially radioactive rhenium-, yttrium-, and phosphorus-containing adsorbates have been assembled on 2D gold substrates, after which they have been studied by wettability measurements, electrochemistry, and X-ray photoelectron spectroscopy (XPS). The stability of these SAMs under simulated physiological conditions (phosphate buffered saline, PBS solution) for periods up to two months has been demonstrated. Alternatively, potentially radioactive monolayers have been prepared by exposure of SAMs of mono-, bi-, and tridentate ligands to a solution containing a radiometal (rhenium) in order to bind the metal to the monolayer. The polydentate ligands exhibit excellent binding capacity, leading to SAMs containing over 10±10 mol/cm2 of the radiometal, which is more than sufficient to make this system viable for the delivery of therapeutical dosages of radiation