Displacement noise from back scattering and specular reflection of input optics in advanced gravitational wave detectors

The second generation of ground-based interferometric gravitational wave detectors are currently being built and installed. They are designed to be better in strain sensitivity by about a factor 10 with respect to the first generation. Light originating from the laser and following unintended paths, called stray light, has been a major problem during the commissioning of all of the first generation detectors. Indeed, stray light carries information about the phase of the emitting object. Therefore, in the next generation all the optics will be suspended in the vacuum in order to mitigate their associated stray light displacement noise. Despite this additional precaution, the challenging target sensitivity at low frequency which is partially limited by quantum radiation pressure combined with up-conversion effects, requires more detailed investigation. In this paper, we turn our attention to stray light originating from auxiliary optical benches. We use a dedicated formalism to compute the re-coupling of back-reflected and back-scattered light. We show, in particular, how much care should be taken in designing and setting requirements for the input bench optics

Thermal Performance of the LHC Connection Cryostat

The 16 connection cryostats for the Large Hadron Collider (LHC) being built at CERN are designed to fill the gap existing between the dispersion suppressor zones and the standard arcs of the accelerator. The first connection cryostat was cold tested down to superfluid helium temperature in August 2005, and the measured thermal performance was as expected. This paper presents the test results and a new thermal modeling of the connection cryostat based on the measurement of the thermal resistances of the braids used for thermalisation, allowing the precise determination of cool down times and equilibrium temperatures of the shielding under various conditions such as lead heating

Inhibitors of nuclear factor kappa B cause apoptosis in cultured macrophages

The precise role of the transcription factor nuclear factor kappa B (NF- κB) in the regulation of cell survival and cell death is still unresolved and may depend on cell type and position in the cell cycle. The aim of this study was to determine if three pharmacologic inhibitors of NF-κB, pyrrolidine dithiocarbamate, N-tosyl-L-lysl chloromethyl ketone and calpain I inhibitor, induce apoptosis in a murine macrophage cell line (RAW 264.7) at doses similar to those required for NF-κB inhibition. We found that each of the three inhibitors resulted in a dose- and time-dependent increase in morphologic indices of apoptosis in unstimulated, LPS-stimulated and TNF-stimulated cells. Lethal doses were consistent with those required for NF- κB inhibition. We conclude that nuclear NF-κB activation may represent an important survival mechanism in macrophages

Performance of a thermally deformable mirror for correction of low-order aberrations in laser beams

The thermally deformable mirror is a device aiming at correcting beam-wavefront distortions for applications where classical mechanical methods are precluded by noise considerations, as in advanced gravitational wave interferometric detectors. This moderately low-cost technology can be easily implemented and controlled thanks to the good reproducibility of the actuation. By using a flexible printed circuit board technology, we demonstrate experimentally that a device of 61 actuators in thermal contact with the back surface of a high-reflective mirror is able to correct the low-order aberrations of a laser beam at 1064 nm and could be used to optimize the mode matching into Fabry-Perot cavities

The LHC superconducting cavities

The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported

High-vacuum-compatible high-power Faraday isolators for gravitational-wave interferometers

Faraday isolators play a key role in the operation of large-scale gravitational-wave detectors. Second-generation gravitational-wave interferometers such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo will use high-average-power cw lasers (up to 200 W) requiring specially designed Faraday isolators that are immune to the effects resulting from the laser beam absorption–degraded isolation ratio, thermal lensing, and thermally induced beam steering. In this paper, we present a comprehensive study of Faraday isolators designed specifically for high-performance operation in high-power gravitational-wave interferometers

Entrevistando professores da disciplina Arte que lecionam o conteúdo música: encontro entre identidades profissionais

http://dx.doi.org/10.5902/198373487218O presente artigo poblematiza os resultados de uma pesquisa de mestrado na qual foram entrevistadas professoras de artes que lecionam o conteúdo música no contexto educacional do sudoeste do Paraná. O estudo centra-se na área da Educação Musical versando a lei 11.769/08 que reza a inserção da Música na educação básica como conteúdo obrigatório. A coleta de dados da pesquisa foi realizada no ano de 2009. Os objetivos propostos para o desenvolvimento desta pesquisa dizem respeito a transitar pelas narrativas das docentes, relativas à identidade das mesmas enquanto professoras da disciplina Arte. A metodologia utilizada é de abordagem qualitativa, cujos dados foram coletados a partir de entrevistas de História Oral Temática. As participantes da pesquisa foram sete professoras de escolas estaduais do núcleo regional de Pato Branco no estado do Paraná. Na análise de dados, problematiza-se a formação e atuação dos professores, as visões sobre as diversas linguagens artísticas e a possível abordagem dos conteúdos de Música pelo professor/a com formação em Artes Visuais. Ambiciona-se que as professoras entrevistadas e os leitores deste artigo, por empatia, possam olhar para a atuação profissional com uma nova perspectiva que auxilie a “ser um professor/a” mais crítico e consciente das possibilidades que a Arte traz. Desta forma, almeja-se contribuir para o estudo de narrativas de professores/as, dos problemas específicos da disciplina Arte na escola básica e dos encaminhamentos da implementação da lei 11.769/08