Astronomical instrumentation

Abstract:

HSE challenges are substantial in sour gas projects; the poisonous nature of H2S introduces the risk of a toxic release with potential to cause multiple fatalities both inside and outside the site boundary. Learning from recent sour projects emphasises a "keep it in the pipe" philosophy: appropriate materials selection, use of high-integrity components for facilities, wells and flow lines, and removal of as many leak sources as is practicable. Effort is also required to reduce personnel exposure, either through minimum intervention / minimum manning, or by spacing facilities to minimise the impact of a toxic cloud. However, the implementation of these apparently simple elements involves a complex balance of HSE goals against operability, maintainability, availability and Capex/Opex targets. Conflicting factors include: • Very high costs associated with corrosion-resistant materials. • Potential maintainability / operability hindrance associated with removal of leak sources (valves, flanges, instrumentation). • Availability losses imposed by prohibiting online maintenance (forcing turnaround maintenance shutdowns). • Costs and operability difficulties associated with large-scale plant spacing. The solution lies in a design that optimises these elements to achieve risk levels that are as low as reasonably practicable, or ALARP. In doing so, it is important that the HSE Risk Assessment methodology aligns with the Reliability, Availability and Maintainability (RAM) premises, and that both are underpinned by the Operations Philosophy. This critically requires Operations input from a very early stage of the project. Emergency Response capability also needs to be considered early in sour projects, since this too will underpin fundamental design and Operations Philosophy decisions such as layout spacing and requirements for cascade air systems and safe refuges. As a result, H2S release detection mechanisms; personnel H2S response training and respiratory protective equipment will also play a critical role in the ALARP demonstration. Critically, Sour Gas developments should take an asset lifecycle view to understand the feasibility of incremental facility changes, field Simultaneous Operations (SimOps) and replacement of aging equipment. Finally, there must be a consistent and integrated approach to HSE in sour projects all along the value chain, since the chain is only as strong as its weakest link, and there are no second chances with H2S. "Sour Mindset" responsibility must be demonstrated during design, throughout construction and commissioning, and into operations, by both Company and Contractor personnel. Only by this means can ALARP really be achieved. Copyright 2009, International Petroleum Technology Conference.

Abstract:

We study the radiation tolerance of the silicon and GaAs PiN diodes that will be the part of the readout system of the upgraded ATLAS pixel detector. The components were irradiated by 200 MeV protons up to total accumulated dose 1.2×1015 p/cm2 and by 24 GeV protons up to 2.6×1015 p/cm2. Based on obtained results, we conclude that radiation hardness does not depend on the sensitive area or cut off frequency of PiN diodes. We identify two diodes that can be used for the SLHC upgrade.

Abstract:

The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgraded LHC with ten times higher luminosity. We study the radiation-hardness of VCSELs (Vertical-Cavity Surface-Emitting Laser) and GaAs and silicon PINs using 24 GeV/c protons at CERN for possible application in the data transmission upgrade. The optical power of VCSEL arrays decreases significantly after the irradiation but can be partially annealed with high drive currents. The responsivities of the PIN diodes also decrease significantly after irradiation, but can be recovered by operating at higher bias voltage. This provides a simple mechanism to recover from the radiation damage.

Abstract:

The silicon trackers of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN (Geneva) use optical links for data transmission. An upgrade of the trackers is planned for the Super LHC (SLHC), an upgraded LHC with ten times higher luminosity. We study the radiation-hardness of VCSELs (Vertical-Cavity Surface-Emitting Laser) and GaAs and silicon PINs using 24 GeV/c protons at CERN for possible application in the data transmission upgrade. The optical power of VCSEL arrays decreases significantly after the irradiation but can be partially annealed with high drive currents. The responsivities of the PIN diodes also decrease significantly after irradiation, but can be recovered by operating at higher bias voltage. This provides a simple mechanism to recover from the radiation damage.

Abstract:

We present the Spectroscopic Imaging survey in the near-infrared (near-IR) with SINFONI (SINS) of high-redshift galaxies. With 80 objects observed and 63 detected in at least one rest-frame optical nebular emission line, mainly Hα, SINS represents the largest survey of spatially resolved gas kinematics, morphologies, and physical properties of star-forming galaxies at z 1-3. We describe the selection of the targets, the observations, and the data reduction. We then focus on the "SINS Hα sample," consisting of 62 rest-UV/optically selected sources at 1.3 < z < 2.6 for which we targeted primarily the Hα and [N II] emission lines. Only ≈ 30% of this sample had previous near-IR spectroscopic observations. The galaxies were drawn from various imaging surveys with different photometric criteria; as a whole, the SINS Hα sample covers a reasonable representation of massive M* ≳ 1010 M ·star-forming galaxies at z 1.5-2.5, with some bias toward bluer systems compared to pure K-selected samples due to the requirement of secure optical redshift. The sample spans 2 orders of magnitude in stellar mass and in absolute and specific star formation rates, with median values ≈ 3 × 1010 M ·, ≈ 70 M· yr-1, and 3 Gyr-1. The ionized gas distribution and kinematics are spatially resolved on scales ranging from 1.5 kpc for adaptive optics assisted observations to typically 4-5 kpc for seeing-limited data. The Hα morphologies tend to be irregular and/or clumpy. About one-third of the SINS Hα sample galaxies are rotation-dominated yet turbulent disks, another one-third comprises compact and velocity dispersion-dominated objects, and the remaining galaxies are clear interacting/merging systems; the fraction of rotation-dominated systems increases among the more massive part of the sample. The Hα luminosities and equivalent widths suggest on average roughly twice higher dust attenuation toward the H II regions relative to the bulk of the stars, and comparable current and past-averaged star formation rates. © 2009. The American Astronomical Society.