Handling and Transport of Oversized Accelerator Components and Physics Detectors

For cost, planning and organisational reasons, it is often decided to install large pre-built accelerators components and physics detectors. As a result surface exceptional transports are required from the construction to the installation sites. Such heavy transports have been numerous during the LHC installation phase. This paper will describe the different types of transport techniques used to fit the particularities of accelerators and detectors components (weight, height, acceleration, planarity) as well as the measurement techniques for monitoring and the logistical aspects (organisation with the police, obstacles on the roads, etc). As far as oversized equipment is concerned, the lowering into the pit is challenging, as well as the transport in tunnel galleries in a very scare space and without handling means attached to the structure like overhead travelling cranes. From the PS accelerator to the LHC, handling systems have been developed at CERN to fit with these particular working conditions. This paper will expose the operating conditions of the main transport equipments used at CERN in PS, SPS and LHC tunnels

Development of SRF Cavity Tuners for CERN

Superconducting RF cavity developments are currently on-going for new accelerator projects at CERN such as HIE ISOLDE and HL-LHC. Mechanical RF tuning systems are required to compensate cavity frequency shifts of the cavities due to temperature, mechanical, pressure and RF effects on the cavity geometry. A rich history and experience is available for such mechanical tuners developed for existing RF cavities. Design constraints in the context of HIE ISOLDE and HL-LHC such as required resolution, space limitation, reliability and maintainability have led to new concepts in the tuning mechanisms. This paper will discuss such new approaches, their performances and planned developments

A study of the link between cosmic rays and clouds with a cloud chamber at the CERN PS

Recent satellite data have revealed a surprising correlation between galactic cosmic ray (GCR) intensity and the fraction of the Earth covered by clouds. If this correlation were to be established by a causal mechanism, it could provide a crucial step in understanding the long-sought mechanism connecting solar and climate variability. The Earth's climate seems to be remarkably sensitive to solar activity, but variations of the Sun's electromagnetic radiation appear to be too small to account for the observed climate variability. However, since the GCR intensity is strongly modulated by the solar wind, a GCR-cloud link may provide a sufficient amplifying mechanism. Moreover if this connection were to be confirmed, it could have profound consequences for our understanding of the solar contributions to the current global warming. The CLOUD (Cosmics Leaving OUtdoor Droplets) project proposes to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. CLOUD plans to perform detailed laboratory measurements in a particle beam at CERN, where all the parameters can be precisely controlled and measured. The beam will pass through an expansion cloud chamber and a reactor chamber where the atmosphere is to be duplicated by moist air charged with selected aerosols and trace condensable vapours. An array of external detectors and mass spectrometers is used to analyse the physical and chemical characteristics of the aerosols and trace gases during beam exposure. Where beam effects are found, the experiment will seek to evaluate their significance in the atmosphere by incorporating them into aerosol and cloud models.Recent satellite data have revealed a surprising correlation between galactic cosmic ray (GCR) intensity and the fraction of the Earth covered by clouds. If this correlation were to be established by a causal mechanism, it could provide a crucial step in understanding the long-sought mechanism connecting solar and climate variability. The Earth's climate seems to be remarkably sensitive to solar activity, but variations of the Sun's electromagnetic radiation appear to be too small to account for the observed climate variability. However, since the GCR intensity is strongly modulated by the solar wind, a GCR-cloud link may provide a sufficient amplifying mechanism. Moreover if this connection were to be confirmed, it could have profound consequences for our understanding of the solar contributions to the current global warming. The CLOUD (Cosmics Leaving OUtdoor Droplets) project proposes to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. CLOUD plans to perform detailed laboratory measurements in a particle beam at CERN, where all the parameters can be precisely controlled and measured. The beam will pass through an expansion cloud chamber and a reactor chamber where the atmosphere is to be duplicated by moist air charged with selected aerosols and trace condensable vapours. An array of external detectors and mass spectrometers is used to analyse the physical and chemical characteristics of the aerosols and trace gases during beam exposure. Where beam effects are found, the experiment will seek to evaluate their significance in the atmosphere by incorporating them into aerosol and cloud models

CLOUD: an atmospheric research facility at CERN

This report is the second of two addenda to the CLOUD proposal at CERN (physics/0104048), which aims to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. The document places CLOUD in the framework of a CERN facility for atmospheric research, and provides further details on the particle beam requirements

Addendum to the CLOUD proposal

This report is the first of two addenda to the CLOUD proposal at CERN (physics/0104048), which aims to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. The document provides further details on the detector design, scientific motivation and experimental programme

The Mechanical Design of a Collimator and Cryogenic Bypass for Installation in the Dispersion Suppressors of the LHC

A project to install collimators in the dispersion suppressor regions of the LHC was launched early 2010, aiming to reduce the power deposition in superconducting magnets by a factor of 10. To be placed in the continuous arc cryostat, the design of such collimators had to comply with challenging integration, functional and time constraints. A pre-study for a cold collimator solution was launched in parallel with an alternative design consisting of a room temperature collimator and a cryogenic bypass. The second was eventually preferred, as it was based on proven LHC technologies for cryogenic, vacuum, electrical and collimator material solutions, despite the increased difficulty on the mechanical integration and assembly. This paper presents the mechanical design of a cryogenic bypass for the LHC continuous cryostat andrespective collimator unit, both made to comply with the functionality of existing LHC systems. The approach taken to achieve a reliable design within schedule will be explained alongside the measures adopted to validate new solutions, in particular, when dealing with welding distortions, systems routing, thermal loads and precision mechanics

An ultra-pure gas system for the CLOUD experiment at CERN

The Cosmics Leaving Outdoor Droplets (CLOUD) experiment aims to recreate atmospheric conditions inside a large chamber where the mechanisms for the formation of aerosol and cloud are studied. Aerosol and cloud are recognized as representing the largest uncertainty in the current understanding of climate change together with the influence of the cosmic rays. The CLOUD chamber, a 26 m^3 cylinder, has been built to the highest technical standard of cleanliness. A key aspect of the CLOUD experiment is the gas system. It is made of several units with specific function and it was built following the highest cleanliness standard as the chamber. A detailed description of the gas system units is given in the present contribution. Data taking periods are scheduled two times per year and important physics results have been already obtained by the CLOUD collaboration

Development of the gas system for the CLOUD experiment at CERN

The Cosmics Leaving Outdoor Droplets (CLOUD) experiment aims to recreate atmospheric conditions inside a large chamber where the mechanisms for the formation of aerosol and cloud are studied. Aerosol and cloud are recognized as representing the largest uncertainty in the current understanding of climate change together with the influence of the cosmic rays. The CLOUD chamber, a 26 m^3 cylinder, has been built to the highest technical standard of cleanliness. A key aspect of the CLOUD experiment is the gas system. The present contribution describes the last modifications and upgrades introduced for the 2013 data taking period

A fibre-optic UV system for H2_{2}SO4_{4} production in aerosol chambers causing minimal thermal effects

A novel fibre-optic UV illumination system for sulphuric acid (H(2)SO(4)) production has been developed. The illumination system described in this paper provides sufficient ultraviolet light (UV) power while causing practically no thermal effect on the aerosol chamber (temperature variation <0.005 degrees C at full UV illumination). A similar thermal stability has not been achieved in other comparable experimental set-ups so far. The spectrum provided by the fibre-optic UV system corresponds to the UVB region, illuminates the chamber in a reasonably uniform way and is comparable to the ground level actinic flux. The UV system has been installed for the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber experiments at CERN. Precise, easily-adjustable and reproducible concentrations of H(2)SO(4) were generated by adjusting the UV light intensity. This paper gives an overview on the design of this new system as well as insights on its performance and application. (C) 2011 Elsevier Ltd. All rights reserved

Characterisation of organic contaminants in the CLOUD chamber at CERN

d'Aguilar Jacques. Brown (A. W. A). — Insect Control by chemicals (La lutte contre les Insectes par les substances chimiques). London 1951. In: Bulletin de la Société entomologique de France, volume 57 (9), novembre 1952. p. 144