LGC: Analysis and pratical example of direct levelling observations referenced on the CERN local Geoid model

Direct levelling is performed extensively in the CERN surveying processes for accelerator elements’ alignment and positioning. LGC software (Logiciel Général de Compen- sation1) computes results and associated statistics for ob- servations used by surveyors. Traditionally, direct levelling campaigns are computed separately from the planimetry, using simple differences of height -called in LGC *DVER observation- between two measured points. LGC provides another observation model, called *DLEV, using offsets to a horizontal plane at the position of the station. The level plani- metric position must therefore be known or be computable by additional observations. This more rigorous model al- lows a better integration in 3D computation involving other instruments, such as laser trackers or total stations. This article reviews the traditional method and analyses the use of geo-referenced levelling stations for accelerator element surveying. The influence of the station planimetric position precision and of the geoid model used are studied and illustrated with a practical case

Mathis software for controlling BCAM-based monitoring and alignment systems

The MATHIS Software (Monitoring and Alignment Tracking for HIE-Isolde Software) aims at providing 3D positions of physical components of the HIE-Isolde superconducting modules, accurately and permanently measured by well-designed networks of BCAM devices (Brandeis Camera Angle Monitoring). Although it is originally intended for the HIE-Isolde project, its architecture and its use cases have been extended and optimized for more general setups. Most of the configuration data are stored either within XML-formatted files or within databases. The adaptation of MATHIS for different BCAM monitoring systems therefore does not require any further code rewriting. Moreover, the software is fully cross-platform and can either be run on the specific Linux machines driving the accelerator electronic devices, or be used on independent Windows workstations as a stand-alone software. In the first case, the software mainly relies on FESA (Front End Software Architecture) which is an object-oriented real-time framework that ensures equipment software portability across CERN accelerators. Through this standardized module, MATHIS communicates with dedicated servers networks and publishes in real-time the computed positions to any workstation, and more specifically to the concerned control room operators. This paper describes the main features and explains the modular architecture of the software

HIE-Isolde: Commissioning and first results of the Mathilde system monitoring the positions of cavities and solenoids inside cryomodules

The new superconducting HIE-ISOLDE Linac replaced most of pre-existing REX ISOLDE facility at CERN. This upgrade involves the design, construction, installation and commissioning of 4 high-β cryomodules. Each high-β cryomodule houses five superconducting cavities and one superconducting solenoid. Beam-physics simulations show that the optimum linac working conditions are obtained when the main axes of the active components, located inside the cryostats, are aligned and permanently monitored on the REX Nominal Beam Line (NBL) within a precision of 0.3 mm for the cavities and 0.15 mm for the solenoids at one sigma level along directions perpendicular to the beam axis. The Monitoring and Alignment Tracking for HIE-ISOLDE (MATHILDE) system has been developed to fulfil the alignment and monitoring needs for components exposed to non-standard environmental conditions such as high vacuum or cryogenic temperatures. MATHILDE is based on opto-electronic sensors (HBCAM) observing, through high quality viewports, spherical retroreflectors made of high index (~2) glass. Precise mechanical parts, metrological tables and the, so called, MATHIS software were designed to be able to reconstruct the position of the active elements within a precision of 0.1 mm. The commissioning of MATHILDE and its first results to monitor the cavity and solenoid positions, especially during the installation and tests of the two first cryomodules on the HIE-ISOLDE Linac, are reviewed in this contribution

Alignment Monitoring System for the PIP-II Prototype SSR1 Cryomodule

For the first prototype PIP-II SSR1 cryomodule, an alignment monitor system based on HBCAM will be used. The main focus will be changes in alignment due to shipping and handling or during cool down and operation process. The SSR1 cryomodule contains eight 325 MHz superconducting single spoke cavities and four solenoid’based focusing lenses, and an alignment error better than 0.5 mm RMS for the transverse solenoid, based on function requirement specification. The alignment monitor system has been configured to the objectives of SSR1 cryomodule: low space for integration; presence of magnetic fields; exposure to non-standard environmental conditions such as high vacuum and cryogenic temperatures. The mechanical design and first results of system performance will be presented

HIE Isolde – General Presentation of MATHILDE

In the frame of the HIE-ISOLDE project a superconducting Linac will upgrade the energy and intensity of the REX ISOLDE facility at CERN. It will be made of 2 low β and 4 high β cryomodules. Each high β cryomodule houses five superconducting RF cavities and one superconducting solenoid (respectively 6 and 2 for the low β). Beam physics simulations show that the optimum linac working conditions are obtained with components aligned and monitored on the Nominal Beam Line within 0.3 mm for the cavities and 0.15 mm for the solenoids at one sigma level. The Monitoring and Alignment Tracking for HIE-ISOLDE (MATHILDE) system is based on opto electronic sensors, optical and mechanical elements partly exposed to high vacuum and cryogenic temperatures. This paper summarizes the MATHILDE studies and focuses on the viewport crossing, the MATHIS software, the newly designed HBCAM cameras and the retro-reflective targets based on high index glass properties

3D calculation for the alignment of LHC low-beta quadrupoles

The low beta triplet quadrupoles magnets of the Large Hadron Collider (LHC) are located on both sides of the ATLAS, CMS, ALICE and LHCb experiments. The alignment tolerances of these components are particularly stringent with ±0.5 mm at 3σ and are tracked by an alignment system consisting of micrometric sensors and motorized jacks used for components remote adjustment. The system has been installed in 2008 with the purpose of monitoring the triplets relative displacements with respect to their nominal position. After the development of appropriate calibration benches, the first absolute calibrations of the sensors have been performed in 2016, allowing a determination of the magnet positions in an absolute reference frame. The radial and vertical (plus roll) data were separated in two different calculations steps. During the LHC Long Shutdown 2 (LS2, 2019- 2021), consolidation works have been carried out on all triplets allowing to perform absolute calculation in 3D, and significantly increasing the position determination accuracy. This paper gives an overview of the 3D calculations used currently for the alignment of low beta quadrupoles magnets and summarizes their positions change since LS2

Progress on the HIE-ISOLDE Facility

After 20 years of successful ISOLDE operation at the PS-Booster*, a major upgrade of the facility, the HIE-ISOLDE (High Intensity and Energy ISOLDE) project was launched in 2010. It is divided into three parts; a staged upgrade of the REX post-accelerator to increase the beam energy from 3.3 MeV/u to 10 MeV/u using a super-conducting linac, an evaluation of the critical issues associated with an increase in proton-beam intensity and a machine design for an improvement in RIB quality. The latter two will be addressed within the HIE-ISOLDE Design Study. This presentation aims to provide an overview of the present status of the overall project by providing; an insight to the infrastructure modifications, installation and tests of the HEBT lines as well as progress on the commissioning of the SC linac. Plans for the second phase of the project will be highlighted

Alignment and Monitoring Systems for Accelerators and Experiments Based on BCAM - First Results and Benefits of Systems Developed for ATLAS, LHCb and HIE-ISOLDE

In the last few years alignment and monitoring systems based on BCAM* cameras active sensors, or their HBCAM evolution, have been developed at the request of the Technical Coordination of LHC experiments and HIE-ISOLDE facility Project Leader. ADEPO (ATLAS DEtector POsition) has been designed to speed up the precise closure - 0.3 mm - of large detector parts representing in total ~2500 tons. For LHCb a system has been studied and installed to monitor the positions of the Inner Tracker stations during the LHCb dipole magnet cycles. The MATHILDE (Monitoring and Alignment Tracking for HIE-ISOLDE) system has been developed to fulfil the alignment and monitoring needs for components of the LINAC enclosed in successive Cryo-Modules. These systems have been in each case configured and adapted to the objectives and environmental conditions: low space for integration; presence of magnetic fields; exposure to non-standard environmental conditions such as high vacuum and cryogenic temperatures. After a short description of the different systems and of the environmental constraints, this paper summarizes their first results, performances and their added value

The Assembly Experience of the First Cryo-module for HIE-ISOLDE at CERN

The HIE ISOLDE project aims at increasing the energy of the radioactive ion beams of the existing REX ISOLDE facility from the present 3 MeV/u up to 10 MeV/u for A/q to 4.5. The upgrade includes the installation of a superconducting linac in successive phases, for a final layout containing two low-β and four high-β cryo-modules. The first phase involves the installation of two high-B cryo-modules, each housing five high-β superconducting cavities and one superconducting solenoid, aligned within tight tolerances. After having designed and procured the cryo-module components, the first units is now being assembled at CERN, in a dedicated facility including class100 (ISO5) clean rooms equipped with specific tooling. The assembly is foreseen to be ultimate and the cryo-module cold tested by May 2015. In this paper, after a brief description of the main design features of the cryo-module , we present the assembly of the first unit, including the methodology, special tools, assembly procedures and quality assurance aspects. We report on the experience from this first assembly, including tests results, and present prospects for the next-coming cryo-module assemblies

HIE-ISOLDE: First Commissioning Experience

The HIE ISOLDE project [1] reached a major milestone in October 2015, with the start of the first physics run with radioactive ion beams. This achievement was the culminating point of intense months during which the first cryomodule of the HIE ISOLDE superconducting Linac and its high-energy beam transfer lines were first installed and subsequently brought into operation. Hardware commissioning campaigns were conducted in order to define the envelope of parameters within which the machine could be operated, to test and validate software and controls, and to investigate the limitations preventing the systems to reach their design performance. Methods and main results of the first commissioning of HIE ISOLDE post accelerator, including the performance of the superconducting cavities with beam, will be reviewed in this contribution