The Compact Linear Collider (CLIC) study aims at the development of a Multi-TeV e+ e-collider. The micro-precision CLIC structures will have an accelerating gradient of 100 MV/m and will be aligned on so-called girders. The girder construction constrains are mainly dictated by the beam physics and RF requirements. The study of such girders is a challenging case involving material choice, mechanical design as well as prototype fabrication and experimental testing.

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Abstract. RF Crab Cavities are an essential part of the HL-LHC upgrade. Two concepts of such systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A cryomodule with two DQW cavities is in advanced fabrication stage for the tests with protons in the SPS. The cavities must be operated at 2 K, without excessive heat loads, in a low magnetic environment and in compliance with CERN safety guidelines on pressure and vacuum systems. A large set of components, such as a thermal shield, a two layers magnetic shield, RF lines, helium tank and tuner are required for the successful and safe operation of the cavities. The sum of all these components with the cavities and their couplers forms the cryomodule. An overview of the design and fabrication strategy of this cryomodule is presented. The main components are described along with the present status of cavity fabrication and processing and cryomodule assembly. The lesson learned from the prototypes and first manufactured systems are also included.

The accurate characterisation of a copper–beryllium wire with a diameter of 0.1 mm is one of the steps to increase the precision of future accelerators’ pre-alignment. Novelties in measuring the wire properties were found in order to overcome the difficulties brought by its small size. This paper focuses on an implementation of a chromatic-confocal sensor leading to a sub-micrometric uncertainty on the form measurements. Hence, this text reveals a high-accuracy metrology technique applicable to objects with small diameters: it details the methodology, describes a validation by comparison with a reference and specifies the uncertainty budget of this technique.

The Compact LInear Collider (CLIC), currently under study at CERN, aims at the development of a Multi-TeV e + e -collider. The micro-precision CLIC RF-structures will have an accelerating gradient of 100 MV/m and will be mounted and aligned on specially developed supporting girders. The girder fabrication constraints are dictated by stringent physics requirements. The micrometric pre-alignment over several kilometers of girders, allow for the CLIC structures to fulfill their acceleration and collision functionality. Study of such girders and their sophisticated alignment method, is a challenging case involving dedicated mechanical design as well as prototype production and experimental testing.