David Tshilumba

Conceptual design and scaled experimental validation of an actively damped carbon tie rods support system for the stabilization of future particle collider superstructures

This paper presents a simple solution to increase the stability of the large superstructures supporting the final electromagnets of future linear particle collider. It consists of active carbon fiber tie rods, fixed at one end on the structure and at the other end to the detector through active tendons. In the first part of the paper, the solution has been tested on a finite element model of one half of the CLIC_ILD final focus structure. With a reasonable design, it is shown numerically that the compliance can be decreased by at least a factor 4, i.e., that the structure is 4 times more robust to technical noise at low frequency. Two additional features of the active rods are that they can also actively damp the structural resonances and realign the superstructures. The second part of the paper presents a successful experimental validation of the concept, applied to a scaled test bench, especially designed to contain the same modal characteristics as the full scale superstructure.

Sensors applications within the research framework of the PACMAN project on metrology for particle accelerators at CERN

Within the framework of the Compact Linear Collider Study (CLIC) [1] at CERN, new sensing and actuators technologies must be developed in order to achieve the required performance. An ITN Marie Curie Skowoska project funded by the European Union was launched in 2013. This project is a study on Particle Accelerator Components Metrology and Alignment to the Nanometre Scale, named PACMAN [2]. The project team consists of ten early stage researchers, divided in four work packages focusing on different tasks. Each of them is developing innovative transducers overperforming the current state of the art. Their main tasks are high-precision metrology and fiducialization, magnets prequalification and determination of magnetic axis under the constraint of small aperture (below 10 mm), determination of electrical center of a 15 GHz Radio Frequency-Beam Position Monitor (RF-BPM) and the electro-magnetic axis of an accelerating cavity, improvement of an existing seismic sensor to guarantee an optimized alignment process. The project has now been running for two years at CERN, resulting in dramatic progress for each of the early stage researchers. Their work already lead to building new experiments and proofs of concepts that are to be assembled in a unique, flexible, and compact test bench.

JACoW : A Wire-Based Methodology to Analyse the Nanometric Resolution of an RF Cavity BPM

Resonant Cavity Beam Position Monitors (RF-BPMs) are diagnostic instruments capable of achieving beam position resolutions down to the nanometre scale. To date, their nanometric resolution capabilities have been predicted by simulation and verified through beam-based measurements with particle beams. In the frame of the PACMAN project at CERN, an innovative methodology has been developed to directly observe signal variations corresponding to nanometric displacements of the BPM cavity with respect to a conductive stretched wire. The cavity BPM of this R&D study operates at the TM110 dipole mode frequency of 15GHz. The concepts and details of the RF stretched wire BPM testbench to achieve the best resolution results are presented, along with the required control hardware and software.