Manfred Wendt

Design of the 15 GHz BPM test bench for the CLIC test facility to perform precise stretched-wire RF measurements

The Compact Linear Collider (CLIC) requires a low emittance beam transport and preservation, thus a precise control of the beam orbit along up to 50 km of the accelerator components in the sub-μm regime is required. Within the PACMAN3 (Particle Accelerator Components Metrology and Alignment to the Nanometer Scale) PhD training action a study with the objective of pre-aligning the electrical centre of a 15 GHz cavity beam position monitor (BPM) to the magnetic centre of the main beam quadrupole is initiated. Of particular importance is the design of a specific test bench to study the stretched-wire setup for the CLIC Test Facility (CTF3) BPM, focusing on the aspects of microwave signal excitation, transmission and impedance-matching, as well as the mechanical setup and reproducibility of the measurement method.

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.