Development of the Beam Position Monitors for the Diagnostics of the Test Beam Line in the CTF3 at CERN

Abstract

The work for this thesis is in line with the field of Instrumentation for Particle Accelerators, so called Beam Diagnostics. It is presented the development of a series of electro-mechanical devices called Inductive Pick-Ups (IPU) for Beam Position Monitoring (BPM). A full set of 17 BPMunits (16 + 1 spare), named BPS, were built and installed into the Test Beam Line (TBL), an electron beam decelerator, of the 3rd CLIC Test Facility (CTF3) at CERN —European Organization for the Nuclear Research—. The CTF3, built at CERN by an international collaboration, was meant to demonstrate the technical feasibility of the key concepts for CLIC —Compact Linear Collider— as a future linear collider based on the novel two-beam acceleration scheme, and in order to achieve the next energy frontier for a lepton collider in the Multi-TeV scale. Here the BPS device is first described mechanically to after focus on the electronic design, electromagnetic features and operational parameters according to the TBL specifications. Moreover, it will be described the two main test carried out on the BPS units at low and high frequencies needed for their parametric characterization, as well as their respective specifically designed test stands. The low frequency test, in the beam pulse time scale (until 10ns/100MHz), was built to determine the BPS parameters related to the beam position monitoring, which is based on the precise motion of a stretched wire emulating the beam current. On the other hand, the high frequency test, beyond the microwave X band and around the beam bunching time scale (83ps/12GHz), is for measuring the longitudinal impedance of the BPS device in the frequency range of interest which is based on the S-parameters measurements of the propagating TEM mode in a matched coaxial waveguide able to emulate an ultra-relativistic electron beam. Finally, the beam test performance of the BPS units installed in the TBL line is also shown.