Development of Beam Instrumentation for Exotic Particle Beams

Modern nuclear physics makes extensive use of exotic particle beams created using accelerators, such as unstable ion isotopes and antiprotons. These give access to a wide range of fundamental studies that are at the cutting edge of science. The commissioning and operation of these accelerators require powerful beam diagnostic devices that are specially adapted to these unusual, and often very faint, beams. The work leading to this thesis, focuses on the development of the beam diagnostic system of the future superconducting linear accelerator at the High Intensity and Energy Isotope Separator On-Line Device (HIE-ISOLDE), which shall deliver stable and unstable isotope beams ranging from Helium to Radium at beam energies between 0.3 and 10 MeV/u and intensities from few particles per second up to 1 nA. The main elements of the diagnostics system are a Faraday cup for the measurement of the absolute beam current, a scanning blade with a V-shaped slit, which together with the Faraday cup allows one to measure the transverse beam profile and the beam position, a silicon detector for energy spectroscopy and time of flight measurements, plus a set of collimators and attenuating or stripping foils. The performance of the beam instrumentation will impact directly on the operation of the facility, therefore a lot of care has been put to identify the performance requirements and ensure that the design fulfills the needs. The techniques used by the systems studied during this work are widely used, but had to be adapted to the special design of the superconducting HIE-ISOLDE Radioactive EXperiment (REX) linac. In particular the compactness of the accelerator, and as a consequence of the diagnostic devices, required pushing the understanding of the physics behind the techniques in order to overcome limitations in the design parameters usually considered unbreakable. For this realistic models of all devices had to be developed that allowed detailed numerical studies. This new set of diagnostics for the HIE-ISOLDE REX linac is the most compact in the facility, and has been tested extensively in a wide range of ion beams. In addition to the HIE-ISOLDE work, a Secondary Emission Monitor (SEM) was tested at the Antiproton Decelerator (AD) facility using a 300 keV antiproton beam, together with other detector groups in the AEgIS collaboration such as nuclear emulsions, the MIMOTERA and the 3D pixel detector. In the frame of this thesis, a performance comparison among these detector technologies is done with the aim to identify an ideal set of diagnostics for the AD and for other similar antiproton facilities. This thesis first presents the models developed as well as the results of the numerical simulations, then the design of the prototypes and the experimental results obtained with beams in antiproton and ion accelerator facilities. All devices and techniques part of this R&D are characterized in detail, their performance and limitations described and options for further improvements indicated.