Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
Capacitive pick-ups for closed-orbit measurements are presently under development for an Ultra-low energy Storage Ring (USR) at the future Facility for Low-energy Antiproton and Ion Research (FLAIR). Low-intensity, low-energy antiprotons impose challenging demands on the sensitivity of the monitoring system. The non-destructive beam position monitors (BPMs) should be able to measure 107 particles and give sufficient information on the beam trajectory. This contribution presents the status of the BPM project development. Main goals of the investigation include optimization of the mechanical design and preparation of a narrowband signal processing system.
Cockcroft Institute, Warrington, Cheshire
The University of Liverpool, Liverpool
For destructive beam intensity measurements, electrostatic Faraday cups will be incorporated into the Ultra-low energy Storage Ring (USR) and its transfer lines at the Facility for Low-energy Antiproton and Ion Research (FLAIR). This multipurpose machine will offer both slow and fast extracted beams resulting in a wide range of intensities and varying time structure of the beam. In this contribution we present the particular challenges of measuring the beam intensity in the USR, results from numerical optimization studies, as well as the design of the cup.
Fermilab, Batavia
A system was developed for bunch-by-bunch detection of transverse proton and antiproton coherent oscillations based on the signal from a single beam-position monitor (BPM) located in a region of the ring with large amplitude functions. The signal is digitized over a large number of turns and Fourier-analyzed offline with a dedicated algorithm. To enhance the signal, the beam is excited with band-limited noise for about one second, and this was shown not to significantly affect the circulating beams even at high luminosity. The system is used to measure betatron tunes of individual bunches and to study beam-beam effects. In particular, it is one of the main diagnostic tools in an ongoing study of nonlinear beam-beam compensation studies with Gaussian electron lenses. We present the design and operation of this tool, together with results obtained with proton and antiproton bunches.
GSI, Darmstadt
TUD, Darmstadt
In this paper, a method for measuring the absolute signal delays of active optical transmission lines will be presented. This measurement method is an essential part of the timing system for FAIR (Facility for Antiproton and Ion Research). To prevent interference of the timing signals whose delays are to be measured with the measurement signal sequence, the latter is transmitted on a separate optical carrier in the same fibre. By using a wavelength selective mirror at the end of the transmission line, the optical measurement signals are reflected and lead back to the measurement unit. The measurement sequence consists of a number of sinusoidal signals with different frequencies that are modulated one by one on the optical carrier. For each frequency a phase comparison of the outgoing and returning signal is performed. In the last step, the absolute delay is calculated from the obtained phase values by using an algorithm. It will be shown that this method enables cost efficient delay measurements with an accuracy of better than 100 fs.