Diamond, Oxfordshire
With refined lattice tuning it becomes increasingly important to monitor or feedback on many parameters to keep stable optimum operating conditions. To this end we present techniques to measure betatron tune, chromaticity, betafunction magnitude/phase, and orbit response matrices all in such a way that no disturbance to the stored beam can be observed by the users of the light source. Examples of measurements for the various categories are compared to established methods, and their use in feedback schemes is discussed.
Fermilab, Batavia
Ionization profile monitors (IPMs) are installed in the Fermilab Booster, Main Injector and Tevatron. They are used routinely for injection matching measurements. For emittance measurements the IPMs have played a secondary role to the Flying Wires, with the exception of the Booster (where it is the only profile diagnostics). As Fermilab is refocusing its attention on the intensity frontier, non-intercepting diagnostics such as IPMs are expected to become even more important. This paper gives an overview of the operational use of IPMs for emittance and injection matching measurements at Fermilab, and summarizes the future plans.
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.
BNL, Upton, Long Island, New York
Slow variations of the RHIC closed orbit have been strongly influenced by diurnal variations. These variations affect the reproducibility of RHIC operation and might have contributed to proton beam polarization degradation during past polarized proton runs. We have developed and commissioned a slow orbit feedback system in RHIC Run-10 to diminish these variations and improve energy ramp commissioning and tuning efficiency. This orbit feedback uses multiple dipole correctors and orbit data from an existing beam position monitor system. The precision of the orbit feedback system has resulted directly from application of an improved algorithm for measurement of the average orbit, from improved survey offsets and various measures taken to ensure deterministic delivery of the BPM data. Closed orbit corrections are calculated with an online model-based SVD algorithm, and applied by a control loop operating at up to 1 Hz rate. We report on the feedback design and implementation, and commissioning and operational experience in RHIC Run-10.
JLAB, Newport News, Virginia
The advent of the energy recovering linac (ERL) brings with it the promise of linac-quality beams generated with near storage ring efficiency. This potential will not, however, be fulfilled without overcoming a number of technical and operational challenges. We will review the basics of ERL dynamics and operation, and give examples of idiosyncratic ERL behavior and requirements posing particular challenges from the perspective of diagnostics and instrumentation. Beam performance parameters anticipated in next-generation ERLs will be discussed, and a “wish list” for the instrumentation of these machines presented.