CERN, Geneva
The protection of the LHC equipment against beam-induced destruction is given by losses lasting up to three revolutions and longer losses. For the fast losses a passive system consisting of collimators, absorbers and masks is used. For the others an active system consists of beam loss monitors, a beam interlock system and the beam dump. The LHC protection requirements are different to other accelerators. The differences are mainly due to its energy, its stored beam intensity and its dimension. At the LHC top energy the beam intensity is about 3 orders of magnitude above the destruction limit of the superconducting magnet coils and 11 orders above their fast loss quench limit. These extreme conditions require a very reliable damage protection and quench prevention with a high mean time between failures. The numerous amounts of loss locations require an appropriate amount of detectors. In such a fail safe system the false dump probability has to be kept low to keep high operation efficiency. A balance was found between a reliable protection and operational efficiency. The main protection systems and beam instrumentation aspects of the measurement systems will be discussed.
KIP, Heidelberg
CERN, Geneva
GSI, Darmstadt
Synchrotron radiation has proven to be a flexible and effective tool for measuring a wide range of beam parameters in storage rings, in particular information about the longitudinal beam profile. It is today an established and widely used diagnostic method providing online measurements and thus allowing for continuous optimization of the machine performance. At the CLIC Test Facility (CTF3), synchrotron radiation is routinely used at a number of diagnostic stations, in particular in the Delay Loop and the Combiner Ring. Measurements with both standard CCDs and a streak camera showed the wide range of possible applications of this method, including determination of inter-bunch spacing, charge per pulse and monitoring of the manipulation of the effective path length by an undulator. This contribution first addresses the critical points during the design phase of long optical lines with lengths of more than 30 meters as they had to be realized at CTF3. Second, a summary of the present installations is given and results from measurements are shown.
I-Tech, Solkan
ESRF, Grenoble
Libera, the beam position processor, features the so-called Turn-by-Turn (TbT) data output, the data rate being exactly the revolution frequency of the accelerator. This data is essential for commissioning of the accelerator as well as for various machine physics studies. However, due to the "natural" properties of correctly structured filters (respecting the Nyquist theorem), the smearing between adjacent TbT samples is not negligible. The purpose of the modified DDC filter is to remove smearing between adjacent TbT samples, especially with partial fill patterns. The usage of Modified DDC filters gives the best results for the studies using the Turn-by-Turn measurements, with the benefit of "true & pure" Turn-by-Turn results (no smearing). The method, its implementation and first results are discussed in this paper.
BNL, Upton, Long Island, New York
In this paper we present algorithm of coupling correction in a storage ring based on monitoring the vertical size of a stored beam, while varying skew quadrupoles. The details of the algorithm realized as Matlab script and experimental results of its application are presented.
LBNL, Berkeley, California
At the Advanced Light Source (ALS), imperfections in the injection system plus electron diffusion result in storage ring RF bucket contamination. A Virtex-4 FPGA is used to generate a Direct-Digital Synthesized (DDS) sinewave waveform at the vertical betatron tune frequency, which is synchronously gated on or off at the 1.6MHz ring orbit frequency. Any pattern on/off/invert in 328 buckets by 2ns at the ring orbit frequency can be set. An embedded Power-PC core in the FPGA provides TCP access for control and monitoring via a remote PC running LabVIEW.