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Based on the encouraging results obtained with a Rest Gas Ionization Profile Monitor of a first generation, a new monitor was designed and then installed in the SPS at the beginning of 2002. Its design fulfills all the requirements for a future installation in the LHC where four such monitors are foreseen. After the initial tests performed during the run of 2002, a few upgrading steps appeared necessary mainly in order to cope with the nominal LHC beam characteristics. They were implemented during the subsequent winter stop and the operation of the monitor was resumed in 2003 under various conditions of beam, ranging from an LHC pilot bunch up to beams having nominal distributions in bunch number, intensity and energy in the SPS for injection into the LHC. After a description of the monitor design, the measurements performed with the instrument during these last two years are discussed with the difficulties encountered and the corresponding implemented cures. Data acquired in 2003 on the whole spectrum of LHC beam characteristics are presented and the modifications made to prepare the 2004 campaign with a view to still improve the performance are also discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

At the LHC a beam loss system will be installed for continuous surveillance of particle losses. The system is designed to prevent hardware destructions, to avoid magnet coil quenches and to provide quantitative loss values. Over 3000 ionization chambers will be used to initiate the beam abort if the loss rates exceed the quench levels. The time and beam energy dependent quench levels require the acquisition of chamber currents in the range from 50 pA to 0.5 mA and an update of the values every 89 µs. The acquisition and control electronics will consist of a front end electronics near (< 400 m) to the ionization chambers and a threshold controller in the surface buildings. The front end will include a charge balance converter, a counter and multiplexer part. The charge balance converter is most suiteable to cover the large dynamic range. The introduced error is smaller than few % in the required dynamic range. Six channels will be transmitted over one cable of up to 3 km length. The threshold controller will issue warnings and dump signals depending on the beam energy and the loss durations. [ABSTRACT FROM AUTHOR]

Measurements have regularly been performed during the 1999 run, using the Rest Gas Monitor installed in the SPS. The exploited signal resulted from electrons produced by ionisation of the rest gas during the circulating beam passage. A magnetic field parallel to the electric extraction field was applied to channel the electrons. Proton beam horizontal transverse distributions were recorded during entire SPS acceleration cycles, between 14 GeV/c and 450 GeV/c and for different beam structures and bunch intensities. The influence of several parameters on the measured beam profiles was investigated. Results are presented and analysed in order to determine the performance that can be expected. [ABSTRACT FROM AUTHOR]

The BGIP is a proposal for a new, non-destructive beam profile monitor for the future Large Hadron Collider (LHC). This device provides the rms beam size value by means of the analysis of the velocity spectrum of the rest gas ions created and accelerated by the beam itself. After a thorough computer simulation study of the related physics, a first prototype of the BGIP has been conceived, built up and installed in the SPS main ring during 1999. This paper contains a short presentation of the simulation work and a description of the test set-up. The first experimental results are presented and compared with theoretical computations. [ABSTRACT FROM AUTHOR]