WP13: Beam Diagnostics

The extensive array of beam instrumentation with which the LHC is equipped, has played a major role in its commissioning, rapid intensity ramp-up and safe and reliable operation. HL-LHC will require similar diagnostics and in addition, brings a number of new challenges in terms of instrumentation that are being addressed through this work package.

The beam loss system, designed to protect the LHC from losses that could cause damage or quench a superconducting magnet, will need a significant upgrade in order to be able to cope with the new demands of HL-LHC. In particular cryogenic BLMs are under investigation for deployment in the new inner triplet magnets to distinguish between collision debris and primary beam losses, while radiation tolerant electronics are being developed to allow the front-end electronics to sit much closer to the detectors in order to reduce the influence of noise currently picked-up on long cables.

The proposed use of crab cavities (WP4) also implies new instrumentation in order allow for optimisation of their performance. Two additional diagnostic systems will therefore be investigated, namely high bandwidth electro-optical pick-ups and a streak camera installation. These would be able to perform intra-bunch measurements of transverse position on a turn by turn basis.

Development of a long range beam-beam compensator is also included in this work package. The aim of this device is to provide compensation of the parasitic long-range encounters that the proton bunches of opposite beams undergo on their way to and from the collision points. This would, in principle, allow for much smaller crossing angles before the onset of beam instabilities. A prototype of the device, based on a wire carrying a current of a few hundred amps placed close to the beam, is foreseen to be tested by 2017.

An upgrade to several existing systems is also envisaged, namely the BPM system, the wirescanner system and the synchrotron light diagnostics.

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