Search

Diamond detectors are used as beam loss and luminos- ity monitors for CMS and LHC. A time resolution in the nanosecond range allows to detect beam losses and lumi- nosities of single bunches. The radiation hardness and neg- ligible temperature dependence allow the usage of diamond sensors in high radiation fields without cooling. Two differ- ent diamond detector types are installed at LHC and CMS. One is based on pcCVD (polycrystalline chemical vapor deposition) diamonds and installed at different locations in the LHC tunnel for beam loss monitoring. Measurements of these detectors are used to perform a bunch-by-bunch beam loss analysis. They allow to disentangle the origin of beam losses. The second type uses scCVD (single crystal chemical vapor deposition) diamonds and is located inside CMS for van-der-Meer scan, beam halo and online lumi- nosity monitoring and around the LHC tunnel for beam loss observation. Results on the performance of these detectors will be presented and examples of the use for analyzing the beam conditions will be given. In order to persist the en- hanced requirements of the LHC after the long shutdown, e.g. higher luminosity, an upgrade of the detectors is re- quired. The concept of the new detectors will be presented and first results will be shown.

A novel detector system has been designed for an efficient online measurement of the machineinduced background in the CMS experimental cavern. The suppression of the CMS cavern background originating from pp collision products and the 25 ns bunch spacing have set the requirements for the detector design. Each detector unit will be a radiation hard, cylindrical Cherenkov radiator optically coupled to an ultra-fast UV-sensitive photomultiplier tube, providing a prompt, directionally sensitive measurement. Simulation and test beam measurements have shown the achievability of the goals that have driven the baseline design. The system will consist of 20 azimuthally distributed detectors per end, installed at a radius of r ~ 180 cm and a distance 20.6 m away from the CMS interaction region. The detector units will enable a measurement of the transverse distribution of the bunchby- bunch machine induced background flux. This will provide important feedback from the CMS on the beam conditions during the LHC machine setup and comparisons to expectations based on FLUKA simulations.

The objective of the CLIC Test Facility CTF3 is to demonstrate the feasibility issues of the CLIC two-beam technology: the efficient generation of a very high current drive beam, used as the power source to accelerate the main beam to multi-TeV energies with gradients of over 100 MeV/m, and stable drive beam deceleration. Results of successful beam acceleration with over 100 MeV/m energy gain are shown. Measurements of drive beam deceleration over a chain of Power Extraction Structures (PETS) are presented. The achieved RF power levels, the stability of the power production and of the deceleration are discussed. Finally, we give an overview of the remaining issues to be addressed by the end of 2011.

The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration in order to test the feasibility of the proposed Compact Linear Collider (CLIC) two-beam acceleration scheme. The monitoring and control of the bunch length throughout the CTF3 complex is important since this affects the efficiency and the stability of the final RF power production process. Bunch length diagnostics therefore form an essential component of the beam instrumentation at CTF3. This paper presents longitudinal profile measurements based on Streak camera and non-destructive RF power and microwave spectrometry techniques.