45 research outputs found

    CMS Optical Links: Lessons learned from Mass Production

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    The CMS Tracker will install over 40000 optical links in its data-readout and control system, representing an unprecedented deployment of this technology in a Particle Physics Experiment. After reviewing the Quality Process employed in this project, a summary of the performance data measured during production will be shown. The analysis of this data will then be used to illustrate how the performance of the installed system may be predicted, giving confidence that the specified functionality will be attained in the final system. Completion of the production has allowed reflection upon the processes used and improvements for future such projects will be given in the form of some lessons learned

    The CMS Phase-1 pixel detector upgrade

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    The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.Peer reviewe

    CMS physics technical design report : Addendum on high density QCD with heavy ions

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    Alignment of the CMS tracker with LHC and cosmic ray data

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    © CERN 2014 for the benefit of the CMS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation and DOI.The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multi-processor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10μm

    Combined radiation damage, annealing, and ageing studies of InGaAsP /InP 1310 nm lasers for the CMS tracker optical links

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    A summary is presented of the combined effects of radiation damage, accelerated annealing and accelerated ageing in 1310 nm InGaAsP/InP multi-quantum-well lasers, the type chosen for use in the CMS Tracker optical links. The radiation damage effects are compared for a variety of radiation sources: /sup 60/Co-gamma, 0.8 MeV (average energy) neutrons, 20 MeV (average energy) neutrons and 300 MeV/c pions that represent important parts of the spectrum of particles that will be encountered in the CMS Tracker. The relative damage factors of the various sources are calculated by comparing the laser threshold current increase due to radiation damage giving approximately=0 : 0.12 : 0.53 : 1 for /sup 60/Co-gamma, approximately =0.8 MeV neutrons, approximately=20 MeV neutrons with respect to 300 MeV/c pions. The effects of bias current and temperature on the annealing were measured and, in all cases, the annealing is proportional to log(annealing time). A bias current of 60 mA increases the annealing, in terms of the time taken to anneal a given amount, by a factor of 10 relative to 0 mA. The annealing rate is also accelerated by heating the irradiated lasers and recovery occurs approximately=10 times faster at 60 degrees C than at 20 degrees C. The long-term ageing properties of irradiated lasers were also measured in an accelerated test carried out at 80 degrees C, for 2500 hours, at a bias current of 60 mA. No wearout-related degradation was observed in any of the devices. The combined results of these studies have been used to estimate the long-term damage expected for this type of laser operating inside the CMS Tracker. In the worst case of a laser operating at a distance of 22 cm from the beam-axis in the forward region of the Tracker, the maximum threshold increase will be approximately=6 mA over the first 10 years of LHC running. (20 refs)

    Quality Assurance Programme for the Environmental Testing of the CMS Tracker Optical Links

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    The QA programme is reviewed for the environmental compliance tests of commercial off-the-shelf (COTS) components for the CMS Tracker Optical link system. These environmental tests will take place in the pre-production and final production phases of the project and will measure radiation resistance, component lifetime, and sensitivity to magnetic fields. The evolution of the programme from small-scale prototype tests to the final pre-production manufacturing tests is outlined and the main environmental effects expected for optical links operating within the Tracker are summarised. A special feature of the environmental QA programme is the plan for Advance Validation Tests (AVT's) developed in close collaboration with the various industrial partners. AVT procedures involve validation of a relatively small set of basic samples in advance of the full production of the corresponding batch of devices. Only those lots that have been confirmed as sufficiently rad-tolerant will be purchased and used in the final production
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