16 research outputs found

    Aligning the CMS Muon Endcap Detector with a System of Optical Sensors

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    The positions and orientations of one sixth of 468 large cathode strip chambers in the endcaps of the CMS muon detector are directly monitored by several hundred sensors including 2-D optical sensors with linear CCDs illuminated by cross-hair lasers. Position measurements obtained by photogrammetry and survey under field-off conditions show that chambers in the +Z endcap have been placed on the yoke disks with an average accuracy of ≈1\approx 1 mm in all 3 dimensions. We reconstruct absolute ZCMS_{CMS} positions and orientations of chambers at B=0T and B=4T using data from the optical alignment system. The measured position resolution and sensitivity to relative motion is about 60 ÎŒm\mu m. The precision for measuring chamber positions taking into account mechanical tolerances is \mbox{≈270ÎŒm\approx 270 \mu m}. Comparing reconstruction of optical alignment data and photogrammetry measurements at B=0T indicates an accuracy of ≈\approx 680 ÎŒm\mu m currently achieved with the hardware alignment system. Optical position measurements at B=4T show significant chamber displacements of up to 13 mm due to yoke disk deformation

    Design and Performance of the Alignment System for the CMS Muon Endcaps

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    The alignment system for the CMS Muon Endcap detector employs several hundred sensors such as optical 1-D CCD sensors illuminated by lasers and analog distance- and tilt-sensors to monitor the positions of one sixth of 468 large Cathode Strip Chambers. The chambers mounted on the endcap yoke disks undergo substantial deformation on the order of centimeters when the 4T field is switched on and off. The Muon Endcap alignment system is required to monitor chamber positions with \mbox{75-200 ÎŒ\mum} accuracy in the Rϕ\phi plane, ≈\approx400 ÎŒ\mum in the radial direction, and ≈\approx1 mm in the z-direction along the beam axis. The complete alignment hardware for one of the two endcaps has been installed at CERN. A major system test was performed when the 4T solenoid magnet was ramped up to full field for the first time in August 2006. We present the overall system design and first results on disk deformations, which indicate that the measurements agree with expectations

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    Endcap Muon Low Voltage Power Supply Prototype

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    Low voltage power supply for endcap muon chambers using transformers. Input power 3-phase from MG set. DC output power for analog and digital

    Installation of muon chambers on endcap

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    In November 2004, installation of all muon chambers on YE+2 and YE-2 were finished. Gas distribution and cooling for electronics were also installed

    Photos of endcap disk connection prototype

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    Pictures showing the corner assmbly for connecting CMS endcap disk

    Assembly of Endcap started at SX5

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    Assembly of YE-2 endcap disk is progressing at SX5. Pictures show mounting of three sectors on the cart. Center ring on tension side was assembled and pins where inserted to the three sectors

    Assembly of YE-2 finished at SX5

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    Assmebly of first endcap disk, YE-2, was finished at SX5 druing the week of June 11. Assembly of YE-3 started the same week
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