Radiation hardness of the LHCb Outer Tracker van Eijk, D.; Bachmann, S.; Bauer, Th ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2012, Letnik:
685
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This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to ...gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3fb−1 of integrated luminosity corresponding to an integrated charge of 0.055C/cm in the hottest spot of the detector.
Stability tests on channel cooled superconducting windings have revealed the existence of stationary normal zones as a possible response to transient disturbances. We have approached the phenomenon ...in analyzing the sets of solutions yielded by the time-independent heat equation of a conductor cooled with unsaturated superfluid helium. In good quantitative agreement with experiment our model confirms the existence of stable states with more or less extended normal zones in well defined regions of the I-B plane. It is concluded that stability of superconducting magnets should be evaluated in taking into account the absolute values given to the lengths of cooled and uncooled conductor sections rather than the average wetted conductor surface.
One of the main features of the medium-size Tokamak, Tore Supra, starting now to be built in France, relies in its superconducting coils to provide the toroidal magnetic field. This magnet is built ...with a NbTi conductor inside a Cu-CuNi mixed matrix, cooled by a pressurized superfluid helium bath at 1.8 K and 1 atm. With this original arrangement, high values for the maximum field (9 T), current density and fast varying magnetic field amplitudes are simultaneously allowed; this is mainly due to the large heat transfer to the superfluid helium. A short description of the superconducting coils and of the associated cryogenic system will be presented. Their designs are now quite detailed, after the completion of a 2.5 year programme of component development and qualifying tests. Main highlights of its results will be shortly illustrated they concern basic transient heat transfer mechanisms inside superfluid helium, with the stability they provide to superconductor operation, as well as the technological solutions specifically retained for Tore Supra - a model coil has been built and tested against all plausible constraints coming from present Tokamak operation.
The conceptual design of TORUS II SUPRA concerns a large sized Tokamak of the next generation. It takes into account constraints coming from the envisaged superconducting toroïdal magnet, but keeps ...unchanged all the operational facilities and working conditions which a more conventional design, i.e. a water cooled-copper magnet, could offer. The main parameters are R 0 = 2.15 m, a = 0.75 m, B 0 = 4.5 T, I = 1.7 MA. The scientific aims of the device concern the development, at a multimegawatt level, of plasma heating methods, mainly wave absorption and the contribution to high temperature (3-5 keV) Tokamak physics allowed by these methods : main emphasis is put on tentative profile control of plasma parameters during the quasi-steady state possible with a D.C. toroïdal magnetic field.
The LHCb Outer Tracker is a gaseous detector covering an area of 5x6 m2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and ...calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 um. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.
Urgent need for hospital hygiene Seyfert, P H; Reichel, H
Zeitschrift fur die gesamte Hygiene und ihre Grenzgebiete,
1980, Letnik:
26, Številka:
10
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