322 research outputs found

    System design challenges for CO2_2 evaporative cooling in tracking detectors

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    CO2_2 evaporative cooling has become one of the most popular thermal management technologies for silicon detectors to be operated at low temperature. At LHC, this solution is already in use on the LHCb Velo, the ATLAS IBL and the CMS Phase I Pixel. The LHCb Velo upgrade and the UT detectors will be cooled in the same way as of 2019, as well as ATLAS and CMS upgraded tracking and vertexing detectors for the HL-LHC (2025).In order to fully exploit the heat removal capacity which can be achieved with carbon dioxide in evaporative mode, the cooling system needs a very careful design, combining the process, the transfer lines and the on-detector evaporators. This work discusses the challenges for the design of an optimised CO2_2 cooling system, including the mechanics, the thermal interfaces and the process instrumentation for controls and monitoring. Examples of presently adopted solutions are given, together with their limits and the needed further development in order to achieve reliable systems of much higher cooling power as in HL-LHC detectors

    First Steps in Automated Software Development Approach for LHC Phase II Upgrades CO₂ Detector Cooling Systems

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    With refrigerating power of the order of 1.5 kW at -35 °C and full compatibility with Detector Control System standards, Light Use Cooling Appliance for Surface Zones (LUCASZ) is the first movable medium size evaporative CO₂ detector cooling system. By 2018 a series of 4 LUCASZ units has been fully deployed by the EP-DT group at CERN. LUCASZ is capable to provide CO₂ cooling for various needs of detector development and testing required for Phase Iⅈ upgrades of LHC experiments. This paper describes selected software and controls hardware ideas used to develop the LUCASZ control system as baseline solutions for CO₂ cooling systems for Phase II upgrade of ATLAS and CMS trackers. The main challenges for future control system development will come from the number of cooling plants, the modularity, operation, and the implementation of backup philosophy. The introduction of automated software generation for both PLC and SCADA is expected to bring major improvement on the efficiency of control system implementation. In this respect, a unification step between experiments is highly required without neglecting specific needs of ATLAS and CMS

    Altered plasma and mucosal concentration of trace elements and antioxidant in active ulcerative colitis.

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    The production of free radicals is increased in inflammatory bowel disease, and trace elements are crucial components of several antioxidants, Trace elements deficiency may therefore compromise the defense against oxidative damage. The aims of this study were to measure plasma and tissue concentration of trace elements and antioxidants and to relate this to disease activity. Methods: A 10-ml blood sample and six colonic biopsy specimens were obtained from 24 patients with either active ulcerative colitis or in remission and 10 patients with irritable bowel syndrome for measurement of trace elements and trace element-dependent enzymes. Results: Patients with moderately active disease had significantly lower plasma iron, selenium, and glutathione peroxidase levels than patients in remission and controls, whereas no significant differences were found between the zinc and copper values of patients and controls. Mucosal concentrations of zinc and metallothionein were reduced, whereas iron and glutathione peroxidase concentrations were increased in patients with endoscopically active disease as compared with controls and patients in remission. Conclusions: Patients with ulcerative colitis have altered plasma and tissue levels of trace elements and antioxidant-related enzymes. The resulting reduced protection against free radicals may contribute to the inflammatory process