High availability using virtualization - 3RC

High availability has always been one of the main problems for a data center. Till now high availability was achieved by host per host redundancy, a highly expensive method in terms of hardware and human costs. A new approach to the problem can be offered by virtualization. Using virtualization, it is possible to achieve a redundancy system for all the services running on a data center. This new approach to high availability allows the running virtual machines to be distributed over a small number of servers, by exploiting the features of the virtualization layer: start, stop and move virtual machines between physical hosts. The 3RC system is based on a finite state machine, providing the possibility to restart each virtual machine over any physical host, or reinstall it from scratch. A complete infrastructure has been developed to install operating system and middleware in a few minutes. To virtualize the main servers of a data center, a new procedure has been developed to migrate physical to virtual hosts. The whole Grid data center SNS-PISA is running at the moment in virtual environment under the high availability system.Comment: 10 page

Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 $\mu$m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to $3 \cdot 10^{15}$ neq/cm$^2$. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations

Description and performance of track and primary-vertex reconstruction with the CMS tracker

A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tbar t events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of pT > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of pT = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in pT, and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung

Characterisation of irradiated thin silicon sensors for the CMS phase II pixel upgrade

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment's silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to Phi(eq) = 2x10(16) cm(-2), and an ionising dose of approximate to 5 MGy after an integrated luminosity of 3000 fb(-1). Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 mu m thick p-bulk pad diodes and strip sensors irradiated up to fluences of Phi(eq) = 1.3 x 10(16) cm(-2) are shown.Peer reviewe

Alignment of the CMS tracker with LHC and cosmic ray data

© 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

P-Type Silicon Strip Sensors for the new CMS Tracker at HL-L-HC

Abstract: The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type

Iron overload enhances the development of experimental liver cirrhosis in mice

The role of iron in initiating liver fibrosis in iron overload diseases is not clearly established. Partly, this is due to the lack of suitable animal models that can produce the full liver pathology seen in genetic hemochromatosis. Recent advances in this field have demonstrated that iron may be interacting with other potential liver-damaging agents. The aim of this study was to investigate if feeding with carbonyl iron (CI) facilitates the development of carbon tetrachloride (CCl4)-induced liver fibrosis in the mouse. Mice were given a diet containing 3% CI and treated with CCl4 intraperitoneally twice weekly and 5% alcohol added to the drinking water for 12 weeks. Hepatic iron content increased 15- and 22-fold in animals receiving CI and CI + CCl4. At histological examination, iron-laden hepatocytes were found in CI treated animals, whereas these were absent in animals not exposed to CI. Mice receiving iron-enriched diet alone showed a mild fibrosis. Conversely, a marked collagen deposition was observed in CCl4 and CI + CCl4 groups. In particular, in this latter group, there was evidence of liver cirrhosis. Biochemical evaluation of collagen content substantiated histologic analysis. These results demonstrate that the addition of iron facilitates the development of cirrhosis in animals exposed to subtoxic doses of CCl4. This model may be useful in exploring the pathogenesis of liver cirrhosis. Moreover, its use in genetically altered mouse strains might provide new insight on the role of iron in fibrosis

Testing of Compounds in Models of Pulmonary Emphysema

There is a pressing need for the development of new therapies for emphysema, particularly as no existing treatment has been shown to reduce disease progression. Compounds with a potential activity against the pathological mechanisms postulated to play a role in the development and progression of emphysema should be tested in vivo in animal models of this disease. The choice of the model is of capital importance. While models of elastase-induced emphysema are relatively easy to execute, require low personnel capacity and provide fast results, they also have a limited clinical relevance. On the other hand, models of chronic smoke exposure are time-consuming, expensive and require high personnel capacity but have a high clinical relevance. Presently, mainly two pharmacological approaches are being considered and investigated in experimental studies. The first approach consists of pharmacological interventions designed to slow down the rate at which alveolar wall is lost in emphysema. In this approach we find anti-inflammatory agents, protease inhibitors and antioxidants. The attempt to reduce lung inflammatory cell infiltration is most appealing since such an effect would also reduce the lung burden of both proteases and oxidants. The second approach is an attempt to reverse the process of alveolar loss by inducing alveolar growth. To our knowledge here only the effects of retinoids and/or retinoid receptor agonists have been investigated. This report presents a selected review of the literature of animal studies using these pharmacological approaches