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Abstract: In this review paper the present state-of-the-art of muon detection systems using gaseous detectors at the Large Hadron collider (LHC) is described. Beginning with a discussion of the concepts of muon detection systems, a comparison of the various technologies used is made with respect to the challenges at present experiments, and developments for future upgrades are discussed. Starting from wire chambers, micropattern detectors are described and their readiness for upgrades is highlighted. Aging, long-term sustained operation and factors affecting gas choice are discussed. Finally some applications outside particle physics are also presented. [Copyright &y& Elsevier]

Abstract: Past debris-flow activity in the Birchbach torrent (Swiss Alps) was assessed using tree-ring data. Based on the analysis of 210 Larix decidua and Picea abies, 50 events were reconstructed for the period AD 1752–2006. On average, 3.2 events per decade occurred in the torrent during the last century with distinct differences between the decades and a considerable decrease in the number of events during the last decade. Comparison with debris-flow reconstructions in neighboring catchments provided more insight in the similarities and differences in debris-flow occurrence. The recurrent debris-flow activity and current geomorphic settings suggest that the occurrence of debris flows in the torrent is rather transport-limited than supply-limited. Therefore, future investigations on debris-flow occurrence in transport-limited basins should focus on triggering rainfall events. [ABSTRACT FROM AUTHOR]

Abstract: Debris flows and snow avalanches are common processes in the headwaters of steep watersheds worldwide. In forested areas, dendrogeomorphic analyses of trees affected by debris flows and snow avalanches have regularly been used to date past events. Previous studies have, however, almost never focused on both processes at once, as snow avalanche impacts cannot easily be distinguished from debris-flow scars. In a similar way, tree-ring studies have often been limited to conifers, and sites colonized with broad-leaved forests have been widely disregarded. We report on a case from the Valais Alps (Switzerland) where past debris-flow and snow avalanche activity was dated with intraseasonal precision using different broad-leaved and conifer trees. In total, the analysis of 171 cores, 34 wedges, and 11 crosssections from 93 trees allowed identification of 20 debris-flow and 3 snow avalanche events between A.D. 1930 and 2008. Results also indicate that some of the events would have been missed without the sampling of broad-leaved trees. [Copyright &y& Elsevier]

The Data Acquisition System of the Compact Muon Solenoid experiment at the Large Hadron Collider reads out event fragments of an average size of 2 kB from around 650 detector front- ends at a rate of up to 100 kHz. The first stage of event-building is performed by the Super-Fragment Builder employing custom-built electronics and a Myrinet optical network. It reduces the number of fragments by one order of magnitude, thereby greatly decreasing the requirements for the subsequent event-assembly stage. Back-pres- sure from the down-stream event-processing or variations in the size and rate of events may give rise to buffer overflows in the subdetector's front-end electronics, which would result in data corruption and would require a time-consuming re-sync procedure to recover. The Trigger-Throttling System protects against these buffer overflows. It provides fast feedback from any of the subdetector front-ends to the trigger so that the trigger can be throttled be- fore buffers overflow. This paper reports on new performance measurements and on the recent successful integration of a scaled-down setup of the described system with the trigger and with front-ends of all major subdetectors. The ongoing commissioning of the full-scale system is discussed. [ABSTRACT FROM AUTHOR]

For the ALICE experiment at the Large Hadron Collider (LHC) at CERN/Geneva, a high level trigger system (HLT) for online event selection and data compression has been developed and a computing cluster of several hundred dual-processor nodes is being installed. A major system integration test was carried out during the commissioning of the time projection chamber (TPC), where the HLT also provides a monitoring system. All major parts like a small computing cluster, hardware input devices, the online data transportation framework, and the HLT analysis could be tested successfully. A common interface for HLT processing components has been designed to run the components from either the online or offline analysis framework without changes. The interface adapts the component to the needs of the online processing and allows the developer to use the offline framework for easy development, debugging, and benchmarking. Following this approach, results can be compared directly. For the upcoming commissioning of the whole detector, the HLT is currently prepared to run online data analysis for the main detectors, e.g., the inner tracking system (ITS), the TPC, and the transition radiation detector (TRD). The HLT processing capability is indispensable for the photon spectrometer (PHOS), where the online pulse shape analysis reduces the data volume by a factor 20. A common monitoring framework is in place and detector calibration algorithms have been ported to the HLT. The paper describes briefly the architecture of the HLT system. It focuses on typical applications and component development. [ABSTRACT FROM AUTHOR]

The Event Filter (EF) selection stage is a fundamental component of the ATLAS Trigger and Data Acquisition architecture. Its primary function is the reduction of data flow and rate to values acceptable by the mass storage operations and by the subsequent offline data reconstruction and analysis steps. The computing instrument of the EF is organized as a set of independent subfarms, each connected to one output of the Event Builder (EB) switch fabric. Each subfarm comprises a number of processors analyzing several complete events in parallel. This paper describes the design of the ATLAS EF system, its deployment in the 2004 ATLAS combined test beam together with some examples of integrating selection and monitoring algorithms. Since the processing algorithms are not explicitly designed for EF but are adapted from the offline ones, special emphasis is reserved to system reliability and data security, in particular for the case of failures in the processing algorithms. Other key design elements have been system modularity and scalability. The EF shall be able to follow technology evolution and should allow for using additional processing resources possibly remotely located [ABSTRACT FROM PUBLISHER]