The Level-0 Muon Trigger for the LHCb Experiment

A very compact architecture has been developed for the first level Muon Trigger of the LHCb experiment that processes 40 millions of proton-proton collisions per second. For each collision, it receives 3.2 kBytes of data and it finds straight tracks within a 1.2 microseconds latency. The trigger implementation is massively parallel, pipelined and fully synchronous with the LHC clock. It relies on 248 high density Field Programable Gate arrays and on the massive use of multigigabit serial link transceivers embedded inside FPGAs.Comment: 33 pages, 16 figures, submitted to NIM

Conception and Validation Software Tools for the Level 0 Muon Trigger of LHCb

The Level-0 muon trigger processor of the LHCb experiment looks for straight particules crossing muon detector and measures their transverse momentum. It processes 40×106 proton-proton collisions per second. The tracking uses a road algorithm relying on the projectivity of the muon detector. The architecture of the Level-0 muon trigger is complex with a dense network of data interconnections. The design and validation of such an intricate system has only been possible with intense use of software tools for the detector simulation, the modelling of the hardware components behaviour and the validation. A database describing the dataflow is the corner stone between the software and hardware components

Background Light in Potential Sites for the ANTARES Undersea Neutrino Telescope

The ANTARES collaboration has performed a series of {\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by $^{40}$K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to $^{40}$K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.Comment: 18 pages, 8 figures, accepted for publication in Astroparticle Physic

Occupational outcome after surgery in patients with a rotator cuff tear due to a work-related injury or occupational disease. A series of 262 cases

SummaryThe goals of this study were to establish the occupational outcome after surgery in patients with a rotator cuff tear from a work-related injury (WRI) or occupational disease (OD) and determine which factors and conditions affected return to work. Hypothesis: return to work was possible for this type of patient. This questionnaire-based study comprised 262 shoulders in 254 patients with a WRI/OD who had surgery performed on their shoulder between 2000 and 2005. The average age was 50.5±6.4years. The following variables were analysed: employment status (private sector, self-employed, government employee), type of work (non-manual, manual, heavy manual labour), nature of tendon injury and surgical technique (open, mini-open and arthroscopy). Return to work occurred in 59.5% of the cases. Factors that prevented return to work (40.4% of the cases) included retirement (14.1%), an unrelated medical condition (10.3%), and the outcome of the operated shoulder (16.0%). Age had an impact on return to work (P<5×10−4). The type of work and nature of tendon injury did not affect return to work, but did affect time away from work. Employment status and surgical technique had an effect on return to work, but not on time away from work. Age was a decisive factor for return to work. Retirement seemed to be the most common choice starting at 55 years of age. Arthroscopy seemed to have reduced the impact of the WRI on the results, particularly on the time away from work. A preoperative evaluation of the patient's probability of returning to work should be done based on occupational and injury features. There may be a longer delay in returning to work for certain profiles of work (manual labour) and tendon injury. Patient management can be improved by knowing the factors and conditions that influence return to work.Level of evidenceLevel IV - Retrospective study

A synchronous architecture for the L0 muon trigger

In this note we describe a new implementation for the L0 muon trigger. It is based on a fully synchronous and pipeline architecture. The 25920 logical pads and strips data, produced by the muon detector, are sent at once to the muon trigger. The data transfer is performed at a frequency of 40 MHz and relies on ~1250 high speed optical links running at 1.6 Gb/s. The muon trigger processor is distributed over 4 crates. Each of them is connected to a quarter of the muon system. The implementation is based on a unique processing board. Data transfers between boards are performed at 80 MHz via a custom backplane running only point to point connections. Synchronization between data and the bunch crossing identifier is preserved during the whole processing cycle. In this note, we present the data flow, hardware implementation, latency and cost estimate