45 research outputs found
The LHCb upgrade I
The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software
A multipollutant evaluation of APEX using microenvironmental ozone, carbon monoxide, and particulate matter (PM2.5) concentrations measured in Los Angeles by the exposure classification project
This paper describes an operational evaluation of the US Environmental Protection Agency’s (EPA) Air Pollution Exposure Model (APEX). APEX simulations for a multipollutant ambient air mixture, i.e. ozone (O3), carbon monoxide (CO), and particulate matter 2.5 microns in diameter or less (PM2.5), were performed for two seasons in three study areas in central Los Angeles. APEX predicted microenvironmental concentrations were compared with concentrations of these three pollutants monitored in the Exposure Classification Project (ECP) study during the same periods. The ECP was designed expressly for evaluating exposure models and measured concentrations inside and outside 40 microenvironments. This evaluation study identifies important uncertainties in APEX inputs and model predictions useful for guiding further exposure model input data and algorithm development efforts. This paper also presents summaries of the concentrations in the different microenvironments
A multipollutant evaluation of APEX using microenvironmental ozone, carbon monoxide, and particulate matter (PM<sub>2.5</sub>) concentrations measured in Los Angeles by the exposure classification project
<p>This paper describes an operational evaluation of the US Environmental Protection Agency’s (EPA) Air Pollution Exposure Model (APEX). APEX simulations for a multipollutant ambient air mixture, i.e. ozone (O<sub>3</sub>), carbon monoxide (CO), and particulate matter 2.5 microns in diameter or less (PM<sub>2.5</sub>), were performed for two seasons in three study areas in central Los Angeles. APEX predicted microenvironmental concentrations were compared with concentrations of these three pollutants monitored in the Exposure Classification Project (ECP) study during the same periods. The ECP was designed expressly for evaluating exposure models and measured concentrations inside and outside 40 microenvironments. This evaluation study identifies important uncertainties in APEX inputs and model predictions useful for guiding further exposure model input data and algorithm development efforts. This paper also presents summaries of the concentrations in the different microenvironments.</p
The LHCb VELO Upgrade module construction
Abstract
The LHCb detector has undergone a major upgrade for LHC
Run 3. This Upgrade I detector facilitates operation at higher
luminosity and utilises full-detector information at the LHC
collision rate, critically including the use of vertex
information. A new vertex locator system, the VELO Upgrade, has been
constructed. The core element of the new VELO are the double-sided
pixelated hybrid silicon detector modules which operate in vacuum
close to the LHC beam in a high radiation environment. The
construction and quality assurance tests of these modules are
described in this paper. The modules incorporate
200 μm thick, n-on-p silicon sensors bump-bonded to
130 nm technology ASICs. These are attached with high precision to
a silicon microchannel substrate that uses evaporative CO2
cooling. The ASICs are controlled and read out with flexible printed
circuits that are glued to the substrate and wire-bonded to the
chips. The mechanical support of the module is given by a carbon
fibre plate, two carbon fibre rods and an aluminium plate. The
sensor attachment was achieved with an average precision of
21 μm, more than 99.5% of all pixels are fully
functional, and a thermal figure of merit of
3 Kcm2W-1 was achieved. The production of the
modules was successfully completed in 2021, with the final assembly
and installation completed in time for data taking in 2022.</jats:p