We describe a fully GPU-based implementation of the first level trigger for the upgrade of the LHCb detector, due to start data taking in 2021. We demonstrate that our implementation, named Allen, ...can process the 40 Tbit/s data rate of the upgraded LHCb detector and perform a wide variety of pattern recognition tasks. These include finding the trajectories of charged particles, finding proton–proton collision points, identifying particles as hadrons or muons, and finding the displaced decay vertices of long-lived particles. We further demonstrate that Allen can be implemented in around 500 scientific or consumer GPU cards, that it is not I/O bound, and can be operated at the full LHC collision rate of 30 MHz. Allen is the first complete high-throughput GPU trigger proposed for a HEP experiment.
The calorimeter system of LHCb is subdivided into four sub-detectors which provide its longitudinal segmentation: a Scintillator Pad Detector, followed by a Preshower and, then, an electromagnetic, ...an hadronic calorimeter. After a description of these detectors, procedures developed to calibrate their response are discussed together with the degradation of response observed due to the harsh conditions (high radiation and current levels). First results on the calorimeter performance over the two most productive years of physics data taking, 2011 and 2012 are given.
We present a solution made out of Components Out of Shelf (COTS) for the analog processing of the signal of the LHCb calorimeters in the framework of the foreseen upgrade of the detector. The present ...proposal is based on the current functional solution, yet, to meet the stringent noise requirements, a number of modifications are proposed. Preliminary results on the prototype boards show promising results.
The current mode line terminating input stage of an integrated circuit for the upgrade of the LHCb calorimeter front end electronics is presented. The circuit is based on a current mode input stage ...followed by two fully differential interleaved channels, namely a switched integrator and a track and hold. The input stage employs a novel electronically cooled input termination scheme to achieve stringent noise requirements. Compared to previous designs, its novelty relies in the use of two current feedback loops to decrease and control the input impedance of a common base stage. Two prototypes in Austriamicrosystems SiGe BiCMOS 0.35 μm technology have been designed and tested. Key measurements have been performed. Reflection coefficient is smaller than 0.5% for the full dynamic range, which is 12 bits. Relative linearity error is below 1%. Output noise is about 1 LSB after applying correlated double sampling.
Measurements of $C\!P$ observables in $B^\pm \rightarrow D K^\pm$ and $B^\pm \rightarrow D \pi^\pm$ decays are presented where the $D$ meson is reconstructed in the final states $K^\pm\pi^\mp$, ...$\pi^\pm K^\mp$, $K^+K^-$, $\pi^+\pi^-$, $K^\pm\pi^\mp \pi^+ \pi^-$, $\pi^\pm K^\mp \pi^+ \pi^-$ and $\pi^+ \pi^- \pi^+ \pi^-$. This analysis uses a sample of charged $B$ mesons from $pp$ collisions collected by the LHCb experiment in 2011 and 2012, corresponding to an integrated luminosity of 3.0 fb$^{-1}$. Various \CP-violating effects are reported and together these measurements provide important input for the determination of the unitarity triangle angle $\gamma$. The analysis of the four-pion $D$ decay mode is the first of its kind.
A search for the decays of the $B_c^+$ meson to $p\overline p\pi^+$ is performed for the first time using a data sample corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected ...by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. No signal is found and an upper limit, at 95\% confidence level, is set, $\frac{f_c}{f_u}\times\mathcal{B}(B_c^+\to p\overline p\pi^+)<3.6\times10^{-8}$ in the kinematic region $m(p\overline p)<2.85\mathrm{\,Ge\kern -0.1em V\!/}c^2$, $p_{\rm T}(B)<20\mathrm{\,Ge\kern -0.1em V\!/}c$ and $2.0<y(B)<4.5$, where $\mathcal{B}$ is the branching fraction and $f_c$ ($f_u$) is the fragmentation fraction of the $b$ quark into a $B_c^+$ ($B^+$) meson.
In this paper we present an educational resource called LSMaker, a caterpillar mobile robot that has been introduced in the curricula of Engineering Education. The platform has been used to link ...subjects, so common tasks and challenges have been defined. We are looking for updating contents and educational methodology, enhancing the motivation of students and not less important, increasing the number of new students in our engineering school. The interdisciplinary nature of the robotic project should facilitate the assimilation of new concepts. We present how this project has introduced in the first year course in La Salle Engineering school, and then we analyse the results obtained after two years of running this educational methodology.
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