15 research outputs found

    RD50-MPW3: A fully monolithic digital CMOS sensor for future tracking detectors

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    The CERN-RD50 CMOS working group develops the RD50-MPWseries of monolithic high-voltage CMOS pixel sensors for potential use in future high luminosity experiments such as the HL-LHC and FCC-hh. In this contribution, the design of the latest prototype in this series, RD50-MPW3, is presented. An overview of its pixel matrix and digital readout periphery is given, with discussion of the new structures implemented in the chip and the problems they aim to solve. The main analog and digital features of the sensor are already tested and initial laboratory characterisation of the chip is presented

    PACIFIC: The readout ASIC for the SciFi Tracker of the LHCb detector

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    PACIFIC is a 64 channel mixed-signal ASIC designed for the scintillating fiber tracker readoutand developed for the LHCb upgrade in 2019/20. It connects without any extra components tothe 128 channel double-die SiPM arrays sensing the fibres output signal. The analog processingchain begins with a current conveyor followed by a tunable fast shaper and a gated integrator.The signal is digitized with three configurable discriminators at 40MHz. The results of everyfour channels are encoded to two bits per channel, serialized and transmitted at 320MSa/s over adifferential SLVS data link. PACIFIC has been designed using a 130nm CMOS technology andpower consumption kept below 10mW/channel

    PACIFICr5 ASIC Data Sheet

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    The PACIFICr5 ASIC is a 64 channel Silicon Photo Multiplier readout circuit with current mode input and digital output developed for the LHCb Scintillating Fibre Tracker

    Amplitude analysis of B+ψ(2S)K+π+πB^+ \to \psi(2S) K^+ \pi^+ \pi^- decays

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    International audienceThe first full amplitude analysis of B+ψ(2S)K+π+πB^+ \to \psi(2S) K^+ \pi^+ \pi^- decays is performed using proton-proton collision data corresponding to an integrated luminosity of 9fb19\,\text{fb}^{-1} recorded with the LHCb detector. The rich K+π+πK^+ \pi^+ \pi^- spectrum is studied and the branching fractions of the resonant substructure associated with the prominent K1(1270)+K_1(1270)^+ contribution are measured. The data cannot be described by conventional strange and charmonium resonances only. An amplitude model with 53 components is developed comprising 11 hidden-charm exotic hadrons. New production mechanisms for charged charmonium-like states are observed. Significant resonant activity with spin-parity JP=1+J^P = 1^+ in the ψ(2S)π+\psi(2S) \pi^+ system is confirmed and a multi-pole structure is demonstrated. The spectral decomposition of the ψ(2S)π+π\psi(2S) \pi^+ \pi^- invariant-mass structure, dominated by X0ψ(2S)ρ(770)0X^0 \to \psi(2S) \rho(770)^0 decays, broadly resembles the J/ψϕJ/\psi \phi spectrum observed in B+J/ψϕK+B^+ \to J/\psi \phi K^+ decays. Exotic ψ(2S)K+π\psi(2S) K^+ \pi^- resonances are observed for the first time

    Probing the nature of the χc1(3872)\chi_{c1}(3872) state using radiative decays

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    International audienceThe radiative decays χc1(3872)ψ(2S)γ\chi_{c1}(3872)\rightarrow\psi(2S)\gamma and χc1(3872)J/ψγ\chi_{c1}(3872)\rightarrow J/\psi\gamma are used to probe the~nature of the~χc1(3872)\chi_{c1}(3872) state using proton-proton collision data collected with the LHCb detector, corresponding to an~integrated luminosity of~9fb1^{-1}. Using the~B+χc1(3872)K+B^+\rightarrow \chi_{c1}(3872)K^+decay, the χc1(3872)ψ(2S)γ\chi_{c1}(3872)\rightarrow \psi(2S)\gamma process is observed for the first time and the ratio of its partial width to that of the χc1(3872)J/ψγ\chi_{c1}(3872)\rightarrow J/\psi\gamma decay is measured to be Γχc1(3872)ψ(2S)γΓχc1(3872)J/ψγ=1.67±0.21±0.12±0.04, \frac{\Gamma_{\chi_{c1}(3872)\rightarrow \psi(2S)\gamma}} {\Gamma_{\chi_{c1}(3872)\rightarrow J/\psi\gamma}} = 1.67 \pm 0.21 \pm 0.12 \pm0.04 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainties on the branching fractions of the ψ(2S)\psi(2S) and J/ψJ/\psi mesons. The measured ratio makes the interpretation of the χc1(3872)\chi_{c1}(3872) state as a~pure D0Dˉ0+Dˉ0D0D^0\bar{D}^{*0}+\bar{D}^0D^{*0} molecule questionable and strongly indicates a sizeable compact charmonium or tetraquark component within the χc1(3872)\chi_{c1}(3872) state

    Study of bb-hadron decays to Λc+hh\Lambda_c^+ h^- h^{\prime -} final states

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    International audienceDecays of Ξb\Xi_b^- and Ωb\Omega_b^- baryons to Λc+hh\Lambda_c^+ h^- h^{\prime -} final states, with hhh^- h^{\prime -} being ππ\pi^-\pi^-, KπK^-\pi^- and KKK^-K^- meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of 8.7fb18.7\,\mathrm{fb}^{-1} of pppp collisions collected at centre-of-mass energies s=7\sqrt{s} = 7, 88 and 13TeV13\,\mathrm{Te\kern -0.1em V}. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the BΛc+pπB^- \to \Lambda_c^+ \overline{p} \pi^- mode, are measured, with ΞbΛc+Kπ\Xi_{b}^- \to\Lambda_{c}^+ K^- \pi^-, ΞbΛc+KK\Xi_{b}^- \to\Lambda_{c}^+ K^- K^- and ΩbΛc+KK\Omega_{b}^- \to\Lambda_{c}^+ K^- K^- decays being observed at over 5σ5\,\sigma significance. The ΞbΛc+Kπ\Xi_{b}^- \to\Lambda_{c}^+ K^- \pi^- mode is also used to measure the Ξb\Xi_{b}^- production asymmetry, which is found to be consistent with zero. In addition, the BΛc+pKB^- \to \Lambda_{c}^+ \overline{p} K^- decay is observed for the first time, and its branching fraction is measured relative to that of the BΛc+pπB^- \to \Lambda_{c}^+ \overline{p} \pi^- mode

    Study of bb-hadron decays to Λc+hh\Lambda_c^+h^-h^{\prime -} final states

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    Decays of Ξb\Xi_{b}^{-} and Ωb\Omega_{b}^{-} baryons to Λc+hh\Lambda_{c}^{+} h^- h^{\prime -} final states, with hhh^- h^{\prime -} being ππ\pi^{-}\pi^{-}, KπK^{-}\pi^{-} and KKK^{-}K^{-} meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of 8.7fb18.7 \rm fb^{-1} of pppp collisions collected at centre-of-mass energies s=7\sqrt{s} = 7, 88 and 13TeV13 \rm TeV. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the BΛc+pˉπB^{-} \rightarrow \Lambda_{c}^{+} \bar{p} \pi^{-} mode, are measured, with ΞbΛc+Kπ\Xi_{b}^{-} \rightarrow\Lambda_{c}^{+} K^{-} \pi^{-}, ΞbΛc+KK\Xi_{b}^{-} \rightarrow\Lambda_{c}^{+} K^{-} K^{-} and ΩbΛc+KK\Omega_{b}^{-} \rightarrow\Lambda_{c}^{+} K^{-} K^{-} decays being observed at over 5σ5\,\sigma significance. The ΞbΛc+Kπ\Xi_{b}^{-} \rightarrow\Lambda_{c}^{+} K^{-} \pi^{-} mode is also used to measure the Ξb\Xi_{b}^{-} production asymmetry, which is found to be consistent with zero. In addition, the BΛc+pˉKB^{-} \rightarrow \Lambda_{c}^{+} \bar{p} K^{-} decay is observed for the first time, and its branching fraction is measured relative to that of the BΛc+pˉπB^{-} \rightarrow \Lambda_{c}^{+} \bar{p} \pi^{-} mode.Decays of Ξb\Xi_b^- and Ωb\Omega_b^- baryons to Λc+hh\Lambda_c^+ h^- h^{\prime -} final states, with hhh^- h^{\prime -} being ππ\pi^-\pi^-, KπK^-\pi^- and KKK^-K^- meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of 8.7fb18.7\,\mathrm{fb}^{-1} of pppp collisions collected at centre-of-mass energies s=7\sqrt{s} = 7, 88 and 13TeV13\,\mathrm{Te\kern -0.1em V}. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the BΛc+pπB^- \to \Lambda_c^+ \overline{p} \pi^- mode, are measured, with ΞbΛc+Kπ\Xi_{b}^- \to\Lambda_{c}^+ K^- \pi^-, ΞbΛc+KK\Xi_{b}^- \to\Lambda_{c}^+ K^- K^- and ΩbΛc+KK\Omega_{b}^- \to\Lambda_{c}^+ K^- K^- decays being observed at over 5σ5\,\sigma significance. The ΞbΛc+Kπ\Xi_{b}^- \to\Lambda_{c}^+ K^- \pi^- mode is also used to measure the Ξb\Xi_{b}^- production asymmetry, which is found to be consistent with zero. In addition, the BΛc+pKB^- \to \Lambda_{c}^+ \overline{p} K^- decay is observed for the first time, and its branching fraction is measured relative to that of the BΛc+pπB^- \to \Lambda_{c}^+ \overline{p} \pi^- mode

    The LHCb upgrade I

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    International audienceThe 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
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