72 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

    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)Îł\chi_{c1}(3872)\rightarrow\psi(2S)\gamma and χc1(3872)→J/ÏˆÎł\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~9fb−1^{-1}. Using the~B+→χc1(3872)K+B^+\rightarrow \chi_{c1}(3872)K^+decay, the χc1(3872)→ψ(2S)Îł\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/ÏˆÎł\chi_{c1}(3872)\rightarrow J/\psi\gamma decay is measured to be Γχc1(3872)→ψ(2S)ÎłÎ“Ï‡c1(3872)→J/ÏˆÎł=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 D0Dˉ∗0+Dˉ0D∗0D^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 the rare decay J ⁣/ψ→Ό+Ό−Ό+Ό−J\mskip -3mu/\mskip -2mu\psi \to \mu^+\mu^-\mu^+\mu^-

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    The rare electromagnetic J ⁣/ψ→Ό+Ό−Ό+Ό−J\mskip -3mu/\mskip -2mu\psi \to \mu^+\mu^-\mu^+\mu^- decay is observed with a significance greatly exceeding the discovery threshold, using proton-proton collision data collected by the LHCb experiment during 2016--2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−15.4\,\text{fb}^{-1}. The rate of this decay is measured relative to that of the J ⁣/ψ→Ό+Ό−J\mskip -3mu/\mskip -2mu\psi \to \mu^+\mu^- mode. Using the QED model for the four-muon decay in the efficiency estimation, its branching fraction is determined to be \begin{equation*} {\mathcal{B}}(J\mskip -3mu/\mskip -2mu\psi \to \mu^+\mu^-\mu^+\mu^-) = (1.13\pm0.10\pm0.05\pm0.01)\times 10^{-6}, \end{equation*} where the uncertainties are statistical, systematic and due to the uncertainty on the branching fraction of the J ⁣/ψ→Ό+Ό−J\mskip -3mu/\mskip -2mu\psi \to \mu^+\mu^- decay.The rare electromagnetic J/ψ→Ό+Ό−Ό+Ό−J/\psi \to \mu^+\mu^-\mu^+\mu^- decay is observed with a significance greatly exceeding the discovery threshold, using proton-proton collision data collected by the LHCb experiment during 2016-2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−15.4\,\text{fb}^{-1}. The rate of this decay is measured relative to that of the J/ψ→Ό+Ό−J/\psi \to \mu^+\mu^- mode. Using the QED model for the four-muon decay in the efficiency estimation, its branching fraction is determined to be \begin{equation*} {\mathcal{B}}(J/\psi \to \mu^+\mu^-\mu^+\mu^-) = (1.13\pm0.10\pm0.05\pm0.01)\times 10^{-6}, \end{equation*} where the uncertainties are statistical, systematic and due to the uncertainty on the branching fraction of the J/ψ→Ό+Ό−J/\psi \to \mu^+\mu^- decay

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

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    International audienceThe first full amplitude analysis of B+→ψ(2S)K+π+π−B^+ \to \psi(2S) K^+ \pi^+ \pi^- decays is performed using proton-proton collision data corresponding to an integrated luminosity of 9 fb−19\,\text{fb}^{-1} recorded with the LHCb detector. The rich K+π+π−K^+ \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 X0→ψ(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)Îł\chi_{c1}(3872)\rightarrow\psi(2S)\gamma and χc1(3872)→J/ÏˆÎł\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~9fb−1^{-1}. Using the~B+→χc1(3872)K+B^+\rightarrow \chi_{c1}(3872)K^+decay, the χc1(3872)→ψ(2S)Îł\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/ÏˆÎł\chi_{c1}(3872)\rightarrow J/\psi\gamma decay is measured to be Γχc1(3872)→ψ(2S)ÎłÎ“Ï‡c1(3872)→J/ÏˆÎł=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 D0Dˉ∗0+Dˉ0D∗0D^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

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

    No full text
    International audienceThe first full amplitude analysis of B+→ψ(2S)K+π+π−B^+ \to \psi(2S) K^+ \pi^+ \pi^- decays is performed using proton-proton collision data corresponding to an integrated luminosity of 9 fb−19\,\text{fb}^{-1} recorded with the LHCb detector. The rich K+π+π−K^+ \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 X0→ψ(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
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