5 research outputs found

    Comparative evaluation of analogue front-end designs for the CMS Inner Tracker at the High Luminosity LHC

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    The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip

    Comparative evaluation of analogue front-end designs for the CMS Inner Tracker at the High Luminosity LHC

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    The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip

    Comparative evaluation of analogue front-end designs for the CMS Inner Tracker at the High Luminosity LHC

    Get PDF
    International audienceThe CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip

    Hard color-singlet exchange in dijet events in proton-proton collisions at s=\sqrt{s} = 13 TeV

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    International audienceEvents where the two leading jets are separated by a pseudorapidity interval devoid of particle activity, known as jet-gap-jet events, are studied in proton-proton collisions at s=\sqrt{s} = 13 TeV. The signature is expected from hard color-singlet exchange. Each of the highest transverse momentum (pTp_\mathrm{T}) jets must have pTjetp_\mathrm{T}^\text{jet}>\gt 40 GeV and pseudorapidity 1.4 <\ltηjet|\eta^\text{jet}|<\lt 4.7, with ηjet1ηjet2\eta^\text{jet1} \eta^\text{jet2}<\lt 0, where jet1\text{jet1} and jet2\text{jet2} are the leading and subleading jets in pTp_\mathrm{T}, respectively. The analysis is based on data collected by the CMS and TOTEM experiments during a low luminosity, high-β\beta^* run at the CERN LHC in 2015, with an integrated luminosity of 0.66 pb1^{-1}. Events with a low number of charged particles with pTp_\mathrm{T}>\gt 0.2 GeV in the interval η|\eta|<\lt 1 between the jets are observed in excess of calculations that assume only color-exchange. The fraction of events produced via color-singlet exchange, fCSEf_\text{CSE}, is measured as a function of pTjet2p_\mathrm{T}^\text{jet2}, the pseudorapidity difference between the two leading jets, and the azimuthal angular separation between the two leading jets. The fraction fCSEf_\text{CSE} has values of 0.4-1.0%. The results are compared with previous measurements and with predictions from perturbative quantum chromodynamics. In addition, the first study of jet-gap-jet events detected in association with an intact proton using a subsample of events with an integrated luminosity of 0.40 pb1^{-1} is presented. The intact protons are detected with the Roman pot detectors of the TOTEM experiment. The fCSEf_\text{CSE} in this sample is 2.91 ±\pm 0.70 (stat) 1.01+1.08^{+1.08}_{-1.01} (syst) times larger than that for inclusive dijet production in dijets with similar kinematics
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