86 research outputs found
MINERvA neutrino detector response measured with test beam data
The MINERvA collaboration operated a scaled-down replica of the solid
scintillator tracking and sampling calorimeter regions of the MINERvA detector
in a hadron test beam at the Fermilab Test Beam Facility. This article reports
measurements with samples of protons, pions, and electrons from 0.35 to 2.0
GeV/c momentum. The calorimetric response to protons, pions, and electrons are
obtained from these data. A measurement of the parameter in Birks' law and an
estimate of the tracking efficiency are extracted from the proton sample.
Overall the data are well described by a Geant4-based Monte Carlo simulation of
the detector and particle interactions with agreements better than 4%, though
some features of the data are not precisely modeled. These measurements are
used to tune the MINERvA detector simulation and evaluate systematic
uncertainties in support of the MINERvA neutrino cross section measurement
program.Comment: as accepted by NIM
Response of a CMS HGCAL silicon-pad electromagnetic calorimeter prototype to 20-300 GeV positrons
The Compact Muon Solenoid Collaboration is designing a new high-granularity
endcap calorimeter, HGCAL, to be installed later this decade. As part of this
development work, a prototype system was built, with an electromagnetic section
consisting of 14 double-sided structures, providing 28 sampling layers. Each
sampling layer has an hexagonal module, where a multipad large-area silicon
sensor is glued between an electronics circuit board and a metal baseplate. The
sensor pads of approximately 1 cm are wire-bonded to the circuit board and
are readout by custom integrated circuits. The prototype was extensively tested
with beams at CERN's Super Proton Synchrotron in 2018. Based on the data
collected with beams of positrons, with energies ranging from 20 to 300 GeV,
measurements of the energy resolution and linearity, the position and angular
resolutions, and the shower shapes are presented and compared to a detailed
Geant4 simulation
Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20300 GeV/c
The upgrade of the CMS experiment for the high luminosity operation of the
LHC comprises the replacement of the current endcap calorimeter by a high
granularity sampling calorimeter (HGCAL). The electromagnetic section of the
HGCAL is based on silicon sensors interspersed between lead and copper (or
copper tungsten) absorbers. The hadronic section uses layers of stainless steel
as an absorbing medium and silicon sensors as an active medium in the regions
of high radiation exposure, and scintillator tiles directly readout by silicon
photomultipliers in the remaining regions. As part of the development of the
detector and its readout electronic components, a section of a silicon-based
HGCAL prototype detector along with a section of the CALICE AHCAL prototype was
exposed to muons, electrons and charged pions in beam test experiments at the
H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology
as foreseen for the HGCAL but with much finer longitudinal segmentation. The
performance of the calorimeters in terms of energy response and resolution,
longitudinal and transverse shower profiles is studied using negatively charged
pions, and is compared to GEANT4 predictions. This is the first report
summarizing results of hadronic showers measured by the HGCAL prototype using
beam test data.Comment: To be submitted to JINS
Test beam performance measurements for the Phase I upgrade of the CMS pixel detector
A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. In this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency is (99.95 ± 0.05) %, while the intrinsic spatial resolutions are (4.80 ± 0.25) μm and (7.99 ± 0.21) μm along the 100 μm and 150 μm pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.Peer reviewe
The CMS Phase-1 pixel detector upgrade
The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.Peer reviewe
Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker
The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to neq/cm. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations
Comparative evaluation of analogue front-end designs for the CMS Inner Tracker at the High Luminosity LHC
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
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