The PPS (Precision Proton Spectrometer) system consists of tracking and timing detectors installed along the LHC beam line between 210 and 220 m from the interaction point on both sides of the CMS ...experiment. The aim of the apparatus is to measure with high precision the position, direction and time-of-flight of protons which emerge intact from the pp collision. Fully integrated in the CMS data acquisition system, PPS has taken data at high luminosity during the years of the LHC Run2 (2016–2018), with slightly different detector configurations. The tracking system consists of 4 detector stations (two per side) and was instrumented with edgeless silicon strips (2016–2017) and 3D pixel sensors bump-bonded to the PSI46dig ROC (2017–2018). In this contribution, commissioning, operation and performance of the PPS tracking system during Run2 will be discussed, with focus on the challenges posed by operating the detectors at few millimeters from the beam, in highly non-uniform irradiation environment. Prospects for LHC Run3 will be also presented.
In this paper we report on the timing resolution obtained in a beam test with pions of 180 GeV/c momentum at CERN for the first production of 45 μm thick Ultra-Fast Silicon Detectors (UFSD). UFSD are ...based on the Low- Gain Avalanche Detector (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test had a pad area of 1.7 mm2. The gain was measured to vary between 5 and 70 depending on the sensor bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution was determined by doing Gaussian fits to the time-of-flight of the particles between one or more UFSD and the trigger counter. For a single UFSD the resolution was measured to be 34 ps for a bias voltage of 200 V, and 27 ps for a bias voltage of 230 V. For the combination of 3 UFSD the timing resolution was 20 ps for a bias voltage of 200 V, and 16 ps for a bias voltage of 230 V.
Abstract
This paper presents the detailed simulation of a
double-pixel structure for charged particle detection based on the
3D-trench silicon sensor developed for the TIMESPOT project and a
...comparison of the simulation results with measurements performed at
the π-M1 beam at PSI laboratory. The simulation is based on the
combined use of several software tools (TCAD, GEANT4, TCoDe and
TFBoost) which allow to fully design and simulate the device physics
response in very short computational time,
O(1–100 s) per simulated signal, by exploiting
parallel computation using single or multi-thread processors. This
allowed to produce large samples of simulated signals, perform
detailed studies of the sensor characteristics and make precise
comparisons with experimental results.
In the last years, high-resolution time tagging has emerged as a promising tool to tackle the problem of high-track density in the detectors of the next generation of experiments at particle ...colliders. Time resolutions below 50 ps and event average repetition rates of tens of MHz on sensor pixels having a pitch of 50 μm are typical minimum requirements. This poses an important scientific and technological challenge on the development of particle sensors and processing electronics. The TIMESPOT initiative (which stands for TIME and SPace real-time Operating Tracker) aims at the development of a full prototype detection system suitable for the particle trackers of the next-to-come particle physics experiments. This paper describes the results obtained on the first batch of TIMESPOT silicon sensors, based on a novel 3D MEMS (micro electro-mechanical systems) design. We demonstrate that following this approach, the performance of other ongoing silicon sensor developments can be matched and overcome. In addition, 3D technology has already been proved to be robust against radiation damage. A time resolution of the order of 20 ps has been measured at room temperature suggesting also possible improvements after further optimisations of the front-end electronics processing stage.
The recent development in the design of Ultra Fast Silicon Detector (UFSD), aimed at combining radiation resistance up to fluences of 1015neq/cm2 and fine read-out segmentation, makes these sensors ...suitable for high energy physics applications. UFSD is an evolution of standard silicon sensor, optimized to achieve excellent timing resolution (∼30 ps), thanks to an internal low gain (∼20). UFSD sensors are n in p Low Gain Avalanche Diode (LGAD) with an active thickness of ∼5 μm. The internal gain in LGAD is obtained by implanting an appropriate density of acceptors (of the order of ∼ 1016/cm3) close to the p-n junction, that, when depleted, locally generates an electric field high enough to activate the avalanche multiplication; this layer of acceptors is called gain layer. The two challenges in the development of UFSD for high energy physics detectors are the radiation hardness and the fine segmentation of large area sensors. Irradiation fluences of the order of 1015neq/cm2 have a dramatic effect on the UFSD: neutrons and charged hadrons reduce the active acceptor density forming the gain layer; this mechanism, called initial acceptor removal, causes the complete disappearance of the internal gain above fluence of 1015neq/cm2. For the segmentation of UFSDs, the crucial point is the electrical insulation of pads and the extension of the inactive area between pads. In this paper we present the latest results on radiation resistance of LGADs with different gain layer designs, irradiated up to 3ċ1015neq/cm2. Three different segmentation technologies, developed by Fondazione Bruno Kessler in Trento, will also be discussed in detail in the second part of the paper.
The CMS ECAL is a high resolution electromagnetic calorimeter which relies upon precision calibration in order to achieve and maintain its design performance. Variations in light collected from the ...lead tungstate crystals, due to intrinsic differences in crystals/photodetectors, as well as variations with time due to radiation damage for example, need to be taken into account. Sophisticated and effective methods of inter-crystal and absolute calibration have been devised, using collision data from the 2011 LHC run and a dedicated light injection system. For inter-calibration, low mass particle (π0 and η) decays to two photons are exploited, as well as the azimuthal symmetry of the average energy deposition at a given pseudorapidity. The light injection system monitors the channel response in real-time and enables the re-calibration of the measured energies over time. This is cross-checked by the comparison of E/p measurements of electrons from W decays (where the momentum is measured in the CMS tracker) with/without these re-calibrations applied. Absolute calibration has been performed using Z decays into electron–positron pairs.
Abstract
In this paper the results of a beam test characterization campaign of 3D trench silicon pixel sensors are presented. A time resolution in the order of 10 ps was measured both for ...non-irradiated and irradiated sensors up to a fluence of 2.5 × 10
16
1 MeV n
eq
cm
−2
. This feature and a detection efficiency close to 99% make this sensors one of the best candidates for 4D tracking detectors in High-Energy-Physics experiments.
Design optimization of ultra-fast silicon detectors Cartiglia, N.; Arcidiacono, R.; Baselga, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2015, Letnik:
796
Journal Article
Recenzirano
Odprti dostop
Low-Gain Avalanche Diodes (LGAD) are silicon detectors with output signals that are about a factor of 10 larger than those of traditional sensors. In this paper we analyze how the design of LGAD can ...be optimized to exploit their increased output signal to reach optimum timing performances. Our simulations show that these sensors, the so-called Ultra-Fast Silicon Detectors (UFSD), will be able to reach a time resolution factor of 10 better than that of traditional silicon sensors.
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