Beam tests of silicon pixel 3D-sensors developed at SINTEF
Ole Dorholt, Thor-Erik Hansen, Andreas Heggelund, Angela Kok, Nicola Pacifico, Ole Rohne, Heidi Sandaker, Bjarne Stugu, Zongchang Yang, Marco Bomben, Andre Rummler, Jens Weingarten
For the purpose of withstanding very high radiation doses, silicon pixel sensors with a 3D electrode geometry are being developed. Detectors of this kind are highly interesting for harch radiation environments such as expected in the High Luminosity LHC, but also for space physics and medical applications. In this paper, prototype sensors developed at SINTEF are presented and results from tests in a pion beam at CERN are given. These tests shows that these 3D sensors perform as expected with full efficiency at bias voltages between 5 and 15V.
In this paper, we describe the development of monolithic pixel detectors by using a Silicon-on-Insulator (SOI) technology for X-ray and charged particle applications. The detectors are based on a 0.2 μm CMOS fully depleted SOI process (Lapis Semiconductor Co., Ltd). The SOI wafer consists of a thick high-resistivity substrate for sensing and a thin low resistivity Si layer for CMOS circuits. We developed the integration-type SOI pixel detector, INTPIX4 mainly for X-ray imaging; it is made of a Float Zone (FZ) or Czochralski (Cz) silicon wafer. Since 2005, Cz SOI detectors were used initially. …
We propose the use of germanium-on-silicon technology for indirect time-of-flight based three-dimensional sensing, and demonstrate a novel lock-in pixel featuring high quantum efficiency and large frequency bandwidth. Compared to silicon pixels, germanium-on-silicon pixels simultaneously maintain a high quantum efficiency and a high demodulation contrast deep into GHz frequency regime, which enable consistently superior depth accuracy in both indoor and outdoor scenarios. Physical model, numerical simulation, device fabrication and characterization, system performance comparison, and laser saf…
A 100um thick silicon detector with 1mm2 pad readout optimized for sub-nanosecond time resolution has been developed and tested. Coupled to a purposely developed amplifier based on SiGe HBT technology, this detector was characterized at the H8 beam line at the CERN SPS. An excellent time resolution of (106+-1)ps for silicon detectors was measured with minimum ionizing particles.
We present a concept to improve the spatial resolution of silicon pixel-detectors via the implementation of a sub-pixel cross-coupling, which introduces directional charge sharing between pixels. The charge-collection electrode is segmented into sub-pixels and each sub-pixel is coupled to the closest sub-pixel of the neighboring pixel. Such coupling schema is evaluated for a model sensor design with $50 μm \times 50 μm$ pixels and AC-coupled sub-pixels. A first-order SPICE simulation is used, to determine feasible coupling strengths and assess the influence on the charge-collection efficiency.…
Timepix3 is a multi-purpose readout ASIC for hybrid pixel detectors. It can measure time and energy simultaneously by employing time-of-arrival (ToA) and time-over-threshold (ToT) techniques. Both methods are systematically affected by timewalk. In this paper, a method for pixel-by-pixel calibration of the time response is presented. Assemblies of Timepix3 ASICs bump-bonded to thin planar silicon pixel sensors of different thicknesses between 50 um and 150 um are calibrated and characterised in particle beams. For minimum ionising particles, time resolutions down to 0.72 $\pm$ 0.04 ns are achi…
Hybrid pixel single-photon-counting detectors have been successfully employed and widely used in Synchrotron radiation X-ray detection. In this paper, the silicon pixel sensors for single X-ray photon detection, which operate in full-depletion mode have been studied. The pixel sensors were fabricated on 4-inch, N type, 320μm thick, high-resistivity silicon wafers. The pixel sensors has a p+-in-n structure with varies of pixel size and gap size including guard-ring structures. Later, the pixel sensor was wire bonded to the ASIC circuits and tested for the performance of X-ray response in the sy…
In view of the LHC upgrade phases towards HL-LHC the ATLAS experiment plans to upgrade the Inner Detector with an all silicon system. The n-in-p silicon technology is a promising candidate for the pixel upgrade thanks to its radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. We present the characterization and performance of novel n-in-p planar pixel sensors produced by CiS (Germany) connected by bump bonding to the ATLAS readout chip FE-I3. These results are obtained before and after irradiation up to a fluence of 10^16 1-MeV n_eq/c…
We derive expressions for the time resolution of silicon detectors, using the Landau theory and a PAI model for describing the charge deposit of high energy particles. First we use the centroid time of the induced signal and derive analytic expressions for the three components contributing to the time resolution, namely charge deposit fluctuations, noise and fluctuations of the signal shape due to weighting field variations. Then we derive expressions for the time resolution using leading edge discrimination of the signal for various electronics shaping times. Time resolution of silicon detect…
The tracking system of the CMS experiment, currently under construction at the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland), will include a silicon pixel detector providing three spacial measurements in its final configuration for tracks produced in high energy pp collisions. In this paper we present the results of test beam measurements performed at CERN on irradiated silicon pixel sensors. Lorentz angle and charge collection efficiency were measured for two sensor designs and at various bias voltages.
Sterile neutrinos are a minimal extension of the Standard Model of Particle Physics. A laboratory-based approach to search for this particle is via tritium beta-decay, where a sterile neutrino would cause a kink-like spectral distortion. The Karlsruhe Tritium Neutrino (KATRIN) experiment extended by a multi-pixel Silicon Drift Detector system has the potential to reach an unprecedented sensitivity to the keV-scale sterile neutrino in a lab-based experiment. The new detector system combines good spectroscopic performance with a high rate capability. In this work, we report about the characteriz…
We have developed a neutron imaging sensor based on an INTPIX4-SOI pixelated silicon device. Neutron irradiation tests are performed at several neutron facilities to investigate sensor's responses for neutrons. Detection efficiency is measured to be around $1.5$\% for thermal neutrons. Upper bound of spatial resolution is evaluated to be $4.1 \pm 0.2 ~μ$m in terms of a standard deviation of the line spread function.
The European X-ray Free Electron Laser (XFEL), currently being constructed in Hamburg and planning to be operational in 2017 for users, will deliver 27,000 fully coherent, high brilliance X-ray pulses per second with duration less than 100 fs. The unique features of the X-ray beam pose major challenges for detectors used at the European XFEL for imaging experiments, in particular a radiation tolerance of silicon sensors for doses up to 1 GGy for 3 years of operation at an operating voltage above 500 V. One of the detectors under development at the European XFEL is the Adaptive Gain Integrating…
We are developing DAQ for Si-pixel detectors by using a Slicon-On-Insulator (SOI) technology. This DAQ consists of firmware works on SEABAS (Soi EvAluation BoArd with Sitcp) DAQ board and software works on PC. We have been working on the development of firmware/software. Now we accomplished to speed up the readout (~90Hz) and to add a function for frame rate control. This is the report of our development work for the High Speed DAQ system.
The CMS experiment at the LHC includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The barrel region consists of n-in-n sensors with 100X150 um^2 cell size processed on diffusion oxygenated float zone silicon. A biasing grid is implemented and pixel isolation is achieved with the moderated p-spray technique. An extensive test program was carried out on the H2 beam line of the CERN SPS. In this paper we describe the sensor layout, the beam test setup and the results obtained with both irradiated and non-irradiated prototype devices. …
A monolithic silicon pixel detector prototype has been produced in the SiGe BiCMOS SG13G2 130 nm node technology by IHP. The ASIC contains a matrix of hexagonal pixels with pitch of approximately 100 $μ$m. Three analog pixels were calibrated in laboratory with radioactive sources and tested in a 180 GeV/c pion beamline at the CERN SPS. A detection efficiency of $\left(99.9^{+0.1}_{-0.2}\right)$% was measured together with a time resolution of $(36.4 \pm 0.8)$ps at the highest preamplifier bias current working point of 150 $μ$A and at a sensor bias voltage of 160 V. The ASIC was also characteri…
The High Luminosity LHC (HL-LHC) upgrade requires the planned Inner Tracker (ITk) of the ATLAS detector to tolerate extremely high radiation doses. Specifically, the innermost parts of the pixel system will have to withstand radiation fluences above $1\times10^{16}$ $n_{eq}cm^{-2}$. Novel 3D silicon pixel sensors offer a superior radiation tolerance compared to conventional planar pixel sensors, and are thus excellent candidates for the innermost parts of the ITk. This paper presents studies of 3D pixel sensors with pixel size $50 \times 50$ $μm^2$ mounted on the RD53A prototype readout chip. …
Particle identification using the energy loss in silicon detectors is a powerful technique for probing the Standard Model (SM) as well as searching for new particles beyond the SM. Traditionally, such techniques use the truncated mean of the energy loss on multiple layers, in order to mitigate heavy tails in the charge fluctuation distribution. We show that the optimal scheme using the charge in multiple layers significantly outperforms the truncated mean. Truncation itself does not significantly degrade performance and the optimal classifier is well-approximated by a linear combination of the…
In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goliath magnet at the H4 proton beamline. Behind the magnet, scintillating-fibre, drift-tube and RPC detectors were placed. The purpose of this run was to validate the measurement's feasibility, to develop the required analysis tools and fine-tune the detector layout. In this paper, we present the track reconstruction in the pixel tracker and the…
3D silicon detectors are characterized by cylindrical electrodes perpendicular to the surface and penetrating into the bulk material in contrast to standard Si detectors with planar electrodes on its top and bottom. This geometry renders them particularly interesting to be used in environments where standard silicon detectors have limitations, such as for example the radiation environment expected in an LHC upgrade. For the first time, several 3D sensors were assembled as hybrid pixel detectors using the ATLAS-pixel front-end chip and readout electronics. Devices with different electrode confi…
Recent progress in active-edge technology of silicon sensors enables the development of large-area tiled silicon pixel detectors with small dead space between modules by utilizing edgeless sensors. Such technology has been proven in successful productions of ATLAS and Medipix-based silicon pixel sensors by a few foundries. However, the drawbacks of edgeless sensors are poor radiation hardness for ionizing radiation and non-uniform charge collection by edge pixels. In this work, the radiation hardness of edgeless sensors with different polarities has been investigated using Synopsys TCAD with X…
We show that doubly peaked electric fields are necessary to describe grazing-angle charge collection measurements of irradiated silicon pixel sensors. A model of irradiated silicon based upon two defect levels with opposite charge states and the trapping of charge carriers can be tuned to produce a good description of the measured charge collection profiles in the fluence range from 0.5x10^{14} Neq/cm^2 to 5.9x10^{14} Neq/cm^2. The model correctly predicts the variation in the profiles as the temperature is changed from -10C to -25C. The measured charge collection profiles are inconsistent wit…
A new method for the extraction of the electric field in the bulk of heavily irradiated silicon pixel sensors is presented. It is based on the measurement of the Lorentz deflection and mobility of electrons as a function of depth. The measurements were made at the CERN H2 beam line, with the beam at a shallow angle with respect to the pixel sensor surface. The extracted electric field is used to simulate the charge collection and the Lorentz deflection in the pixel sensor. The simulated charge collection and the Lorentz deflection is in good agreement with the measurements both for non-irradia…
3D silicon pixel detectors have been investigated as radiation-hard candidates for the innermost layers of the HL-LHC upgrade of the ATLAS pixel detector. 3D detectors are already in use today in the ATLAS IBL and AFP experiments. These are based on 50x250 um2 large pixels connected to the FE-I4 readout chip. Detectors of this generation were irradiated to HL-LHC fluences and demonstrated excellent radiation hardness with operational voltages as low as 180 V and power dissipation of 12--15 mW/cm2 at a fluence of about 1e16 neq/cm2, measured at -25 degree C. Moreover, to cope with the higher oc…
The TT-PET collaboration is developing a PET scanner for small animals with 30 ps time-of-flight resolution and sub-millimetre 3D detection granularity. The sensitive element of the scanner is a monolithic silicon pixel detector based on state-of-the-art SiGe BiCMOS technology. The first ASIC prototype for the TT-PET was produced and tested in the laboratory and with minimum ionizing particles. The electronics exhibit an equivalent noise charge below 600 e- RMS and a pulse rise time of less than 2 ns, in accordance with the simulations. The pixels with a capacitance of 0.8 pF were measured to …
The performance of novel n-in-p planar pixel detectors, designed for future upgrades of the ATLAS Pixel system is presented. The n-in-p silicon sensors technology is a promising candidate for the pixel upgrade thanks to its radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. The n-in-p modules presented here are composed of pixel sensors produced by CiS connected by bump-bonding to the ATLAS readout chip FE-I3. The characterization of these devices has been performed before and after irradiation up to a fluence of 5 x 10**15 1 MeV neq…
In view of the LHC upgrade for the High Luminosity Phase (HL-LHC), the ATLAS experiment is planning to replace the Inner Detector with an all-Silicon system. The n-in-p bulk technology represents a valid solution for the modules of most of the layers, given the significant radiation hardness of this option and the reduced cost. The large area necessary to instrument the outer layers will demand to tile the sensors, a solution for which the inefficient region at the border of each sensor needs to be reduced to the minimum size. This paper reports on a joint R&D project by the ATLAS LPNHE Paris …
The physics aims at the proposed high-energy $e^+e^-$ collider CLIC pose challenging demands on the performance of the detector system. Precise hit-time tagging, an excellent spatial resolutions, and a low mass are required for the vertex and tracking detectors. To meet these requirements, an all-silicon vertex and tracking detector system is foreseen, for which a broad R&D programme on a variety of novel silicon detector technologies is being pursued. For the ultra-low mass vertex detector, different hybrid technologies with innovative sensor concepts and interconnection techniques are explor…
SiGe BiCMOS technology can be used to produce ultra-fast, low-power silicon pixel sensors that provide state-of-the-art time resolution even without an internal gain mechanism. The development of such sensors requires the identification of the main factors that may degrade the timing performance and the characterisation of the dependance of the sensor time resolution on the amplifier power consumption. Measurements with a $ \mathrm{^{90}Sr} $ source of a prototype sensor produced in SG13G2 technology from IHP Microelectronics, shows a time resolution of 140 ps at an amplifier current of 7 $ \m…
Silicon detectors have gained in popularity since silicon became a widely used micro/nanoelectronic semiconductor material. Silicon detectors are used in particle physics as well as imaging for pixel based detecting systems. Over the past twenty years a lot of experimental efforts have been focused on the effects of ionizing and non-ionizing radiation on silicon pixels. Some of this research was done in the framework of high luminosity particle physics experiments, along with radiation hardness studies of basic semiconductors devices. In its simplest form the semiconductor pixel detectors redu…
The performance of pixel modules built from 75 micrometer thin silicon sensors and ATLAS read-out chips employing the Solid Liquid InterDiffusion (SLID) interconnection technology is presented. This technology, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It allows for stacking of different interconnected chip and sensor layers without destroying the already formed bonds. In combination with Inter-Chip-Vias (ICVs) this paves the way for vertical integration. Both technologies are combined in a pixel module concept which is the basis for the modules …
We investigate the performance of large area radiation detectors, with high energy- and spatial-resolution, intended for the development of a Total Energy Detector with gamma-ray imaging capability, so-called i-TED. This new development aims for an enhancement in detection sensitivity in time-of-flight neutron capture measurements, versus the commonly used C6D6 liquid scintillation total-energy detectors. In this work, we study in detail the impact of the readout photosensor on the energy response of large area (5050 mm2) monolithic LaCl3(Ce) crystals, in particular when replacing a convention…
A systematic experimental study of the main challenges for silicon-pixel sensors at the European XFEL is presented. The high instantaneous density of X-rays and the high repetition rate of the XFEL pulses result in signal distortions due to the plasma effect and in severe radiation damage. The main parameters of X-ray-radiation damage have been determined and their impact on p+n sensors investigated. These studies form the basis of the optimized design of a pixel-sensor for experimentation at the European XFEL.
For operation at the High Luminosity Large Hadron Collider (LHC), the ATLAS experiment is building a new all-silicon inner tracker (ITk). The production and testing of thousands of silicon pixel and strip modules is required to cover the estimated 180 m$^{2}$ of the total surface area. A compact, affordable and robust module characterization system is required for in-situ testing prior any test beam campaign or installation. A test bench setup based on an infrared laser was developed at IJCLab, allowing also for the use of micro-metric precision scanning with a radioactive source. A detailed s…
First measurements are presented from a newly commissioned two-photon absorption (TPA) setup at Nikhef. The characterisation of the various components of the system is discussed. Two planar silicon sensors, one being electron collecting and one hole collecting, are characterised with detailed measurements of the charge collection and time resolution. The TPA spot is determined to have a radius of 0.975(11) $μ\text{m}$ and length of 23.8 $μ\text{m}$ in silicon. The trigger time resolution of the system is shown to be maximally 30.4 ps. For both sensors, uniform charge collection is observed ove…
Hybrid silicon pixel detectors are currently used in the innermost tracking system of the Compact Muon Solenoid (CMS) experiment. Radiation tolerance up to fluences expected for a few years of running of the Large Hadron Collider (LHC) has already been proved, although some degradation of the part of the silicon detector closer to the interaction point is expected. During the LHC upgrade phases, the level of dose foreseen for the silicon pixel detector will be much higher. To face this aspect, dedicated irradiation tests with fluences above $\mathcal{O}(10^{15})$ n$_{\textrm{eq}}$/cm$^2$ have …
A pixelated silicon detector, developed originally for particle physics experiments, was used for a beam profile measurement of a Co-60 irradiator in a water phantom. The beam profile was compared to a profile measured with a pinpoint ionization chamber. The differences in the pixel detector and pinpoint chamber relative profiles were within approximately 0.02, and after calculating correction factors with Monte Carlo simulations for the pixel detector, the differences were decreased to almost less than 0.005. The detector's capability to measure pulse-height was used to record an electron pul…
The inner drift chamber of the BESIII is encountering serious aging problem after five year's running. For the first layer, the decrease in gas gain is about 26% from 2009 to 2013. The upgrade of the inner tracking detector has become an urgent problem for the BESIII experiment. An inner tracker using CMOS pixel sensors is an important candidate because of its great advantages on spatial resolution and radiation hardness. In order to carry out a Monte Carlo study on the expected performance, a Geant4-based full simulation for the silicon pixel detector has been implemented. The tracking method…
3D silicon detectors, in which the electrodes penetrate the sensor bulk perpendicular to the surface, have recently undergone a rapid development from R\&D over industrialisation to their first installation in a real high-energy-physics experiment. Since June 2015, the ATLAS Insertable B-Layer is taking first collision data with 3D pixel detectors. At the same time, preparations are advancing to install 3D pixel detectors in forward trackers such as the ATLAS Forward Proton detector or the CMS-TOTEM Proton Precision Spectrometer. For those experiments, the main requirements are a slim edge and…
The European X-ray Free Electron Laser (XFEL) will deliver 27000 fully coherent, high brilliance X-ray pulses per second each with a duration below 100 fs. This will allow the recording of diffraction patterns of single molecules and the study of ultra-fast processes. One of the detector systems under development for the XFEL is the Adaptive Gain Integrating Pixel Detector (AGIPD), which consists of a pixel array with readout ASICs bump-bonded to a silicon sensor with pixels of 200 μm \times 200 μm. The particular requirements for the detector are a high dynamic range (0, 1 up to 10E5 12 keV p…
The concept of the deep trapping gate device was introduced fairly recently on the basis of technological and transport simulations currently used in the field of classical electron devices. The concept of a buried gate containing localized deep level centers for holes (Deep Trapping Gate or DTG) renders possible the operation of this field effect pixel detector. One alternative to Deep Level introduction is the use of a quantum box, which is a hole quantum-well and an electron barrier. In all of these cases the buried gate modulates the drain-source current. This principle was formerly evalua…
The existing ATLAS Tracker will be at its functional limit for particle fluences of 10^15 neq/cm^2 (LHC). Thus for the upgrades at smaller radii like in the case of the planned Insertable B-Layer (IBL) and for increased LHC luminosities (super LHC) the development of new structures and materials which can cope with the resulting particle fluences is needed. N-in-p silicon devices are a promising candidate for tracking detectors to achieve these goals, since they are radiation hard, cost efficient and are not type inverted after irradiation. A n-in-p pixel production based on a MPP/HLL design a…
In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC), the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon technology is a promising candidate to achieve a large area instrumented with pixel sensors, since it is radiation hard and cost effective. The paper reports on the performance of novel n-on-p edgeless planar pixel sensors produced by FBK-CMM, making use of the active trench for the reduction of the dead area at the periphery of the device. After discussing the sensor technology an overview of the first beam test res…
The deep trapping gate pixel device was described recently as an alternative to CMOS 3T pixel. The feasibilty of this device was studied with technological and transport simulations used in classical electron devices and process design. A buried gate containing localized deep level centers (Deep Trapping Gate or DTG) is the key for the operation of this field effect pixel detector. This can be made with deep levels or a quantum box. This buried gate can modulates the drain-source current, the same way the upper gate does. This principle was evaluated with realistic simulations physical paramet…
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 $2.5 \cdot 10^{16}\,1\,MeV\, n_{eq}\,cm^{-2}$. 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.
The ATLAS Forward Physics (AFP) project plans to install 3D silicon pixel detectors about 210 m away from the interaction point and very close to the beamline (2-3 mm). This implies the need of slim edges of about 100-200 $μ$m width for the sensor side facing the beam to minimise the dead area. Another challenge is an expected non-uniform irradiation of the pixel sensors. It is studied if these requirements can be met using slightly-modified FE-I4 3D pixel sensors from the ATLAS Insertable B-Layer production. AFP-compatible slim edges are obtained with a simple diamond-saw cut. Electrical char…
In view of the LHC upgrade phases towards HL-LHC, the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon technology is a promising candidate for the pixel upgrade thanks to its radiation hardness and cost effectiveness, that allow for enlarging the area instrumented with pixel detectors. We report on the development of novel n-in-p edgeless planar pixel sensors fabricated at FBK (Trento, Italy), making use of the "active edge" concept for the reduction of the dead area at the periphery of the device. After discussing the sensor technology and fa…
We are investigating the feasibility of using CMOS foundries to fabricate silicon detectors, both for pixels and for large-area strip sensors. The availability of multi-layer routing will provide the freedom to optimize the sensor geometry and the performance, with biasing structures in poly-silicon layers and MIM-capacitors allowing for AC coupling. A prototyping production of strip test-structures and RD53A compatible pixel sensors was recently completed at LFoundry in a 150$\,$nm CMOS process. This paper will focus on the characterization of irradiated and non-irradiated pixel modules, comp…
Using the simulation framework of the SiD detector to study the Higgs -> mumu decay channel showed a considerable gain in signal significance could be achieved through an increase in charged particle momentum resolution. However more detailed simulations of theZ -> mumu decay channel demonstrated that significant improvement in the resolution could not be achieved through an increase in tracker granularity. Conversely detector stability studies into missing/dead vertex layers using longer lived particles displayed an increase in track resolution. The existing 9.15 cm x 25 μm silicon strip geom…
This paper presents the design and test results of a prototype monolithic pixel sensor manufactured in deep-submicron fully-depleted Silicon-On-Insulator (SOI) CMOS technology. In the SOI technology, a thin layer of integrated electronics is insulated from a (high-resistivity) silicon substrate by a buried oxide. Vias etched through the oxide allow to contact the substrate from the electronics layer, so that pixel implants can be created and a reverse bias can be applied. The prototype chip, manufactured in OKI 0.15 micron SOI process, features both analog and digital pixels on a 10 micron pit…
A monolithic pixelated silicon detector designed for high time resolution has been produced in the SG13G2 130 nm SiGe BiCMOS technology of IHP Mikroelektronik. This proof-of-concept chip contains hexagonal pixels of 65 μm and 130 μm side. The SiGe front-end electronics implemented provides an equivalent noise charge of 90 and 160 electrons for a pixel capacitance of 70 and 220 fF, respectively, and a total time walk of less than 1 ns. Lab measurements with a 90Sr source show a time resolution of the order of 50 ps. This result is competitive with silicon technologies that integrate an avalanch…
Silicon pixel detectors developed to meet LHC requirements were tested in a beam at CERN in the framework of the ATLAS collaboration. The experimental behaviour of irradiated and not-irradiated sensors in a magnetic field is discussed. The measurement of the Lorentz angle for these sensors at different operating conditions is presented. A simple model of the charge drift in silicon before and after irradiation is presented. The good agreement between the model predictions and the experimental results is shown.
The development of an innovative position sensitive pixelated sensor to detect and measure with high precision the coordinates of the ionizing particles is proposed. The silicon avalanche pixel sensors (APiX) is based on the vertical integration of avalanche pixels connected in pairs and operated in coincidence in fully digital mode and with the processing electronics embedded on the chip. The APiX sensor addresses the need to minimize the material budget and related multiple scattering effects in tracking systems requiring a high spatial resolution in the presence of a large occupancy. The ex…
