arXiv subjects

M. Boscardin

Publications and source records attributed to M. Boscardin.

At least 19 recordsLinked to original sources

arXiv2025

Measurements and TCAD simulations of innovative RSD and DC-RSD LGAD devices for future 4D tracking

This paper summarizes the beam test results obtained with a Resistive Silicon Detector (RSD) (also called AC-Low Gain Avalanche Diode, AC-LGAD) pixel array tested at the DESY beam test facility with a 5 GeV/c electron beam. Furthermore, it describes in detail the simulation results of DC-RSD, an evolution of the RSD design. The simulations campaign described in this paper has been instrumental in the definition of the structures implemented in the Fondazione Bruno Kessler FBK first DC-RSD production. The RSD matrix used in this study is part of the second FBK RSD production, RSD2. The best position resolution reached in this test is sigma_x = 15 micron, about 3.4% of the pitch. DC-RSD LGAD, are an evolution of the AC-coupled design, eliminating the dielectric and using a DC-coupling to the electronics. The concept of DC-RSD has been finalized using full 3D Technology-CAD simulations of the sensor behavior. TCAD simulations are an excellent tool for designing this innovative class of detectors, enabling the evaluation of different technology options (e.g., the resistivity of the n+ layer, contact materials) and geometrical layouts (shape and distance of the read-out pads).

physics.ins-det↗

arXiv2025

Measured gain suppression in FBK LGADs with different active thicknesses

In recent years, the gain suppression mechanism has been studied for large localized charge deposits in Low-Gain Avalanche Detectors (LGADs). LGADs are a thin silicon detector with a highly doped gain layer that provides moderate internal signal amplification. Using the CENPA Tandem accelerator at the University of Washington, the response of LGADs with different thicknesses to MeV-range energy deposits from a proton beam were studied. Three LGAD prototypes of 50~$μ$m, 100~$μ$m, 150~$μ$m were characterized. The devices' gain was determined as a function of bias voltage, incidence beam angle, and proton energy. This study was conducted in the scope of the PIONEER experiment, an experiment proposed at the Paul Scherrer Institute to perform high-precision measurements of rare pion decays. LGADs are considered for the active target (ATAR) and energy linearity is an important property for particle ID capabilities.

physics.ins-det↗

arXiv2025

Synchrotron light source focused X-ray detection with LGADs, AC-LGADs and TI-LGADs

The response of Low Gain Avalanche Diodes (LGADs), a type of thin silicon detector with internal gain, to X-rays of energies between 6-16~keV was characterized at the Stanford Synchrotron Radiation Lightsource (SSRL). The utilized beamline at SSRL was 7-2, with a nominal beam size of 30~$μ$m, repetition rate of 500~MHz, and with an energy dispersion $ΔE/E$ of $10^{-4}$. Multi-channel LGADs, AC-LGADs, and TI-LGADs of different thicknesses and gain layer configurations from Hamamatsu Photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested. The sensors were read out with a discrete component board and digitized with a fast oscilloscope or a CAEN fast digitizer. The devices' energy response, energy resolution, and time resolution were measured as a function of X-ray energy and position. The charge collection and multiplication mechanism were simulated using TCAD Sentaurus, and the results were compared with the collected data.

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arXiv2025

Innovative DC-coupled Resistive Silicon Detector for 4D tracking

In the past 10 years, two design innovations, the introduction of low internal gain (LGAD) and of resistive read-out (RSD), have radically changed the performance of silicon detectors. The LGAD mechanism, increasing the signal-to-noise ratio by about a factor of 20, leads to improved time resolution (typically 30 ps for a 50-$μ$m thick sensor), while resistive read-out, sharing the collected charge among read-out electrodes, leads to excellent spatial resolution even using large pixels (about 15 $μ$m for 450-$μ$m pixel size). This contribution outlines the design strategy and presents the first performance results of the latest evolution of silicon sensors for 4D tracking, the DC-coupled Resistive Silicon Detector (DC-RSD). The DC-RSD is a thin LGAD with a DC-coupled resistive read-out. This design leads to signal containment within a predetermined number of electrodes using isolating trenches (TI technology). Several test structures and application-oriented devices have been implemented in the wafer layout. The sensors, produced at Fondazione Bruno Kessler (FBK) in the framework of the 4DSHARE project, have been characterized with a laser TCT system and recently tested at DESY with an electron beam. The study of this first prototype production will provide us with immediate feedback on the soundness of the DC-RSD concepts.

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arXiv2024

Plasma-Based Etching Approach for GEM Detector Microfabrication at FBK for X-ray polarimetry in space

Gas Electron Multiplier (GEM) detectors are crucial for enabling high-resolution X-ray polarisation of astrophysical sources when coupled to custom pixel readout ASIC in Gas Pixel Detectors (GPD), as in the Imaging X-ray Polarimetry Explorer (IXPE), the Polarlight cubesat pathfinder and the PFA telescope onboard the future large enhanced X-ray Timing and Polarimetry (eXTP) Chinese mission. The R&D efforts of the IXPE collaboration have resulted in mature GPD technology. However, limitations in the classical wet-etch or laser-drilled fabrication process of GEMs motivated our exploration of alternative methods. This work focuses on investigating a plasma-based etching approach for fabricating GEM patterns at Fondazione Bruno Kessler (FBK). The objective is to improve the aspect ratio of the GEM holes, to mitigate the charging of the GEM dielectric which generates rate-dependent gain changes. Unlike the traditional wet-etch process, Reactive Ion Etching (RIE) enables more vertical etching profiles and thus better aspect ratios. Moreover, the RIE process promises to overcome non-uniformities in the GEM hole patterns which are believed to cause systemic effects in the azimuthal response of GPDs equipped with either laser-drilled or wet-etch GEMs. We present a GEM geometry with 20 micrometers in diameter and 50 micrometers pitch, accompanied by extensive characterisation (SEM and PFIB) of the structural features and aspect ratios. The collaboration with INFN Pisa and Turin enabled us to compare the electrical properties of these detectors and test their performance in their use as electron multipliers in GPDs. Although this R&D work is in its initial stages, it holds promise for enhancing the sensitivity of the IXPE mission in X-ray polarimetry measurements through GEM pattern with more vertical hole profiles.

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arXiv2022

High-Precision 4D Tracking with Large Pixels using Thin Resistive Silicon Detectors

The basic principle of operation of silicon sensors with resistive read-out is built-in charge sharing. Resistive Silicon Detectors (RSD, also known as AC-LGAD), exploiting the signals seen on the electrodes surrounding the impact point, achieve excellent space and time resolutions even with very large pixels. In this paper, a TCT system using a 1064 nm picosecond laser is used to characterize sensors from the second RSD production at the Fondazione Bruno Kessler. The paper first introduces the parametrization of the errors in the determination of the position and time coordinates in RSD, then outlines the reconstruction method, and finally presents the results. Three different pixel sizes are used in the analysis: 200 x 340, 450 x 450, and 1300 x 1300 microns^2. At gain = 30, the 450 x 450 microns^2 pixel achieves a time jitter of 20 ps and a spatial resolution of 15 microns concurrently, while the 1300 x 1300 microns^2 pixel achieves 30 ps and 30 micron, respectively. The implementation of cross-shaped electrodes improves considerably the response uniformity over the pixel surface.

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arXiv2022

Solid State Detectors and Tracking for Snowmass

Tracking detectors are of vital importance for collider-based high energy physics (HEP) experiments. The primary purpose of tracking detectors is the precise reconstruction of charged particle trajectories and the reconstruction of secondary vertices. The performance requirements from the community posed by the future collider experiments require an evolution of tracking systems, necessitating the development of new techniques, materials and technologies in order to fully exploit their physics potential. In this article we summarize the discussions and conclusions of the 2022 Snowmass Instrumentation Frontier subgroup on Solid State and Tracking Detectors (Snowmass IF03).

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arXiv2022

Quality Control (QC) of FBK Preproduction 3D Si Sensors for ATLAS HL-LHC Upgrades

The challenging demands of the ATLAS High Luminosity (HL-LHC) Upgrade aim for a complete swap of new generation sensors that should cope with the ultimate radiation hardness. FBK has been one of the prime foundries to develop and fabricate such radiation-hard 3D silicon (Si) sensors. These sensors are chosen to be deployed into the innermost layer of the ATLAS Inner Tracker (ITk). Recently, a pre-production batch of 3D Si sensors of 50x50 um2 pixel geometry, compatible with the full-size ITKPix (RD53B) readout chip, was fabricated. Two wafers holding temporary metal were diced at IZM, Germany, and a systematic QC test campaign was carried out at the University of Trento electronics laboratory. The paper briefly describes the 3D Si sensor design for ATLAS ITk and the required QC characterization setups. It comprises electrical tests (i.e., I-V, C-V, and I-T) of non-irradiated RD53B sensors. In addition, the study of several parametric analyses, i.e., oxide charge density, oxide thickness, inter-pixel resistance, inter-pixel capacitance, etc., are reported with the aid of Process Control Monitor (PCM) structures.

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arXiv2022

Inter-pad dead regions of irradiated FBK Low Gain Avalanche Detectors

Low Gain Avalanche Detectors (LGADs) are a type of thin silicon detector with a highly doped gain layer. LGADs manufactured by Fondazione Bruno Kessler (FBK) were tested before and after irradiation with neutrons. In this study, the Inter-pad distances (IPDs), defined as the width of the distances between pads, were measured with a TCT laser system. The response of the laser was tuned using $β$-particles from a 90Sr source. These insensitive "dead zones" are created by a protection structure to avoid breakdown, the Junction Termination Extension (JTE), which separates the pads. The effect of neutron radiation damage at \fluence{1.5}{15}, and \fluence{2.5}{15} on IPDs was studied. These distances are compared to the nominal distances given from the vendor, it was found that the higher fluence corresponds to a better matching of the nominal IPD.

physics.ins-det↗

arXiv2022

Beam test results of 25 $μ$m and 35 $μ$m thick FBK UFSD]{Beam test results of 25 $μ$m and 35 $μ$m thick FBK ultra fast silicon detectors

This paper presents the measurements on first very thin Ultra Fast Silicon Detectors (UFSDs) produced by Fondazione Bruno Kessler; the data have been collected in a beam test setup at the CERN PS, using beam with a momentum of 12 GeV/c. UFSDs with a nominal thickness of 25 $μ$m and 35 $μ$m and an area of 1 $\times$ 1 $\text{mm}^2$ have been considered, together with an additional HPK 50-$μ$m thick sensor, taken as reference. Their timing performances have been studied as a function of the applied voltage and gain. A time resolution of about 25 ps and of 22 ps at a voltage of 120 V and 240 V has been obtained for the 25 and 35 $μ$m thick UFSDs, respectively.

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arXiv2022

The second production of RSD (AC-LGAD) at FBK

In this contribution we describe the second run of RSD (Resistive AC-Coupled Silicon Detectors) designed at INFN Torino and produced by Fondazione Bruno Kessler (FBK), Trento. RSD are n-in-p detectors intended for 4D particle tracking based on the LGAD technology that get rid of any segmentation implant in order to achieve the 100% fill-factor. They are characterized by three key-elements, (i) a continuous gain implant, (ii) a resistive n-cathode and (iii) a dielectric coupling layer deposited on top, guaranteeing a good spatial reconstruction of the hit position while benefiting from the good timing properties of LGADs. We will start from the very promising results of our RSD1 batch in terms of tracking performances and then we will move to the description of the design of the RSD2 run. In particular, the principles driving the sensor design and the specific AC-electrode layout adopted to optimize the signal confinement will be addressed.

physics.ins-det↗

arXiv2022

DC-coupled resistive silicon detectors for 4-D tracking

In this work, we introduce a new design concept: the DC-Coupled Resistive Silicon Detectors, based on the LGAD technology. This new approach intends to address a few known features of the first generation of AC-Coupled Resistive Silicon Detectors (RSD). Our simulation exploits a fast hybrid approach based on a combination of two packages, Weightfield2 and LTSpice. It demonstrates that the key features of the RSD design are maintained, yielding excellent timing and spatial resolutions: a few tens of ps and a few microns. In the presentation, we will outline the optimization methodology and the results of the simulation. We will present detailed studies on the effect of changing the ratio between the n+ layer resistivity and the low-resistivity ring and on the achievable temporal and spatial resolution.

physics.ins-det↗

arXiv2022

Novel Sensors for Particle Tracking: a Contribution to the Snowmass Community Planning Exercise of 2021

Five contemporary technologies are discussed in the context of their potential roles in particle tracking for future high energy physics applications. These include sensors of the 3D configuration, in both diamond and silicon, submicron-dimension pixels, thin film detectors, and scintillating quantum dots in gallium arsenide. Drivers of the technologies include radiation hardness, excellent position, vertex, and timing resolution, simplified integration, and optimized power, cost, and material.

physics.ins-det↗

arXiv2022

Testing of planar hydrogenated amorphous silicon sensors with charge selective contacts for the construction of 3D- detectors

Hydrogenated Amorphous Silicon (a-Si:H) is a material well known for its intrinsic radiation hardness and is primarily utilized in solar cells as well as for particle detection and dosimetry. Planar p-i-n diode detectors are fabricated entirely by means of intrinsic and doped PECVD of a mixture of Silane (SiH4) and molecular Hydrogen. In order to develop 3D detector geometries using a-Si:H, two options for the junction fabrication have been considered: ion implantation and charge selective contacts through atomic layer deposition. In order to test the functionality of the charge selective contact electrodes, planar detectors have been fabricated utilizing this technique. In this paper, we provide a general overview of the 3D fabrication project followed by the results of leakage current measurements and x-ray dosimetric tests performed on planar diodes containing charge selective contacts to investigate the feasibility of the charge selective contact methodology for integration with the proposed 3D detector architectures.

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arXiv2022

Tuning of gain layer doping concentration and Carbon implantation effect on deep gain layer

Next generation Low Gain Avalanche Diodes (LGAD) produced by Hamamatsu photonics (HPK) and Fondazione Bruno Kessler (FBK) were tested before and after irradiation with ~1MeV neutrons at the JSI facility in Ljubljana. Sensors were irradiated to a maximum 1-MeV equivalent fluence of 2.5E15 Neq/cm2. The sensors analysed in this paper are an improvement after the lessons learned from previous FBK and HPK productions that were already reported in precedent papers. The gain layer of HPK sensors was fine-tuned to optimize the performance before and after irradiation. FBK sensors instead combined the benefit of Carbon infusion and deep gain layer to further the radiation hardness of the sensors and reduced the bulk thickness to enhance the timing resolution. The sensor performance was measured in charge collection studies using \b{eta}-particles from a 90Sr source and in capacitance-voltage scans (C-V) to determine the bias to deplete the gain layer. The collected charge and the timing resolution were measured as a function of bias voltage at -30C. Finally a correlation is shown between the bias voltage to deplete the gain layer and the bias voltage needed to reach a certain amount of gain in the sensor. HPK sensors showed a better performance before irradiation while maintaining the radiation hardness of the previous production. FBK sensors showed exceptional radiation hardness allowing a collected charge up to 10 fC and a time resolution of 40 ps at the maximum fluence.

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arXiv2021

Resistive AC-Coupled Silicon Detectors: principles of operation and first results from a combined analysis of beam test and laser data

This paper presents the principles of operation of Resistive AC-Coupled Silicon Detectors (RSDs) and measurements of the temporal and spatial resolutions using a combined analysis of laser and beam test data. RSDs are a new type of n-in-p silicon sensor based on the Low-Gain Avalanche Diode (LGAD) technology, where the $n^+$ implant has been designed to be resistive, and the read-out is obtained via AC-coupling. The truly innovative feature of RSD is that the signal generated by an impinging particle is shared isotropically among multiple read-out pads without the need for floating electrodes or an external magnetic field. Careful tuning of the coupling oxide thickness and the $n^+$ doping profile is at the basis of the successful functioning of this device. Several RSD matrices with different pad width-pitch geometries have been extensively tested with a laser setup in the Laboratory for Innovative Silicon Sensors in Torino, while a smaller set of devices have been tested at the Fermilab Test Beam Facility with a 120 GeV/c proton beam. The measured spatial resolution ranges between $2.5\; μm$ for 70-100 pad-pitch geometry and $17\; μm$ with 200-500 matrices, a factor of 10 better than what is achievable in binary read-out ($bin\; size/ \sqrt{12}$). Beam test data show a temporal resolution of $\sim 40\; ps$ for 200-$μm$ pitch devices, in line with the best performances of LGAD sensors at the same gain.

physics.ins-det↗

arXiv2020

MEMS Mirror Manufacturing and Testing for Innovative Space Applications

In the framework of the GLARE-X (Geodesy via LAser Ranging from spacE X) project, led by INFN and funded for the years 2019-2021, aiming at significantly advance space geodesy, one shows the initial activities carried out in 2019 in order to manufacture and test adaptive mirrors. This specific article deals with manufacturing and surface quality measurements of the passive substrate of 'candidate' MEMS (Micro-Electro-Mechanical Systems) mirrors for MRRs (Modulated RetroReflectors); further publications will show the active components. The project GLARE-X was approved by INFN for the years 2019-2021: it involves several institutions, including, amongst the other, INFN-LNF and FBK. GLARE-X is an innovative R&D activity, whose at large space geodesy goals will concern the following topics: inverse laser ranging (from a laser terminal in space down to a target on a planet), laser ranging for debris removal and iterative orbit correction, development of high-end ToF (Time of Flight) electronics, manufacturing and testing of MRRs for space, and provision of microreflectors for future NEO (Near Earth Orbit) cubesats. This specific article summarizes the manufacturing and surface quality measurements activities performed on the passive substrate of 'candidate' MEMS mirrors, which will be in turn arranged into MRRs. The final active components, to be realized by 2021, will inherit the manufacturing characteristics chosen thanks to the presented (and further) testing campaigns, and will find suitable space application to NEO, Moon, and Mars devices, like, for example, cooperative and active lidar scatterers for laser altimetry and lasercomm support.

astro-ph.IM↗

arXiv2020

Silicon Sensors for Future Particle Trackers

Several future high-energy physics facilities are currently being planned. The proposed projects include high energy $e^+ e^-$ circular and linear colliders, hadron colliders and muon colliders, while the Electron-Ion Collider (EIC) has already been approved for construction at the Brookhaven National Laboratory. Each proposal has its own advantages and disadvantages in term of readiness, cost, schedule and physics reach, and each proposal requires the design and production of specific new detectors. This paper first presents the performances required to the future silicon tracking systems at the various new facilities, and then it illustrates a few possibilities for the realization of such silicon trackers. The challenges posed by the future facilities require a new family of silicon detectors, where features such as impact ionization, radiation damage saturation, charge sharing, and analog readout are exploited to meet these new demands.

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