arXiv subjects

Lucio Pancheri

Publications and source records attributed to Lucio Pancheri.

6 recordsLinked to original sources

arXiv2026

Spatial resolution for gamma ray interactions in stacks of monolithic silicon sensors

We are developing a new implementation of Compton imaging for nuclear medicine using a large volume of stacked monolithic silicon sensors. In this work we investigate how the spatial resolution is impacted by the pixel size, an important input to the design of the sensors. In general CMOS design is less challenging with larger pixels leaving more space for analog and digital electronics. On the other hand, spatial resolution is one of the key parameters that will impact the performance of the Compton imaging system. It is also important to consider the range of the recoil electron produced in Compton or photoelectric interactions, which impacts how accurately the interaction point can be estimated. The achievable resolution was evaluated with two interaction position reconstruction algorithms: one based on a Gaussian fit of the detected charge and a second based on the characteristic energy deposition along the electron track, with the former performing better at lower energies. Monte Carlo simulations were performed for 140 keV and 511 keV sources embedded in a water phantom, with pixel pitches ranging from 25 $\mu m$ to 250 $\mu m$. Energy-averaged in-plane resolution degraded from 8 $\mu m$ to 94 $\mu m$ as pixel size increased. The out-of-plane resolution was 216 $\mu m$ at low energies, limited by sensor thickness, and improved to 155 $\mu m$ at higher energies. The results suggest that pixel sizes in the order of 100 $\mu m$ can achieve spatial resolutions on the order of tens of micrometers.

physics.ins-det↗

arXiv2022

Optimization of the Gain Layer Design of Ultra-Fast Silicon Detectors

In the past few years, the need of measuring accurately the spatial and temporal coordinates of the particles generated in high-energy physics experiments has spurred a strong R\&D in the field of silicon sensors. Within these research activities, the so-called Ultra-Fast Silicon Detectors (UFSDs), silicon sensors optimized for timing based on the Low-Gain Avalanche Diode (LGAD) design, have been proposed and adopted by the CMS and ATLAS collaborations for their respective timing layers. The defining feature of the Ultra-Fast Silicon Detectors (UFSDs) is the internal multiplication mechanism, determined by the gain layer design. In this paper, the performances of several types of gain layers, measured with a telescope instrumented with a $^{90}$Sr $β$-source, are reported and compared. The measured sensors are produced by Fondazione Bruno Kessler (FBK) and Hamamatsu Photonics (HPK). The sensor yielding the best performance, both when new and irradiated, is an FBK 45\mum-thick sensor with a carbonated deep gain implant, where the carbon and the boron implants are annealed concurrently with a low thermal load. This sensor is able to achieve a time resolution of 40~ps up to a radiation fluence of~\fluence{2.5}{15}, delivering at least 5~fC of charge.

physics.ins-det↗

arXiv2021

Sensor design optimization of innovative low-power, large area MAPS for HEP and applied science

Fully Depleted Monolithic Active Pixels (FD-MAPS) represent a state-of-the-art detector technology and profit from a low material budget and cost for high energy physics experiments and other fields of research like medical imaging and astro-particle physics. Compared to the MAPS currently in use, fully depleted pixel sensors have the advantage of charge collection by drift, which enables a fast and uniform response overall the pixel matrix. The functionality of these devices has been shown in previous proof-of-concept productions. In this article we describe the optimization of the test pixel designs, that will be implemented in the first engineering run of the demonstrator chip of the ARCADIA project. These optimization procedures include radiation damage models, that have been employed in Technology Computer Aided Design simulations to predict the sensors behavior in different working environments.

physics.ins-det↗

arXiv2021

Fully Depleted Monolithic Active Microstrip Sensors: TCAD simulation study of an innovative design concept

The paper presents the simulation studies of 10 $μ$m pitch microstrips on a fully depleted monolithic active CMOS technology and describes their potential to provide a new and cost-effective solution for particle tracking and timing applications. The Fully Depleted Monolithic Active Microstrip Sensors (FD-MAMS) described in this work, which are developed within the framework of the ARCADIA project, are compliant with commercial CMOS fabrication processes. A TCAD simulation campaign was performed in the perspective of an upcoming engineering production run with the aim of designing FD-MAMS, studying their electrical characteristics and optimising the sensor layout for enhanced performance in terms of low capacitance, fast charge collection and low-power operation. A very fine pitch of 10 $μ$m was chosen to provide very high spatial resolution. This small pitch still allows readout electronics to be monolithically integrated in the inter-strip regions, enabling the segmentation of long strips and the implementation of distributed readout architectures. The effects of surface radiation damage expected for total ionising doses of the order of 10 to 10$^5$ krad were also modelled in the simulations. The results of the simulations exhibit promising performance in terms of timing and low power consumption and motivate R&D efforts to further develop FD-MAMS; the results will be experimentally verified through measurements on the test structures that will be available at the beginning of 2021.

physics.ins-det↗

arXiv2003

Opposite effects of NO$_2$ on electrical injection in porous silicon gas sensors

The electrical conductance of porous silicon fabricated with heavily doped p-type silicon is very sensitive to NO$_2$. A concentration of 10 ppb can be detected by monitoring the current injection at fixed voltage. However, we show that the sign of the injection variations depends on the porous layer thickness. If the thickness is sufficiently low -- of the order of few \micro\meter{} -- the injection decreases instead of increasing. We discuss the effect in terms of an already proposed twofold action of NO$_2$, according to which the free carrier density increases, and simultaneously the energy bands are bent at the porous silicon surface.

cond-mat.mtrl-sci↗

arXiv2003

Role of microstructure in porous silicon gas sensors for NO$_2$

Electrical conductivity of porous silicon fabricated form heavily doped p-type silicon is very sensitive to NO$_2$, even at concentrations below 100 ppb. However, sensitivity strongly depends on the porous microstructure. The structural difference between sensitive and insensitive samples is independently confirmed by microscopy images and by light scattering behavior. A way to change the structure is by modifying the composition of the electrochemical solution. We have found that best results are achieved using ethanoic solutions with HF concentration levels between 13% and 15%.

cond-mat.mtrl-sci↗