1,721,015 research outputs found
Experimental Characterization of a Wireless Personal Sensor Node for the Dosimetry During Interventional Radiology Procedures
No full textWireless sensor networks featuring portable devices are widely used for healthcare applications such as real-time patient monitoring. For such applications, design constraints are limited in the amount of energy, network capacity (short communication range and low bandwidth), and processing and memory resources in each node. In the framework of the real-time active pixel dosimetry project, the attention has been focused on the design of a dosimetric system for online dose monitoring of interventional radiology (IRad) operators. This paper describes the experimental characterization of the prototype used during several IRad procedures. The wireless link of the prototype has been characterized by measuring the packet error rate of the network in different scenarios: the worst obtained result was lower than 0.4%, which is acceptable for the specific application. The prototype has also been compared with a reference acquisition system to fully validate the system in operating condition. A linear correlation has been observed between the observables for all the working conditions. Moreover, the average pixel response could be used as an indicator of the goodness of the data acquisition for a given procedure showing that it does not depend on the procedure, hence on the particular spectrum of the diffused radiation. Finally, the measurement of absorbed dose (μGy) has been calculated for different IRad procedures
Analysis of the performance of CMOS APS imagers after proton damage
No full textIn this work we have irradiated a standard commercial CMOS imager with a 24MeV
proton beam at INFN Laboratori Nazionali del Sud, Catania (Italy) up to a nominal fluence of
1014 [protons/cm2]. The device under test was a standard VGA detector, fabricated with a 130 nm
technology without radiation hardening. During the irradiation the detector was operated to monitor
the progressive damaging of the sensor and the associated on-pixel electronics. After 18 months
from the irradiation damage session, with the detector stored at room temperature, a study on the
detection efficiency and charge collection capability has been carried out using fluorescent X-ray
photons, emitted from copper target. We found that the detector is still working at 1013 protons/cm2,
with a moderate increase of the noise and a slightly decrease of the detection capabilities
Experimental Characterization of a Personal Wireless Sensor Network for the Medical X-Ray Dosimetry
No full textWireless sensor networks are an important technology for large-scale monitoring, providing sensor measurements at high temporal and spatial resolution. In healthcare applications, a variety of system prototypes and commercial products have been designed and manufactured with the aim to provide an alternative and more efficient method for real-time operator monitoring during medical procedures. In the framework of the Real-Time Active Pixel Dosimetry project, the attention has been focused on dose monitoring of interventional radiology (IRad) operators. A sensor network has been developed, which consists of several personal sensor nodes (PSNs), monitoring the absorbed dose in different positions of the operator body (e.g., on the head or arms) and providing a measurement of the absorbed dose for each medical procedure. In this paper, we describe the first characterization of the final version of a system by measuring the radiation diagram and exposing the system to a direct X-ray beam showing a linearity of the response up to 3.3 mGy/s of dose rate. The system has been characterized during several IRad procedures when two PSNs have been simultaneously used in the network. The packet error rate of the network has been measured and the absorbed dose has been evaluated for each medical procedure, showing an uncertainty on the dose measurement lower than 10% with respect to the reference dosimetric devices
Polycrystalline CVD diamond device level modeling for particle detection applications
No full textDiamond is a promising material whose excellent physical properties foster its use for
radiation detection applications, in particular in those hostile operating environments where the
silicon-based detectors behavior is limited due to the high radiation fluence.
Within this framework, the application of Technology Computer Aided Design (TCAD) simu-
lation tools is highly envisaged for the study, the optimization and the predictive analysis of sensing
devices. Since the novelty of using diamond in electronics, this material is not included in the
library of commercial, state-of-the-art TCAD software tools.
In this work, we propose the development, the application and the validation of numerical
models to simulate the electrical behavior of polycrystalline (pc)CVD diamond conceived for
diamond sensors for particle detection. The model focuses on the characterization of a physically-
based pcCVD diamond bandgap taking into account deep-level defects acting as recombination
centers and/or trap states. While a definite picture of the polycrystalline diamond band-gap is still
debated, the effect of the main parameters (e.g. trap densities, capture cross-sections, etc.) can be
deeply investigated thanks to the simulated approach. The charge collection efficiency due to
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particle irradiation of diamond materials provided by different vendors and with different electrode
configurations has been selected as figure of merit for the model validation. The good agreement
between measurements and simulation findings, keeping the traps density as the only one fitting
parameter, assesses the suitability of the TCAD modeling approach as a predictive tool for the
design and the optimization of diamond-based radiation detectors
Numerical Modelling of Polycrystalline Diamond device for Advanced Sensor Design
No full textTechnology Computer Aided Design (TCAD) simulation tools are routinely adopted within the design flow of semiconductor
devices to simulate their electrical characteristics. However, the device level simulation of diamond is not straightforward within
the state-of-the-art TCAD tools. Physical models have to be specifically formulated and tuned for single-crystalline (sCVD) and
poly-crystalline (pCVD) diamond in order to account for, among others, incomplete ionization, intrinsic carrier free material,
dependences of carrier transport on doping and temperature, impact ionization and traps and recombination centers effects.
In this work, we propose the development and the application of a numerical model to simulate the electrical characteristics of
polycrystalline diamond conceived for sensor fabrication. The model is based on the introduction of an articulated, yet physically
based, picture of deep-level defects acting as recombination centers and/or trap states. This approach fosters the exploration and
optimization of innovative semiconductor devices conjugating the capabilities of CMOS electronics devices and the properties of
diamond substrates, e.g. for biological sensor applications or single particle detectors for High Energy Physics experiments
First result on biased CMOS MAPs-on-diamond devices
No full textRecently a new type of device, the MAPS-on-diamond, obtained bonding a thinned to 25 μm CMOS Monolithic Active Pixel Sensor to a standard 500 μm pCVD diamond substrate, has been proposed and fabricated, allowing a highly segmented readout (10×10 μm pixel size) of the signal produced in the diamond substrate. The bonding between the two materials has been obtained using a new laser technique to deliver the needed energy at the interface. A biasing scheme has been adopted to polarize the diamond substrate to allow the charge transport inside the diamond without disrupting the functionalities of the CMOS Monolithic Active Pixel Sensor. The main concept of this class of devices is the capability of the charges generated in the diamond by ionizing radiation to cross the silicon-diamond interface and to be collected by the MAPS photodiodes. In this work we demonstrate that such passage occurs and measure its overall efficiency. This study has been carried out first calibrating the CMOS MAPS with monochromatic X-rays, and then testing the device with charged particles (electrons) either with and without biasing the diamond substrate, to compare the amount of signal collected
Polycrystalline diamond detectors with three-dimensional electrodes
No full textThe three-dimensional concept in diamond detectors has been applied, so far, to high quality single-crystal material, in order to test this technology in the best available conditions. However, its application to polycrystalline chemical vapor deposited diamond could be desirable for two reasons: first, the short inter-electrode distance of three-dimensional detectors should improve the intrinsically lower collection efficiency of polycrystalline diamond, and second, at high levels of radiation damage the performances of the poly-crystal material are not expected to be much lower than those of the single crystal one. We report on the fabrication and test of three-dimensional polycrystalline diamond detectors with several inter-electrode distances, and we demonstrate that their collection efficiency is equal or higher than that obtained with conventional planar detectors fabricated with the same material
A wireless personal sensor node for the Dosimetry of Interventional Radiology operators
No full textWireless sensor networks (WSNs) are an important technology for large-scale monitoring, providing sensor measurements at high temporal and spatial resolution. In healthcare applications, a variety of system prototypes and commercial products have been designed and manufactured with the aim to provide an alternative and more efficient method for real time patient monitoring. In the framework of the Real time Active PIxel Dosimetry (RAPID) project, the attention has been focused on dose monitoring of Interventional Radiology operators. In this work, we present a study on the RF interface
with the optimization of the antenna design to obtain a compact solution making the system portable. The effect of human body influence on the performance of the antenna has been simulated: a distance of 1.5 cm from the body shows that the artificial body structure has a negligible detuning effect on the antenna performances. The Packet Error Rate (PER) of the network has been evaluated considering different values of Transmitter Output Power (TPO) and comparing the performance of two different antennas: the maximum obtained PER was lower than 0.2%, which is acceptable for the specific application
Progettazione di una G.U.I. per il database di CMS
No full textThe design and implementation of a construction database and its GUI for the CMS experiment at CERN
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