Showing papers by "Matteo Perenzoni published in 2014"

A Fully Digital 8 $\,\times\,$ 16 SiPM Array for PET Applications With Per-Pixel TDCs and Real-Time Energy Output

Abstract: An 8 × 16 pixel array based on CMOS small-area silicon photomultipliers (mini-SiPMs) detectors for PET applications is reported. Each pixel is 570 × 610 μm2 in size and contains four digital mini-SiPMs, for a total of 720 SPADs, resulting in a full chip fill-factor of 35.7%. For each gamma detection, the pixel provides the total detected energy and a timestamp, obtained through two 7-b counters and two 12-b 64-ps TDCs. An adder tree overlaid on top of the pixel array sums the sensor total counts at up to 100 Msamples/s, which are then used for detecting the asynchronous gamma events on-chip, while also being output in real-time. Characterization of gamma detection performance with an 3 × 3 × 5 mm3 LYSO scintillator at 20°C is reported, showing a 511-keV gamma energy resolution of 10.9% and a coincidence timing resolution of 399 ps.

Physics and applications of terahertz radiation

Abstract: THz Detectors 1 Quantum Well Photodetectors Fabrizio Castellano. 1.1 Fundamentals of photoconductors and photodiodes. 1.2 Semiconductor quantum wells. 1.3 Intersubband transitions. 1.4 Transport in multi-quantum-well systems. 1.5 Quantum well detectors. 1.6 Quantum dot detectors. 2 Bolometric Detectors Francois Simoens. 2.1 Bolometric detection. 2.2 Cooled THz bolometers. 2.3 Uncooled THz bolometers. 2.4 Conclusions. 2.5 Acknowledgements. 3 Terahertz Plasma Field-Effect Transistors Wojciech Knap, Dominique Coquillat, Nina Dyakonova, Dmitry But, Taiichi Otsuji and Frederic Teppe. 3.1 Introduction. 3.2 Experiments on THz Emission from Field Effect Transistors. 3.3 Experiments on THz Detection by Field Effect Transistors. 3.4 Detection by double grating gate FETs. 3.5 Summary. THz Sources. 4 Quantum Cascade Lasers Douglas Paul. 4.1 Background. 4.2 Quantum wells and quantum mechanical tunneling. 4.3 QCL lasing requirements. 4.4 Gain in quantum cascade lasers. 4.5 Active region designs. 4.6 Waveguide designs and losses. 4.7 Exemplar experimental laser results. 4.8 Future requirements from THz quantum cascade lasers. 4.9 Summary. 5 Relativistic Electrons Based Sources Andrea Doria. 5.1 The Electron Photon Interaction. 5.2 The Free Electron Laser (FEL) Mechanism. 5.3 Compact FELs. 5.4 The Frascati FEL Facility. 5.5 The Compact Advanced THz Source (CATS). 6 Non-linear Optical Generation Graeme Malcolm, David A. Walsh, Marc Chateauneuf. 6.1 Intracavity THz generation in OPOs. 6.2 Application of Intracavity THz OPO in stand-off spectroscopy. Systems and Applications. 7 THz Control with Metamaterials David R. S. Cumming, Timothy D. Drysdale, James P. Grant. 7.1 Diffractive optics. 7.2 Polarisation control. 7.3 Terahertz filters. 7.4 Metamaterials and surface plasmon resonance. 7.5 Summary. 8 Time Domain Spectroscopy Jean-Francois Roux, Frederic Garet, Jean-Louis Coutaz. 8.1 Introduction. 8.2 Principles of THz-TDS. 8.3 Generation and detection of short electromagnetic pulses. 8.4 Characteristics of a TDS setup. 8.5 Principles for extraction of optical parameters from THz-TDS measurements. 8.6 Examples of applications of THz-TDS. 8.7 Uncertainties and precision of THz-TDS. 8.8 Comparison with FTIR measurements. 8.9 Conclusions. 9 Security and Safety Roger Appleby, Martyn Chamberlain. 9.1 Overview. 9.2 Nature of security threats, ethical considerations. 9.3 Physical principles. 9.4 Review of previous topical reviews (2006-2010). 9.5 Review of available commercial and near-to-market systems. 9.6 New developments. 9.7 Terahertz safety. 9.8 Overall conclusions.

SPADnet: Embedded coincidence in a smart sensor network for PET applications

Abstract: In this paper we illustrate the core technologies at the basis of the European SPADnet project (www. spadnet.eu), and present the corresponding first results. SPADnet is aimed at a new generation of MRI-compatible, scalable large area image sensors, based on CMOS technology, that are networked to perform gamma-ray detection and coincidence to be used primarily in (Time-of-Flight) Positron Emission Tomography (PET). The project innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction algorithms. In addition, SPADnet introduced the first computational model enabling study of the full chain from gamma photons to network coincidence detection through scintillation events, optical coupling, etc.

Comparison of gate driven and source driven FET structures as THz detectors

Abstract: A 600 GHz Field Effect Transistor (FET) is implemented in 0.18 um CMOS technology as a THz detector for imaging applications. A total of 4 FET test structures were fabricated and measured for comparison purposes. Each structure is accompanied by an on-chip bow-tie antenna that directly feeds the detector with THz signal. The detectors are characterized by a THz source and a lock-in amplifier at a sensitivity of 100uV. Measurement results indicate the potential of using both these FET configurations as THz detectors in imaging applications. A normalized frequency sweep analysis shows the broadband nature of Source Driven (SD) FET over the Gate Driven (GD) counterpart. However, the GD structures are more responsive than SD structures. The measurement results also indicate that FET structures with smaller widths show higher voltage response than those with smaller widths for a given channel length.

SPADnet: a fully digital, scalable, and networked photonic component for time-of-flight PET applications

Abstract: The SPADnet FP7 European project is aimed at a new generation of fully digital, scalable and networked photonic components to enable large area image sensors, with primary target gamma-ray and coincidence detection in (Time-of-Flight) Positron Emission Tomography (PET). SPADnet relies on standard CMOS technology, therefore allowing for MRI compatibility. SPADnet innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction algorithms. It is built around a natively digital, intelligent SPAD (Single-Photon Avalanche Diode)-based sensor device which comprises an array of 8x16 pixels, each composed of 4 mini-SiPMs with in situ time-to-digital conversion, a multi-ring network to filter, carry, and process data produced by the sensors at 2Gbps, and a 130nm CMOS process enabling mass-production of photonic modules that are optically interfaced to scintillator crystals. A few tens of sensor devices are tightly abutted on a single PCB to form a so-called sensor tile, thanks to TSV (Through Silicon Via) connections to their backside (replacing conventional wire bonding). The sensor tile is in turn interfaced to an FPGA-based PCB on its back. The resulting photonic module acts as an autonomous sensing and computing unit, individually detecting gamma photons as well as thermal and Compton events. It determines in real time basic information for each scintillation event, such as exact time of arrival, position and energy, and communicates it to its peers in the field of view. Coincidence detection does therefore occur directly in the ring itself, in a differed and distributed manner to ensure scalability. The selected true coincidence events are then collected by a snooper module, from which they are transferred to an external reconstruction computer using Gigabit Ethernet. We will detail the SPADnet core technologies as well as the latest project achievements in all project areas.

Design and characterization of a readout circuit for FET-based THz imaging

Abstract: A switched-capacitor integrator readout circuit for FET-based terahertz (THz) detectors was fabricated in a 0.13 μm standard CMOS technology. The designed readout circuit is suitable for implementation in pixel arrays due to its compact size and power consumption. In order to find the optimum bias point of the FET detector, responsivity, noise equivalent power (NEP) and signal-to-noise ratio (SNR) curves in function of the FET gate voltage (V G ) have been measured for an arbitrary number of 10 accumulation cycles and two different operating clock frequencies. A responsivity peak of 1.8 kV/W was obtained with a clock frequency of 200 kHz, and of 1.3 kV/W at 400 kHz. A minimum NEP of 7.3 nW/√Hz was obtained with a 400 kHz clock frequency, while at 200 kHz the NEP is 8.5 nW/√Hz. The presented THz measurements with 100 accumulation cycles at 200 kHz and 400 kHz clock frequencies show a SNR improvement after each operation cycle, which means 500 and 1000 measurements per second with on-off modulation of the source, respectively. A test structure containing only a FET detector and a bowtie THz antenna was used to evaluate the impact of the readout circuit in the FET THz detection.

Measurement of spatial response of CMOS antenna-coupled FET detector at 325GHz

Abstract: A FET detector, fabricated in a standard CMOS technology and coupled to a bow-tie antenna is characterized in terms of spatial response by using a deconvolution method. An optical setup is used to produce a predictable impulse response. The resulting spatial response shows interaction with other structures present on the chip, while the measured shape is in agreement with the antenna effective area calculations.

Updates from the SPADnet project (fully digital, scalable and networked photonic component for Time-of-Flight PET applications)

Abstract: SPADnet is aimed at a new generation of fully digital, scalable and networked photonic components to enable large area image sensors, with primary target gamma-ray and coincidence detection in (Time-of-Flight) PET. The SPADnet photonic module, which lies at the heart of the concept, is built around an array of tessellated single-photon TSV sensor chips, manufactured in standard CMOS technology. The resulting sensor tile is connected on the back to an FPGA-based data processing and communication unit, whereas its front size is glued to scintillator crystals. The resulting modules are then connected in a token ring structure to form the actual PET system. Coincidence detection occurs directly in the ring itself, in a differed and distributed manner to ensure scalability. We have fabricated and tested the first version of the SPADnet photosensor, a fully digital CMOS SiPM with 8×16 pixels individually capable of photon time stamping and energy accumulation, together with the corresponding sensor tiles. The sensor also provides a real-time output of the total detected energy at up to 100Msamples/s and on-chip discrimination of gamma events. These events can then be routed to the SPADnet ring network, which operates at 2 Gbps providing real-time processing and coincidence determination; this architecture simplifies the construction of the overall system and allows the scaling of the system to larger arrays of detectors. This may result in better and faster image reconstruction. SPADnet will not only impact PET scalability but also performance robustness and cost; another advantage is the capability of being compatible with magnetic resonance imaging (MRI), thus prompting advances in multimodal imaging and medical diagnostics as a whole. SPADnet is being designed with scalability in mind, with the idea of being able to redeploy at reduced effort the SPADnet photonic module in other configurations such as brain PET.