Conception d’un circuit de lecture d’une matrice de photodiodes à avalanche monophotonique pour les détecteurs de physique des particules dans les gaz nobles liquéfiés

Les détecteurs aux gaz nobles liquéfiés prennent une plus grande part dans les expériences de physique des particules. Le photomultiplicateur en silicium (SiPM ) devient le photodé- tecteur d’excellence pour détecter la lumière de scintillation dans les liquides cryogéniques. Pour répondre aux questions de la physique moderne, des expériences comme le next En- riched Xenon Observatory (nEXO) étudient les neutrinos en tentant d’observer la double désintégration bêta sans neutrinos. D’autres collaborations focalisent leurs travaux sur la matière noire en examinant diverses signatures dans l’argon. La réalisation de ces détec- teurs présente plusieurs défis de conception. Par exemple, la radioactivité des matériaux utilisés doit être contrôlée pour limiter les scintillations parasites. De plus, leur grande sur- face requiert une électronique d’instrumentation in situ. Mais, l’utilisation des SiPM et de leur circuit de lecture dans les liquides nobles limite la puissance permise pour en éviter l’ébullition. Malgré leurs atouts, ces SiPM nécessitent, pour fonctionner, une chaîne de lecture composée d’un préamplificateur suivi de filtrage et d’un convertisseur analogique- numérique. Ces circuits peuvent s’avérer énergivores et plusieurs compromis en diminuent, par exemple, les performances temporelles ou le rapport signal sur bruit. En tirant avantage de la nature binaire des photodiodes à avalanche monophotoniques (SPAD) qui composent les SiPM, ces travaux présentent un nouveau circuit numérique de lecture d’une matrice de SPAD à faible consommation. Il est dédié à instrumenter des expériences de physique des particules à grande surface dans les gaz nobles liquéfiés. Un nouveau procédé de SPAD, actuellement en développement, sera collé sur cette électro- nique grâce à un assemblage vertical en trois dimensions (3D). La puce interface 4096 SPAD répartis dans une superficie de 25 mm 2 . La surface totale de la puce mesure 31 mm 2 , ce qui résulte en un facteur de remplissage de plus de 80 %. Des SPAD intégrés en deux dimensions à même le circuit intégré permettent de le tester sans attendre le développement des SPAD sur mesure et de l’assemblage en trois dimensions. Trois sorties fournissent des informations complémentaires. D’abord, une sortie d’inter- ruption (flag) avec une résolution temporelle inférieure à 90 ps RMS indique la présence de photons. Puis, une somme numérique donne la quantité détectée. Elle peut opérer jus- qu’à 100 MHz. Enfin, une somme analogique en courant vient valider les deux premières sorties. Cette puce asynchrone peut fonctionner avec une horloge intermittente. Dans le contexte de l’expérience nEXO, en tenant compte du taux d’événements, sa consommation de puissance moyenne atteint 140 μW. Suite aux étapes de caractérisation, la première révision de ce photodétecteur novateur répond aux différentes exigences. De légères imperfections persistent, mais une prochaine révision permettra de facilement corriger ces dernières. Ce convertisseur photon-numérique proposera donc une alternative prometteuse aux SiPM analogiques

3D Photon-To-Digital Converter for Radiation Instrumentation: Motivation and Future Works

Analog and digital SiPMs have revolutionized the field of radiation instrumentation by replacing both avalanche photodiodes and photomultiplier tubes in many applications. However, multiple applications require greater performance than the current SiPMs are capable of, for example timing resolution for time-of-flight positron emission tomography and time-of-flight computed tomography, and mitigation of the large output capacitance of SiPM array for large-scale time projection chambers for liquid argon and liquid xenon experiments. In this contribution, the case will be made that 3D photon-to-digital converters, also known as 3D digital SiPMs, have a potentially superior performance over analog and 2D digital SiPMs. A review of 3D photon-to-digital converters is presented along with various applications where they can make a difference, such as time-of-flight medical imaging systems and low-background experiments in noble liquids. Finally, a review of the key design choices that must be made to obtain an optimized 3D photon-to-digital converter for radiation instrumentation, more specifically the single-photon avalanche diode array, the CMOS technology, the quenching circuit, the time-to-digital converter, the digital signal processing and the system level integration, are discussed in detail

3D Photon-To-Digital Converter for Radiation Instrumentation: Motivation and Future Works

Analog and digital SiPMs have revolutionized the field of radiation instrumentation by replacing both avalanche photodiodes and photomultiplier tubes in many applications. However, multiple applications require greater performance than the current SiPMs are capable of, for example timing resolution for time-of-flight positron emission tomography and time-of-flight computed tomography, and mitigation of the large output capacitance of SiPM array for large-scale time projection chambers for liquid argon and liquid xenon experiments. In this contribution, the case will be made that 3D photon-to-digital converters, also known as 3D digital SiPMs, have a potentially superior performance over analog and 2D digital SiPMs. A review of 3D photon-to-digital converters is presented along with various applications where they can make a difference, such as time-of-flight medical imaging systems and low-background experiments in noble liquids. Finally, a review of the key design choices that must be made to obtain an optimized 3D photon-to-digital converter for radiation instrumentation, more specifically the single-photon avalanche diode array, the CMOS technology, the quenching circuit, the time-to-digital converter, the digital signal processing and the system level integration, are discussed in detail

Towards a Multi-Pixel Photon-to-Digital Converter for Time-Bin Quantum Key Distribution

We present an integrated single-photon detection device custom designed for quantum key distribution (QKD) with time-bin encoded single photons. We implemented and demonstrated a prototype photon-to-digital converter (PDC) that integrates an 8 × 8 single-photon avalanche diode (SPAD) array with on-chip digital signal processing built in TSMC 65 nm CMOS. The prototype SPADs are used to validate the QKD functionalities with an array of time-to-digital converters (TDCs) to timestamp and process the photon detection events. The PDC uses window gating to reject noise counts and on-chip processing to sort the photon detections into respective time-bins. The PDC prototype achieved a 22.7 ps RMS timing resolution and demonstrated operation in a time-bin setup with 158 ps time-bins at an optical wavelength of 410 nm. This PDC can therefore be an important building block for a QKD receiver and enables compact and robust time-bin QKD systems with imaging detectors

Wafer-Level Characterization and Monitoring Platform for Single-Photon Avalanche Diodes

When developing a technology based on single-photon avalanche diodes (SPADs), the SPAD characterization is mandatory to debug, optimize and monitor the microfabrication process. This is especially true for the development of SPAD arrays 3D integrated with CMOS readout electronics, where SPAD testing is required to qualify the process, independently from the final CMOS readout circuit. This work reports on a characterization and monitoring platform dedicated to SPAD testing at die and wafer level, in the context of a 3D SPAD technology development. The platform relies on a dedicated integrated circuit made in a standard CMOS technology and used in different configurations from a prototype printed circuit board (die-level testing) to active probe cards (wafer-level mapping). The platform gives full access to SPAD characteristics in Geiger mode such as the dark noise, photon detection efficiency and timing resolution. The integrated circuit and its configuration are described in detail as well as results obtained on different SPAD test structures. In particular, the dark count rate mapping demonstrates the benefits of testing SPADs at wafer level at the R&D stage

Wafer-level Characterization and Monitoring Platform for Single-Photon Avalanche Diodes

When developing a technology based on single-photon avalanche diodes (SPADs), the SPAD characterization is mandatory to debug, optimize and monitor the microfabrication process. This is especially true for the development of SPAD arrays 3D integrated with CMOS readout electronics, where SPAD testing is required to qualify the process, independently from the final CMOS readout circuit. This work reports on a characterization and monitoring platform dedicated to SPAD testing at die and wafer level, in the context of a 3D SPAD technology development. The platform relies on a dedicated integrated circuit made in a standard CMOS technology and used in different configurations from a prototype printed circuit board (die-level testing) to active probe cards (wafer-level mapping). The platform gives full access to SPAD characteristics in Geiger mode such as the dark noise, photon detection efficiency and timing resolution. The integrated circuit and its configuration are described in detail as well as results obtained on different SPAD test structures. In particular, the dark count rate mapping demonstrates the benefits of testing SPADs at wafer level at the R&D stage.</p