Добірка наукової літератури з теми "Dark Count Rate (DCR)"

A single photon avalanche diode (SPAD) structure designed with standard 180 nm CMOS technology is investigated in detail. The SPAD employs a [Formula: see text]-well anode, rather than the conventional [Formula: see text] layer, and with a [Formula: see text]-well/deep [Formula: see text]-well junction with square shape, a deep retrograde [Formula: see text]-well virtual guard ring which prevents the premature edge avalanche breakdown. The analytical and simulation results show that the SPAD exhibits a uniform electric field distribution in [Formula: see text]-well/deep [Formula: see text]-well junction with the active area of [Formula: see text], and the avalanche breakdown voltage is as low as 9 V, the peak of the photon detection efficiency (PDE) is about 33% at 500 nm, the relatively low dark count rate (DCR) of 0.66 KHz at room temperature is obtained.

To reduce the afterpulsing in single photon detection based on avalanche diodes, an advanced passive quenching circuit for operation in free-running mode is developed. The measurement setup is designed. The dark count rate (DCR) and afterpulsing of Single photon avalanche diodes (SPADs) are measured. The results show that the new passive quenching circuit has a better afterpulsing performance compared to traditional circuits.

The radiation hardness of 180 nm complementary metal–oxide–semiconductor (CMOS) and 55 nm bipolar–CMOS–double-diffused MOS single-photon avalanche diodes (SPADs) is studied using 10 MeV and 100 MeV protons up to a displacement damage dose of 1 PeV/g. It is found that the dark count rate (DCR) levels are dependent on the number and the type of defects created. A new stepwise increase in the DCR is presented. Afterpulsing was found to be a significant contributor to the observed DCR increase. A new model for DCR increase prediction is proposed considering afterpulsing. Most of the samples under test retain reasonable DCR levels after irradiation, showing high tolerance to ionizing and displacement damage caused by protons. Following irradiation, self-healing was observed at room temperature. Furthermore, high-temperature annealing shows potential for accelerating recovery. Overall, the results show the suitability of SPADs as optical detectors for long-term space missions or as detectors for high-energy particles.

Silicon Photomultiplier (SiPM) is a sensor that can detect low-light signals lower than the single-photon level. In order to study the properties of neutrinos at a low detection threshold and low radioactivity experimental background, a low-temperature CsI neutrino coherent scattering detector is designed to be read by the SiPM sensor. Less thermal noise of SiPM and more light yield of CsI crystals can be obtained at the working temperature of liquid nitrogen. The breakdown voltage (Vbd) and dark count rate (DCR) of SiPM at liquid nitrogen temperature are two key parameters for coherent scattering detection. In this paper, a low-temperature test is conducted on the mass-produced ON Semiconductor J-Series SiPM. We design a cryogenic system for cooling SiPM at liquid nitrogen temperature and the changes of operating voltage and dark noise from room to liquid nitrogen temperature are measured in detail. The results show that SiPM works at the liquid nitrogen temperature, and the dark count rate drops by six orders of magnitude from room temperature (120 kHz/mm2) to liquid nitrogen temperature (0.1 Hz/mm2).

The effects of proton irradiation on CMOS Single-Photon Avalanche Diodes (SPADs) are investigated in this article. The I–V characteristics, dark count rate (DCR), and photon detection probability (PDP) of the CMOS SPADs were measured under 30 MeV and 52 MeV proton irradiations. Two types of SPAD, with and without shallow trench isolation (STI), were designed. According to the experimental results, the leakage current, breakdown voltage, and PDP did not change after irradiation at a DDD of 2.82 × 108 MeV/g, but the DCR increased significantly at five different higher voltages. The DCR increased by 506 cps at an excess voltage of 2 V and 10,846 cps at 10 V after 30 MeV proton irradiation. A γ irradiation was conducted with a TID of 10 krad (Si). The DCR after the γ irradiation increased from 256 cps to 336 cps at an excess voltage of 10 V. The comparison of the DCR after proton and γ-ray irradiation with two structures of SPAD indicates that the major increase in the DCR was due to the depletion region defects caused by proton displacement damage rather than the Si-SiO2 interface trap generated by ionization.

Abstract In this work we will document the design and the performances of a SiPM-based photo-detector with a surface area of 100 cm2 conceived to operate as a replacement for PMTs. The signals from 94 SiPMs are summed up to produce an aggregated output that exhibits in liquid nitrogen a dark count rate (DCR) lower than 100 cps over the entire surface, a signal to noise ratio better than 13, and a timing resolution better than 5.5 ns. The module feeds about 360 mW at 5 V with a dynamic range in excess of 500 photo-electrons on a 100 Ω differential line. The unit can also operate at room temperature, at the cost of an increase of DCR to 108 cps.

Single-photon avalanche diodes (SPADs) can detect extremely weak optical signals and are mostly used in single-photon imaging, quantum communication, medical detection, and other fields. In this paper, a low dark count rate (DCR) single-photon avalanche diode device is designed based on the 180 nm standard BCD process. The device has a good response in the 450~750 nm spectral range. The active area of the device adopts a P+/N-Well structure with a diameter of 20 µm. The low-doped N-Well increases the thickness of the depletion region and can effectively improve the detection sensitivity; the P-Well acts as a guard ring to prevent premature breakdown of the PN junction edge; the isolation effect of the deep N-Well reduces the noise coupling of the substrate. Use the TCAD simulation tool to verify the SPAD’s basic principles. The experimental test results show that the avalanche breakdown voltage of the device is 11.7 V. The dark count rate is only 123 Hz when the over-bias voltage is 1 V, and the peak photon detection efficiency (PDE) reaches 37.5% at the wavelength of 500 nm under the 0.5 V over-bias voltage. PDE exceeds 30% in the range of 460~640 nm spectral range, which has a good response in the blue band. The SPAD device provides certain design ideas for the research of fluorescence detectors.

Abstract We introduce a technique to mitigate the effects of low frequency noise on precision timing. The example of Dark Count Noise Rate (DCR) in Silicon Photomultipliers (SiPMs) is emphasized. This technique exploits the correlation between time shifts on the leading edge of a signal and the residual slope of the baseline (due to noise) which remains after baseline subtraction. In fast timing applications (such as for Time-of-flight particle ID) the signal arrival time is typically captured on the signal leading edge. The signal risetime is often fixed by the physics of the sensor and input circuit. Then accurate pulse timing can be achieved by correcting a leading edge threshold time (depending on a slope proportional to both the Amplitude and the risetime) to a “constant fraction” time. This compensation for time walk due to amplitude fluctuations breaks down once we introduce interference from low frequency noise on the leading edge. In this paper we demonstrate that an additional measurement of the slope at threshold can be used to correct for this noise jitter.

Silicon photomultipliers (SiPMs) have improved significantly over the last years and now are widely employed in many different applications. However, the custom fabrication technologies exploited for commercial SiPMs do not allow the integration of any additional electronics, e.g., on-chip readout and analog (or digital) processing circuitry. In this paper, we present the design and characterization of two microelectronics-compatible SiPMs fabricated in a 0.16 µm–BCD (Bipolar-CMOS-DMOS) technology, with 0.67 mm × 0.67 mm total area, 10 × 10 square pixels and 53% fill-factor (FF). The photon detection efficiency (PDE) surpasses 33% (FF included), with a dark-count rate (DCR) of 330 kcps. Although DCR density is worse than that of state-of-the-art SiPMs, the proposed fabrication technology enables the development of cost-effective systems-on-chip (SoC) based on SiPM detectors. Furthermore, correlated noise components, i.e., afterpulsing and optical crosstalk, and photon timing response are comparable to those of best-in-class commercial SiPMs.

A compact probe for charged particle imaging, with potential applications in source activity mapping and radio-guided surgery was designed and tested. The development of this technology holds significant implications for medical imaging, offering healthcare professionals accurate and efficient tools for diagnoses and treatments. To fulfill the portability requirements of these applications, the probe was designed for battery operation and wireless communication with a PC. The core sensor is a dual-layer CMOS SPAD detector, fabricated using 150 nm technology, which uses overlapping cells to produce a coincidence signal and reduce the dark count rate (DCR). The sensor is managed and interfaced with a microcontroller, and custom firmware was developed to facilitate communication with the sensor. The performance of the probe was evaluated by characterizing the on-board SPAD detector in terms of the DCR, and the results were consistent with the characterization measurements taken on the same chip samples using a purposely developed benchtop setup.

Les diodes à avalanche à photon unique (SPAD) sont utilisées pour les capteurs à temps de vol afin de déterminer la distance d'une cible. Cependant, ils sont sujets à des déclenchements parasites par des porteurs de charge générés de manière parasitaire, quantifiés en tant que taux de comptage dans l’obscurité (DCR), ce qui peut compromettre la précision de la distance mesurée. Pour résoudre ce problème, une méthodologie de simulation a été mise en place pour évaluer le DCR. Cela est réalisé en simulant la probabilité de claquage d'avalanche, intégrée avec le taux de génération de porteurs de charge à partir de défauts. Cette méthodologie permet d'identifier les sources potentielles de DCR avant stress. Pour garantir l'intégrité des mesures de distance sur une longue période, il est nécessaire de prédire le niveau de DCR dans diverses conditions d'exploitation. La méthodologie de simulation susmentionnée est utilisée pour identifier les sources potentielles de DCR après stress. Pour un modèle cinétique précis de dégradation de type porteurs chauds (HCD), il est essentiel de considérer non seulement la distribution d'énergie des porteurs, mais également la distribution de l'énergie de dissociation de la liaison Si-H à l'interface Si/SiO2. La probabilité de dissociation d'ionisation d'impact est utilisée pour modéliser le processus de création de défauts, qui présente une dépendance temporelle sous-linéaire en raison de l'épuisement progressif des précurseurs de défauts. Une mesure précise de la distance nécessite de distinguer le signal du bruit ambiant et du plancher de DCR. L'impact de DCR peut être estimé en considérant la réflectance de la cible et les conditions d'éclairage ambiant. En résumé, ce travail utilise une méthodologie de caractérisation et de simulation approfondie pour prédire le DCR dans les dispositifs de type SPAD le long de sa durée de vie, permettant ainsi d'évaluer son impact sur les mesures de distance
Single-Photon Avalanche Diode (SPAD) are used for Time-of-Flight (ToF) sensors to determine distance from a target by measuring the travel time of an emitted pulsed signal. These photodetectors work by triggering an avalanche of charge carriers upon photon absorption, resulting in a substantial amplification which can be detected. However, they are subject to spurious triggering by parasitic generated charge carriers, quantified as Dark Count Rate (DCR), which can compromise the accuracy of the measured distance. Therefore, it is crucial to identify and eliminate the potential source of DCR. To tackle this issue, a simulation methodology has been implemented to assess the DCR. This is achieved by simulating the avalanche breakdown probability, integrated with the carrier generation rate from defects. The breakdown probability can be simulated either in a deterministically, based on electric-field streamlines, or stochastically, by means of drift-diffusion simulation of the random carrier path. This methodology allows for the identification of the potential sources of pre-stress DCR by comparing simulation results to experimental data over a wide range of voltage and temperature. To ensure the accuracy of distance range measurements over time, it is necessary to predict the DCR level under various operating conditions. The aforementioned simulation methodology is used to identify the potential sources of post-stress DCR by comparing simulation results to stress experiments that evaluate the principal stress factors, namely temperature, voltage and irradiance. Furthermore, a Monte-Carlo study has been conducted to examine the device-to-device variation along stress duration. For an accurate Hot-Carrier Degradation (HCD) kinetics model, it is essential to consider not only the carrier energy distribution function but also the distribution of Si−H bond dissociation energy distribution at the Si/SiO2 interface. The number of available hot carriers is estimated from the carrier current density according to the carrier energy distribution simulated by means of a full-band Monte-Carlo method. The impact-ionization dissociation probability is employed to model the defect creation process, which exhibits sub-linear time dependence due to the gradual exhaustion of defect precursors. Accurate distance ranging requires distinguishing the signal from ambient noise and the DCR floor, and ensuring the target’s accumulated photon signal dominates over other random noise sources. An analytical formula allows to estimate the maximum distance ranging using the maximum signal strength, ambient noise level, and confidence levels. The impact of DCR can be estimated by considering the target’s reflectance and the ambient light conditions. In a nutshell, this work makes use of a in-depth characterization and simulation methodology to predict DCR in SPAD devices along stress duration, thereby allowing the assessment of its impact on distance range measurements

This thesis explores Single-Photon Avalanche Diodes (SPADs), which are solid-state devices for photon timing and counting, and concentrates on SPADs integrated in nano-scale CMOS. The thesis focuses on: the search for new theory regarding Geiger-mode operation; proving the utility of calibrated Technology Computer- Aided Design (TCAD) tools for accurately simulating SPADs for the first time; the investigation of how manufacture influences device operation; and the integration of high performance SPADs into CMOS which rival discrete devices. The accepted theories of SPAD operation are revisited and it is discovered that previously neglected minority carriers have many significant roles such as determining: after-pulsing, Dark Count Rate (DCR), bipolar “SPAD latch-up,” nonequilibrium DCR, and “quenching”. The “quenching” process is revisited and it is concluded that it is the “probability time” of ≈100-200ps, and not the previously thought latching current that is important. SPADs are also found to have transient negative differential resistance. The new theories of SPADs are also supported by steady-state 1D, 2D and 3D TCAD simulations as well as novel transient simulations and videos. It is demonstrated as possible to simulate DCR, Photon Detection Efficiency (PDE), guard ring performance, breakdown voltage, breakdown voltage variation, “quenching,” and transient operation of SPADs with great accuracy. The manufacture of SPADs is studied focusing on the operation and optimisation of guard rings and it is found that ion implantation induced asymmetry from the tilt and rotation/twist is critical. Where symmetric, guard rings fail first along the <100> directions due to enhanced mobility. Process integration rules are outlined for obtaining high performance SPADs in CMOS while maintaining compatibility with transistors. The minimisation of tunnelling with lightly-doped junctions and the reduction of ion implantation induced defects by additional annealing are found essential for achieving low DCR. The thesis demonstrates that it is possible to realise high performance SPADs in CMOS through the innovation of a “Deep SPAD” which achieves record PDE of ≈72% at 560nm with >40% PDE from 410-760nm, combined with 18Hz DCR, <60ps FWHM timing resolution, and <4% after-pulsing which is demonstrated to have potential for significant further improvement. The findings suggest that CMOS SPAD-based micro-systems could outperform existing photon timing and counting solutions in the future.

2008/2009
Remarkable interest has recently arisen about the search for Weakly Inter- acting Sub-eV Particles (WISPs), such as axions, Axion Like Particles (ALPs), Minicharged and chameleon particles, all of which are not included in the Stan- dard Model. Precision experiments searching for WISPs probe energy scales as high as 10^6 TeV and are complementary to accelerator experiments, where the energy scale is a few TeV. The axion, in particular, is the oldest studied and has the strongest theoretical motivation, having its origin in Quantum Chromodynamics. It was introduced for the first time in 1973 by Peccei and Quinn to solve the strong CP problem, while later on the cosmological implications of its postulated existence also became clear: it is a good candidate for the cold dark matter, and it is necessary to fully explain the evolution of galaxies. Among the different interactions of axions, the most promising for its detection, from an experimental point of view, is the coupling to two photons (Primakoff effect). Using this coupling, several bounds on the axion mass and energy scale have been set by astrophysical observations, by laboratory experiments and by the direct observation of celestial bodies, such as the Sun. Most of these considerations, as was recently recognized, not only constrain the mass and coupling of the axion, but are more generally applicable to all ALPs. The current best limits on the coupling, over a wide range of ALP masses, come from the the CAST (Cern Axion Solar Telescope) experiment at Cern, which looks for ALPs produced in the solar core. The experiment is based on the Primakoff effect in a high magnetic field, where solar ALPs can be reconverted in photons. The CAST magnet, a 10 T, 10 m long LHC superconducting dipole, is placed on a mobile platform in order to follow the Sun twice a day, during sunrise and sunset, and has two straight bores instrumented with X-ray detectors at each end. The re- generated photon flux is, in fact, expected to be peaked at a few keV. On the other hand, there are suggestions that the problem of the anomalous temperature profile of the solar corona could be solved by a mechanism which could enhance the low energy tail of the regenerated photon spectrum. A low energy photon counter has, for this reason, been designed and built to cover one of the CAST ports, at least temporarily. Low energy, low background photon counters such as the one just mentioned, are also crucial for most experiments searching for WISPs. The low energy photon counting system initially developed to be coupled to CAST will be applicable, with proper upgrades, to other WISPs search experiments. It consists of a Galilean telescope to match the CAST magnet bore cross section to an optical fiber leading photons to the sensors, passing first through an optical switch. This last device allows one to share input photons between two different detectors, and to acquire light and background data simultaneously. The sensors at the end of this chain are a photomultiplier tube and an avalanche photodiode operated in Geiger mode. Each detector was preliminary characterized on a test bench, then it was coupled to the optical system. The final integrated setup was subsequently mounted on one of the CAST magnet bores. A set of measurements, including live sun tracking, was carried out at Cern during 2007-2008. The background ob- tained there was the same measured in the test bench measurements, around 0.4 Hz, but it is clear that to progress from these preliminary measurements a lower background sensor is needed. Different types of detectors were considered and the final choice fell on a Geiger mode avalanche photodiode (G-APD) cooled at liquid nitrogen temperature. The aim is to drastically reduce the dark count rate, al- though an increase in the afterpulsing phenomenon is expected. Since the detector is designed to be operated in a scenario where a very low rate of signal photons is predicted, the afterpulsing effect can be accepted and corrected by an increase in the detector dead time. First results show that a reduction in background of a factor better than 10^4 is obtained, with no loss in quantum e ciency. In addition, an optical system based on a semitransparent mirror (transparent to X-rays and re ective for 1-2 eV photons) has been built. This setup, covering the low energy spectrum of solar ALPs, will be installed permanently on the CAST beamline. Current work is centered on further tests on the liquid nitrogen cooled G-APD concept involving different types of sensors and different layouts of the front-end read-out electronics, with a particular attention to the quenching cir- cuit, whether active or passive. Once these detector studies are completed, the final low background sensor will be installed on the CAST experiment. It is important to note that the use of a single photon counter for low energy photons having a good enough background (<1 Hz at least) is not limited to the CAST case, but is of great importance for most WISPs experimental searches, with special regard for photon regeneration experi- ments, and, in general, for the field of precision experiments in particle physics.
Negli ultimi tempi è riemerso un notevole interesse nel campo della ricerca di particelle leggere debolmenti interagenti (Weakly Interacting Sub-eV Particles - WISPs), come ad esempio assioni, particelle con comportamenti simili agli assioni (Axion Like Particles - ALPs), particelle con carica frazionaria e particelle camaleonte; tutti tipi di particelle non inclusi nel Modello Standard. Vista la loro natura debolmente interagente, la scala di energia coinvolta è dell'ordine dei 10^6 TeV, queste particelle non sono visibili nelle collisioni realizzabili negli attuali acceleratori e possono invece essere studiate in esperimenti di precisione, che, sotto questo punto di vista, diventano complementari agli esperimenti su acceleratori. L'assione in particolare è la prima particella, da un punto di vista cronologico, ad essere stata ipotizzata, ed inoltre la sua esistenza è supportata da forti basi teoriche: la sua origine va infatti ricercata all'interno della Cromodinamica Quantistica (QCD). L'assione fu introdotto per la prima volta nel 1973 da Peccei e Quinn come soluzione del problema di violazione di CP nelle interazioni forti, mentre le sue implicazioni cosmologiche risultarono chiare solo in seguito. L'assione infatti può essere considerato un buon candidato per la materia oscura fredda e la sua introduzione è necessaria per spiegare l'evoluzione delle galassie. Tra le diverse interazione degli assioni con la materia e la radiazione, la più interessante da un punto di vista sperimentale è l'accoppiamento con due fotoni (effetto Primakoff). Usando questo tipo di accoppiamento numerosi limiti, sia sulla massa dell'assione che sulle scale di energia coinvolte, possono essere ottenuti da osservazioni astrofisiche e da esperimenti di laboratorio così come dalla diretta osservazione di oggetti celesti tipo il Sole. Queste considerazioni possono essere applicate non solo all'assione ma più in generale a tutte le ALPs. Attualmente i limiti migliori sulla costante di accoppiamento, su un largo spettro di masse di ALPs, si sono ottenuti dall'esperimento CAST (Cern Axion Solar Tele- scope) al Cern, che guarda agli ALPs prodotti nel Sole. L'esperimento è basato sull'effetto Primakoff in un campo magnetico elevato, dove gli ALPs solari sono riconvertiti in fotoni. Il magnete dell'esperimento CAST è costituito da un prototipo per un dipolo superconduttore di LHC, lungo 10 m e con un campo magnetico totale di 10 T. Il magnete è posto su di un affusto mobile per poter seguire il sole durante le fasi di alba e tramonto. Alle due estremità del magnete sono disposti quattro rivelatori sensibili nel campo degli X molli. Il picco del usso di fotoni rigenerato è infatti atteso a pochi keV. Tuttavia, ci sono suggerimenti che il prob- lema ancora aperto del profilo di temperatura della corona solare può essere risolto tramite un meccanismo che contemporaneamente incrementerebbe le code a bassa energia dell'atteso usso di fotoni rigenerati. A questo scopo un contatore di fotoni sensibile nell'intervallo del visibile è stato progettato ed assemblato per coprire una delle quattro porte del magnete di CAST, almeno temporaneamente. I contatori di fotoni studiati hanno un largo campo di applicazione e possono essere usati in altri tipi di esperimenti per la ricerca di WISPs. Il sistema inizialmente sviluppato per CAST consiste in un telescopio Galileiano per accoppiare una fibra ottica all'apertura del magnete di CAST, la fibra ottica è quindi collegata ad un interruttore ottico che permette di utilizzare due rivelatori contemporaneamente. La fibra in ingresso è infatti collegata alternativamente a due fibre in uscita, in questo modo ciascun rivelatore acquisisce per metà del tempo segnale e per metà del tempo fondo, lasciando inalterato il tempo totale di integrazione. I sensori utilizzati fino ad ora al termine della catena ottica sono un tubo fotomoltiplicatore e un avalanche photodiode operato in modalità Geiger. Ciascun rivelatore è stato preliminarmente caratterizzato su un banco di prova e quindi collegato al sistema ottico. Il sistema finale è stato quindi installato su CAST. Una serie di misure, che includono reali prese dati, sono state condotte al Cern durante il 2007-2008. La misura del fondo ottenuta a CAST è stata la stessa misurata durante i test di prova a Trieste, circa 0.4 Hz, ma risulta chiaro che il vero sviluppo futuro è basato su un sensore a fondo molto più basso. A questo scopo sono stati considerati diversi tipi di sensore e la scelta finale è ricaduta su di un avalanche photodiode operato in modalità Geiger e raffreddato all'azoto liquido. Lo scopo è quello di ridurre drasticamente i conteggi di fondo, sebbene a queste temperature sia atteso un incremento del rateo di afterpulses. Tuttavia il rivelatore è pensato per essere utilizzato in un applicazione a basso rateo e quindi il fenomeno degli afterpulses può essere ridotto agendo direttamente sul tempo morto del rivelatore, cioè aumentandolo. I primi test condotti sul rivelatore mostrano un decremento del fondo pari ad un fattore meglio di 10^4, senza rilevabili variazioni in efficienza. In aggiunta a questo sistema, per ottenere un'installazione permanente sul fascio di CAST, è stato realizzato uno specchio semitrasparente, che lascia pressocchè inalterato il fascio di raggi X e invece de ette il fascio di fotoni con energia nel visibile. Il lavoro attuale è incentrato sullo sviluppo del rivelatore a basso fondo raffreddato all'azoto liquido, includendo anche lo studio di diversi tipi di sensore e diversi tipi di elettronica di lettura, con particolare attenzione all'elettronica di quenching del circuito con le varianti attiva e passiva. Una volta terminati gli studi sui diversi tipi di rivelatori, l'apparato finale sarà installato su CAST. E' comunque importante notare che l'uso di un rivelatore a singolo fotone sensibile tra 1-2 eV con un fondo sufficientemente basso (<1 Hz almeno) non è limitato all'uso su CAST ma in tutti gli altri esperimenti per la ricerca di WISPs, con particolare riguardo agli esperimenti di rigenerazione risonante, e in generale, nel campo di applicazione degli esperimenti di precisione alla fisica delle particelle.
1982

碩士
國立交通大學
電子研究所
101
In this thesis, we propose and demonstrate a device structure of low dark-count-rate (DCR) single photon detector. To avoid the breakdown events triggered by the trap of shallow trench isolation (STI) in the active region, we design a guard-ring structure to keep the STI in distance or relocate the active region from the top region to the deeper one. TCAD simulation tool is used to calculate the spatial distributions of electric field and impact ionization to confirm the feasibility of our design. With the 0.25-µm high-voltage standard CMOS technology, we have fabricated the designed devices successfully. The DCRs of devices under various excess voltages have been characterized with the setup in our lab and with the passive quenching circuit. The results show that the DCR of designed structure is lowered by more than two orders comparing with that of the conventional one. The lowest DCR less than 10 Hz is obtained. With a precise calibration of incident power, we have also measured the photon detection efficiency (PDE) of the devices under various excess voltage and incident wavelengths. The highest PDE reaches 15.4 % at 650 nm. At last, we discuss the DCR mechanism of the best device and suggest the direction for further improvement in the future.

AbstractGamma radiation detection finds many applications in different fields, including astrophysics, nuclear physics and medical diagnostics. Nowadays large Lanthanum Bromide crystals coupled to Photomultiplier Tubes (PMTs) represent the state of the art for gamma detection modules, in particular for spectroscopic measurements. Nevertheless, there is an interest in substituting photomultiplier tubes with solid state photodetectors like Silicon Photomultipliers (SiPMs), owing to the latter’s significant advantages. These include insensitivity to magnetic fields, low bias voltage, compactness, fast response and mechanical robustness. The aim of this thesis work, which was carried out within the context of the GAMMA project supported by IstitutoNazionale di FisicaNucleare (INFN), is the design, development and experimental characterization of a -ray spectrometer based on large Lanthanum Bromide scintillator crystals coupled with Silicon Photomultipliers. This detector specifications are compliant with nuclear physics experiments with energies ranging from 100 keV to 20 MeV, characterized by state-of-the-art energy resolution and imaging capability, in a compact, modular and robust structure. In order to perform the readout of large scintillator crystals, a matrix of 144 Silicon Photomultipliers was designed using NUV-HD SiPMs from Fondazione Bruno Kessler (FBK). These were chosen due to their high Photon Detection Efficiency in correspondence with the peak emission wavelength of the crystal, the high cell density and low Dark Count Rate.