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Very-high Energy (VHE) gamma-ray astroparticle physics is a relatively young field, and observations over the past decade have surprisingly revealed almost two hundred VHE emitters which appear to act as cosmic particle accelerators. These sources are an important component of the Universe, influencing the evolution of stars and galaxies. At the same time, they also act as a probe of physics in the most extreme environments known - such as in supernova explosions, and around or after the merging of black holes and neutron stars. However, the existing experiments have provided exciting glimpses, but often falling short of supplying the full answer. A deeper understanding of the TeV sky requires a significant improvement in sensitivity at TeV energies, a wider energy coverage from tens of GeV to hundreds of TeV and a much better angular and energy resolution with respect to the currently running facilities. The next generation gamma-ray observatory, the Cherenkov Telescope Array Observatory (CTAO), is the answer to this need. In this talk I will present this upcoming observatory from its design to the construction, and its potential science exploitation. CTAO will allow the entire astronomical community to explore a new discovery space that will likely lead to paradigm-changing breakthroughs. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, placing it as a key instrument in the future of multi-messenger and multi-wavelength time domain astronomy. I will conclude the talk presenting the first scientific results obtained by the LST-1, the prototype of one CTAO telescope type - the Large-Sized Telescope, that is currently under commission., PoS: Proceedings of Science, 395, ISSN:1824-8039, Proceedings of 37th International Cosmic Ray Conference (ICRC2021)

We report on the first detection of very high-energy (VHE) gamma-ray emission from the Crab Nebula by a Cherenkov telescope in dual-mirror Schwarzschild-Couder (SC) configuration. The result has been achieved by means of the 4 m size ASTRI-Horn telescope, operated on Mt. Etna (Italy) and developed in the context of the Cherenkov Telescope Array Observatory preparatory phase. The dual-mirror SC design is aplanatic and characterized by a small plate scale, allowing us to implement large field of view cameras with small-size pixel sensors and a high compactness. The curved focal plane of the ASTRI camera is covered by silicon photo-multipliers (SiPMs), managed by an unconventional front-end electronics based on a customized peak-sensing detector mode. The system includes internal and external calibration systems, hardware and software for control and acquisition, and the complete data archiving and processing chain. The observations of the Crab Nebula were carried out in December 2018, during the telescope verification phase, for a total observation time (after data selection) of 24.4 h, equally divided into on- and off-axis source exposure. The camera system was still under commissioning and its functionality was not yet completely exploited. Furthermore, due to recent eruptions of the Etna Volcano, the mirror reflection efficiency was reduced. Nevertheless, the observations led to the detection of the source with a statistical significance of 5.4 sigma above an energy threshold of ~3 TeV. This result provides an important step towards the use of dual-mirror systems in Cherenkov gamma-ray astronomy. A pathfinder mini-array based on nine large field-of-view ASTRI-like telescopes is under implementation., 6 pages, 2 figures

The Muon Portal Project was born as a joint initiative between Italian research and industrial partners, aimed at the construction of a real-size working detector prototype to inspect the content of traveling containers by means of secondary cosmic-ray muon radiation and recognize potentially dangerous hidden materials. The tomographic image is obtained by reconstructing the incoming and outgoing muon trajectories when crossing the inspected volume, employing two tracker planes located above and below the container under inspection. In this paper, the design and development of the front-end electronics of the Muon Portal detector is presented, with particular emphasis being devoted to the photo-sensor devices detecting the scintillation light and to the read-out circuitry which is in charge of processing and digitizing the analog pulse signals. In addition, the remote control system, mechanical housing, and thermal cooling system of all structural blocks of the Muon Portal tracker are also discussed, demonstrating the effectiveness and functionality of the adopted design.

ASTRI-Horn is a prototypal telescope of an imaging atmospheric Cherenkov telescope developed by the Italian National Institute of Astrophysics (INAF), proposed for the Cherenkov Telescope Array (CTA) Observatory. The CTA Observatory represents the next generation of imaging atmospheric Cherenkov telescopes and will explore the very highenergy domain from a few tens of GeV up to few hundreds of TeV. It will be composed of large-, medium-, and small sized telescopes; ASTRI-Horn is an end-to-end prototype proposed for the Small Sized array. The main scientific instrument of the ASTRI-Horn telescope is an innovative and compact Camera with Silicon- Photomultiplier based detectors and a specifically designed fast read-out electronics based on a custom peak-detector mode. The thermo-mechanical assembly is designed to host both the entire electronics chain, from the sensors to the raw data transmission system and the calibration system, and the complete thermoregulation system. This contribution gives a high level description of the T/M and electrical design of the Cherenkov Camera, it describes the assembling procedure of its different subsystems and their integration into the complete camera system. A discussion about possible design improvements coming from the problems/difficulties encountered during assembly is also presented. Finally, results from engineering tests conducted in-field are also presented.

Within the framework of the Cherenkov Telescope Array (CTA) observatory, the Italian National Institute for Astrophysics (INAF) is leading the “Astrofisica con Specchi a Tecnologia Replicante Italiana” (ASTRI) Project mainly devoted to the definition and development of a set of small-size class telescopes with dual-mirror optical design (SST-2M) for the CTA southern site. The prototype of such telescopes, named ASTRI SST-2M, is installed in Italy at the INAF “M.C. Fracastoro” observing station located in Serra La Nave, Mount Etna, Sicily. In addition to the dual-mirror optical design based on the Schwarzschild-Couder configuration, the ASTRI SST-2M telescope adopts a focal plane camera formed by an array of monolithic silicon photomultiplier sensors coupled with a specifically designed front-end electronics and back-end electronics that represent a further innovative solution for the detection of atmospheric Cherenkov light. The ASTRI SST-2M prototype is currently under completion of the overall commissioning phase: structure, mirrors, camera, control software, data archiving and analysis pipeline. This contribution focuses the attention on the software devoted to the control and monitoring operations of the ASTRI camera. We will provide a brief description of the electronic assemblies and of the software architecture designed, according to software engineering modularization, in terms of functional blocks and how they are deployed in the back-end electronics. Then, we will show how all these functionalities are accessible by the user through the graphical user interface developed and currently used for the engineering tests performed on site.

The Cherenkov Telescope Array (CTA) foresees, in its southern site (Chile), the implementation of up to 70 small-sized telescopes (SSTs), which will extend the energy coverage up to hundreds of TeV. It has been proposed that one of the first set of CTA SSTs will be represented by the ASTRI mini-array, which includes (at least) nine ASTRI telescopes. The endto-end prototype of such telescopes, named the ASTRI SST-2M, is installed in Italy and it is now completing the overall commissioning and entering the science verification phase. ASTRI telescopes are characterized by an optical system based on a dual-mirror Schwarzschild-Couder design and a camera at the focal plane composed of silicon photomultiplier sensors managed by a fast read-out electronics specifically designed. Based on a custom peak-detector mode, the ASTRI camera electronics is designed to perform Cherenkov signal detection, trigger generation, digital conversion of the signals and data transmission to the camera server. In this contribution we will describe the main features of the ASTRI camera, its performance and results obtained during the commissioning phase of the ASTRI SST-2M prototype in view of the ASTRI mini-array implementation.

The Muon Portal is a recently started Project aiming at the construction of a large area tracking detector that exploits the muon tomography technique to inspect the contents of traveling cargo containers. The detection planes will be made of plastic scintillator strips with embedded wavelength-shifting fibres. Special designed silicon photomultipliers will read the scintillation light transported by the fibres along the strips and a dedicated electronics will combine signals from different strips to reduce the overall number of channels, without loss of information. Different silicon photomultiplier prototypes, both with the p-on-n and n-on-p technologies, have been produced by STMicroelectronics during the last years. In this paper we present the main characteristics of the silicon photomultipliers designed for the Muon Portal Project and describe the setup and the procedure implemented for the characterization of these devices, giving some statistical results obtained from the test of a first batch of silicon photomultipliers.

This work addresses a systematic and in-depth electro-optical characterization of the Multi-Pixel Photon Counter (MPPC) sensors constituting the camera detection system at the focal plane of the ASTRI telescope prototype. The paper reports the experimental results of a large set of measurements on the MPPC devices in order to provide a reliable qualification of the detector performance and evaluate its compliance with the telescope focal plane requirements. In particular, breakdown voltage, internal gain, dark count rate, cross-talk and extra-charge probability, and absolute photon detection efficiency measurements are performed on the basic sensor device unit as a function of the detector operating conditions.

A comprehensive and in-depth characterization procedure for obtaining very accurate measurements on silicon photomultiplier detectors (SiPMs) is here described. A large amount of optical tests are systematically carried out and discussed in terms of the most important SiPM performance parameters; in particular, an accurate estimation of the photon detection efficiency in the 350-900-nm wavelength spectral range and in steps of 10 nm is achieved, based on the single-photon counting technique, with substraction of the dark noise contribution and avoiding the additional noise sources of crosstalk and afterpulsing. Some recently produced detectors are analyzed and their relevant electro-optical parameters are evaluated in order to demonstrate the effectiveness and efficacy of the adopted characterization procedure and data-handling protocols in assessing the overall SiPM performance, regardless of the specific device tested. Tests repeatibility is carefully verified and all the evaluated parameter trends are proved to be compatible with the physics theory of the SiPM device.

Cosmic ray tomography is a technique which exploits the multiple Coulomb scattering of highly penetrating cosmic ray-produced muons to perform non-destructive inspection of high-Z materials without the use of artificial radiation. A muon tomography detection system can be used as a portal monitor at border crossing points for detecting illegal targeted objects. The Muon Portal Project is a joint initiative between Italian research and industrial partners, aimed at the construction of a real size detector prototype (6×3×7 m 3 ) for the inspection of cargo containers by the muon scattering technique. The detector consists of four XY tracking planes, two placed above and two below the container to be inspected. After a research and development phase, which led to the choice and test of the individual components, the construction and installation of the detection modules is almost completed. In this paper the present status of the Project is reported, focusing on the design and construction phase, as well as on the preliminary results obtained with the first detection planes.

The present work aims to address a comprehensive analytical analysis of a new accurate equivalent electrical model of silicon photomultiplier (SiPM) detectors. The proposed circuit model allows to truthfully reproduce the output signal waveform generated by the light sensors apart from the specific technology adopted for the fabrication process, and can also be profitably exploited to perform reliable circuit-level simulations. A detailed and in-depth investigation of the functional parameters involved in the output pulse signals is here developed, and the most significant physical relationships are analytically derived as well. Experimental measurements are finally carried out on real devices, in order to validate the accuracy of the attained expressions, and good fittings are achieved between the analytical curve plots and the associated measurements results. The adopted analysis turns out to be particularly helpful when designing an optimum front-end architecture for SiPM detectors, since the performance of the entire detection system, especially in terms of dynamic range and timing resolution, can be accurately predicted as a function of the SiPM model parameters and the foremost features of the coupled front-end electronics.

The present work introduces an improved SPICE equivalent electrical model of silicon photomultiplier (SiPM) detectors, in order to simulate and predict their transient response to avalanche triggering events. In particular, the developed circuit model provides a careful investigation of the magnitude and timing of the read-out signals and can therefore be exploited to perform reliable circuit-level simulations. The adopted modeling approach is strictly related to the physics of each basic microcell constituting the SiPM device, and allows the avalanche timing as well as the photodiode current and voltage to be accurately simulated. Predictive capabilities of the proposed model are demonstrated by means of experimental measurements on a real SiPM detector. Simulated and measured pulses are found to be in good agreement with the expected results.

In this letter, a recently published model of silicon photomultiplier (SiPM) sensors is profitably extended to include the important effects of the read-out electronics on the shape of the output pulse waveforms. An improved analytical expression has been developed, also accounting for the loading effect and bandwidth limitation of the coupled front-end, through which the SiPM dynamic response can be accurately reproduced and predicted. Experimental tests on actual detection systems corroborate the SiPM model and the analytical results.

Due to the recent advances in silicon photomultiplier technology, new types of Silicon Photomultiplier (SiPM), also named Multi-Pixel Photon Counter (MPPC) detectors have become recently available, demonstrating superior performance in terms of their most important electrical and optical parameters. This paper presents the latest characterization results of the novel Low Cross-Talk (LCT) MPPC families from Hamamatsu, where a noticeable fill-factor enhancement and cross-talk reduction is achieved. In addition, the newly adopted resin coating has been proven to yield improved photon detection capabilities in the 280–320 nm spectral range, making the new LCT MPPCs particularly suitable for emerging applications like Cherenkov Telescope Array, and Astroparticle Physics.

This paper presents the latest characterization results of a novel Low Cross-Talk (LCT) large-area (6×6-mm 2 ) Multi-Pixel Photon Counter (MPPC) detector manufactured by Hamamatsu, belonging to the recent LCT5 family and achieving a fill-factor enhancement and cross-talk reduction. In addition, the newly adopted resin coating is demonstrated to yield improved photon detection capabilities in the 290–350 nm spectral range, making the new LCT MPPC particularly suitable for emerging applications like Cherenkov Telescopes. For a 3×3-mm 2 version of the new MPPC under test, a comparative analysis of the large pixel pitch (75-µm) detector versus the smaller pixel pitch (50-µm) detector is also undertaken. Furthermore, measurements of the 6×6-mm 2 MPPC response versus the angle of incidence are provided for the characterized device.

The Cherenkov Imaging Telescope Integrated Read Out Chip, CITIROC, is the front-end chip of the camera for the ASTRI SST-2M, one of the prototypes for the small sized telescopes of the Cherenkov Telescope Array, CTA. The telescope, operating in the energy range from a few TeV to beyond 300 TeV, is characterized by innovative technological solutions. The optical system is arranged in a dual-mirror configuration and the focal plane camera consists of a matrix of multi-pixel Silicon Photo-Multipliers. Among others, one of the most important project issue consists in the thermal characterization of the camera that, in the ASTRI SST-2M prototype, is thermo-controlled in a narrow temperature range. A set of at least nine similar telescopes will form the ASTRI mini-array proposed to be installed at the CTA southern site. In the cameras of the ASTRI mini-array telescopes the thermal control could be relaxed with a considerable gain in terms of power consumption, cost and simplicity. So, a study of the temperature dependence of the camera components is needed. The present work addresses this issue showing the results of the measurements carried out on CITIROC as a function of the temperature. We focused our investigation on the pedestal stability, linearity of the charge output signal, preamplifier gain and trigger uniformity in the temperature range 15-30°C. Our results show, for each of the above-mentioned measurable quantities, that temperature dependency is at the level of a few percent.

ASTRI SST-2M is an Imaging Atmospheric Cherenkov Telescope (IACT) developed by the Italian National Institute of Astrophysics, INAF. It is the prototype of the ASTRI telescopes proposed to be installed at the southern site of the Cherenkov Telescope Array, CTA. The optical system of the ASTRI telescopes is based on a dual mirror configuration, an innovative solution for IACTs, and the focal plane of the camera is composed of silicon photo-multipliers (SiPM), a recently developed technology for light detection, that exhibit very fast response and an excellent single photoelectron resolution. The ASTRI camera electronics is specifically designed to directly interface the SiPM sensors, detecting the fast pulses produced by the Cherenkov flashes, managing the trigger generation, the digital conversion of the signals and the transmission of the data to an external camera server connected through a LAN. In this contribution we present the general architecture of the camera electronics developed for the ASTRI SST-2M prototype, with special emphasis to some innovative solutions.

Silicon photomultipliers (SiPMs) are emerging semiconductor-based photosensors, addressing the challenge of low-light detection down to the single-photon counting level. A design of high-performance front-end electronics for SiPM readout requires the development of accurate electrical models. Numerous SiPM reliable models have matured in recent years; however, circuit parameter extraction is rather cumbersome and involves extensive measurement steps to be performed. Starting from a recently developed model of the SiPM device coupled to the conditioning electronics, a new effective analytical procedure is, here, devised for extracting the SiPM model parameters from experimental measurements. The proposed extraction technique is applied to a $3\times 3$ -mm2 SiPM sensor, and is validated by comparing SPICE simulations and measurement results. Independent cross-check validation based on experimental tests corroborates the effectiveness of the adopted extraction procedure.

The present work proposes an improved PSPICE implementation of the equivalent electrical model of silicon photomultipliers (SiPMs) to simulate and predict their transient re-sponse to avalanche trigger events. In particular, the developed model provides a detailed investigation of magnitude and timing of the read-out signals and can therefore be exploited to perform reliable circuit-level simulations. The modeling approach used is strictly related to the physics of each basic microcell constituting the SiPM device, and allows the avalanche timing as well as the photodiode current and voltage to be accurately simulated. Predictive capabilities of the proposed model are demonstrated by means of experimental measurements on a real detector. Versatility of the proposed model is also confirmed.

The Muon Portal Project [1] is a joint initiative between research and industrial partners, aimed at the construction of a real size detector protoype (6×3×7 m3) for the inspection of containers by the muon scattering technique, devised to search for hidden high-Z fissile materials and provide a full 3D tomography of the interior of the container in a scanning time of the order of minutes. The muon tracking detector is based on a set of 48 detection modules (size 1 m × 3 m), each built with 100 extruded scintillator strips, so as to provide four X-Y detection planes, two placed above and two below the container to be inspected. Two wavelength shifting (WLS) fibres embedded in each strip convey the emitted photons to Silicon Photomultipliers (SiPM) which act as photosensors. After a research and development phase, which led to the choice and test of the individual components, the construction of the full size detector has already started. The paper describes the results of the mass characterization of the photosensors and the construction and test measurements of the first detection modules of the Project.

The Muon Portal Project has as its goal the design and construction of a real-size working detector prototype in scale 1:1, to inspect the content of travelling containers by means of the secondary cosmic-ray muon radiation and to recognize high-Z hidden materials (i.e. U, Pu). The tomographic image is obtained by reconstructing the input and output trajectories of each muon when it crosses the container and, consequently, the scattering angle, making use of two trackers placed above and below the container. The scan is performed without adding any external radiation, in a reasonable time (few minutes) and with a good spatial and angular resolution. The detector consists of 8 planes each segmented in 6 identical modules. Each module is made of scintillating strips with two WaveLength Shifting fibers (WLS) inside, coupled to Silicon photomultipliers. The customized read-out electronics employs programmable boards. Thanks to a smart read-out system, the number of output channels is reduced by a factor 10. The signals from the front-end modules are sent to the read-out boards, in order to convert analog signals to digital ones, by comparison with a threshold. The data are pre-analyzed and stored into a data acquisition PC. After an intense measurement and simulation campaign to carefully characterize the detector components, the first detection modules ( $1 \times 3 ~\hbox{m}^{2}$ ) have been already built. In this paper the detector architecture, particularly focusing on the used electronics and the main preliminary results will be presented.

The Cherenkov Imaging Telescope Integrated Read Out Chip, CITIROC, is a chip adopted as the front-end of the camera at the focal plane of the imaging Cherenkov ASTRI dual-mirror small size telescope (ASTRI SST-2M) prototype. This paper presents the results of the measurements performed to characterize CITIROC tailored for the ASTRI SST-2M focal plane requirements. In particular, we investigated the trigger linearity and efficiency, as a function of the pulse amplitude. Moreover, we tested its response by performing a set of measurements using a silicon photomultiplier (SiPM) in dark conditions and under light pulse illumination. The CITIROC output signal is found to vary linearly as a function of the input pulse amplitude. Our results show that it is suitable for the ASTRI SST-2M camera., 25 pages, 16 figures, 1 table

In this paper a comprehensive analytical analysis is performed based on a new accurate electrical model of silicon photomultiplier (SiPM) detectors. The proposed circuit model allows to accurately reproduce the SiPM output time response regardless of the particular technology adopted for the fabrication process, and can also be profitably exploited to perform reliable circuit-level simulations. A novel expression of the detector photoelectron response due to a single photon absorption is systematically developed. The obtained waveform accurately reproduces the fast detector ignition, the ensuing avalanche self-quenching and the final slow recharging operation. Predictive capabilities of the adopted analytical model are demonstrated by means of experimental measurements on a real SiPM device.

The Cherenkov Telescope Array (CTA) is a worldwide new gene ration project aimed at realizing an array of a hundred ground based gamma-ray telescopes. ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is the Italian project whose primary target is the development of an end-to-end prototype, named ASTRI SST-2M, of the CTA small size class of telescopes devoted to investigation of the highest energy region, from 1 to 100 TeV. Next target is the implementation of an ASTRI/CTA mini-array based on seve n identical telescopes. Silicon Photo-Multipliers (SiPMs) are the semiconductor photosensor devices designated to constitute the camera detection system at the focal plane of the ASTRI telescopes. SiPM photosensors are suitable for the detection of the Cherenkov flashes, since they are very fast and sensitive to the light in the 300-700nm wavelength spectrum. Their drawbacks compared to the traditional photo-multiplier tubes are high dark count rates, after-pulsing and optical cross-talk contributions, and intrinsic gains strongly dependent on temperature. Nonetheless, for a single pixel, the dark count rate is well below the Night Sky Background, the effects of cross-talk and afterpulses are typically lower th an 20%, and the gain can be kept stable against temperature variations by means of adequate bias voltage compensation strategies. This work presents and discusses some experimental results from a large set of measurements performed on the SiPM sensors to be used for the ASTRI SST-2M prototype camera and on recently developed detectors demonstrating outstanding performance for the future evolution of the project in the ASTRI/CTA mini-array. Keywords: ASTRI, CTA, detectors, characterizations, phot on detection efficiency, silicon photomultipliers.

In the context of the Cherenkov Telescope Array observatory project, the ASTRI SST-2M end-to-end prototype telescope, entirely supported by the Italian National Institute of Astrophysics, is designed to detect cosmic primary gamma ray energies from few TeV up to hundreds of TeV. The ASTRI SST-2M prototype camera is part of the challenging synergy of novel optical design, camera sensors, front-end electronics and telescope structure design. The camera is devoted to imaging and recording the Cherenkov images of air showers induced by primary particles into the Earth’s atmosphere. In order to match the energy range mentioned above, the camera must be able to trigger events within a few tens of nanoseconds with high detection efficiency. This is obtained by combining silicon photo-multiplier sensors and suitable front-end electronics. Due to the characteristic imprint of the Cherenkov image that is a function of the shower core distance, the signal dynamic range of the pixels and consequently of the front-end electronics must span three orders of magnitude (1:1000 photo-electrons). These and many other features of the ASTRI SST-2M prototype camera will be reported in this contribution together with a complete overview of the mechanical and thermodynamic camera system.

The Muon Portal Project goal is the design and construction of a working detector prototype in scale 1∶1, to inspect the content of travelling containers by means of the secondary cosmic-ray muon radiation and recognize high-Z hidden materials (U, Pu or other fissile samples). The radiographic image is obtained by reconstructing the input and output trajectories of each muon and consequently the scattering angle, exploiting two trackers placed above and below the container. The scan is performed without adding any external radiation, in a reasonable time (a few minutes) and with a good spatial and angular resolution. The detector consists of 8 planes segmented in 6 identical modules. Each module is made of scintillating strips with two WaveLength Shifting fibers (WLS) inside, coupled to Silicon photomultipliers. The customized read-out electronics employs trading programmable boards. Thanks to a smart read-out system, the number of output channels is reduced by a factor 10. The signals from the front-end modules are sent to the read-out boards, in order to convert the analog signal to a digital signal, by a comparison to a threshold. The data are pre-analyzed and stored into a data acquisition PC. Actually, an intense measurement and simulation campaign is in progress to characterize carefully the detector components. The first detection modules (1 × 3 m2) is now under construction. The detector architecture with a particular attention to the used electronics and the main preliminary results will be presented.

The Muon Portal Project aims at the construction of a large volume detector to inspect the content of travelling containers for the identification of high-Z hidden materials (U, Pu or other fissile samples), exploiting the secondary cosmic-ray muon radiation. An image of these materials is achieved reconstructing the deviations of the muons from their original trajectories inside the detector volume, by means of two particle trackers, placed one below and one above the container. The scan is performed without adding any external radiation, in a few minutes and with a high spatial and angular resolution. The detector consists of 4800 scintillating strips with two wavelength shifting (WLS) fibers inside each strip, coupled to Silicon photomultipliers (SiPMs). A smart strategy for the read out system allows a considerable reduction of the number of the read-out channels. Actually, an intense measurement campaign is in progress to carefully characterize any single component of the detector. A prototype of one of the 48 detection modules (1 × 3 m2) is actually under construction. This paper presents the detector architecture and the preliminary results.

The present paper is intended to implement and simulate the Extended Analogue Silicon-photomultiplier Integrated Read-Out Chip (EASIROC) fully analogue front-end model, in order to investigate its foremost characteristics and demonstrate its practical effectiveness when its analogue inputs are driven by the silicon photomultiplier (SiPM) signals. The circuit models of all functional blocks are described. Frequency and dynamic features of all circuit front-end sections are briefly addressed, and design mathematical equations are derived as well. PSPICE simulations of each single model are carried out to analyse and confirm its analogue behaviour.

This paper addresses a comprehensive analytical analysis of a new accurate electrical model of silicon photomultiplier (SiPM) detectors. The adopted circuit model allows to truly reproduce the SiPM output signal waveform apart from the specific technology employed for the fabrication process, and can also be profitably exploited to perform reliable circuit-level simulations. A novel analytical expression of the transient single-photoelectron response due to photon absorption is systematically developed. The attained function accurately reproduces the fast detector ignition, ensuing avalanche self-quenching, and final slow recharging operation. Predictive capabilities of the adopted analytical model are demonstrated by means of experimental measurements on a real detector.

Traditional techniques, such as those based on X-rays absorption, to inspect shipping container in search of potential fissile threats cannot be employed on occupied vehicles and are of limited use in presence of a large amount of shielding materials. To overcome such limitations, prototypes of detection systems employing the muon tomography technique, based on cosmic muon scattering from high-Z materials, are being tested worldwide. The Muon Portal project aims to build a large area muon detector (18 m2) for the inspection of TEU containers with good spatial and angular resolution. The detector is made by four XY tracking planes of plastic scintillator bars with embedded WLS fibers and SiPM readout, placed above and below the volume to be inspected. Different imaging and visualization algorithms are being designed and tested over tomographic scenarios simulated with a detailed software replica of the entire detector. Experimental tests of the individual detection modules are already in progress. The design and operational parameters of the portal under construction are reported, together with the preliminary detector tests and imaging results.

ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana), is a flagship project of the Italian Ministry of Education, University and Research whose main goal is the design and construction of an end-to-end prototype of the Small Size of Telescopes of the Cherenkov Telescope Array. The prototype, named ASTRI SST-2M, will adopt a wide field dual mirror optical system in a Schwarzschild-Couder configuration to explore the VHE range of the electromagnetic spectrum. The camera at the focal plane is based on Silicon Photo-Multipliers detectors which is an innovative solution for the detection astronomical Cherenkov light. This contribution reports some preliminary results on the evaluation of the optical cross talk level among the SiPM pixels foreseen for the ASTRI SST-2M camera., Comment: 7 pages, 4 figures

The Muon Portal is a recently born project that plans to build a large area muon detector for a noninvasive inspection of shipping containers in the ports, searching for the presence of potential fissile (U, Pu) threats. The technique employed by the project is the well-known muon tomography, based on cosmic muon scattering from high-Z materials. The design and operational parameters of the muon portal under construction will be described in this paper, together with preliminary simulation and test results.

Using a gradient purified leishmania donovani infantum antigen, the sensitivity and specificity of the IIF test in detecting anti-leishmania antibodies are investigated. The "purified" antigen increases the specificity and sensitivity of the IIF test, at the same time, eliminating false positiviness caused by connective diseases, tuberculosis, etc.