Analytical models of probability distribution and excess noise factor of Solid State Photomultiplier signals with crosstalk

Silicon Photomultipliers (SiPM), also so-called Solid State Photomultipliers (SSPM), are based on Geiger mode avalanche breakdown limited by strong negative feedback. SSPM can detect and resolve single photons due to high gain and ultra-low excess noise of avalanche multiplication in this mode. Crosstalk and afterpulsing processes associated with the high gain introduce specific excess noise and deteriorate photon number resolution of the SSPM. Probabilistic features of these processes are widely studied because of its high importance for the SSPM design, characterization, optimization and application, but the process modeling is mostly based on Monte Carlo simulations and numerical methods. In this study, crosstalk is considered to be a branching Poisson process, and analytical models of probability distribution and excess noise factor (ENF) of SSPM signals based on the Borel distribution as an advance on the geometric distribution models are presented and discussed. The models are found to be in a good agreement with the experimental probability distributions for dark counts and a few photon spectrums in a wide range of fired pixels number as well as with observed super-linear behavior of crosstalk ENF.Comment: 10 pages, 2 tables, 3 figures, Reported at 6th International Conference on "New Developments In Photodetection - NDIP11

Silicon photomultipliers: characterization and application to fluorescence flucturation spectroscopy.

This thesis originates from and develops around Silicon Photomultipliers (SiPMs): starting from a description of the working principles of these devices, this work presents a review on this technology and on some of its possible applications. The great part of this work took place within the framework of an international scientific and industrial collaboration (RAPSODI1, a project funded by the European Commetee), with the aim of developing three radiation detectors using the SiPM technology; in order to find the optimal sensor for each application, an exhaustive protocol to provide a characterization of the performances of the main SiPM parameters (gain, photo-detection efficiency, dark count rate, optical cross-talk, breakdown voltage dependence from temperature) has been provided. In order to further improve the knowledge on Silicon PhotoMultipliers, a phenomenological model describing the statistics of Geiger-Müller avalanches for impinging photons with known probability distribution has been elaborated: this model takes into account the contribution given by the thermally generated avalanches and by the cross-talk, thus providing a model for the SiPM deviations from the ideal bernoullian detection. Last, a feasibility study on the possibility of using this sensors as detecting technology in Fluorescence Fluctuation Spectroscopy (FFS) biophysical experiments had been conducted. In FFS experiments the parameters describing the system under study (proteins ligated with fluorophores in a solution) are measured from the deviations of the fluorescence intensity around its mean value: the use of fast (with a sub-nanosecond temporal resolution) detectors with an large photon number resolution can costitute an improvement of the experimental conditions. Thus a dedicated setup had been commissioned and SiPMs demonstrated to be able to perform an effective Photon Counting Histogram (one of the FFS techniques) measurement. 1RAdiation Protection with Silicon Optoelectronic Devices and Instruments – COOP 3299

Silicon photomultipliers: characterization and application to fluorescence flucturation spectroscopy.

This thesis originates from and develops around Silicon Photomultipliers (SiPMs): starting from a description of the working principles of these devices, this work presents a review on this technology and on some of its possible applications. The great part of this work took place within the framework of an international scientific and industrial collaboration (RAPSODI1, a project funded by the European Commetee), with the aim of developing three radiation detectors using the SiPM technology; in order to find the optimal sensor for each application, an exhaustive protocol to provide a characterization of the performances of the main SiPM parameters (gain, photo-detection efficiency, dark count rate, optical cross-talk, breakdown voltage dependence from temperature) has been provided. In order to further improve the knowledge on Silicon PhotoMultipliers, a phenomenological model describing the statistics of Geiger-M\ufcller avalanches for impinging photons with known probability distribution has been elaborated: this model takes into account the contribution given by the thermally generated avalanches and by the cross-talk, thus providing a model for the SiPM deviations from the ideal bernoullian detection. Last, a feasibility study on the possibility of using this sensors as detecting technology in Fluorescence Fluctuation Spectroscopy (FFS) biophysical experiments had been conducted. In FFS experiments the parameters describing the system under study (proteins ligated with fluorophores in a solution) are measured from the deviations of the fluorescence intensity around its mean value: the use of fast (with a sub-nanosecond temporal resolution) detectors with an large photon number resolution can costitute an improvement of the experimental conditions. Thus a dedicated setup had been commissioned and SiPMs demonstrated to be able to perform an effective Photon Counting Histogram (one of the FFS techniques) measurement. 1RAdiation Protection with Silicon Optoelectronic Devices and Instruments \u2013 COOP 3299

Response of Silicon photo-multipliers to a constant light flux

The response of a Silicon Photomultiplier to a constant illumination has been interpreted in term of Geiger- Mueller avalanche frequency, actually correlated to the photon flux via the photon detection efficiency. The hypothesis has been verified in laboratory tests and applied throughout the development of a device for real-time dosimetry in mammography

Photon-number correlations by photon-number resolving detectors

We demonstrate that by using a pair of photodetectors endowed with internal gain we are able to quantify the correlation coefficient between the two components of a pulsed bipartite state in the mesoscopic intensity regime (less than 100 mean photons)

Development of an electrical impedance tomography set-up for the quantification of mineralization in biopolymer scaffolds

Objective. 3D cell cultures are becoming a fundamental resource for in-vitro studies, as they mimic more closely in-vivo behavior. The analysis of these constructs, however, generally rely on destructive techniques, that prevent the monitoring over time of the same construct, thus increasing the results variability and the resources needed for each experiment. Approach. In this work, we focus on mineralization, a crucial process during maturation of artificial bone models, and propose electrical impedance tomography (EIT) as an alternative non-destructive approach. In particular, we discuss the development of an integrated hardware/software system capable of acquiring experimental data from 3D scaffolds and reconstructing the corresponding conductivity maps. We also show how the same software can test how the measurement is affected by biological features such as scaffold shrinking during the culture. Main results. An initial validation, comprising the acquisition of both a non-conductive phantom and alginate/gelatin scaffolds with known calcium content will be presented, together with the in-silico study of a cell-induced mineralization process. This analysis will allow for an initial verification of the systems functionality while limiting the effects of biological variability due to cell number and activity. Significance. Our results show the potential of EIT for the non-destructive quantification of matrix mineralization in 3D scaffolds, and open to the possible long term monitoring of this fundamental hallmark of osteogenic differentiation in hybrid tissue engineered constructs

Binary Sequences for Online Electrochemical Impedance Spectroscopy of Battery Cells

Online diagnostic of lithium-ion battery (LIB) cells may have significant impact on chemical energy storage systems. Electrochemical impedance spectroscopy (EIS) is widely used for the characterization of LIBs and could be the most appropriate technique for online diagnostic, but its response time should be shortened. This work investigates the usage of multisine excitation to shorten the measurement time and simplify the hardware implementation for EIS of battery cells. Two types of multisine binary sequences are considered: sigma-delta modulated multisine sequences (SDMSs) and maximum length binary sequences (MLBSs). Their applicability to online and in situ EIS monitoring is evaluated by designing a measurement architecture also suitable to be implemented in a system-on-chip. The calibrated measurement system is compared with a benchtop reference instrument, reporting an RMSE deviation smaller than 5% in the frequency range of interest 1-200 Hz. The realized system is then used for online monitoring of the discharge process of a commercial 18650 LIB cell. The two proposed sequences are compared in terms of accuracy using a digital battery emulator circuit. Both the sequences demonstrated to be suitable for fast measurement and simple hardware integration, enabling online in situ EIS monitoring at cell level

Crosstalk calibration of multi-pixel photon counters using coherent states

We present a novel method of calibration of crosstalk probability for multi-pixel photon counters (MPPCs) based on the measurement of the normalized second-order intensity correlation function of coherent light. The method was tested for several MPPCs, and was shown to be advantageous over the traditional calibration method based on the measurements of the dark noise statistics. The method can be applied without the need of modification for different kinds of spatially resolved single photon detectors.Comment: 8 pages, 3 figures, 2 table