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Silicon photomultiplier as fluorescence light detector


  Fluorescence measurements are often used in biochemical and biotechnological analysis where a fluorescent dyes are used as markers. Dye-labelled number of molecules can be estimated by measurement of fluorescent light intensity. Fluorescein and resorufin are dyes commonly used in biology. Both pigments have different wavelength of light for absorption and emission. Their efficiency of absorption and emission in solution with pH factor equal 8 is shown in Fig. 1. Detection of fluorescent light is very complicated, especially for a low number of fluorescence substance molecules. For this purpose many companies usually use vacuum photomultiplier tubes (PMTs). Constant innovations of these sensors have contributed to their adaptation in many fields of science because of their speed and sensitivity for single photons. Their main drawbacks are: sensitivity to the influence of magnetic field and high voltage supply. Silicon photomultipliers (SiPM) which were invented in 1998 didn’t have these defects [2, 3]. They have very small dimensions and low breakdown voltage which provide opportunities for reducing the size of light probes. Silicon photomultiplier consists of an array of avalanche photodiodes operated in Geiger mode. Each photodiode is connected to quenching resistor which is responsible for returning to steady state from avalanche breakdown. Parallel connection all circuits photodiode-resistor causes a current flows through a photomultiplier which is proportional to number of photons. Internal photodiodes circuits and structure of a single pixel of SiPM are presented in Fig. 2. Silicon photomultiplier is not without drawbacks. From the perspective of designers, the most important ones are: thermally generated dark current, cross-talk and after-pulsing. System described in the paper doesn’t eliminate these drawbacks during the acquisition data process. It was taken into account only in a data analysis process. In [...]

Front-End electronics for Silicon Photomultiplier detectors implemented in CMOS VLSI integrated circuit

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Silicon Photomultiplier (SiPM) detectors are of great interest mostly because they can operate with light levels of few photons at room temperature and have fast response with typical rise time of 2-5ns. The paper presents an integrated circuit of front-end electronics designed in CMOS technology, dedicated for Silicon Photomultiplier (SiPM) detectors. The circuits was produced in the AMS 0,35m technology and preliminary test results show its high performance. Streszczenie. Krzemowe fotodetektory cieszą sie dużym zainteresowaniem e względu na możliwość rejestracji światła w temperaturze pokojowej na poziomie pojedynczych fotonów. W artykule przestawiono układ scalony elektroniki odczytowej do krzemowych fotopowielaczy zrealizowany w technologii CMO (AMS 0,35 m) oraz wstępne wyniki testów potwierdzające jego funkcjonalność. (Układ scalony elektroniki odczytowej do krzemowych fotopowielaczy zrealizowany w technologii CMOS) Keywords: SiPM, CMOS, photodetector, photon counting Słowa kluczowe: Krzemowy fotopowielacz, CMOS, fotodetektor, zliczanie fotonów Introduction Silicon photomultipliers (SiPM) are high performance photodetectors capable of dealing with extremely low photon fluxes. They are strong competitors of widely used Photomultiplier Tubes (PMT) which require high voltage (kV range) for operation and are quite expensive. State-of-theart SiPM’s work with bias voltages at the order of 25-100V, have much smaller dimensions than a PMT’s and its unit cost can be very low (for large quantities the cost can be ~10 euro) [1, 2]. Moreover the SiPM can be operated in strong magnetic field. There are several important applications where silicon photomultipliers appear to be extremely attractive: Positron Emission Tomography, Real-time dosimetry (i.e. Mammography) and High Energy Physics experiments (i.e. calorimetry). There is a lot of research ongoing to exploit the potential of SiPM sensors related to those[...]

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