Development of a scintillating optical fiber dosimeter with silicon photomultipliers (original) (raw)
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Silicon Photomultiplier and CsI(Tl) scintillator in application to portable H*(10) dosimeter
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2018
Portable dosimeter for ambient dose equivalent (H*(10)) and ambient dose rate equivalent (Ḣ*(10)) measurements based on Silicon Photomultiplier (SiPM) coupled to CsI(Tl) scintillator was designed and tested. Nonequivalence of the scintillator to the human tissue is corrected by the method which uses restoration of the radioactive source energy spectrum from secondary electron spectrum in scintillator. Due to that, the energy dependence response of the dosimeter is lower then 20% in range 50-3000 keV. As measured by 137 Cs nuclide sources, a dynamic range 0.1 μSv/h-10 mSv/h with a sensitivity 30 cps/(μSv/h) are achieved. Temperature stability is better then 10% in range −40-+50 • C due to combination of Zener diode and adjustment of the bias supply with DAC based on thermometer data.
Development of a compact radiation detection system based on the use of silicon photomultipliers
In this work we describe the development and the prototype of a new compact radiation detection system based on the use of the recent solid-state photosensors, the silicon photomultipliers (SiPMs). Scintillation exploits atomic or molecular excitation due to the passage of a charged particle. De-excitation then results in the emission of light, a process known as fluorescence. This light then acts as a detectable signal. For the detection system prototype, we used an organic scintillator from Eljen (EJ-204). Light travels along the thin scintillator undergoing many total internal reflections. To avoid losses and improving light collection efficiency, scintillator had been wrapped with an aluminum foil. Scintillation light readout is performed by using the Multi-Pixel Photon Counters (MPPCs) series (S10931-100P), Hamamatsu Japan. Each MPPC photosensor has 3 × 3 mm 2 active area and consists of 900 avalanche photodiodes (APDs), with a fill factor of 78.5 %. The maximum photo-detection efficiency is 55 % at 440 nm. For testing the prototype detection system, it has been irradiated with an energetic beta-particles emitted from Strontium-90 (Sr 90) radioactive isotope. The preliminary results showed that in response to the penetrating radiations, detector system prototype has succeeded to monitor beta-particles with good efficiency. The proposed prototype module could be a valuable option for a broad range of experiments if cost-effectiveness and small form factor are required.
2011
Silicon Photomultipliers (SiPMs) are semiconductor photo-sensitive devices built from a matrix of Single Photon Avalanche Diodes (SPADs) on a common silicon substrate, working in the limited Geiger mode and with a common readout. The fast counting ability, high timing resolution, immunity to magnetic field up to 15 T, low power consumption and relative small temperature dependence together with the small dimensions make SiPMs excellent candidates as commercially available solid state detectors, and a promising alternative to traditional photomultiplier tubes for single photon detection. Nevertheless, SiPMs do suffer from erroneous counting due to noise effects that can deteriorate their performance. These effects are, in general, heavily dependent on manufacturing quality. In this contribution, results are reported from the characterization of different models of SiPMs in terms of noise spectra and response to light, and a procedure for determining the quality of manufacturing is de...
First results of scintillator readout with silicon photomultiplier
IEEE Transactions on Nuclear Science, 2000
A new type of silicon device has been realized that has many properties comparable to, or better than, a conventional PMT (Photomultiplier Tube). This paper presents the first results of using these photodetectors in place of a PMT in the readout of scintillators for possible PET (Positron Emission Tomography) applications. This device, the Silicon Photomultiplier (SiPM), is effectively an avalanche photodiode operated in Geiger mode. In Geiger-mode detectors, a very large current signal is produced regardless of the size of the input, giving just logical rather than proportional information. However, the SiPM is subdivided into a large number (1440) of microcells that act as independent and virtually identical Geiger-mode photodiodes. The outputs of all these individual microcells are connected so that the total output signal is the sum of the signals from all of the microcells that were activated. In this way proportional information can be obtained. As a consequence of their design, these detectors have potentially very fast timing, high gain (10 5 10 6 ) at low bias voltage ( 50 V), a high quantum efficiency (35% at 500 nm), excellent single photoelectron resolution and are cheap to manufacture. Here we present results obtained with this new photodetector when used with pulsed LED and scintillator pixels.
Recent Advances in Scintillating Optical Fibre Dosimeters
Toward a Science Campus in Milan, 2018
Scintillating optical fibres have shown interesting results for ionizing radiation monitoring. Since they may enable a remote, punctual and real-time dose assessment, their application in medical dosimetry is very promising. This work aims to summarize some recent progresses in the development and characterization of rareearth doped silica optical fibres. The radioluminescent and dosimetric properties of Ce, Eu and Yb-doped fibres are presented and the advantages and challenges in the use of these sensors for radiation therapy dosimetry are discussed. For such application, an effective approach to deal with the stem effect, i.e. the spurious luminescent signal originated in the light guide as a consequence of its exposition to ionizing radiations (i.e. Cerenkov light and intrinsic fluorescence) must be considered. The stem effect mainly occurs in the UV-VIS region. We demonstrated that the use of a dopant emitting in the near infrared, like Yb, is suitable for an optical discrimination of the dosimetric signal. Indeed, through a characterization of the dosimetric properties of
Optimizing the design of a silicon photomultiplier-based radiation detector
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011
The silicon photomultiplier (SiPM) is a novel photo-sensor technology. This paper presents the design optimization process for implementing this technology in a scintillator-based radiation detector. The device provides the advantages of low current consumption, small dimensions, and high gain. These properties make SiPM of great interest for applications involving portable instrumentation. However, a novel approach to establish a set of parameters and their limits is required to optimize the performance of this new technology in radiation detection applications. The trade-offs and the influences of factors such as the photon detection efficiency (PDE), dynamic range (DR), various scintillation crystal characteristics, and light-reflecting materials are discussed. This study investigates the incorporation of CsI(Tl) scintillation crystals with SiPMs based on measurements and results for different photocoupling configurations, and the obtained achievements are described. A method for evaluating the photon collection efficiency of scintillator-SiPM-based detectors is proposed.
A scintillating fiber dosimeter for radiotherapy
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
Radiotherapy, together with chemotherapy and surgery, is one of the main methods applied in the fight against cancer; in order to increase the chances of a successful radiotherapy treatment the dose delivery to the tumor and the surrounding normal tissues has to be computed with high accuracy. Traditional dosimeters are accurate but single channel (ionization chambers and diodes) or non real-time (radiographic films) devices. At present there is no device water equivalent that can perform real-time and bidimensional measurements of a dose distribution.
Validation of dose measurements by scintillating fiber optic dosimeters for medical applications
8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications, 2013
Organic scintillators have been promoted and widely used in scintillating fiber-optic dosimeters (SFOD) due to their tissue-equivalent characteristics, small sensitive volume combined with high spatial resolution, and emission of visible light proportional to the absorbed electron and gamma dose rate. In this paper we will present the validation of Monte Carlo simulations of dose measurements assisted by scintillating fiber optic dosimeters operating in the visible spectral range, in the context of the development of fiber optic dosimeters targeted to Brachytherapy. The Monte Carlo simulation results are compared to measurements performed with SFOD test probes, assembled with BCF-60 (Saint Gobain) samples of 1 mm diameter and 0.35 to 1.5 cm length, coupled to PMMA optical fiber. The optical signal resulting from scintillation and Cherenkov light is transmitted through an additional optical fiber link to a remote measuring device. For SFOD probes irradiation a dedicated PMMA phantom was used. The results were validated against measurements obtained with a properly calibrated pinpoint ionization chamber (PTW). The probes were positioned in a radial arrangement, with a radioactive source at its center point. The γ-rays source is a Nucletron Microselectron-V2 192 Ir. The dose curves are obtained according to the different positions in the phantom with the SFOD dosimeters. The system is able to use a Fiber Optic Multiplexer (FOM) controlled with Labview software.