It has already been shown how the shape of the current pulse produced by a SiPM in response to an incident photon is sensibly affected by the characteristics of the front-end electronics (FEE) used ...to read out the detector. When the application requires to approach the best theoretical time performance of the detection system, the influence of all the parasitics associated to the coupling SiPM–FEE can play a relevant role and must be adequately modeled. In particular, it has been reported that the shape of the current pulse is affected by the parasitic inductance of the wiring connection between SiPM and FEE. In this contribution, we extend the validity of a previously presented SiPM model to account for the wiring inductance. Various combinations of the main performance parameters of the FEE (input resistance and bandwidth) have been simulated in order to evaluate their influence on the time accuracy of the detection system, when the time pick-off of each single event is extracted by means of a leading edge discriminator (LED) technique.
CMOS multichannel front-end electronics suitable for Silicon Photomultiplier detectors has been developed, mainly intended for medical imaging applications. The architecture of the analog channel, DC ...coupled to the detector, is based on a full current-mode approach, which allows to achieve a wide input dynamic range of about 70
pC while retaining very fast self-triggering capabilities. An 8-channel ASIC with on-chip ADC and a 32-channel prototype have been designed and manufactured, both featuring serial and sparse readout capabilities and a fast-OR circuit, able to generate a high-speed trigger signal from the discriminator outputs of the analog channels. Measurements obtained by coupling the 8-channel prototypes to an injection capacitance have been carried out for characterization purposes. The circuit has been also used to read-out SiPMs coupled to different kinds of light sources, such as a blue LED and a small LYSO scintillation crystal excited by gamma photons with different energies. The results obtained from these tests are presented and discussed, confirming the effectiveness of the proposed front-end architecture.
An innovative detector concept for hybrid 4D-PET/MRI imaging Cerello, P.; Pennazio, F.; Bisogni, M.G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2013, Letnik:
702
Journal Article
Recenzirano
The importance of a high-quality hybrid imaging, providing morphological and functional information with only one acquisition session, is widely acknowledged by the scientific community. The ...historical limitations to the quality of PET images are related to the unsatisfactory measurement of the depth of interaction (DOI) in the crystals and of the time of flight (TOF), that cause a parallax error and an unfavorable signal to background condition in the image reconstruction process, respectively. The 4DMPET project is developing a high performance PET block-detector featuring 4D image reconstruction capabilities. The detector module is based on a fast scintillating continuous crystal coupled on both sides to arrays of Silicon PhotoMultipliers (SiPM). The SiPMs collect the scintillation light and provide the trigger signal, the time and the energy released in the crystal at the pixel level. The photon depth of interaction (DOI) is reconstructed by measuring the cluster size asymmetry on the two faces of the crystal, thus obtaining a comparable spatial resolution in the three coordinates and removing the parallax error. The event position along the line of response can be measured with high precision by means of TOF techniques. We discuss the module design concept and the results of the detailed Monte Carlo detector simulation, which inspire the architectural solutions selected for the layout and the front-end The expected resolution for 3D spatial coordinates of the interaction point in the crystal (1mm) and the TOF (about 110ps) would provide a substantial improvement of the image quality. 4DMPET aims at building a prototype block detector demonstrating that the proposed layout meets the expected performance and is suitable for designing a detector focused on a specific application.
CMOS analog front-end channel for silicon photo-multipliers Corsi, F.; Foresta, M.; Marzocca, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
A complete self-triggered CMOS analog front-end suitable for silicon photo-multiplier detectors (SiPM) is proposed here, mainly intended for medical imaging applications. The exploitation of a ...current mode approach allows to achieve the large dynamic range and fast timing required by this kind of detectors without excessive power consumption. Results from characterization measurements on the prototype of the analog channel are also reported: the trigger signal produced by the circuit in response to a fast input current pulse exhibits a measured timing accuracy better than 60
ps and a dynamic range of about 50
pC has been obtained.
In the frame of INFN-ITC-irst collaboration new Silicon PhotoMultiplier (SiPM) prototypes have been produced at ITC-irst (Trento, Italy). Each SiPM covers an area of 1
mm
2 and brings together 625 ...micro-cells of 40×40
μm
2 size connected in parallel as to form a single read-out element. Each micro-cell consists of a Geiger Mode Avalanche Photodiode (GM-APD) in series with its quenching resistance. This article reports the main characteristics of these prototypes as well as the ongoing activity of our collaboration on the development of SiPM devices for medical and space physics applications.
Silicon photomultipliers (SiPMs) with quantum efficiency maximized for a wavelength between 420 and 470 nm have been developed at ITC-irst Trento (Italy), and are being tested for their application ...in the construction of a ultra high resolution small animal PET tomograph. The devices have an area of 1 mm times 1 mm and 625 microcells. The breakdown voltage is around 30 V, and the gain of the order of 10 6 . The intrinsic timing resolution is 70 ps rms at the single photoelectron level. The first tests as readout for scintillators show an energy resolution of 21% FWHM with Na-22 employing LSO crystals. The first matrices of SiPMs have been produced and are being tested.
Carbon monoxide (CO) is a signaling gas produced intracellularly by heme oxygenase (HO) enzymes using heme as a substrate. During heme breakdown, HO-1 and HO-2 release CO, biliverdin, and Fe(2+). In ...this study, we investigated the effects of manipulation of the HO-1 system in an in vivo model of focal ischemia-reperfusion (FIR) in the rat heart. Male Wistar albino rats, under general anesthesia and artificial ventilation, underwent thoracotomy, the pericardium was opened, and a silk suture was placed around the left descending coronary artery; ischemia was induced by tightening the suture and was monitored for 30 min. Subsequently, the ligature was released to allow reperfusion lasting for 60 min. The first group of rats was sham operated and injected intraperitoneally (i.p.) with saline. The second group underwent FIR. The third group was treated ip 18 hr before FIR with hemin (4 mg/kg). The fourth group was pretreated ip 24 hr before FIR and 6 hr before hemin with zinc protoporphyrin IX (ZnPP-IX, 50 microg/kg). Specimens of the left ventricle were taken for determination of HO expression and activity, infarct size, malonyldialdehyde (MDA) production, and tissue calcium content. FIR led to a significant increase in the generation of MDA and notably raised tissue calcium levels. Induction of HO-1 by hemin significantly decreased infarct size, incidence of reperfusion arrhythmias, MDA generation, and calcium overload induced by FIR. These effects were prevented by the HO-1 inhibitor ZnPP-IX. The present experiments show that the concerted actions of CO, iron, and biliverdin/bilirubin modulate the FIR-induced myocardial injury.
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