Characterization of a large area silicon photomultiplier Nagai, A.; Alispach, C.; Barbano, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2019, Letnik:
948
Journal Article
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This work illustrates and compares some methods to measure the most relevant parameters of silicon photo-multipliers (SiPMs), such as photon detection efficiency as a function of over-voltage and ...wavelength, dark count rate, optical cross-talk, afterpulse probability. For the measurement of the breakdown voltage, VBD, several methods using the current–voltage IV curve are compared, such as the “IV Model”, the “relative logarithmic derivative”, the “inverse logarithmic derivative”, the “second logarithmic derivative”, and the “third derivative” models. We also show how some of these characteristics can be quite well described by few parameters and allow, for example, to build a function of the wavelength and over-voltage describing the photodetection efficiency. This is fundamental to determine the working point of SiPMs in applications where external factors can affect it.
These methods are applied to the large area monolithic hexagonal SiPM S10943-2832(X), developed in collaboration with Hamamatsu and adopted for a camera for a gamma-ray telescope, called the SST-1M. We describe the measurements of the performance at room temperature of this device. The methods used here can be applied to any other device and the physics background discussed here are quite general and valid for a large phase-space of the parameters.
This manuscript describes the optimization of the front-end readout electronics for high granularity hybrid pixel detectors. The theoretical study aims at minimizing the noise and jitter. The model ...presented here is validated with both circuit post layout simulations and measurements on the Timepix4 Application Specific Integrated Circuit (ASIC). The analog front-end circuit and the procedure to optimize the dimensions of the main transistors are described with detail.
The Timepix4 is the most recent ASIC designed in the framework of the Medipix4 Collaboration. It was manufactured in 65nm CMOS process, and consists of a four side buttable matrix of 448 × 512 pixels with 55µm pitch. The analog front-end has a gain of ∼36mV/ke- when configured in High Gain Mode, and ∼20mV/ke- when configured in Low Gain Mode. The Equivalent Noise Charge (ENC) is ∼68e-rms and ∼80e-rms in High Gain Mode and in Low Gain Mode respectively. In event driven mode the incoming hits can be time stamped within a ∼ 200ps time bin and the chip can deal with a maximum flux of ∼ 3.6MHzmm−2s−1. In photon counting mode, the chip can deal with up to ∼ 5GHzmm−2s−1.
The routine designed to optimize the Timepix4 front-end is then used to analyze the performance limits in terms of jitter and noise for Charge Sensitive Amplifiers in pixel detectors.
The proven potential of 3D geometries at higher than 1016n˙eq/cm2 radiation fluences, in combination with a small cell approach, makes them an excellent choice for a combined precision timing ...tracker. In this study, the preliminary results on timing resolution of a single 50×50μm2 3D pixel cell are presented through charge collection measurements with discrete electronics in a laboratory setup. Additionally, in a test-beam campaign with 160 GeV SPS pions, a detailed timing, field and efficiency map is presented using a multi-plane timing telescope with an integrated pixelated matrix. Finally, another testbeam campaign has been completed with the help of the EUDET telescope, to study field uniformity, Landau contribution, collected charge and incidence angles of +/−12°; with a preliminary 5μm spatial resolution through MIMOSA CMOS tracking at CERN SPS pion beams.
•Sensors for vertex detectors in high energy physics with high luminosity scenarios.•Testbeam setup development for time and spatial resolution measurements.•3D silicon Pixel sensor time resolution results.
Background
Mitral valve apparatus is complex and involves the mitral annulus, the leaflets, the chordae tendinae, the papillary muscles as well as the left atrial and ventricular myocardium. ...Secondary mitral regurgitation is a consequence of regional or global left ventricle remodeling due to an acute myocardial infarction (75% of cases) or idiopathic dilated cardiomyopathy (25% of cases). It is associated with an increase in mortality and poor outcome. There is a potential survival benefit deriving from the reduction in the degree of severity of mitral regurgitation. So the correction of the valve defect can change the clinical course and prognosis of the patient. The rationale for mitral valve treatment depends on the mitral regurgitation mechanism. Therefore, it is essential to identify and understand the pathophysiology of mitral valve regurgitation.
Aim of the Study
The aim of this review is to describe the crucial role of transthoracic and trans‐esophageal echocardiography, in particular with three‐dimensional echocardiography, for the assessment of the severity of secondary mitral regurgitation, anatomy, and hemodynamic changes in the left ventricle. Moreover, the concept that the mitral valve has no organic lesions has been abandoned. The echocardiography must allow a complete anatomical and functional evaluation of each component of the mitral valve complex, also useful to the surgeon in choosing the best surgical approach to repair the valve.
Conclusions
Echocardiography is the first‐line imaging modality for a better selection of patients, according to geometrical modifications of mitral apparatus and left ventricle viability, especially in preoperative phase.
Towards radiation tolerant sensors for pico-second timing, several dopants are explored. Using a common mask, CNM produced LGADs with boron, boron + carbon and gallium gain layers are studied, under ...neutron and proton irradiation. With fluences ranging from
10
14
to
6 × 10
15
n
eq
/cm
2
on both particle species, results focus on acceptor removal, gain reduction via electrical characterization, timing performance and charge collection. An emphasis is placed on stability via dark rate and operating voltage studies.
A familial case of Dowling–Degos disease on the vulva Coco, V.; Guerriero, C.; Esposito, I. ...
Clinical and experimental dermatology,
December 2019, 2019-Dec, 2019-12-00, 20191201, Letnik:
44, Številka:
8
Journal Article
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