Rise time

About: Rise time is a research topic. Over the lifetime, 4748 publications have been published within this topic receiving 47512 citations.

A fast preamplifier concept for SiPM-based time-of-flight PET detectors

Abstract: Silicon photomultipliers (SiPMs) offer high gain and fast response to light, making them interesting for fast timing applications such as time-of-flight (TOF) PET. To fully exploit the potential of these photosensors, dedicated preamplifiers that do not deteriorate the rise time and signal-to-noise ratio are crucial. Challenges include the high sensor capacitance, typically 4 300 pF for a 3 mm � 3 mm SiPM sensor, as well as oscillation issues. Here we present a preamplifier concept based on low noise, high speed transistors, designed for optimum timing performance. The input stage consists of a transimpe- dance common-base amplifier with a very low input impedance even at high frequencies, which assures a good linearity and avoids that the high detector capacitance affects the amplifier bandwidth. The amplifier has a fast timing output as well as a 'slow' energy output optimized for determining the total charge content of the pulse. The rise time of the amplifier is about 300 ps. The measured coincidence resolving time (CRT) for 511 keV photon pairs using the amplifiers in combination with 3m m� 3 mm SiPMs (Hamamatsu MPPC-S10362-33-050C) coupled to 3 mm � 3m m� 5 mm LaBr 3 :Ce and LYSO:Ce crystals equals 95 ps FWHM and 138 ps FWHM, respectively.

High-frequency strain response in ferroelectrics and its measurement using a modified Mach-Zehnder interferometer

Abstract: In this paper we report on a modified Mach‐Zehnder interferometer which is capable of measuring the ultrashort time strain response of a sample Using this instrument, the dispersion of piezoelectric and electrostrictive coefficients of several commonly used ferroelectrics was measured The strain switching behavior of lead lanthanum zirconate titanate (PLZT) 9/65/35 driven by a square pulse electric field was studied The results show that the switching rise time of the strain response for PLZT 9/65/35 can be much shorter than 5 μs at a pulse field strength near 25 kV/cm and that the fall time of the strain response is considerably shorter than the rise time in the experimental field strength range

Time Domain Oscillographic Microwave Network Analysis Using Frequency-Domain Data

Abstract: Oscillographic plots of various time-domain responses of microwave networks are generated by computer simulation, based upon measurements taken in the frequency domain. Frequency-response data are obtained with a computer-controlled automatic network analyzer, this information is processed in an associated computer, and selected time-domain responses are plotted immediately on an x-y recorder. Voltage versus time responses have been simulated for various excitations includlng impulse, step, and pulse-modulated RF waves. When impedance data are used, the plots are interpretable as from a time-domain reflectometer with high precision, high sensitivity, and high resolving power. As an oscillograph the rise time may be as short as 0.04 ns. In transmission 70 dB or more loss can be tolerated. In reflection measurements, the results are interpretable for discrete discontinuities with 40 dB or more return loss, and with separations on the order of 1 cm in space. In certain types of circuits, time-domain data can be used to reconstruct the frequency-domain response data in an approximate manner for separate parts of a network without separate measurements. In this manner, the interference of generator, load, and transducer mismatches can be substantially reduced.

Thermo-electro-mechanical Performance of Piezoelectric Stack Actuators for Fuel Injector Applications

Abstract: Piezoelectric actuators are increasingly used in fuel injectors due to their quick response, high efficiency, accuracy, and excellent repeatability. Current understanding of their thermo-electro-mechanical performance under dynamic driving conditions appropriate for fuel injection is, however, limited. In this paper, the thermo-electro-mechanical performance of soft Lead Zirconate Titanate (PZT) stack actuators is experimentally investigated over a temperature range of -30°C to 80°C, under driving electric fields of up to 2.0 kV/mm (using an AC drive method and a biased DC offset), different frequencies, and a constant preload of about 5 MPa. Experimental results show that the dynamic stroke of the actuators increases with the magnitude and frequency of the applied electric field, as well as ambient temperature. The dynamic stroke was also found to increase with decreased driving field rise time, which is equivalent to increasing the driving field frequency. At driving frequencies lower than the resonance...

Multiple‐wire array load for high‐power pulsed generators

Abstract: Exploding wire loads have been used for several years to generate a hot dense plasma. For a generator with a rise time of tens of nsec and an impedance of 1 Ω or less, the inductance of the wire load and the tendency of current to flow outside the wire limits the energy that can be transferred to the wire. An array of several wires has now been used to lower the inductance and improve the energy transfer.