Pulse rise time

Corona discharges have been investigated extensively for NO removal [38-54], The effect of electrodes configuration, electrical circuit, gas composition and flow rate were studied. When the discharge was operated in pulsed mode, the influence of pulse rise time, duration, and repetition frequency, as well as the effect of the voltage polarity on NO conversion, were considered by numerous authors. 

When a model for a CUORICINO detector (see Section 15.3.2) was formulated and the pulses simulated by the model were compared with those detected by the front-end electronics, it was evident that a large difference of about a factor 3 in the pulse rise time existed. This discrepancy was mainly attributed to the uncertainty in the values of carrier-phonon decoupling parameter. For the thermistor heat capacity, a linear dependence on temperature was assumed down to the lowest temperatures. As we shall see, this assumption was wrong. 

Up to now, in the formulation of a bolometer model, only the heat capacity of itinerant carriers was considered [57], However, our measurements show that, even at 24 mK, the presence of a spurious heat capacity in the thermometer increases the expected value of the pulse rise time. We expect that the spurious contribution in Fig. 12.17 increases down to the temperature of the Schottky peak at T = k.E/khT about 10 mK. Since gc decreases at low temperatures, the total effect on pulse rise time and pulse amplitude can be dramatic at lowest temperatures. In reality, the measured rise time of CUORICINO pulses is about three times longer than that obtained from a model which neglects the spurious heat capacity of the thermistor. For the same reason, also the pulse amplitude is by a factor two smaller than the expected value (see Section 15.3.2). 

The light decay time constant in Nal is about 0.25 (is. Typical charge sensitive preamplifiers translate this into an output pulse rise time of about 0.5 (is. Fast coincidence measurements cannot achieve the very short resolving times that are possible with plastic, especially at low gamma ray energies. 

Varying pulse rise time by simply changing the pulse duration is not straightfoward because the laser pulses may differ in other respects. The principle of the interferometric method is to split each laser pulse into two pulses of unequal intensity, delay the main pulse and recombine them such that the low-intensity prepulse can interfere constructively or destructively with the leading edge of the main pulse, producing an increase or decrease in rise time. 

To measure spike intensity versus steepness of voltage pulse edges we introduced small variable capacitor connected in parallel with the sample. Increase in capacitive load led to a commensurate increase of the voltage pulse rise time. As we varied pulse rise-time from 2 ns to 90 ns, we observed the attenuation and eventual disappearance of transient EL peak. Therefore transient EL spikes can... 

Of course, a simple leading edge discriminator cannot be used to trigger on such pulses. The amplitude jitter would introduce a timing jitter of the order of the pulse rise time (Fig. 4.1, left). In practice the timing jitter is even larger because any discriminator has an intrinsic delay that depends on the signal slope speed and the amount of overdrive. 

S. Dionissopoulou, Th. Mercouris, C.A. Nicolaides, Variation of harmonic generation from He interacting with short laser pulses of 5 eV as a function of pulse rise time and intensity, Phys. Rev. A 61 (2000) 063402 Erratum 62 (2000) 039901. 

Fig. 6.11 Measured pulses of a mode-locked argon laser at A = 488 nm (a) monitored with a fast photodiode and a sampling oscilloscope (500 ps/div). The small oscillations after the pulse are cable reflections (b) the attenuated scattered laser light was detected by a photomultiplier (single-photon counting) and stored in a multichannel analyzer. The time resolution is limited by the pulse rise times of the photodiode and photomultiplier, respectively [656]...

For experiments demanding high time resolution, the rise time of this anode pulse should be as small as possible. Let us consider which effects may contribute to the anode pulse rise time, caused by the spread of transit times... 

Tilt can be determined for both test signal ranges. The measurement is made on a portion of the square wave derived from a demodulator. Particular start and end points of the measurement are suggested to avoid ringing as a result of pulse rise times. To ensure the best measurements, the sweep range and vertical sensitivity of the oscilloscope are set as wide as possible to accommodate the entire length of trace segment of interest. Tops and bottoms of the square waves should be measured separately (see Fig. 20.34.)... 

The need for interpolation introduces inaccuracies in the measurement process. Determination of exact values is especially difficult in the microsecond ranges, where even small increments can make a big difference in the measurement. It is also difficult with a conventional scope to make a close-up examination of specific portions of a waveform. For this purpose, an oscilloscope with two independently adjustable sweep generators is recommended. A small section of the waveform can be selected for closer examination by adjusting the B channel sweep-time and delay-time controls while observing an intensified portion of the waveform. The intensified section can then be expanded across the screen. This type of close-up examination is useful for measuring pulse rise times and viewing details in complex signals, such as video horizontal sync or color burst. 

Pulse rise time The time required for the leading edge of a pulse to rise from 10 percent to 90 percent of... 

The unknown fractional number e < 2 takes into account that the trigger signals from PDl, which define the start and stop times to and h (Fig. 4.69), may not exactly coincide with the pulse rise times in channel 2. The two worst cases are shown in Fig. 4.70. For case a, the trigger pulse at to just misses the rise of the signal pulse, but the trigger at t just coincides with the rise of a signal pulse. This means that the... 

For experiments demanding high time resolution, the rise time of this anode pulse should be as small as possible. Let us consider which effects may contribute to the anode pulse rise time, caused by the spread of transit times for the different electrons [255, 256]. Assume that a single photoelectron is anitted from the photocathode, and is accelerated to the first dynode. The initial velocities of the secondary electrons vary because these electrons are released at different depths of the dynode material and their initial energies, when leaving the dynode surface, are between 0 and 5 eV. The transit time between two parallel electrodes with distance d and potential difference V is obtained from d = af- with a = eV/ md), which gives... 

Where it is required to measure neutrons in the presence of a significant y-ray background, it is possible to make use of the properties of certain scintillators to distinguish the pulses produced by neutrons from those due to y rays. This is known as a pulse-shape discrimination (PSD) system. In stilbene and some organic liquid scintillators, the pulse rise time for the fluorescence caused by the secondary electrons from a y-ray interaction is considerably shorter than that due to the recoil protons produced by neutron scattering. By the use of fast timing discriminators, it is possible to separate the pulses caused by neutrons from those due to the y rays. 

The probability of initiating the first anode mode appears to depend on the voltage level for the pulse rise time (300 ns) used in the experiments (McKenny and McGrath, 1984). When a potential difference of 20 kV was applied across a 1.5 mm gap, between one-third and one-half of the breakdowns involved the production of the 1st anode mode. If the peak voltage were raised to 24 kV, however, none of the breakdowns involved the 1st anode mode. 

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