Rise time

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

Edge smoothing for real-time simulation of a polygon face object system as viewed by a moving observer

Abstract: The visual system within an aircraft flight simulation system receives flight data and terrain data which is formated into a buffer memory. The image data is forwarded to an image processor which translates the image data into face vertex vectors Vf, defining the position relationship between the vertices of each terrain object and the aircraft. The image processor then rotates, clips, and projects the image data into two-dimensional display vectors (Vd). A display generator receives the Vd faces, and other image data to provide analog inputs to CRT devices which provide the window displays for the simulated aircraft. The video signal to the CRT devices passes through an edge smoothing device which prolongs the rise time (and fall time) of the video data inversely as the slope of the edge being smoothed. An operational amplifier within the edge smoothing device has a plurality of independently selectable feedback capacitors each having a different value. The values of the capacitors form a series which doubles as a power of two. Each feedback capacitor has a fast switch responsive to the corresponding bit of a digital binary control word for selecting (1) or not selecting (0) that capacitor. The control word is determined by the slope of each edge. The resulting actual feedback capacitance for each edge is the sum of all the selected capacitors and is directly proportional to the value of the binary control word. The output rise time (or fall time) is a function of the feedback capacitance, and is controlled by the slope through the binary control word.

Operating parameters of CVD diamond detectors for radiation dosimetry

Abstract: A prototype clinical radiation detector based on commercially available single crystal diamond film made via chemical vapor deposition was investigated to determine optimal operating parameters for clinical dosimetry. This study examined how changes in applied electric field affected dosimetric performance, and determined a preferred operating voltage within the limits of clinical dosimetry equipment. Dosimetric analysis included leakage current, response dynamics such as rise and fall times, sensitivity, polarity and dependence on dose and dose rate. The results of this study indicate a preference for using a setting of 62.5 V due to its minimal rise time of 2 s, including a faster time to equilibrium, yet sufficient sensitivity of 37 nC Gy−1, which was nearly independent of polarity. At this voltage, a wider range of dose may therefore be recorded with charge collecting instruments than at higher voltages. Additionally, no clear trend was found over the range of voltages tested when evaluating dose dependence (R2=1 for 0.78–7.8 Gy) and dose rate dependence using Fowler fitting parameter Δ (0.95≤Δ≤1.01). Leakage currents were negligible (

Electron beam switched P-N junctions

Abstract: A high-speed, high-power switching device is analyzed and experimental results presented. The device consists of a back-biased p-n junction switched by an electron beam. A single position tube for use as a magnetic core driver has been tested. The device operated at a beam voltage of 19 kv and can give a 150-v, 1.5-a output pulse with a rise time of less than 4 nsec and a maximum device power dissipation of 14 w. Designs for a multiposition device and also a high-power amplifier, similar in operation to the single position device are discussed.

Formation of 1.4 MeV runaway electron flows in air using a solid-state generator with 10 MV/ns voltage rise rate

Abstract: Fulfillment of the condition that the voltage rise time across an air gap is comparable with the time of electron acceleration from a cathode to an anode allows a flow of runaway electrons (REs) to be formed with relativistic energies approaching that determined by the amplitude of the voltage pulse. In the experiment described here, an RE energy of 1.4 MeV was observed by applying a negative travelling voltage pulse of 860-kV with a maximum rise rate of 10 MV/ns and a rise time of 100-ps. The voltage pulse amplitude was doubled at the cathode of the 2-cm-long air gap due to the delay of conventional pulsed breakdown. The above-mentioned record-breaking voltage pulse of ∼120 ps duration with a peak power of 15 GW was produced by an all-solid-state pulsed power source utilising pulse compression/sharpening in a multistage gyromagnetic nonlinear transmission line.

Properties of HPK UFSD after neutron irradiation up to 6e15 n/cm2

Abstract: In this paper we report results from a neutron irradiation campaign of Ultra-Fast Silicon Detectors (UFSD) with fluences of 1e14, 3e14, 6e14, 1e15, 3e15, 6e15 n/cm2. The UFSD used in this study are circular 50 micro-meter thick Low-Gain Avalanche Detectors (LGAD), with a 1.0 mm diameter active area. They have been produced by Hamamatsu Photonics (HPK), Japan, with pre-radiation internal gain in the range 10-100 depending on the bias voltage. The sensors were tested pre-irradiation and post-irradiation with minimum ionizing particle (MIPs) from a 90Sr based \b{eta}-source. The leakage current, internal gain and the timing resolution were measured as a function of bias voltage at -20C and -30C. The timing resolution was extracted from the time difference with a second calibrated UFSD in coincidence, using the constant fraction method for both. The dependence of the gain upon the irradiation fluence is consistent with the concept of acceptor removal and the gain decreases from about 80 pre-irradiation to 7 after a fluence of 6e15 n/cm2. Consequently, the timing resolution was found to deteriorate from 20 ps to 50 ps. The results indicate that the most accurate time resolution is obtained at a value of the constant fraction discriminator (CFD) threshold used to determine the time of arrival varying with fluence, from 10% pre-radiation to 60% at the highest fluence. Key changes to the pulse shape induced by irradiation, i.e. (i) a reduce sensitivity of the pulse shape on the initial non-uniform charge deposition, (ii) the shortening of the rise time and (iii) the reduced pulse height, were compared with the WF2 simulation program and found to be in agreement.