Minimum Trigger Research Articles

Bulk properties of Pb–Pb collisions at TeV measured by ALICE

Global variables, such as the charged particle multiplicity and the transverse energy, are important observables to characterize relativistic heavy-ion collisions and to constrain model calculations. The charged particle multiplicity dNch/dη and the transverse energy dET/dη are measured at TeV in Pb–Pb collisions as a function of centrality and in pp collisions. The fraction of an inelastic cross section seen by the ALICE detector is calculated either using a Glauber model or the data corrected by simulations of nuclear and electromagnetic processes, or data collected with a minimum bias interaction trigger. The centrality, defined by the number of nucleons participating in the collision, is obtained, via the Glauber model, by relating the multiplicity distributions of various detectors in the ALICE Central Barrel and their correlation with the spectator energy measured by the Zero-Degree Calorimeters. The results are compared to corresponding results obtained at the significantly lower energies of the BNL AGS, the CERN SPS and the BNL RHIC, and with models based on different mechanisms for particle production in nuclear collisions. Particular emphasis will be given to a discussion on systematic studies of the dependence of the centrality determination on the details of the Glauber model, and the validity of the Glauber model at unprecedented collision energies.

Meows – time to review the trigger threshold?

IntroductionThe 2003–2005 Confidential Enquiry into Maternal and Child Health (CEMACH) encouraged ‘the routine use of a national obstetric early warning chart’. Our trust trialled the CEMACH example of a MEOWS...

Evaluation of seismic events detection algorithms

Identification of seismic events from continuously recorded seismic data in real-time through a Digital Seismic Data Recording system is a difficult task. Despite the vast amount of research in this field, the signal processing and event parameters discrimination algorithms have not yet fully come of age. Presently, we have a wide spectrum of trigger algorithms, ranging from a very simple amplitude threshold type to the sophisticated ones based on pattern recognition approaches. Some of the other approaches use adaptive technique and neural network methods. Researchers are continuously making efforts for the development of algorithms using various techniques, which produce minimum false trigger. Some approaches have been reported which are accurate for detecting first phase of events and take minimum possible computational time. In this paper several approaches for detecting event signals in background noise are presented and their precision evaluation is discussed.

Bootstrap quantification of cardiac pulsation artifact in DTI

While several studies have shown the benefit of cardiac gating in diffusion MRI with single-shot EPI acquisition, cardiac gating is still not commonly used. This is probably because it requires additional time and many investigators may not be convinced that cardiac gating is worth the extra effort. Here, we tested a clinically feasible protocol with a minimal increase in scan time, and quantified the effect of cardiac gating under partial or full Fourier acquisition. Eight volunteers were scanned on a 3 T scanner with a SENSE 8-channel head coil. Diffusion-weighted, single-shot spin-echo EPI images were acquired along 32 gradient directions, with or without cardiac gating and with partial or full Fourier acquisition. Vectorcardiography (VCG) was used to trigger acquisition at a minimum delay (30 ms). The uncertainties of DTI derived parameters were estimated using residual bootstrap. With partial Fourier, cardiac gating reduced the uncertainties, and better efficiency in reducing DTI parameter variability was also achieved even allowing for the increase in total scan time. For full Fourier acquisition, minimum time gating slightly decreased the uncertainties but the efficiency was worse. A minimum trigger delay might not be the optimal scheme to avoid the majority of systole but it allows clinically acceptable scan times. We have demonstrated that cardiac gating, especially of partial Fourier acquisitions, can reduce the uncertainties of DTI derived parameters in a time-efficient manner.

Experimental Investigations on Trigger Characteristics of Pseudo-sparkSwitch Based on Surface Flashover Technology

A trigger device and a triggered pseudospark switch (TPSS) weredesigned based on surface flashover technology, in order to meet therequirements from present pulse power technology and pulse currenttest technology such as a long lifetime, reliability in a widevoltage range, a short delay time, as well as small delay jitters.The trigger devices were made from different dielectric materials,with their permittivities from tens to thousands. The triggercharacteristics of TPSS were investigated. The results indicate thatthe high-dielectric trigger device shows better performance andhigher emitted charge of the electron emission within all adjustedparameters including the gas pressure and applied voltage. For thedielectric material with relative permittivity εrof 3460, when the gas pressure is 7 Pa, the hold-off voltage ofTPSS is 28 kV, the minimum trigger switch voltage drops to128 V, the minimum discharging delay time and delay jitter areless than 35ns and 6ns, respectively, and the reliable operationcan be reached within a very large range of charging voltage,between 0.46% and 99% of its self-breakdown voltage.

Explosion properties of highly concentrated ozone gas

The explosive self-decomposition characteristics of gaseous ozone with a concentration of up to almost 100 vol% were quantitatively investigated using a closed system with an electric spark device. The lower self-decomposition (explosion) limit for ozone diluted with oxygen at room temperature and atmospheric pressure was 10–11 vol%, and so ozone at more than 10–11 vol% will lead to an explosive chain decomposition reaction leading to its complete conversion to oxygen in a vessel. The lower explosion limit shifts to a higher concentration with a decrease in pressure. The limit was about 80 vol% under a reduced pressure of 10 Torr. We also confirmed that explosion trigger energy (minimum ignition energy) is strongly dependent on ozone concentration and pressure. For example, the minimum trigger energy for 15 vol% ozone at a pressure of 76 Torr (about 220 mJ) was more than 20-fold that at atmospheric pressure (about 10 mJ), and that for 13 vol% ozone (about 580 mJ) was approximately 30 times higher than that for 20 vol% (about 20 mJ) at the same pressure of 76 Torr. Moreover, the physical characteristics of the trigger energy sources (e.g. spark gap and electrode tip angle) leading to the decomposition (explosion) of ozone were investigated under various conditions.

Evaluation of a high-speed signal-averager for sensitivity enhancement in radio frequency Fourier transform electron paramagnetic resonance imaging

A commercially available high-speed, digital signal-averager is integrated into an existing time-domain radio frequency (rf) electron paramagnetic resonance (EPR) spectrometer/imager. Sensitivity enhancement by the integrated system is estimated by coherent averaging of free induction decay signals, obtained from narrow-line EPR spin probes, and its performance is compared with that of an existing custom-built averager. For the existing custom-built “Analytek” averager, the minimum realizable trigger rate was 50 kHz, whereas for the commercial EG&G 9826 system, due the spectrometer constraints, we set the retrigger rate to 133 kHz. Very short summing and down loading times of the latter enable good temporal resolution in phantom as well as in vivo rf Fourier transform EPR images, obtained by the single point imaging (SPI) modality. For two-dimensional and three-dimensional imaging using the SPI mode, a saving of time by a factor of >2 could be achieved with the EG&G system compared with the Analytek.

On the effects of gating in diffusion imaging of the brain using single shot EPI

To reduce image artifacts in diffusion tensor imaging using single shot EPI, cardiac gating may be performed to prevent brain motion induced signal void in the DWI data. In this work the necessity of performing cardiac gating with single shot echo planar imaging has been explored using F statistics of the variance in DWI data. Peripheral measurement of the cardiac cycle has been employed because of its greater convenience, and hence use, compared to ECG gating. Four volunteers have been studied. Six different trigger delays have been evaluated in the range 18–500 ms relative the peripheral pulse wave. Brain motion was found significant in and inferior to the corpus callosum area. A trigger delay of 500 ms was found to be optimal. However, a long delay allows only for one slice per R-R interval. Therefore, a minimum trigger delay may be the best choice in terms of SNR per unit of experiment time.

Evolution of some correlations with transverse momentum in minimum bias events at CDF

We analyze the structure of the events as described by some average variables like the mean charged multiplicity and the mean multiplicity of the V° ( K s ° + Λ°) as well as the strength of the intermittency like correlation as a function of the average event p t . Multibody final state from minimum bias and jet trigger events are examined for the two available center of mass energies 1800 and 630 GeV.

Resonator-based touch-sensitive probe

Abstract This paper presents a design of a simple low-cost resonator-based touch-sensitive probe. The design exploits the fact that when a stiff element (probe) oscillating near the resonance frequency comes into physical contact with the surface of another body (workpiece), the frequency of vibrational resonance of the probe changes depending on the latter's stiffness. This change can be detected by monitoring the variations in the phase shift between the probe driving force and the resulting strain, which consequently prompts the trigger signal. Standard phase-lock-loop oscillator circuitry is used to adjust the drive frequency to maintain a pre-set phase difference between the input and output signals, thus ensuring that the oscillator remains locked at the probe resonance frequency as contact takes place. A prototype probe has been designed and tested. The probe is excited to resonate at its fundamental frequency by employing piezoelectric drive and pick-up arrangements. The operating frequency of the probe is set at 25.179 kHz (second-mode frequency), which seems to be an adequate choice for excellent static and dynamic characteristics. The shift in the natural frequency as the contact force progresses follows a non-linear trend before it saturates. The maximum frequency shift measured is about 2 kHz, which corresponds to 140 mN contact force in the axial direction, whilst the minimum detectable trigger force is 3.8 mN.

Process and device performance of 1 µm-channel n-well CMOS technology

The process and device performance of 1 µm-channel n-well CMOS have been characterized in terms of substrate resistivities of 40 and 10 Ω.cm, substrate materials with and without an epitaxial layer, n-well surface concentrations ranging from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5 \times 10^{15}</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4 \times 10^{16}</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , n-well depths of 3, 4, and 5 µm, channel boron implantation doses from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 \times 10^{11}</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.3 \times 10^{12}</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , and effective channel lengths down to 0.6 µm. The deeper n-well more effectively improved the short-channel effects in p-channel MOSFET's having lower n-well surface concentrations. The impact-ionization current of the 0.9 µm n-channel MOSFET started to increase at a drain voltage of 5.2 V, while that of the 0.6 µm p-channel MOSFET did not increase until the drain voltage exceeded 12 V. Minimum latchup trigger current was observed when the output terminal of an inverter was driven over the power supply voltage. This minimum latchup trigger current was improved about 25 to 35 percent by changing the n-well depth from 3 to 5 µm and was further improved about 35 to 75 percent by using a substrate resistivity of 10 Ω.cm instead of 40 Ω.cm. The epitaxial wafer with a substrate resistivity of 0.008 Ω.cm improved the minimum latchup trigger current by more than 40 mA. It was estimated from the inverter characteristics that the effective mobility ratio between surface electrons and holes is about 1.4 at effective channel lengths of 1.0 µm for p-channel MOSFET's and 1.4 µm for n-channel MOSFET's. The optimized 1 µm-channel n-well CMOS resulted in a propagation delay time of 200 ps with a power dissipation of 500 µW and attained a maximum clock frequency of 267 MHz in a static ÷ 4 counter. The deep-trench-isolated CMOS structure was demonstrated to break through the scaling effect drawback of n-well depth and surface concentration.

GaAs planar gunn devices with sulfur-ion implanted n layers

Planar type Gunn effect devices have been fabricated by sulfur-ion implantation into the Cr doped semi-insulating GaAs substrates. The high doping efficiency as 90% was obtained as a result of long heat treatment. The mobility of the sulfur-ion implanted n layers with average carrier concentration of 4 × 10 16cm −3 was 5200 cm 2/Vsec at room temperature and 12,000 cm 2/Vsec at 77 K. The minimum gate trigger voltage of the Gunn effect digital devices was 100 mV. Sulfur-ion implanted Gunn effect devices have shown superior current drop ratio dependence on doping-depth product, compared to the devices prepared from the epitaxial layer.

Firing characteristics of a triggered vacuum gap employing a dielectric coated with a semiconducting layer

Some electrical properties of a triggered vacuum gap (TVG) incorporating five different dielectric materials coated with a semiconducting layer to produce a low surface resistance are studied. The dielectric materials used are high-alumina ceramic, steatite ceramic, barium titanate, silicon carbide, and boron nitride. It has been found that the probability of firing and the time delay to firing of such a TVG are practically independent of the substrate material. The time delay to firing generally decreases with an increase of both the trigger energy and the trigger voltage until saturation is reached. The minimum trigger voltage for successful firing is about 300 V for all substrates except for barium titanate which is higher at 700 V. The higher trigger voltage in the case of barium titanate is attributed to the difficulty of coating this material evenly with the particular semiconducting layer used of colloidal solution of aquadag carbon. A new method is described to rejuvenate a TVG which ceased to operate by applying a ’’keep-alive’’ direct current superimposed on the trigger pulse voltage. A mechanism responsible for this phenomenon is also discussed.

Low Voltage Firing Characteristics of a Simple Triggered Vacuum Gap

The firing characteristics of the simple triggered vacuum gap (TVG) using lead zirconate titanate as dielectric material in the triggered gap are described. This TVG has a long life of about 2000 firings without appreciable deterioration of the electrical properties for main discharge currents upto 3 kA and is much superior to these made with Supramica (Mycalex Corporation of America) and silicon carbide as used in our earlier investigations. The effects of the variation of trigger voltage, trigger curcit, trigger pulse duration, trigger pulse energy, main gap voltage, main gap separation and main circuit energy on the firing characteristics have been studied. Trigger resistance progressively decreases with the number of firings of the trigger gap and as well as of the main gap. This decrease in the trigger resistance is more pronounced for main discharge currents exceeding 10 kA. The minimum trigger current required for reliable firing decreases with increase of trigger voltage upto a threshold value of 1.2 kV and there-onwards saturates at 3.0 A. This value is less than that obtained with Supramica as dielectric material. One hundred percent firing probability of the TVG at main gap voltages as low as 50 V is possible and this low voltage breakdown of the main gap appears to be similar to the breakdown at low pressures between moving plasma by other workers. and the cold electrodes immersed in it, as reported

Progress in light activated power thyristors

Light activated power thyristors would have considerable advantages in intermediate- and high-voltage circuits, as power and trigger circuits could be electrically separated by use of glass fiber cables. Besides high-voltage capability, such devices must have turn-on delay times, dv/dt capabilities, and di/dt stabilities which are comparable to conventionally fired thyristors. The necessary trigger power, however, has to be kept low enough to enable firing with GaAs light emitters, which are available now or will be in the near future. The dv/dt sensitivity is an essential limitation for the reduction of the minimum necessary trigger power. Optimizing of the thyristor emitter shunts results in an already acceptable compromise, but much better results can be obtained by a gate structure which actively compensates dv/dt fault triggering. Our test devices show good turn-on behavior. A short survey on different GaAs-light sources and the coupling problem is given.

Breakdown mechanisms and electrical properties of triggered vacuum gaps

Some electrical characteristics of a triggered vacuum gap (TVG) having three different dielectric materials have been studied. Silicon carbide which possesses very high resistance (500 MΩ), steatite ceramic of medium resistance (20 MΩ), and boron nitride of very low resistance (50 Ω) have been used. The resistance of the dielectric is found to decrease with increasing trigger current and this is attributed to the deposition of metal vapor on the surface. The minimum trigger voltage and trigger current nessessary for successful operation of the TVG are measured. Deconditioning (reduction) in the minimum trigger voltage, after repeated firings, has been found and is attributed also to the deposition of metal vapor on the dielectric surface. The minimum trigger current for successful firing of the main gap decreases with increasing trigger voltage. The probability of successful firing of the TVG is found to rise rapidly with increasing trigger voltage. The delay time between the application of the trigger pulse to the breakdown of the main gap decreases with increasing trigger current and trigger voltage. A mechanism is suggested for the operation of the TVG.

A novel peak detector.

ABSTRACTA photoelectric triggering device has been developed with the aim of providing a minimum or maximum trigger on a blood pressure wave. The output from a strain gauge which measures blood pressure is displayed on an oscilloscope, and triggering is done by means of a miniature photocell mounted on a micrometric advance. A transistor circuit transforms the photocell pulse into a relay contact.

Transient Response Characteristics of Unijunction Transistors

Carrier transport in unijunction transistors is due primarily to electric fields rather than diffusion gradients. Thus, the high-frequency and transient response characteristics of unijunction transistors are considerably different from the characteristics associated with diffusion type devices. The high-frequency and transient response characteristics of silicon unijunction transistors are described. A previously published solution of the electrodynamic equations, taking into account field and recombination effects, is used to calculate theoretical frequency and transient response characteristics which are subsequently compared to experimental measurements. It is shown that: 1) Electric field effects lead to resonance characteristics which are somewhat similar to those encountered in wave interference phenomena. 2) The frequency response characteristics of unijunction transistors are predominantly determined by the electric field gradient for high fields and by recombination effects for low fields. 3) The large-signal transient response of unijunction transistors is characterized by at least two time constants, one of which is related to transit time and the other to minority carrier lifetime. 4) The maximum large-signal switching speeds and minimum trigger energy of regenerative unijunction transistor circuits depend upon both the electric field and lifetime characteristics of the device.