Trigger Generator Research Articles

Studies of the possibility to use Gas Pixel Detector as a fast trigger tracking device

Gas Pixel Detector (GPD) technology offers new possibilities, which make them very attractive for application in existing and future accelerator experiments and beyond. GPDs combine advantages of silicon and gaseous detectors. They can be produced radiation hard and with low power consumption using relatively cheap technology. Low capacitance of the individual pixel channel allows us to obtain a large signal to noise ratio. Using a time projection method for GPD readout one obtains 3D track image with precise coordinate (31 µm) and angular information (0.40°). This feature would allow us to achieve performance of one GPD layer equal to a few layers of silicon detectors. Implementation of a fast readout and data processing at the front-end level allows one to reconstruct a track segment in less than 1 μs, and to use this information for the first level trigger generation. The relevant algorithms of data acquisition and analysis are described and the results of simulations are presented in this paper.

Two-electrode gas switch with electrodynamical acceleration of a discharge channel.

High-energy switches and trigger generators are required for MJ-level capacitor banks. We have developed a compact gas switch and a matched series injection trigger generator. A series inductance is required for isolation of the trigger pulse from the surrounded circuit. A saturable inductor is employed here because low inductance is needed after the switch breakdown. The switch is of coaxial two-electrode design with electrodynamic acceleration of a spark channel. The switch operates at atmospheric pressure. The spark gap can be triggered reliably down to zero voltage (at 50 kV self-breakdown voltage) with less than 35 ns timing jitter. Energy losses in this spark gap have been accurately investigated. The main results are as follows: energy losses in the switch do not exceed 4% at voltages higher than 15 kV, i.e., when operation voltage exceeds ∼36% of the self-breakdown voltage. The spark gap is designed for 24 kV charging voltage, at a current up to 250 kA, and ∼70 C charge transfer. In this paper, we present a design for the spark gap, inductor and trigger generator. Test bed schematics and results of the tests are also described.

Study on Graphite-Electrode Gas Switch Applied for Pulsed Power Supply With a 700-kA Peak Current

A 700-kA gas switch with graphite electrodes for pulsed power supply module has been developed. This paper describes the design, construction, and testing of the high-current gas switch and its trigger system. The two-electrode gas switch is selected, which suffers high peak and fast rise time currents. The trigger generator based on resonant charging of a pulse transformer is constructed to trigger the gas spark. An electrodynamic force model of switch electrodes is established. The electrodynamic force of connecting wires is also calculated. By comparison of the mechanical strengths of polyformaldehyde, epoxy, and fiber-reinforced plastic (FRP) rods, where FRP rods are selected as switch rods, the experimental results show that the mechanical strength of the switch increases by 200%. Extensive electric testing has proven the operating parameters of the switch and its trigger system. The experimental results show that the measured discharge current waveform is demonstrated to be over a 700-kA peak current and a 500- $\mu \text{s}$ pulsewidth. The transfer charge per shot is more than 500 C.

The iron component of particulate matter is antiapoptotic: A clue to the development of lung cancer after exposure to atmospheric pollutants?

The classification of outdoor air pollution as carcinogenic for humans strengthens the increasing concern about particulate matter (PM). We previously demonstrated that PM exposure produces an antiapoptotic effect resulting from polycyclic aromatic hydrocarbons (PAH) and water-soluble components. In this study, we investigated transition metallic compounds, particularly iron, in order to decipher their underlying molecular mechanisms that prevent apoptosis. Human bronchial epithelial cells were exposed for 4h to different PM samples with established antiapoptotic effect (e.g. PM-AW) or not (e.g. PM-VS) or to their metallic components (Fe, Mn, Zn and Al) before apoptosis induction by the calcium ionophore A23187 or Staurosporine. PM-AW, Fe, Mn and Al significantly reduced induced apoptosis. The antiapoptotic effect of Fe was enhanced by benzo(a)pyrene, a typical PAH compound, but was totally reversed by the iron chelator, deferiprone. Furthermore, particles and iron triggered cellular ROS generation and prevented the depletion in glutathione levels observed during A23187-induced apoptosis. In contrast to benzo(a)pyrene, PM-AW and Fe rapidly activated NRF2, subsequently upregulated several target genes (HO1, NQO1 and GPX1) and modulated some genes which control cell death (BCL2, BAX and p53). The key role of the NRF2 pathway in the antiapoptotic effect mediated by Fe and PM was demonstrated using siRNA technology. Our results suggest that the iron component participates in the antiapoptotic effect of PM by activating a NRF2-dependent antioxidant process. As resisting to cell death is one of the hallmarks of cancer cells, these findings provide additional clues for understanding the development of lung cancer after atmospheric pollution exposure.

Design and Performance of a Compact Marx Generator for Two-Electrode Gas Switch Used in ICF Power Conditioning System

As the high-current, high-coulomb transfer two-electrode graphite gas switch had no trigger electrode and must be triggered by a nanosecond pulse, a compact Marx generator was developed to produce a nanosecond rise-time, voltage level around 100 kV negative pulse to trigger the gas switch. This paper presented the structure of the compact Marx generator and the performance used in ICF power conditioning system. The effect of the ultraviolet radiation was utilized to decrease the amplitude of the breakdown voltage of the spark gaps. Coaxial structure of the metal shell was employed to reduce the inductance of the Marx generator. Additional isolation circuits were improved to prevent the electromagnetic disturbance which was significant for the application of the two-electrode graphite gas switch. The results showed that the designed compact Marx generator was suitable and have been successfully used as the trigger generator in ICF power conditioning system.

IEEE 1588 Time Synchronization Board in MTCA.4 Form Factor

Distributed data acquisition and control systems in large-scale scientific experiments, like e.g. ITER, require time synchronization with nanosecond precision. A protocol commonly used for that purpose is the Precise Timing Protocol (PTP), also known as IEEE 1588 standard. It uses the standard Ethernet signalling and protocols and allows obtaining timing accuracy of the order of tens of nanoseconds. The MTCA.4 is gradually becoming the platform of choice for building such systems. Currently there is no commercially available implementation of the PTP receiver on that platform. In this paper, we present a module in the MTCA.4 form factor supporting this standard. The module may be used as a timing receiver providing reference clocks in an MTCA.4 chassis, generating a Pulse Per Second (PPS) signal and allowing generation of triggers and timestamping of events on 8 configurable backplane lines and two front panel connectors. The module is based on the Xilinx Spartan 6 FPGA and thermally stabilized Voltage Controlled Oscillator controlled by the digital-to-analog converter. The board supports standalone operation, without the support from the host operating system, as the entire control algorithm is run on a Microblaze CPU implemented in the FPGA. The software support for the card includes the low-level API in the form of Linux driver, user-mode library, high-level API: ITER Nominal Device Support and EPICS IOC. The device has been tested in the ITER timing distribution network (TCN) with three cascaded PTP-enabled Hirschmann switches and a GPS reference clock source. An RMS synchronization accuracy, measured by direct comparison of the PPS signals, better than 20 ns has been obtained.

A digital signal processor-based pulse programmer with performance of run-time information handling for magnetic resonance imaging

A pulse programmer for magnetic resonance imaging based on a digital signal processor (DSP) is described. The pulse programmer not only implements event triggering and control line generation, but also performs the run-time information handling. The DSP, which has features that include a 32-bit data bus, a 24-bit address bus and a clock rate of 60 MHz, is used as the sequence operator. The DSP connects the field programmable gate array (FPGA) devices of all the spectrometer modules via its external bus, and manipulates the operation of each module via setting the control port of the corresponding FPGA. In addition, the run-time information of the spectrometer, which includes the operation status of each module and the external triggers, can be obtained easily using the read instruction, and the operation exceptions of the spectrometer can be treated quickly via the DSP’s interrupt mechanism. Up to 32 control lines can be generated simultaneously in an event, and the minimum interval between successive events is 50 ns. The pulse sequence program is written in the C++ language and is mainly composed of several predefined procedures. The performance of the proposed pulse programmer is validated by multiple imaging experiments.

A Subnanosecond Jitter Trigger Generator Utilizing Trigatron Switch and Avalanche Transistor Circuit

High-performance trigger generators with high amplitude, fast rise time, low jitter are essential for large-scaled pulsed-power systems. Most of the trigger generators are also tiny multistage pulsed-power systems with complicated structures. In this paper, a high-performance trigger generator was proposed by combining the advantages of low-jitter semiconductor switch and high-power gas switch. An avalanche transistor Marx circuit was developed. It was used to trigger a two-stage Marx generator based on trigatron switch. The output characteristics of the Marx circuit based on avalanche transistors and the two-stage Marx generator were studied. The experimental results show that a subnanosecond jitter, nanosecond rise time, high-voltage trigger generator can be achieved by triggering trigatron switch with an avalanche transistor circuit.

Optically isolated, 2 kHz repetition rate, 4 kV solid-state pulse trigger generator.

This paper presents the design and operation characteristics of a solid-state high voltage pulse generator. Its primary utilization is aimed at triggering a gaseous spark gap with high repeatability. Specifically, the trigger generator is designed to achieve a risetime on the order of 0.1 kV/ns to trigger the first stage, trigatron spark gap of a 10-stage, 500 kV Marx generator. The major design components are comprised of a 60 W constant current DC-DC converter for high voltage charging, a single 4 kV thyristor, a step-up pulse transformer, and magnetic switch for pulse steepening. A risetime of <30 ns and pulse magnitude of 4 kV is achieved matching the simulated performance of the design.

Combined Forward Calorimetry Option for Phase II CMS Endcap Upgrade

Traditionally, EM and HAD compartments are thought to be separate and are often optimized individually. However, it is possible to optimize a robust and economical combined calorimeter system for myriad physics objectives. By employing event-by-event compensation afforded by the dual-readout technique, we have shown that excellent jet performance can be attained with a longitudinally un-segmented calorimeter that is calibrated only with electrons. In addition, the linear hadronic energy scale renders complex off-line correction schemes unnecessary. The proposed replacement of the CMS EE and HE calorimeters with a single Combined Forward Calorimeter (CFC) shows excellent jet performance complemented by good EM object detection. In this paper, we give brief snapshots on basic design criteria, timing characteristics of Cherenkov and scintillation pulses, trigger generation criteria and performance under high radiation fields. Although CMS has recently chosen different technologies for its endcap calorimetry in Phase II, the concepts developed here are likely to remain valuable for some time to come.

Note: A novel trigger generator for a pseudospark switch.

A novel trigger generator for operating a pseudospark switch has been developed based on a series connection of several insulated gate bipolar transistors. The trigger generator can be operated in single shot mode up to a repetition rate of 1 kHz. It is characterized by a fast rise time and low jitter between the output trigger pulses of less than 1 ns. It produces 3 kV, 1 μs pulses into a 50 Ω load that can trigger a pseudospark switch. By eliminating bulkier, slower high voltage components, the overall volume of the trigger generator is reduced. This allows for faster, high voltage switching to take place and thereby increasing the power density of the unit. Using this pseudospark trigger generator, it is possible to trigger single or multiple pseudospark gaps without the requirement to use a pulse shaping circuit.

The Pyridone-Annelated Isoindigo (5‘-Cl) Induces Apoptosis, Dysregulation of Mitochondria and Formation of ROS in Leukemic HL-60 Cells

Background/Aims: In our quest to develop an isoindigo with improved efficacy and bioavailability, we recently synthesized a series of novel substituted pyridone-annelated isoindigo and evaluated their antiproliferative effects. We identified the compound [(E)-1-(5'-Chloro-2'-oxoindolin-3'-ylidene)-6-ethyl-2,3,6,9-tetrahydro-2,9-dioxo-1H-pyrrolo[3,2-f] quinoline-8-carboxylic acid], abbreviated as 5'-Cl, which shows selective antiproliferative activities against various cancer cell lines mediated through apoptosis. Here we have investigated the molecular mechanisms underlying the apoptotic activity of 5'-Cl in the human promyelocytic leukemia HL-60 cells. Methods: We employed different methods to determine the apoptotic pathways triggered by 5'-Cl in HL-60 cells, using flow cytometry, nuclear staining, caspases activation, mitochondria functioning, generation of reactive oxygen species (ROS) and Western blotting techniques. Results: Low concentrations (1-8 µM) of 5'-Cl inhibited the growth of HL-60 cells in a dose and time-dependent manner. Cytotoxicity of this compound is found to be mediated by a caspase-dependent apoptosis. Also, there were indications of caspase independent apoptosis as z-VAD-FMK failed to fully rescue the cells from 5‘-Cl-induced apoptosis. In addition, the compound triggered generation of Reactive Oxygen Species (ROS), caused depolarization of the mitochondrial inner membrane, decreased the level of cellular ATP, modulated the expression and phosphorylation of Bcl-2 leading to loss of its association with Bax and increased the release of cytochrome c to the cytosol of treated cells. The effects of 5‘-Cl on mitochondria and apoptosis were substantially blocked in the presence of a combination between z-VAD-FMK and either of the ROS scavenger N-acetyl-L-cysteine (NAC) or pyrrolidine dithiocarbamate (PDTC). Conclusion: We demonstrated that the growth inhibitory effects of 5'-Cl in HL-60 cells involve multiple pathways of apoptosis and dysregulation of mitochondrial functions.

Solvent and [formula omitted] triggered robust and fast stress generation by ultrathin triple-network hydrogels

Solvent-triggered isometric stress generation of an ultrathin and tough triple-network (TN) hydrogel was systematically studied as functions of the pre-strain and ethanol/water mixture solvent. The obtained results along with the solvent-induced changes in the volume and modulus of the hydrogel were further analyzed with emphasis on clarifying the stress generation mechanism of the TN gel. Ca2+-triggered stress generation of the gel was also preliminarily explored. High stress generation of 0.4 MPa was obtained within tens of seconds at the low pre-strain of 25% by alternating water and ethanol. Both negative and positive stress generation of the gel were achieved just by changing the composition of the ethanol/water mixture solvent. Mechanism analysis indicates that, modulus change of the gel is the dominant reason for their solvent-triggered high and fast stress generation. In the case of the Ca2+-triggered stress generation of the gel, it is also attributed to the modulus change induced by the physical cross-linking of Ca2+ between the negatively charged first network chains of the TN hydrogel.

Study on the Performance of High-Voltage Trigger Generators in Pulsed Power Conditioning System

Two-electrode graphite spark gap switch (TGSGS) is used as the main discharge switch and triggered by a reliable trigger generator in pulsed power conditioning system (PPCS). There would be 108 energy modules in PPCS working at the same time. The reliable operating and jitters of the trigger generators will have impact on the PPCSs performance. In this paper, the working modes of the TGSGS are discussed and the performance of trigger generators in PPCS is tested and presented. A protection strategy of the trigger generator in PPCS is introduced, and effect of the blocking capacitor on the trigger pulse transmission is analyzed and tested. The protection strategy of the trigger generator based on blocking capacitor and fuse can effectively prevent the energy anti-irrigation failure when the pulse transformer core saturated. The blocking capacitor has some effect on the trigger pulse transmission, and has the larger capacitance, getting the higher peak amplitude on the cathode of the TGSGS. It is tried to discuss the working characteristics of the thyristors, and proposes a selection reference of the thyristors in this and other similar applications. The combination of analysis and measurement would be useful for the selection of thyristors and other components.

A vacuum switch trigger generator with a low-voltage storage capacitor switched by a thyristor

An improved pulse generator for triggering a vacuum switch is designed. The generator is based on the discharge of a storage capacitor to a trigger gap of the vacuum switch through a pulse step-up transformer. It differs from analogs in an additional capacitor introduced at the output of the transformer. The pulse charging of the additional capacitor allows one to increase the amplitude of the output voltage (in practice, by a factor of over 1.7). This provides a decrease in the transformer ratio for obtaining the specified output voltage and in the value and rise rate of the primary-circuit current to levels, allowing one to use cheap standard thyristors as a switch. The description of the generator, designed for triggering high-current vacuum switches, which are used in switching systems of capacitor banks with an energy storage of 30–100 kJ and discharge-current rise times of 100–250 μs, is given. The generator provides voltage pulses with amplitudes of >5 kV and, after the breakdown of the trigger gap of the vacuum switch, the trigger current in the form of a damped sine wave with an amplitude of over 600 A and a total duration of up to 90 μs.

VEGA: A low-power front-end ASIC for large area multi-linear X-ray silicon drift detectors: Design and experimental characterization

We present the design and the first experimental characterization of VEGA, an Application Specific Integrated Circuit (ASIC) designed to read out large area monolithic linear Silicon Drift Detectors (SDD’s). VEGA consists of an analog and a digital/mixed-signal section to accomplish all the functionalities and specifications required for high resolution X-ray spectroscopy in the energy range between 500eV and 50keV. The analog section includes a charge sensitive preamplifier, a shaper with 3-bit digitally selectable shaping times from 1.6µs to 6.6µs and a peak stretcher/sample-and-hold stage. The digital/mixed-signal section includes an amplitude discriminator with coarse and fine threshold level setting, a peak discriminator and a logic circuit to fulfill pile-up rejection, signal sampling, trigger generation, channel reset and the preamplifier and discriminators disabling functionalities. A Serial Peripherical Interface (SPI) is integrated in VEGA for loading and storing all configuration parameters in an internal register within few microseconds. The VEGA ASIC has been designed and manufactured in 0.35µm CMOS mixed-signal technology in single and 32 channel versions with dimensions of 200µm×500µm per channel. A minimum intrinsic Equivalent Noise Charge (ENC) of 12 electrons r.m.s. at 3.6µs peaking time and room temperature is measured and the linearity error is between −0.9% and +0.6% in the whole input energy range. The total power consumption is 481µW and 420µW per channel for the single and 32 channels version, respectively. A comparison with other ASICs for X-ray SDD’s shows that VEGA has a suitable low noise and offers high functionality as ADC-ready signal processing but at a power consumption that is a factor of four lower than other similar existing ASICs.

Improved monitoring of acoustic emissions in concrete structures by multi-triggering and adaptive acquisition time interval

Damage evaluation by Acoustic Emission (AE) signals is a promising technique for the non-invasive and continuous monitoring of concrete structures. The triggered acquisition modality is adopted in order to reduce the amount of acquired data in continuous monitoring. However, two main inconveniences can occur: either loss or partial acquisition of AE signals. Propagation can attenuate the signal below the trigger level causing signal loss, while the occurrence of multiple AE events can cause the loss or partial acquisition of signal due to the unpredictability of the Acquisition Time Interval (ATI). In fact, lower trigger level and wider ATI are not valid solutions in all real contexts. The proposal of the paper consists in the introduction of the multi-triggering acquisition modality and adaptive evaluation of the ATI, with the proper hardware Logic Flat Amplifier and Trigger (L-FAT) generator block designed and pointed-out to this purpose. As an evolution of the previously pointed out FAT, it generates the logical trigger whatever the transducer detecting the AE signal and adapts the ATI to the width of the multiple AE events as a further improvement. The adaptive evaluation of the ATI is based on the property that the AE length in concrete is well established. This property is used to foresee the end of the last AE by restarting the countdown at each trigger condition. The hardware architecture, the operative modality and the actual realization of the L-FAT are presented. Experimental tests assess the effectiveness of the L-FAT to monitor all the AE events, reducing the amount of acquired data, and to improve the damage evaluation of concrete structures.

Transmission line transformer for reliable and low-jitter triggering of a railgap switch.

The performance of railgap switch critically relies upon multichannel breakdown between the extended electrodes (rails) in order to ensure distributed current transfer along electrode length and to minimize the switch inductance. The initiation of several simultaneous arc channels along the switch length depends on the gap triggering technique and on the rate at which the electric field changes within the gap. This paper presents design, construction, and output characteristics of a coaxial cable based three-stage transmission line transformer (TLT) that is capable of initiating multichannel breakdown in a high voltage, low inductance railgap switch. In each stage three identical lengths of URM67 coaxial cables have been used in parallel and they have been wounded in separate cassettes to enhance the isolation of the output of transformer from the input. The cascaded output impedance of TLT is ~50 Ω. Along with multi-channel formation over the complete length of electrode rails, significant reduction in jitter (≤2 ns) and conduction delay (≤60 ns) has been observed by the realization of large amplitude (~80 kV), high dV/dt (~6 kV/ns) pulse produced by the indigenously developed TLT based trigger generator. The superior performance of TLT over conventional pulse transformer for railgap triggering application has been compared and demonstrated experimentally.

On a New Mechanism of Trigger Generation for Post-Silicon Debugging

The main goal of post-silicon debugging is to locate errors undetected during the pre-silicon verification. Although high speed of hardware prototype can be leveraged to expedite running a large number of realistic test vectors, the low level of observability and controllability of signals inside a prototype is a big concern. Design for Debug (DFD) techniques aim to improve the observability of signals and speed up the root-cause analysis of errors. Incorporation of an Embedded Logic Analyzer (ELA) is introduced as one of the practical DFD techniques. An ELA contains a trigger unit that controls conditions for which trace signals should be captured in a buffer for post-processing. In this paper, we propose a tool to generate hierarchical triggers, providing compact trace information for root-cause analysis. Major advantages of our technique as a means to generate trigger units are: 1) failure localization and root-cause analysis is expedited by keeping the hierarchical trace of interactions leading to failures, 2) overlapped failure patterns can be found by mechanism which results in a 60-65% reduction in hardware overhead compared to the previously proposed method, 3) it can be parameterized to generate several units, making it possible to incorporate checkers into scarce silicon area and enabling on-chip debugging by means of time-multiplexing scheme.

Improved Accuracy of Damage Index Evaluation in Concrete Structures by Simultaneous Hardware Triggering

Abstract Non-invasive damage monitoring of concrete structures by means of Acoustic Emission (AE) requires multitransducers, multi-channel acquisition, high sampling frequency and long observation time. Owing to its propagation in concrete, the signal from AE reduces its amplitude during the propagation, and, consequently, some events can be lost due to lower signal intensity than the trigger level set on one sensor only. The innovative proposal discussed in the paper consists in the introduction of a Flat Amplifier and Trigger generator block (FAT) in order to generate a logical trigger when the AE is detected by any transducer. Experimental tests confirm the effectiveness of the FAT to acquire all the AE events and to increase the evaluation accuracy of damage indexes.