Signal Rise Time Research Articles

The CMS Beam Halo Monitor electronics

The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes (PMTs). The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few nanosecond resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is read out via IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providing online feedback on the beam quality. A dedicated calibration monitoring system has been designed to generate short triggered pulses of light to monitor the efficiency of the system. The electronics has been in operation since the first LHC beams of Run II and has served as the first demonstration of the new QIE10, Microsemi Igloo2 FPGA and high-speed 5 Gbps link with LHC data.

MOCCA: A 4k-Pixel Molecule Camera for the Position- and Energy-Resolving Detection of Neutral Molecule Fragments at CSR

We present the design of MOCCA, a large-area particle detector that is developed for the position- and energy-resolving detection of neutral molecule fragments produced in electron–ion interactions at the Cryogenic Storage Ring at the Max Planck Institute for Nuclear Physics in Heidelberg. The detector is based on metallic magnetic calorimeters and consists of 4096 particle absorbers covering a total detection area of $$44.8\,\mathrm {mm} \times 44.8\,\mathrm {mm}$$ . Groups of four absorbers are thermally coupled to a common paramagnetic temperature sensor where the strength of the thermal link is different for each absorber. This allows attributing a detector event within this group to the corresponding absorber by discriminating the signal rise times. A novel readout scheme further allows reading out all 1024 temperature sensors that are arranged in a $$32 \times 32$$ square array using only $$16+16$$ current-sensing superconducting quantum interference devices. Numerical calculations taking into account a simplified detector model predict an energy resolution of $$\Delta E_\mathrm {FWHM} \le 80\,\mathrm {eV}$$ for all pixels of this detector.

Investigating the Effect of Tones and Frequency Sweeps on the Collective Behavior of Penned Herring (Clupea harengus).

We experimentally played back tones and sweeps to captive herring (Clupea harengus) in a net pen and measured the collective response of a large and a small group of fish using a camera, echo sounder, and multibeam sonar. The playbacks ranged in frequency from 160 to 500 Hz and 131 to 147 dB re 1 μPa in received sound pressure level. Herring behavior was scored by a team that blindly evaluated the observations. Overall, the responses were modest. Stronger reactions were observed at higher source levels, lower frequencies, and smaller school sizes, but there was no effect on signal rise time.

The Design and Optimization of Combined Rogowski Coil Based on Printed Circuit Board

Rogowski coil has been widely used for measurement of small magnitude with fast rise time signal such as partial discharge (PD), but Rogowski coil based on Printed circuit board (PCB Rogowski) has limitation for this application. This paper presents the prototype of Combined Rogowski coil that can overcome the drawback of PCB Rogowski coil. Experimental results showed that the proposed coil was able to measure a simulated of PD signal and its output signal indicated that the coil is suitable for a detection of small magnitude signal when compare with the other coils. The proposed Combined Rogowski coil in this research has upper frequency ( f h ) of 53.59 MHz and mutual inductance ( M )of 0.417 μH , while PCB Rogowski coil has f h of 22.48 MHz and M of 0.026 μH. The oscillation of signal output that caused by non-uniform winding also has diminished. The electrical parameters that affected the performance of coil were controlled by the geometric variables and optimized by multi-objective genetic algorithm to achieve the optimum design of coil.

Balloon flight test of a Compton telescope based on scintillators with silicon photomultiplier readouts

We present the results of the first high-altitude balloon flight test of a concept for an advanced Compton telescope making use of modern scintillator materials with silicon photomultiplier (SiPM) readouts. There is a need in the fields of high-energy astronomy and solar physics for new medium-energy gamma-ray (~0.4–10MeV) detectors capable of making sensitive observations of both line and continuum sources over a wide dynamic range. A fast scintillator-based Compton telescope with SiPM readouts is a promising solution to this instrumentation challenge, since the fast response of the scintillators permits both the rejection of background via time-of-flight (ToF) discrimination and the ability to operate at high count rates. The Solar Compton Telescope (SolCompT) prototype presented here was designed to demonstrate stable performance of this technology under balloon-flight conditions. The SolCompT instrument was a simple two-element Compton telescope, consisting of an approximately one-inch cylindrical stilbene crystal for a scattering detector and a one-inch cubic LaBr3:Ce crystal for a calorimeter detector. Both scintillator detectors were read out by 2×2 arrays of Hamamatsu S11828-3344 MPPC devices. Custom front-end electronics provided optimum signal rise time and linearity, and custom power supplies automatically adjusted the SiPM bias voltage to compensate for temperature-induced gain variations. A tagged calibration source, consisting of ~240 nCi of 60Co embedded in plastic scintillator, was placed in the field of view and provided a known source of gamma rays to measure in flight. The SolCompT balloon payload was launched on 24 August 2014 from Fort Sumner, NM, and spent ~3.75h at a float altitude of ~123,000ft. The instrument performed well throughout the flight. After correcting for small (~10%) residual gain variations, we measured an in-flight ToF resolution of ~760ps (FWHM). Advanced scintillators with SiPM readouts continue to show great promise for future gamma-ray instruments.

Preliminary Results for Estimating Pulse Transit Time Using Seismocardiogram1

Preliminary Results for Estimating Pulse Transit Time Using Seismocardiogram1

Characterization of stacked-crystal PET detector designs for measurement of both TOF and DOI

A PET detector with good timing resolution and two-level depth-of-interaction (DOI) discrimination can be constructed using a single-ended readout of scintillator stacks of Lanthanum Bromide (LaBr3), with various Cerium dopant concentrations, including pure Cerium Bromide (CeBr3). The stacked crystal geometry creates a unique signal shape for interactions occurring in each layer, which can be used to identify the DOI, while retaining the inherently good timing properties of LaBr3 and CeBr3. In this work, single pixel elements are used to optimize the choice of scintillator, coupling of layers, and type of photodetector, evaluating the performance using a fast, single-channel photomultiplier tube (PMT) and a single 4 × 4 mm2 silicon photomultiplier (SiPM). We also introduce a method to quantify and evaluate the DOI discrimination accuracy. From signal shape measurements using fast waveform sampling, we found that in addition to differences in signal rise times, between crystal layers, there were also differences in the signal fall times. A DOI accuracy of 98% was achieved using our classification method for a stacked crystal pair, consisting of a 15 mm long LaBr3(Ce:20%) crystal on top of a 15 mm long CeBr3 crystal, readout using a PMT. A DOI accuracy of 95% was measured with a stack of two, identical, 12 mm long, CeBr3 crystals. The DOI accuracy of this crystal pair was reduced to 91% when using a SiPM for readout. For the stack of two, 12 mm long, CeBr3 crystals, a coincidence timing resolution (average of timing results from the top and bottom layer) of 199 ps was measured using a PMT, and this was improved to 153 ps when using a SiPM. These results show that with stacked LaBr3/CeBr3 scintillators and fast waveform sampling nearly perfect DOI accuracy can be achieved with excellent timing resolution—timing resolution that is only minimally degraded compared to results from a single CeBr3 crystal of comparable length to the stacked crystals. The interface in the stacked crystal geometry itself plays a major role in creating the differences in signal shape and this can be used to construct stacked DOI detectors using the same scintillator type, thereby simplifying and broadening the application of this technique.

Chronic balance disorders after acoustic neuroma surgery: assessment of gravitational vertical perception

Conclusion: The head tilt response (HTR) test performed in a group of patients with chronic dizziness after acoustic neuroma surgery showed alterations in the gravitational vertical perception (GV). Objective: The assessment of the accuracy in the GV through the HTR test in patients with long-term balance disorders after acoustic neuroma surgery. Methods: The HTR was performed in two groups of patients that had undergone acoustic neuroma surgery: six uncompensated patients (UPs) who maintained vestibular symptoms 1 year after surgery and two compensated patients (CPs) without vestibular symptoms. Twelve healthy control adults were also tested (control group, CG). Three parameters were measured in the HTR test: steady-state error (SSE), rise time (TRS), and mean energy of the error signal per step (MEE). Results: The UP group showed higher values for the TRS and MEE parameters compared with the CG (p < 0.05) when performing the HTR test to the side of the lesion and to the contralateral side, while the SSE only showed significant higher values when the patient estimated the GV towards the side of the lesion. The two patients in the CP group did not have differences in the three parameters assessed when compared with the CG.

Structure optimization of a grain impact piezoelectric sensor and its application for monitoring separation losses on tangential-axial combine harvesters.

Grain separation losses is a key parameter to weigh the performance of combine harvesters, and also a dominant factor for automatically adjusting their major working parameters. The traditional separation losses monitoring method mainly rely on manual efforts, which require a high labor intensity. With recent advancements in sensor technology, electronics and computational processing power, this paper presents an indirect method for monitoring grain separation losses in tangential-axial combine harvesters in real-time. Firstly, we developed a mathematical monitoring model based on detailed comparative data analysis of different feeding quantities. Then, we developed a grain impact piezoelectric sensor utilizing a YT-5 piezoelectric ceramic as the sensing element, and a signal process circuit designed according to differences in voltage amplitude and rise time of collision signals. To improve the sensor performance, theoretical analysis was performed from a structural vibration point of view, and the optimal sensor structural has been selected. Grain collide experiments have shown that the sensor performance was greatly improved. Finally, we installed the sensor on a tangential-longitudinal axial combine harvester, and grain separation losses monitoring experiments were carried out in North China, which results have shown that the monitoring method was feasible, and the biggest measurement relative error was 4.63% when harvesting rice.

Time-resolved radiation chemistry: dynamics of electron attachment to uracil following UV excitation of iodide-uracil complexes.

Electron attachment to uracil was investigated by applying time-resolved photoelectron imaging to iodide-uracil (I(-)U) complexes. In these studies, an ultraviolet pump pulse initiated charge transfer from the iodide to the uracil, and the resulting dynamics of the uracil temporary negative ion were probed. Five different excitation energies were used, 4.00 eV, 4.07 eV, 4.14 eV, 4.21 eV, and 4.66 eV. At the four lowest excitation energies, which lie near the vertical detachment energy of the I(-)U complex (4.11 eV), signatures of both the dipole bound (DB) as well as the valence bound (VB) anion of uracil were observed. In contrast, only the VB anion was observed at 4.66 eV, in agreement with previous experiments in this higher energy range. The early-time dynamics of both states were highly excitation energy dependent. The rise time of the DB anion signal was ∼250 fs at 4.00 eV and 4.07 eV, ∼120 fs at 4.14 eV and cross-correlation limited at 4.21 eV. The VB anion rise time also changed with excitation energy, ranging from 200 to 300 fs for excitation energies 4.00-4.21 eV, to a cross-correlation limited time at 4.66 eV. The results suggest that the DB state acts as a "doorway" state to the VB anion at 4.00-4.21 eV, while direct attachment to the VB anion occurs at 4.66 eV.

Influence of Loading Conditions during Tensile Testing on Acoustic Emission

The Acoustic Emission (AE) monitoring technique is widely used in mechanical and material research for detection of plastic deformation, fracture initiation and crack growth. However, the influence of AE features (such as signal amplitude, frequency, rise time and duration) on the fracture parameters (such as brittle or ductile mode of propagation and fracture propagation speed) is not completely understood. In this paper, the effect of loading conditions on fracture behavior was studied using AE monitoring during tensile testing of an aluminum alloy specimen. The fracture development was observed using a high speed video camera and was analyzed using the finite element method. The hardware and software produced by Physical Acoustics Corporation (USA) was used. Variations in AE parameters were analyzed and correlated to the stress-strain curves obtained during testing. It is shown that the strain rate and the presence of a crack (modeled by a notch on the sample), affect the fracture mode (brittle or ductile) and a relative amount of the mode dependent AE signatures.

Optical and EPR spectroscopy of Zn:Cr:ZnSe and Zn:Fe:ZnSe crystals

Optical and EPR characterization of Cr and Fe doped ZnSe crystals annealed in Zn vapor revealed a strong bleaching of the divalent state of transition metal ions. Photo induced EPR kinetics were studied in 20–80K temperature range. Analysis of time-dependent data reveals Cr1+ signal rise time decreases with increasing temperature. The non-exponential decay of Cr1+ concentration were analyzed using Auger-type recombination process. The photoluminescence quantum yield of Cr2+ ions at 5E(D)→5T2(D) mid-IR transition excited via chromium ionization process was measured to be close to 100%.

Study of the time response of 4H-SiC Schottky junctions for radiation high speed detection

A study of the time response of 4H-SiC radiation detectors by means of a custom simulator is presented. The detector response to X-rays has been studied under different bias conditions and interaction points within the detector active region. The contributions of electrons and holes to the current and voltage signals have been disentangled to determine their effects on the detector response speed. Signal rise-times between 340 ps and 710 ps and pulse widths of 0.93 ns and 1.12 ns Full Width at Half Maximum (FWHM) have been derived, in good agreement with experimental results.

Electromagnetic Compatibility of PCB Based on Electromagnetic Simulation Methods

With the circuit fabrication technology continues toward high-speed, high-density, low-power direction, modern circuit design techniques have changed radically. The speed improvement of digital system means rise and fall time of signals as short as possible, the improvement of frequency and edge rates will bring a series of high-speed design problems, these problems bring great challenges to the system hardware design, the correct design from logical point of view, if there is improper in the actual PCB design will lead to failure of the entire design. EMI radiation of PCB is analyzed, EMC simulation of PCB and optimizing improved are finished. The PCB electromagnetic compatibility is analyzed by using Protel 99SE and Ansoft Designer 2.2 software, and simulation result indicates optimizing design is correct and effective.

Study on Transient Temperature Generator and Dynamic Compensation Technology

According to the problem of dynamic calibration of the thermocouple, especially impossible to evaluate the rise time and to unify the calibration method, a new method of thermocouple calibration is proposed. Based on the method rise time of the input signal of thermocouple and step amplitude could evaluate accurately. The practical process of calibration shows that the method is effective.

Time‐resolved electroabsorption measurement of carrier velocity in inverted polarity In1‐xGax N/GaN heterostructures due to internal electric fields

AbstractCarrier transport measurements were made in a c ‐plane inverted‐polarity n ‐GaN/i ‐In1–xGax N/p ‐GaN heterostructure with a 200 nm thick In1–xGax N layer using ultrafast spectroscopy techniques. Time‐domain THz measurements indicate that the direction of electron transport is dominated by drift towards the n ‐GaN layer. Time‐resolved electroabsorption measurements were used to determine carrier velocities by monitoring the change in transmission of a probe beam tuned to the In1‐xGax N absorption edge due to the transport of photogenerated carriers under the built‐in internal electric field. Carrier transit times associated with screening of the electroabsorption are resolved at the lowest injection level. The signal rise time shows two distinct time scales, which correspond to an electron velocity of 3.3 ± 0.5 x 107 cm/s and a hole velocity of 6.7 ± 0.3 x 106 cm/s in an internal electric field of ∼150 kV/cm. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Concept of Metallic Magnetic Calorimeters for Rare Event Search in the LUMINEU Project

The project LUMINEU is mainly aiming at the search for neutrinoless double-beta decay of the candidate nuclide \(^{100}\)Mo using cryogenic ZnMoO\(_4\) detectors with simultaneous heat and scintillation light detection for radioactive background rejection. It also includes some development for dark matter search using cryogenic Ge detectors with simultaneous heat and ionization detection for background rejection. For both cases, metallic magnetic calorimeters (MMCs) are studied among several thermometer types. In double-beta decay search, the intrinsically fast response of MMCs reading out the light detector may allow for a very fast signal rise time and help to reduce the potential background due to pile-up of two-neutrino double beta decay events. In dark matter search, MMCs reading out the heat channel may improve the energy resolution with respect to the standard NTD Ge thermistor readout and hence the sensitivity of the detectors for low-mass WIMPs.

Temporal response of optical intensity modulation based on side-mode injection locked single-mode Fabry–Pérot laser diode

In this paper, we have experimentally demonstrated time domain characteristics of all-optical intensity modulation using cross-gain modulation induced by side-mode injection locking in a single-mode Fabry–Pérot laser diode (SMFP-LD). Both bistable hysteresis and injection locking behaviors are observed and discussed for different wavelength detuning between the injection beam and the selected side mode, which is the direct physical mechanism to successfully perform optical intensity modulation in the laser chip. Both the modulation depth of the injection signal and wavelength detuning have very important influences on the optical characteristics, including the modulation depth, and rise and fall time of the output signal at the dominant mode. The obtained modulation depth in the output signal can reach as high as ∼25 dB when a pulsed injection beam with a time duration of 8 ns is introduced into the laser chip under conditions of a bias current of 12 mA and an operating temperature of 16 ° C.

DOI Determination by Rise Time Discrimination in Single-Ended Readout for TOF PET Imaging

Clinical TOF PET systems achieve detection efficiency using thick crystals, typically of thickness 2-3cm. The resulting dispersion in interaction depths degrades spatial resolution for increasing radial positions due to parallax error. Furthermore, interaction depth dispersion results in time pickoff dispersion and thus in degraded timing resolution, and is therefore of added concern in TOF scanners. Using fast signal digitization, we characterize the timing performance, pulse shape and light output of LaBr3:Ce, CeBr3 and LYSO. Coincidence timing resolution is shown to degrade by ~50ps/cm for scintillator pixels of constant cross section and increasing length. By controlling irradiation depth in a scintillator pixel, we show that DOI-dependence of time pickoff is a significant factor in the loss of timing performance in thick detectors. Using the correlated DOI-dependence of time pickoff and charge collection, we apply a charge-based correction to the time pickoff, obtaining improved coincidence timing resolution of <200ps for a uniform 4×4×30mm3 LaBr3 pixel. In order to obtain both DOI identification and improved timing resolution, we design a two layer LaBr3[5%Ce]/LaBr3[30%Ce] detector of total size 4×4×30mm3, exploiting the dependence of scintillator rise time on [Ce] in LaBr3:Ce. Using signal rise time to determine interaction layer, excellent interaction layer discrimination is achieved, while maintaining coincidence timing resolution of <250ps and energy resolution <7% using a R4998 PMT. Excellent layer separation and timing performance is measured with several other commercially-available TOF photodetectors, demonstrating the practicality of this design. These results indicate the feasibility of rise time discrimination as a technique for measuring event DOI while maintaining sensitivity, timing and energy performance, in a well-known detector architecture.

Theoretical Studies of the Influence of Temperature on Photoluminescence Dynamics in GaInNAs/GaAs Quantum Wells

Dynamics of excitons in GaInNAs/GaAs quantum wells (QWs) is studied theoretically within a model of hopping excitons. In this model the temporal evolution of photoluminescence (PL) is described by the system of rate equations which takes into account hopping of excitons between randomly generated localizing states. In this work we study the influence of temperature on such characteristic features of PL as the decay and rise time of PL signal as well as their spectral dependences. It is clearly shown that our model reproduces experimental data very well.