Detector Output Research Articles

Resolving Photon Numbers Using a Superconducting Nanowire with Impedance-Matching Taper.

Time- and number-resolved photon detection is crucial for quantum information processing. Existing photon-number-resolving (PNR) detectors usually suffer from limited timing and dark-count performance or require complex fabrication and operation. Here, we demonstrate a PNR detector at telecommunication wavelengths based on a single superconducting nanowire with an integrated impedance-matching taper. The taper provides a kΩ load impedance to the nanowire, making the detector's output amplitude sensitive to the number of photon-induced hotspots. The prototyping device was able to resolve up to four absorbed photons with 16.1 ps timing jitter and <2 c.p.s. device dark count rate. Its exceptional distinction between single- and two-photon responses is ideal for high-fidelity coincidence counting and allowed us to directly observe bunching of photon pairs from a single output port of a Hong-Ou-Mandel interferometer. This detector architecture may provide a practical solution to applications that require high timing resolution and few-photon discrimination.

Modified FMCW system for non-contact sensing of human respiration

Small displacement detection capability becomes an important key for developing non-contact sensor for human respiration based on radar system. Frequency modulated continuous wave (FMCW) radar has been widely studied and applied for many applications. With respect to the conventional perspective, large bandwidth is needed for detecting the small displacement related to the human respiration. Meanwhile, extracting the respiration pattern from Doppler response has a drawback in identifying the small displacement location. In this paper, the modification on FMCW system was proposed for obtaining the capability in detecting the human respiration and its distance from the radar. Detecting the phase value of the low pass filter (LPF), output from conventional FMCW was investigated and applied as a modification concept. The pattern, rate and amplitude of respiration are extracted from phase detector output. Beat frequency detection is still elaborated for synthesising the reference signal for phase detection. The result shows that the modified FMCW system proposed the capability of detecting the rate and amplitude respiration and location of the target.

Handheld fluorometer for in-situ melamine detection via interference synthesis of dsDNA-templated copper nanoparticles.

Fluorescent copper nanoparticles templated by dsDNA have gained significant research interest as they are inexpensive and easy to synthesize, and have found applications in the detection of a wide range of analytes. The presence of the analyte in the reaction mixture interferes with the synthesis of the copper nanoparticles and the subsequent drop in fluorescence can be correlated to the concentration of the analyte present in the solution. Analyte detection using copper nanoparticle-based assays is amenable for in-situ applications as the test does not require expensive reagents and can be performed at room temperature. However, expensive and sophisticated detection systems are required for the detection of copper nanoparticles due to the low fluorescence emission signal from these nanoparticles. This restricts the use of the technology to centralized labs. Utilizing a recently developed chemical technique for fluorescence enhancement, this paper presents the first report of a handheld fluorometer capable of detecting DNA-templated copper nanoparticles. The fluorometer is portable and constructed with low-cost, off-the-shelf components like a UV-LED and a PIN photodiode. The performance of the developed system is demonstrated through the detection of melamine in milk samples via the interference synthesis of copper nanoparticles. Melamine is an adulterant used in dairy products that is harmful to human health if present in levels above 1ppm. The developed system is capable of detecting up to 0.1ppm of melamine in milk samples with a linear relationship observed between the detector output and concentration of melamine in the range from 0.1ppm to 100ppm (R2=0.9979).

Characterization of a microSilicon diode detector for small-field photon beam dosimetry.

This study characterized a new unshielded diode detector, the microSilicon (model 60023), for small-field photon beam dosimetry by evaluating the photon beams generated by a TrueBeam STx and a CyberKnife. Temperature dependence was evaluated by irradiating photons and increasing the water temperature from 11.5 to 31.3°C. For Diode E, microSilicon, microDiamond and EDGE detectors, dose linearity, dose rate dependence, energy dependence, percent-depth-dose (PDD), beam profiles and detector output factor (OFdet) were evaluated. The OFdet of the microSilicon detector was compared to the field output factors of the other detectors. The microSilicon exhibited small temperature dependence within 0.4%, although the Diode E showed a linear variation with a ratio of 0.26%/°C. The Diode E and EDGE detectors showed positive correlations between the detector reading and dose rate, whereas the microSilicon showed a stable response within 0.11%. The Diode E and microSilicon demonstrated negative correlations with the beam energy. The OFdet of microSilicon was the smallest among all the detectors. The maximum differences between the OFdet of microSilicon and the field output factors of microDiamond were 2.3 and 1.6% for 5 × 5 mm2 TrueBeam and 5 mm φ CyberKnife beams, respectively. The PDD data exhibited small variations in the dose fall-off region. The microSilicon and microDiamond detectors yielded similar penumbra widths, whereas the other detectors showed steeper penumbra profiles. The microSilicon demonstrated favorable characteristics including small temperature and dose rate dependence as well as the small spatial resolution and output factors suitable for small field dosimetry.

Wavelet transforms in separation science for denoising and peak overlap detection

Wavelet transform is a versatile time-frequency analysis technique, which allows localization of useful signals in time or space and separates them from noise. The detector output from any analytical instrument is mathematically equivalent to a digital image. Signals obtained in chemical separations that vary in time (e.g., high-performance liquid chromatography) or space (e.g., planar chromatography) are amenable to wavelet analysis. This article gives an overview of wavelet analysis, and graphically explains all the relevant concepts. Continuous wavelet transform and discrete wavelet transform concepts are pictorially explained along with their chromatographic applications. An example is shown for qualitative peak overlap detection in a noisy chromatogram using continuous wavelet transform. The concept of signal decomposition, denoising, and then signal reconstruction is graphically discussed for discrete wavelet transform. All the digital filters in chromatographic instruments used today potentially broaden and distort narrow peaks. Finally, a low signal-to-noise ratio chromatogram is denoised using the procedure. Significant gains(>tenfold) in signal-to-noise ratio are shown with wavelet analysis. Peaks that were not initially visible were recovered with good accuracy. Since discrete wavelet transform denoising analysis applies to any detector used in separation science, researchers should strongly consider using wavelets for their research.

DISTRIBUTION OF TRAFFIC SPEED IN DIFFERENT TRAFFIC CONDITIONS: AN EMPIRICAL STUDY IN BUDAPEST

Fundamental diagram, a graphical representation of the relationship among traffic flow, speed, and density, has been the foundation of traffic flow theory and transportation engineering for many years. Underlying a fundamental diagram is the relation between traffic speed and density, which serves as the basis to understand system dynamics. Empirical observations of the traffic speed versus traffic density show a wide-scattering of traffic speeds over a certain level of density, which would form a speed distribution over a certain level of density. The main aim of the current research is to study on the distribution of traffic speed in different traffic conditions in the urban roads since the distribution of traffic speed is necessary for many traffic engineering applications including generating traffic in micro-simulation systems. To do so, the traffic stream is videotaped at various locations in the city of Budapest (Hungary). The recorded videos were analysed by traffic engineering experts and different traffic conditions were extracted from these recorded videos based on the predefined scenarios. Then their relevant speeds in that time interval were estimated with the so-called “g-estimator method” using the outputs of the available loop detectors among the videotaped locations. Then different parametric candidate distributions have been fitted to the speeds by Maximum Likelihood Estimation (MLE) method. Having fitted different parametric distributions to speed data, they were compared by three goodness-of-fit tests along with two penalized criteria (Akaike Information Criterion – AIC and Bayesian Information Criterion – BIC) in order to overcome the over-fitting problems. The results showed that the speed of traffic flow follows exponential, normal, lognormal, gamma, beta and chisquare distribution in the condition that traffic flow followed over-saturated congestion, under saturated flow, free flow, congestion, accelerated flow and decelerated flow respectively.

Development of a Fluence Generating Programme for Patient-Specific Quality Assurance and Calibration of an Amorphous Silicon EPID

Patient-specific quality assurance (QA) is an essential part of intensity-modulated radiotherapy (IMRT) and volumetric arc therapy (VMAT) treatments. This study aims to develop a Patient-specific QA system through the development of a fluence generating programme and utilization of amorphous silicon (aSi) electronic portal imaging device (EPID). The EPID was investigated on the dependency of dose rate, uniformity of detector sensitivity and output factor. A fluence generating programme was written using MATLAB. Five simple dynamic arc plans and one patient VMAT plan were created using the Monaco treatment planning system which were used in the programme to generate fluence maps. The accuracy of the programme was evaluated by performing gamma analysis between the generated and measured fluence. EPID signal was found to be linearly proportional to dose (1-1000 MU) and independent of dose rate. The mean uniformity ratio was 1.07 ± 0.04%. The measured fluence maps were corrected for uniformity before gamma analysis. Output factor and dose deposition were taken into account in the process. The average result of the gamma analysis passed the 95% threshold. A fluence generating programme was developed, serving as the foundation of the Patient-specific QA system using aSi EPID for IMRT/VMAT delivery in this centre.

A New Technique for Improving the Estimation of a Reflective Optical Color Sensor

This paper proposes and experimentally demonstrates a novel technique of a precise color estimation by using a low cost reflective optical color sensor. The digital output signal of this sensor is a pulses series with a frequency proportional to the intensity of the incident light. In this sensor, three independent detector output signals with optimized spectral responsiveness allow discrimination between red, green and blue (RGB) light spectral components. The analytical expressions for RGB absorption efficiencies, which detect the color information, have been derived. An experimental set-up has been designed to determine the color difference, involving design of a portable color analyzer with wired and wireless computer interface. The detailed description and implementation of each design element are presented, while a developed algorithm is also discussed. The proposed algorithm apply a linear transformation to realize standardized colorimetric RGB and CIE31-XYZ color space coordinates responses. To that end, a correlation of the sensor outputs is established, a wide band correction matrix in old estimations is replaced by many narrowband correction matrices and the CIE standard curves of wavelengths are extracted and used to select a suitable narrowband correction matrix. Also, the sequential algorithm has been parallelized to reduce the response time in multiple measurement applications which need the big data processing. The experimental results in the vision spectrum confirm the theoretical analysis. Based on the findings of this experiment, the proposed system constitutes a high resolution and low cost solution for various color-sensing applications and colorimetric fields.

Doppler filtering approach to reduce the effect of in‐band interference in FMCW propagation data

This Letter proposes a method to reduce the effect of in-band interference in average power delay profiles obtained from frequency modulated continuous wave (FMCW) radio propagation data. The method is based on filtering the detector output in the Doppler domain. Results show that the Doppler filtering can be effective.

SciFi detector and associated method for real-time determination of profile and output factor for small fields in stereotactic radiotherapy.

PurposeFor determining small‐field profile and output factor during stereotactic radiotherapy quality assurance (QA) procedures, we propose a novel system based on the scintillating fiber (SciFi) detector with output image acquisition and processing to allow real‐time monitoring of profile and output factor.Materials and methodsThe employed detector is a SciFi detector made of tissue‐equivalent scintillating plastic fibers arranged in 6‐layer fiber ribbons with a fiber pitch of 275 μm in each layer. The scintillating signal at the detector output is acquired by a sCMOS (scientific complementary metal–oxide–semiconductor) camera and represents the projected field profile along the fibers axis. An iterative reconstruction method of the field from its projected profile based on a priori knowledge of some features of the radiation field defined by the stereotactic cones is suggested. The detector with implemented data processing has been tested in clinical conditions, for determining beam profiles and output factors, using cone collimators of different sizes from 4 to 15 mm diameter. The detector under test was placed at 1.4 cm depth and 98.6 cm source to surface distance (SSD) in a water‐equivalent phantom and irradiated by a 6 MV photon beam.ResultsThe reconstructed field profiles obtained from the detector are coherent with data from EBT3 radiochromic films, with differences within ±0.32 mm for both the FWHM and the penumbra region. For real‐time determination of the field output factor, the measured data are also in good agreement with data independently determined by the French Institute for Radiological Protection and Nuclear Safety (IRSN) based on radiochromic films and thermoluminescent 1 × 1 mm2 micro‐cubes dosimeters (TLD). The differences are within ±1.6% for all the tested cone sizes.ConclusionsWe propose and have tested a SciFi plastic scintillating detector with an optimized signal processing method to characterize small fields defined by cone collimators. It allows the determination of key field parameters such as full width at half maximum (FWHM) and field output factors. The results are consistent with those independently measured using TLD and radiochromic films. As the SciFi detector does not require a correction factor, it is in line with the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) TRS‐483 recommendations, and can be suitable for online QA of small radiation fields used in photon beam radiotherapy, and is compatible with MRI‐LINAC.

Low counting rate measurement on thermal neutron induced fission using cross-correlation technique

The measurement procedure based on the continuous thermal neutron beam modulation with a mechanical chopper was developed for delayed neutron yield measurement of the thermal neutron induced fission of [Formula: see text]Np. The idea of the procedure is similar to that widely used in modern computer communications to prevent unauthorized data access. The data is modulated with a predefined pattern before transmission to the public network, and only the recipient that has the modulation pattern is able to demodulate it upon receipt. For thermal neutron induced reaction applications, the thermal neutron beam modulation pattern was used to demodulate the measured delayed neutron intensity signals on the detector output, resulting in nonzero output only for the detector signals correlated with the beam modulation. The comparison of the method with the conventional measurement procedure was provided, and it was demonstrated that the cross-correlation procedure has special features making it superior to the conventional one, especially when the measured value is extremely small in comparison with the background. Due to the strong sensitivity of the measurement procedure on the modulation pattern of the neutron beam, one can implement the modulation pattern of a specific shape to separate the effect of the thermal part of the beam from the higher energy part in the most confident way in the particular experiment. The remarkable property of our method is related to the unique possibility of separation of the effects caused exclusively by thermal neutrons using the neutron time-of-flight measurement available on the IBR-2 pulsed reactor.

Developing signal processing of echo sounder for measuring acoustic backscatter

The method used to determine the condition of marine biological resources is still conventional, not systematic and not comprehensive. So far, the methods used include divers where the depth of observation is very limited. Another method using sonar for which the acquisition of data is still qualitative. For this reason, it is necessary to strive for new methods that can guarantee careful and accurate observation. This study proposes the detection, classification and quantification of underwater target algorithms using Intelligent Biomass Active Sonar Transducer (IBAST) using a microcontroller unit. IBAST uses acoustic pulses and features that are narrow spectral so as to provide the ability to detect underwater targets (underwater targets) accurately and be able to classify such targets as fish, zooplankton, marine mammals, coral reefs, and other targets. IBAST uses a tracking algorithm and output detector which reduces errors in target detection. The application of the algorithm will be carried out to test the classification method and quantification of underwater targets. This research is very useful in the aspects of quantification of marine life, protection of fishery resources and seabed habitat.

Anti-Sweep-Jamming Method Based on the Averaging of Range Side Lobes for Hybrid Modulation Proximity Detectors

Hybrid modulation continuous waveform (HMCW) proximity detectors emit binary phase-coded chirp (BPCC) waveforms. Therefore, they possess the advantages of binary phase-coded modulation and chirp modulation simultaneously. To enhance the anti-sweep-jamming performance of HMCW detectors, this paper analyses the response of an HMCW detector under sweep jamming and proposes an anti-jamming method based on the novel average range side lobe (ARS) approach. Similar to the instant correlation with harmonic demodulation (ICHD) method, the ARS method also combines time-domain instantaneous correlation with frequency-domain harmonic demodulation to obtain the range information of the target. The difference is that the ARS method uses a fast Fourier transform (FFT) instead of a band pass filter (BPF) to extract the harmonic envelope and averages multiple harmonic coefficients obtained via the FFT. Because the correlation side lobes of chaotic codes follow a Gaussian distribution, the output of an HMCW detector under sweep jamming is suppressed after ARS processing. The proposed method is proven to be feasible and effective through numerical simulations. The results show that the ARS method offers improved anti-sweep-jamming performance.

Compact Switched-Capacitor Power Detector With Frequency Compensation in 65-nm CMOS

This work presents a compact switched-capacitor power detector (PD) with frequency compensation technique in a 65-nm CMOS process. Utilizing self-biased MOSFET as switches, the PD works both at the positive and the negative cycle to increase the dynamic range (DR). The output of traditional power detectors usually change with the variations of input frequencies which make the measurement of PD more difficult. In this design, by adding a feed-forward frequency detection circuit, the load resistors of the power detector are changed according to the input frequencies. Thus, the effect of input frequency variation is minimized. The measured operation frequency of the power detector is from 3 GHz to 5 GHz with a dynamic range of 20 dB with an error of ±2 dB. The variations of the output voltage are reduced from more than 4 dB to ±0.5 dB, achieving a variation of less than ±0.25 dB/GHz. To the authors’ knowledge, it is the first power detector with input frequency compensation. The core of the power detector occupies an area of 0.014mm2 and consumes 2.04mW static power.

Iterative Receivers for Large-Scale MIMO Systems With Finite-Alphabet Simplicity-Based Detection

In this paper, we consider large-scale MIMO systems and we define iterative receivers which use the simplicity-based detection algorithm referred to as Finite Alphabet Simplicity (FAS) algorithm. First, we focus on uncoded systems and we propose a novel successive interference cancellation algorithm with an iterative processing based on the shadow area principle and we optimize its parameters by exploiting the theoretical analysis of the detector output. Secondly, we assume FEC-encoded systems and we propose an iterative receiver based on a maximum likelihood-like detection with restricted candidate subset defined by the FAS algorithm output. We also introduce another receiver based on FAS detection whose criterion is penalized with the mean absolute error function. Simulations results show the efficiency of all proposed iterative receivers compared to the state-of-the-art methods.

UAV TARGET DETECTION USING RADIOMETERS OF X, K, KA, AND W BANDS

In this work, an optimal algorithm for detecting a UAV from the analysis of the registration data of its radio-thermal radiation in a mixture with atmospheric radiation and internal noise of the receiver has been synthesized. The structures of the probability densities of the distribution of the detector output effect in the presence and absence of UAVs in the observation area are analyzed. To calculate the detection probabilities all the conditions of experiments performing with variations of false alarm probabilities, sounding angles, atmospheric brightness temperature, UAV dimensions, noise temperatures, and receiver bandwidths have been analyzed. All results of detection probability for the X-, K-, Ka-, and W-frequency bands are illustrated and summarized.

Power Calibration Loop With High Accuracy of 10 dBm ±0.5 dB for a 77-GHz Radar Application

A TX power calibration loop with high accuracy for millimeter-Wave (mm-Wave) automotive radar application is presented. The loop consists of a calibration logic, a variable gain amplifier (VGA), a power amplifier, a power detector, an analog-to-digital convertor (ADC) and a temperature sensor fabricated in a 40-nm CMOS process. The digital power calibration loop is implemented to adjust the monitored detector output voltage to a predetermined target voltage according to a temperature by controlling the gain of the VGA. To achieve high power accuracy and stability against temperature variation, the proposed power detector is designed to realize flat or monotonic characteristics against temperatures by optimizing a second distortion. Measured calibrated output power shows 10 dBm ±0.5 dB over wide temperatures ranging from −20 °C to 125 °C.

Small-field dosimetry of TrueBeamTM flattened and flattening filter-free beams: A multi-institutional analysis.

PurposeDetector‐dependent interinstitutional variations of the beam data may lead to uncertainties of the delivered dose to patients. Here we evaluated the inter‐unit variability of the flattened and flattening filter‐free (FFF) beam data of multiple TrueBeam (Varian Medical Systems) linear accelerators focusing on the small‐field dosimetry.MethodsThe beam data of 6‐ and 10‐MV photon beams with and without flattening filter measured for modeling of an iPLAN treatment planning system (BrainLAB) were collected from 12 institutions — ten HD120 Multileaf Collimator (MLC) and two Millennium120 MLC. Percent‐depth dose (PDD), off‐center ratio (OCR), and detector output factors (OF det) measured with different detectors were evaluated. To investigate the detector‐associated effects, we evaluated the inter‐unit variations of the OF det before and after having applied the output correction factors provided by the International Atomic Energy Agency (IAEA) Technical Reports Series no. 483.ResultsPDD measured with a field size of 5 × 5 mm2 showed that the data measured using an ionization chamber had variations exceeding 1% from the median values. The maximum difference from median value was 2.87% for 10 MV photon beam. The maximum variations of the penumbra width for OCR with 10 × 10 mm2 field size were 0.97 mm. The OF det showed large variations exceeding 15% for a field size of 5 × 5 mm2. When the output correction factors were applied to the OF det, the variations were greatly reduced. The relative difference of almost all field output factors were within ± 5% from the median field output factors.ConclusionIn this study, the inter‐unit variability of small‐field dosimetry was evaluated for TrueBeam linear accelerators. The variations were large at a field size of 5 × 5 mm2, and most occurred in a detector‐dependent manner.

A Low Cost Ionizing Radiation Monitoring System

It was aim of this project the development of a low - cost system, managing signals coming - out of several detectors (ionization chambers, Nal - detectors, Geiger - Mueller etc.) installed in different areas, monitoring radiation levels. The output of such detectors is a spike - like waveform, that may be introduced to a Schmitt - trigger, producing equal frequency quadratic pulses, that are counted. Alternatively, the output may be introduced to an amplified waveform V(t), corresponding to the monitored rate, will be digitized through a PCL - 812PG A/D I/O card and introduced to a PC (at least 486 DX, 33MHz, 8 MB RAM). Custom - made (Pascal 7.0) software enables the display of the signal, threshold and alarm settings, as well as , hardware parameter settings (amplification, set – off voltage, sampling rate etc.). The system has been tested experimentally. Up to 5 detectors may be mounted to the card but the software supports up to 16. Up to 10000 cpm may be registered, because of the limits of the 400Hz antializing filter, the ADC speed and the MUX PCLD - 889 characteristics. The system may be used as a simple low - cost signal monitoring device, enabling the telemetrie transmission of the signals, if required.

On the Cross-Correlation Based Loop Gain Adaptation for Bang-Bang CDRs

This article describes the cross-correlation function as an alternative method to adapt loop gain in digital CDRs. Cross-correlation function inherent properties and their link with the cross-power spectral density help consolidating the adaptive loop gain technique, XCALG, for clock and data recovery systems that implement bang-bang phase detector. Considering the modulation of the loop gain due to jitter noise, previous works exploit the autocorrelation function at the output of the bang-bang phase detector as a proper indicator to track the system dynamics and perform loop gain adaptation. In contrast, we propose the XCALG as a new alternative to perform loop gain adaptation featuring better observability, less impact from jitter sources while keeping a safe phase margin. Theory behind the idea is enhanced, and the XCALG is demonstrated through behavioral system simulations. In addition, preliminary implementation costs of the cross-correlation function are discussed using a 65nm CMOS technology node.