Large Effective Area Research Articles

The Crystal Eye X and gamma-ray detector for space missions

Crystal Eye idea comes from the analysis of two gravitational waves events: GW170817 and GW190425. Both events were referred to neutron star mergers. In the first case Fermi-GBM and INTEGRAL claimed the detection of a short Gamma Ray Burst (GRB 170817A) and in order to follow up and target the GW electromagnetic counterparts, a huge effort has been made by other satellites and ground-based experiments. In the second case, only INTEGRAL claimed the detection of a faint GRB (GRB 190425) while Fermi satellite was in Earth occultation. Crystal Eye is a space-based X and γ ray all-sky monitor sensitive in the 10 keV - 30 MeV energy range. In its baseline configuration, it consists of a hemisphere, made by 112 pixels, with a wide (about 6 sr) field of view (FOV), a full sky coverage and a very large effective area (6 times Fermi-GBM at 1 MeV) in the energy range of interest. Given the pixel structure – a two-layer crystal scintillator and a plastic scintillator veto layer – and the hemispherical design, Crystal Eye concentrate the pointing capability of a γ-ray telescope and the sky coverage of an all-sky monitor in a single detector. Moreover, the use of Silicon Photomultiplier (SiPM) at the place of traditional PMs, besides being a challenge for their qualification for space missions, allows a more compact and less power-consuming design. A Crystal Eye pathfinder has been designed and realized to be tested in view of the mission on the Space Rider by ESA. The prototype is made by 4 pixels. The mission is aimed at testing in the space environment the LYSO crystals, the MPPC-arrays and the DAQ board.

Current Status of the HERD Space Mission Design

HERD (High Energy Radiation Detector) is a future experiment for space-based detection of cosmic rays and gamma ray astronomy onboard the Chinese Space Station. Its most innovative feature will be the event collection from 5 sides, and with its large size it will result in a one-order-of-magnitude jump in acceptance with respect to current largest calorimetric experiments. This will make possible to investigate cosmic ray spectra for each species up to the so-called knee region at PeV energies. The all-electron spectrum will be also measured up to about 10 TeV (depending on the actual flux) and the gamma sky will be studied with a large effective area from a few hundreds MeV up to few TeV, also allowing for the search for possible signatures from dark matter particles in our galaxy.

Heterogeneously Integrated Multicore Fibers for Smart Oilfield Applications

In the context of Industry 4.0, the smart oilfield is introduced, which relies on large-scale information exchange among various parts, and there is an urgent need for special fiber links for both increased data transmission capacity and high-sensitivity distributed sensing. Multicore fibers can be expected to play a critical role, in the parts of cores that are responsible for data transmission, while others are used for sensing. In this paper, we propose a heterogeneously integrated seven-core fiber for interconnection and awareness applications in smart oilfields, which could not only support digital and analog signal transmission but could also measure temperature and vibration. The core for digital signal transmission has a low differential mode group delay of 10 ps/km over the C-band, and the crosstalk between adjacent cores is lower than −55 dB/km at the pitch of 50 μm. A 25-Gbaud transmission over 50 km is simulated. Each core for analog signal transmission has a large effective area of 172 μm2 to suppress the nonlinear effect due to the watt-scale input power. The proposed heterogeneously multicore fiber exhibits great potential to be applied in smart oilfields, meeting the demand for efficient and cost-effective oil production.

Gas clumping in the outskirts of galaxy clusters, an assessment of the sensitivity ofSTAR-X

AbstractIn the outskirts of galaxy clusters, entropy profiles measured from X-ray observations of the hot intracluster medium (ICM) drops off unexpectedly. One possible explanation for this effect is gas clumping, where pockets of cooler and denser structures within the ICM are present. Current observatories are unable to directly detect these hypothetical gas clumps. One of the science drivers of the proposed STAR-X observatory is to resolve these or similar structures. Its high spatial resolution, large effective area, and low instrumental background make STAR-X ideal for directly detecting and characterizing clumps and diffuse emission in cluster outskirts. The aim of this work is to simulate observations of clumping in clusters to determine how well STAR-X will be able to detect clumps, as well as what clumping properties reproduce observed entropy profiles. This is achieved by using yt, pyXSIM, SOXS, and other tools to inject ideally modelled clumps into 3D models derived from actual clusters using their observed profiles from other X-ray missions. Radial temperature and surface brightness profiles are then extracted from mock observations using concentric annuli. We find that in simulated observations for STAR-X, a parameter space of clump properties exists where gas clumps can be successfully identified using wavdetect and masked, and are able to recover the true cluster profiles. This demonstrates that STAR-X could be capable of detecting substructure in the outskirts of nearby clusters and that the properties of both the outskirts and the clumps will be revealed.

Highly Sensitive Bilirubin Biosensor Based on Photonic Crystal Fiber in Terahertz Region

An unstable bilirubin level in the human blood causes many dangerous health problems, such as jaundice, coronary artery disease, ulcerative colitis, and brain lesions. Therefore, the accurate and early detection of bilirubin concentrations in the blood is mandatory. In this work, a highly sensitive biosensor based on photonic crystal fiber (PCF) for monitoring bilirubin levels is proposed and analyzed. The sensor parameters, including relative sensitivity, effective mode area, confinement loss, and effective material loss, are calculated. The geometrical parameters are studied, and a modal analysis of the suggested sensor is carried out using the full-vectorial finite element method (FEM). The fabrication tolerance of the geometrical parameters is also studied to ensure the fabrication feasibility of the reported design. High sensitivities of 95% and 98% are obtained for the x-polarized and y-polarized modes, respectively. Furthermore, a small material loss of 0.00193 cm−1, a small confinement loss of 2.03 × 10−14 dB/cm, and a large effective mode area of 0.046 mm2 are achieved for the y-polarized mode. It is believed that the presented sensor will be helpful in health care and in the early detection of bilirubin levels in the blood.

Dynamic stress concentrations around a single fiber break in unidirectional composites: a 3D finite element analysis

When a fiber break occurs in longitudinal tension of a unidirectional composite, dynamic stress concentrations arise, which can be different from the ones found considering only static loading. The current paper analyzes the dynamic stress concentration factors (SCF) around a fiber break in unidirectional carbon fiber/epoxy composites. 3D finite element models with random and hexagonal fiber distributions were analyzed to investigate the evolution of stress concentrations as a function of time and position. The results indicate that dynamic effects result in much higher SCFs with a larger effective area around the broken fiber. The increase of SCFs in the closest fibers was determined to be larger for lower fiber volume fractions due to the presence of dynamic effects. Similar to the static case, a lower volume fraction causes higher maximum dynamic SCF in random packings. Results also support the high prevalence of coplanar cluster breaks observed in the experiments.

Analysis of Different Types of Antenna for Television Network and Extracting C Band Channels

Television network is a system of transmitting and receiving television signals over a large area. Antenna is a device that converts electromagnetic waves into electric currents or vice versa. Antenna plays a crucial role in the performance and quality of television network. In this paper, we will analyze different types of antenna for television network, such as dipole antenna, yagi antenna, parabolic antenna and fractal antenna. We will compare their advantages and disadvantages, and suggest some criteria for choosing the best antenna for different scenarios. Dipole antenna is the simplest and most common type of antenna for television network. It consists of two metal rods or wires of equal length that are connected to a transmitter or receiver. Dipole antenna can receive signals from any direction in a horizontal plane, but has a low gain and a narrow bandwidth. Dipole antenna is suitable for local television stations or indoor applications. Yagi antenna is a directional antenna that consists of a dipole antenna and several parasitic elements, such as reflectors and directors. Yagi antenna can focus the signals in one direction and reject the signals from other directions, thus increasing the gain and reducing the interference. Yagi antenna has a moderate bandwidth and can be easily adjusted to different frequencies. Yagi antenna is suitable for long-distance television network or outdoor applications. Parabolic antenna is another directional antenna that consists of a parabolic reflector and a feed horn. Parabolic antenna can concentrate the signals into a narrow beam and achieve a high gain and a wide bandwidth. Parabolic antenna can also receive signals from satellites or other high-altitude sources. Parabolic antenna is suitable for satellite television network or high-definition television network. Fractal antenna is a novel type of antenna that uses fractal geometry to design its shape and structure. Fractal antenna can have multiple resonant frequencies and a large effective area, thus increasing the bandwidth and the efficiency. Fractal antenna can also have self-similarity and scalability, which means it can be miniaturized or enlarged without affecting its performance. Fractal antenna is suitable for digital television network or wireless communication network. In conclusion, different types of antenna have different characteristics and applications for television network. Depending on the factors such as distance, frequency, direction, interference, quality and cost, one can choose the best antenna for their specific needs

PROGRESS IN THE STUDY OF DECAMETER-WAVELENGTH SOLAR RADIO EMISSION WITH UKRAINIAN RADIO TELESCOPES. Part 1. (Invited paper)

Subject and Purpose. Results are presented of the solar corona investigations performed with the world famous Ukrainian radio telescopes. The work has been aimed at offering a consistent review of recent achievements in observations of a variety of low-frequency radio emissions from the Sun. Methods and Methodology. The studies of the quiet (thermal) and sporadic (burst-like) radio emissions from the Sun have been car- ried out with the decameter-wavelength radio telescopes UTR-2, GURT and URAN-2. Specific features of the low-frequency solar radio emissions from a variety of sources are presented, with characterization of the optimized techniques that were applied in each case for evaluating physical parameters of the corona in the areas of decameter-wavelength radio wave generation. Results. The analysis of temporal, frequency and spatial characteristics of solar radio emissions has allowed suggesting a number of models for the coronal electron density distribution, and evaluating magnetic field strengths in the corona. Also, our experimental results have proven to be consistent with the observational data obtained in different frequency ranges and with the use of both ground based and space-borne instruments. Conclusions. The radio observations performed with Ukrainian radio telescopes have permitted studying, with high temporal, fre- quency and spatial resolutions, solar radio frequency emissions from various localized sources. Along with the large effective area and high sensitivity of the antennas, this permits application of a wide range of methods and tools aimed at detecting and analyzing solar bursts, of both strong and weak intensity, against the background of terrestrial interference of natural or artificial origin

Theoretical study of a novel porous penta-TaB with two-dimensional furrow surface as an anode for lithium-ion batteries

The transition metal boride five TaB anode material has small mass density, large effective specific surface area and high specific capacity. The two-dimensional wrinkled surface is favorable for the rapid diffusion of lithium ions.

Terahertz Women Reproductive Hormones Sensor Using Photonic Crystal Fiber With Behavior Prediction Using Machine Learning

In this article, we propose a rectangular hollow core Photonic Crystal Fiber (PCF) sensor for high detection of women’s reproductive hormones (progesterone and estradiol) in the blood sample at THz regime (0.8 THz to 1.7 THz). The numerical sensing performances are evaluated by the full vector finite element method (FVFEM). We have achieved improved relative sensitivity with minimal loss for sensing progesterone concentrations and estradiol concentrations by optimizing structural parameters. The obtained maximum relative sensitivity is 99.87% for 10 n mol/L (progesterone) and 99.88% for 3 n mol/L (Estradiol) at 1.35 THz. Further, we have obtained low effective material loss (EML) and a large effective mode area. The primary takeaway from this research is that it’s critical to monitor estradiol and progesterone levels in order to ensure that a woman’s reproductive system is functioning in a balanced manner and in general health systems. Also, this biosensor can be fabricated by current fabrication technologies. Moreover, the prediction carried out with the help of Locally Weighted Linear Regression, and hyperparameter tuning, we can conclude that for weighting hyperparameter value of 0.02. We have achieved the maximum prediction accuracy with the unity R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> score and this model can be employed for the prediction of relative sensitivity for various parameters.

Spectroradiometry of the Solar Corona on the RATAN-600

Modern studies of solar radio emission are complicated by continuous power amplification and multifrequency external interference, which often completely overlap important frequency ranges. Many topical problems in solar radio astronomy require large effective areas of radio telescopes, high frequency and time resolutions, accurate spatial measurements, and a large dynamic range. It becomes relevant to change the concept of receiving recording equipment. This paper deals with topical problems of the physics of the solar corona in combination with optimal methods of observation with large instruments. The features and difficulties of combining high parameters—dynamic, spatial, temporal, and frequency resolutions—are considered. The proposed solutions of the new-generation observation complex implement the possibilities of intelligent selection of registration conditions in a multioctave mode with multichannel over 8000 channels/GHz with temporary permission up to 8 ms/spectrum. A multiobject observation mode becomes available from powerful flaring objects to faint structures of various nature. High-speed data processing makes it possible to implement an online mode of interference elimination, which is based on a fast statistical analysis of the spectrum with the selection of non-Gaussian (interference) structures. Methods for high-speed analysis of large-volume data (the principal component analysis method) and their presentation to the user are proposed. Examples of the operation of the complex in the range of 1–3 GHz are given. The prospects of a new approach for multiobject radio astronomy observations in the implementation of the RATAN-600 tracking mode are considered: from recombination lines to wide-range spectra, from low-contrast fluctuations to fast changes in flares, etc.

Uniformity calibration for large area XY strip parallel plate ionization chamber

Demand for large area parallel plate ionization chamber (PPIC) or large area ionization chamber (LAIC) has risen in recent years due to several advantages of the large effective area in monitoring therapeutic radiation beams. PPICs are designed for the measurements of beam profile and dosimetry in radiation therapy quality assurance (QA) procedures. Objective. Heterogeneous responses over the large sensitive area pose an undeniable concern for the straightforward applications of PPICs in clinical dosimetry. Uniformity calibration for the detector response is thus essential for the accurate performance of each PPIC unit. Approach. A large area XY strip PPIC, characterized by a large effective area of 345.44 × 345.44 mm2 and 256 readout channels, was investigated in this study. A new systematic uniformity calibration is developed to improve the lateral response of the PPIC over the measurements for both narrow beams and large square field beams. A 2D response map of the PPIC was obtained by a spot-scanning method using a compact x-ray tube (mini x-ray). The mini x-ray, providing stable radiation (uncertainty <0.1%), was moved with a step size of 20 mm in 2 dimensions across the entire PPIC surface to collect a complete spot scan. Different uniformity calibration methods were introduced for the measurement of the PPIC by adopting the information from the detector 2D response map. Main results. Deviation of the detector response, before calibration, was observed to reach about 7% for the testing PPIC unit which is much higher than the recommended uniformity response of 1% (IAEA TRS-398). The uniformity response of the PPIC improved significantly to less than 1% across the detector surface after calibration. Significance. The proposed methods enable the practical application of PPIC in routine clinical dosimetry and can be reliably adopted by any radiation facility to perform daily and monthly QA.

In-situ growth microcircuits on bacterial membranes to enhance ion capture capability for capacitive deionization

The combination of biotechnology and artificial nanotechnology provide new breakthroughs in the design and manufacture of energy materials. In this work, the porous hollow hyphae carbon membrane with different thicknesses were acquired by biological cultivation approach, along with adsorbed Ni2+ as the in-situ growth points. Then, ultrafine hollow carbon tubes generated on the hyphae surface, forming multi-stage composite membrane (CNTs@MC) with tubules covering large tubes. Subsequently, rich amino functional groups were grafted onto MC (hyphae carbon membrane) surface to further improve its hydrophilicity and capacitance. In addition to the hollow structure, the hyphae carbon surface presents many small holes around 50 nm, which not only provides space for Ni2+ adsorption, but also favors the generation of double-layer capacitance. As secondary structure, ultrafine carbon nanotubes as microcircuits capture more charged ions on hyphae surface, thus offering better capacitance performance. The multistage hollow structure enhances the stability of material during ion adsorption. The grafted amino functional groups and intrinsic heteroatomic defects synergically enhance the wettability and pseudocapacitance of material. In general, large effective specific surface area, abundant surface amino functional groups and intrinsic heteroatomic defects guarantee the high capacitance of material, and also exhibits desirable performance in both solid-state supercapacitors and capacitive deionization applications.

Multi-wavelength continuous-wave convertor driven by forward Brillouin scattering in large effective area fiber

Multi-wavelength wavelength convertor (MWC) has many important applications in the fields of optical communications and optical fiber sensing. In this paper, a brand-new MWC driven by forward Brillouin scattering (FBS) in a large effective area fiber (LEAF) is proposed and demonstrated. In the MWC, the incident multi-wavelength light waves excite acoustic vibration in fiber by optomechanical interactions, and causes a change in the refractive index of the fiber through electrostriction effect. The changed refractive index causes phase modulation which applied on a single-wavelength light wave with target wavelength, and the single-wavelength light wave is modulated into multi-wavelength light waves while keeping the target wavelength as the central frequency. In a proof-of-concept experiment, a 2-km long LEAF is used as wavelength conversion medium, and the obtained MWC features very low deteriorations in side-mode suppression ratio (SMSR), multi-wavelength output power flatness and signal to noise ratio (SNR). The demonstrated MWC also has a wide tunable target wavelength ranges up to 23.6 nm, discretely tunable frequency interval up to over 1 GHz, low total output power fluctuation of 4.68%, and a conversion efficiency improvement of 2.55 dB. Its good performance may provide a promising way to design high-performance multi-wavelength convertor.

A novel few-mode multi-core fiber with large effective mode area and low inter-core crosstalk

This paper proposes a novel 7-core 5-mode fiber with large mode area and low inter-core crosstalk(XT). The proposed optical fiber, by adopting a combination of air-trench structure and high-index ring, realizes large mode area and low XT. The numerical analyses reveal that the proposed fiber can stably transmit 5 LP modes in the C+L band; the effective mode area of each of the 5 LP modes is larger than 110 µm2; the XT of in each of the 5 LP modes is smaller than −79 dB/km; each mode has an effective refractive index difference bigger than 1.1 × 10−3. Therefore, a low XT result can still be achieved when the mode area is large. The proposed optical fiber may be well utilized to construct a high-capacity fiber optic transmission system.

Correcting MAGIC Telescope data taken under non-optimal atmospheric conditions with an elastic LIDAR

The Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes are a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs). IACTs make calorimetric use of the Earth’s atmosphere, which allows them to reach large effective areas, but also makes them strongly dependent on the quality of the atmosphere at the time of the observations. Dust intrusions or clouds obscuring the observed Cherenkov light can then lead to a wrong reconstruction of the gamma-ray data. In order to mitigate this problem, the MPP group built and has been operating a single wavelength elastic LIDAR (LIght Detection And Ranging) system to perform real time ranged-resolved measurements of the aerosol transmission. This information is then used to quantify the quality of the telescope data, as well as to correct the data taken under suboptimal aerosol conditions. In this talk, the correction of atmospherically impaired IACT data will be described and the first systematic evaluation of the correction capabilities of the LIDAR system will be presented. The results describe the impact of the LIDAR corrections for a variety of atmospheric and observational conditions, and therefore contribute to a better understanding of the telescope’s performance and related systematic uncertainties.

Gamma Ray Source Localization for Time Projection Chamber Telescopes Using Convolutional Neural Networks

Diverse phenomena such as positron annihilation in the Milky Way, merging binary neutron stars, and dark matter can be better understood by studying their gamma ray emission. Despite their importance, MeV gamma rays have been poorly explored at sensitivities that would allow for deeper insight into the nature of the gamma emitting objects. In response, a liquid argon time projection chamber (TPC) gamma ray instrument concept called GammaTPC has been proposed and promises exploration of the entire sky with a large field of view, large effective area, and high polarization sensitivity. Optimizing the pointing capability of this instrument is crucial and can be accomplished by leveraging convolutional neural networks to reconstruct electron recoil paths from Compton scattering events within the detector. In this investigation, we develop a machine learning model architecture to accommodate a large data set of high fidelity simulated electron tracks and reconstruct paths. We create two model architectures: one to predict the electron recoil track origin and one for the initial scattering direction. We find that these models predict the true origin and direction with extremely high accuracy, thereby optimizing the observatory’s estimates of the sky location of gamma ray sources.

Photocatalytic Performance of ZnO/Ag(NPs) Nanocomposite Thin Films under Natural Conditions

The original technique developed for the direct incorporation and efficient dispersion of silver metal NPs into ZnO precursor solution allowed us to elaborate nanocomposite thin films with a large effective surface area for interaction with the external environment as well as a large surface area for metal–semiconductor interaction suitable for surface photocatalysis reactions. Such photocatalysts have the advantage of being in solid form, combining the benefits of the semiconductor material and the metallic nanoparticles embedded in it, while being eco-friendly. Their photocatalytic performance was analyzed under different operating conditions. The improved photocatalytic performance, stability, and reusability of the nanocomposite were demonstrated under both laboratory and natural conditions of use. The results of the present study provide interesting perspectives for the application of these photocatalysts in water treatment.

Low crosstalk and large effective mode field area heterogeneous 13-core 6-mode fiber with double high refractive index rings

We propose a heterogeneous thirteen-core few-mode fiber, which has the excellent characteristics of low crosstalk (XT), large effective mode field area (Aeff) and low dispersion slope (Dslope). The double high refractive index ring can precisely control the effective refractive index difference between the LP mode in the core and reduce intra-core XT. The relative spatial efficiency (RSE) of the 13-core 6-mode fiber reaches 33.84, and the number of spatial channels is as high as 130. The inter-core crosstalk is less than −60 dB/km at 1550 nm. The results show that the proposed fiber with low crosstalk and large Aeff is sufficient to satisfy the requirements of long-distance transmission in the future.

Strong, Tough, and Adhesive Polyampholyte/Natural Fiber Composite Hydrogels.

Hydrogels with high mechanical strength, good crack resistance, and good adhesion are highly desirable in various areas, such as soft electronics and wound dressing. Yet, these properties are usually mutually exclusive, so achieving such hydrogels is difficult. Herein, we fabricate a series of strong, tough, and adhesive composite hydrogels from polyampholyte (PA) gel reinforced by nonwoven cellulose-based fiber fabric (CF) via a simple composite strategy. In this strategy, CF could form a good interface with the relatively tough PA gel matrix, providing high load-bearing capability and good crack resistance for the composite gels. The relatively soft, sticky PA gel matrix could also provide a large effective contact area to achieve good adhesion. The effect of CF content on the mechanical and adhesion properties of composite gels is systematically studied. The optimized composite gel possesses 35.2 MPa of Young's modulus, 4.3 MPa of tensile strength, 8.1 kJ m-2 of tearing energy, 943 kPa of self-adhesive strength, and 1.4 kJ m-2 of self-adhesive energy, which is 22.1, 2.3, 1.8, 6.0, and 4.2 times those of the gel matrix, respectively. The samples could also form good adhesion to diverse substrates. This work opens a simple route for fabricating strong, tough, and adhesive hydrogels.