Radiation Length Research Articles

Optimization of echo-enabled harmonic generation toward coherent EUV and soft X-ray free-electron laser at NSLS-II.

Prebunching via echo-enabled harmonic generation (EEHG) is an efficient way to reduce the radiator length and improve the longitudinal coherence as well as output stability in storage-ring-based free-electron lasers. We propose a conceptual design, which uses two straight sections to seed coherent extreme-ultraviolet (EUV) and soft X-ray emission with nearly MHz repetition rate. To take the large energy spread (10−3) of a storage ring into account and utilize the existing bending magnets between the two straight sections as the first chicane, we implement a special modeling tool, named EEHG optimizer. This tool has been successfully applied to maximize the prebunching with a reasonably low energy modulation, thereby generating intense coherent X-ray pulses within a short undulator length (a few meters) limited by the available space of a storage ring. Numerical simulations confirm that the optimized EEHG parameters can be directly applied to generate a 10 MW scale peak power with fully coherent ultrafast EUV to soft X-ray pulses based on the NSLS-II parameters. This method can be easily extended to other types of diffraction-limited storage rings.

A semi-passive beam dilution system for the FCC-ee collider

The operation modes for the proposed FCC-ee collider foresee a very small beam spot size and stored beam energies of up to 20.6 MJ in Z production. This necessitates a dedicated beam dumping system. To reduce the complexity of the system as well as to minimize the required space, an optimized, semi-passive system has been designed and is presented here. The beam dilution is done with a defocusing triplet structure, followed by passive beam diluter elements (spoilers). This greatly reduces the risk of possible dilution failure scenarios compared to an active dilution kicker-magnet system. The dump core itself is located {sim}70~text{m} downstream of the spoilers and is designed following the experience gained from the LHC dump.The dilution performance as well as the interaction effects responsible for the energy deposited in the spoiler, are directly related to the radiation length and the dimension of the device in beam direction. Materials for these spoilers have been studied extensively and key requirements have been identified using both Monte Carlo shower simulations and thermo-mechanical Finite Element Analysis. Even though the maximum temperature reached in the spoilers is well within the working temperature range of the material, the induced mechanical stresses can lead to material failure. Thermo-mechanical simulations have shown that the transversal beam shape plays a key role in the magnitude of mechanical stresses as a result of the beam impact and the abrupt temperature change. This problem is addressed in this paper and an optimized solution is presented.

Microchannel cooling for the LHCb VELO Upgrade I

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase CO2 for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This article describes the R&D path supporting the microchannel production and assembly and the motivation for the design choices, together with the achieved fluidic and thermal performance. The Thermal Figure of Merit of the microchannel coolers is measured on the final modules to be between 1.5 and 3.5 K cm2 W−1, depending on glue thickness. The microchannel coolers constitute 18% of the total radiation length of the VELO and less than 2% of the material seen before the second measured point on the tracks. Microchannel cooling is well suited to the VELO implementation due to the uniform mass distribution, close thermal expansion match with the module components and resistance to radiation.

Design, production, burn-in and tests of the hybrid circuits of the Upstream Tracker at the LHCb detector

We present a description of the design process, prototyping and production of the hybrid circuits for the front-end electronics of the Upstream Tracker at LHCb. The multilayer polyamide-based printed circuit boards, or hybrids, are designed to host the front-end ASICs. The ASICs require an optimized power delivery network from 0 to 120 MHz, with a maximum of 10−2 Ohms round-trip resistance, and 100 Ohms differential traces. Hybrids are required to have minimal radiation length, and to withstand the harsh environmental conditions of the data taking through intrinsic radiation hardness characteristics.

Small frequency range discrete bandwidth tunable multiband MIMO antenna for radio/LTE/ISM-2.4 GHz band applications

In this paper, an equilateral triangle inspired a novel triple-band multiple-input-multiple-output (MIMO) antenna is reported for L and S-band applications. The antenna elements are very closely placed at a separation of λmax/20 with isolation better than −15 dB. The proposed antenna operates in 1.06–1.24, 1.52–2.13, and 2.19–2.63 GHz in the first, second, and third bands respectively covering most of the communication bands. The triple-band operation is obtained by extending the electrical length of the main triangular radiator using two pin diode switches and slotted triangular parasitic patches. The bandwidth of the first and second bands can be tuned between 90 and 110 MHz, and 150, 440, and 610 MHz respectively. The bandwidth of the third band can be tuned between 390 and 440 MHz. The antenna has a reasonable gain of above 3.8 dBi, co and cross-polarization isolation better than 14 dB and quasi-omnidirectional radiation pattern. The envelope-correlation-coefficient (ECC) is well below 0.5 and diversity gain (DG) more than 9.5 dB in all operating modes. The proposed work is validated by prototyping and the measurement results.

A Comparative Study of Regression Models and Meteorological Parameters to Estimate the Global Solar Radiation on a Horizontal Surface for Baghdad City, Iraq

In this study, data of the monthly average of daily global solar radiation falling on a horizontal surface, relative humidity, maximum temperature, and duration of sunshine for the city of Baghdad were collected through two sources. First, from the Iraqi Meteorological Authority (IMA) for a period extending from 1961 to 2016. The second is from NASA, for the period from 1984 to 2004. Then, four linear regression models, two single and two polynomials were formulated to calculate the values of the monthly average of daily global horizontal solar radiation (GHSR) incidents. The models calculated the monthly average of daily extraterrestrial radiation and day length, using some data provided by NASA and the IMA. To ensure the validity of the used models, a statistical test was performed for the performance of the proposed models, using the indicators mean bias Error (MBE), root mean square error (RMSE) as well as mean percentage error (MPE). The validation shows the relationship between the measured and computed values (through the analysis of the results), where a great convergence was found between the measured and calculated values. This means that the proposed models can be adapted to predict global solar radiation. The highest values of measured solar radiation were during the month of June, which were 28.555 and 27.280 MJ/m2/day from the IMA and NASA, respectively. The same applies to the radiation calculated using the four empirical models. The month of June was the highest in terms of solar radiation values. The radiation values were 28.947, 26.315, 29.699, and 26.716 MJ/m2/day for the first, second, third, and fourth models, respectively. The lowest values of measured and calculated radiation were during the month of December. Always, radiation measured by the IMA was greater than those of NASA, as well as the values of radiation calculated in the two IMA-based models were greater than the other two NSA-based models. In the absence of a method for measuring the diffuse and direct (beam) solar radiations, as well as the lack of such values by meteorological authorities, and its paramount importance, they were reported to mathematically calculate them in this study. The values of statistical indicators RMSE; MJ/m2/day, MBE; MJ/m2/day and MPE% were (0.4769, 0.0164, 0.2207), (0.8641, 0.1773, -0.9680), (0.6420, 0.3996, -1.1487), (0.9604, 0.218, -1.0225) for the first, second, third and fourth models, respectively. According to the results of the statistical test, it can be indicated that the single linear regression model, based on the IMA’s data (model No.1), is the most accurate to calculate global solar radiation for Baghdad City.

The straw tracking detector for the Fermilab Muon g-2 Experiment

The Muon g-2 Experiment at Fermilab uses a gaseous straw tracking detector to make detailed measurements of the stored muon beam profile, which are essential for the experiment to achieve its uncertainty goals. Positrons from muon decays spiral inward and pass through the tracking detector before striking an electromagnetic calorimeter. The tracking detector is therefore located inside the vacuum chamber in a region where the magnetic field is large and non-uniform. As such, the tracking detector must have a low leak rate to maintain a high-quality vacuum, must be non-magnetic so as not to perturb the magnetic field and, to minimize energy loss, must have a low radiation length. The performance of the tracking detector has met or surpassed the design requirements, with adequate electronic noise levels, an average straw hit resolution of (110 ± 20) μm, a detection efficiency of 97% or higher, and no performance degradation or signs of aging. The tracking detector's measurements result in an otherwise unachievable understanding of the muon's beam motion, particularly at early times in the experiment's measurement period when there are a significantly greater number of muons decaying. This is vital to the statistical power of the experiment, as well as facilitating the precise extraction of several systematic corrections and uncertainties. This paper describes the design, construction, testing, commissioning, and performance of the tracking detector.

Tracking and vertex detectors at FCC-ee

The combined vertexing and tracking performance of the innermost part of the FCC-ee experiments must deliver outstanding precision for measurement of the track momentum together with an impact parameter resolution exceeding by at least a factor five that typically achieved at LHC experiments. Furthermore, precision measurements require stability and fiducial accuracy at a level which is unprecedented in collider experiments. For the innermost vertex layers these goals translate into a target hit resolution of approximately 3 mu hbox {m} together with a material budget of around 0.2% of a radiation length per layer. Typically this performance might be provided by silicon-based tracking, together with a careful choice of a low-mass cooling technology, and a stable, low-mass mechanical structure capable of providing measurements with a low enough systematic error to match the tremendous statistics expected, particularly for the run around the Z resonance. At FCC-ee, the magnetic field will be limited to approximately 2 T, in order to contain the vertical emittance at the Z pole, and a tracking volume up to relative large radius is needed. The technological solution could be silicon- or gaseous-based tracking, in both cases with the focus on optimising the material budget, and particle identification capability would be an advantage. Depending on the global design, an additional silicon tracking layer could be added at the outer radius of the tracker to provide a final precise point contributing to the momentum or possibly time-of-flight measurement. Current developments in monolithic and hybrid silicon technology, as well as advanced gaseous tracking developments, provide an encouraging road map towards the FCC-ee detector. The current state of the art and potential extensions will be discussed and a generic call for technology which could have a significant impact on the performance of an FCC-ee tracking and vertexing detector is outlined.

Enhanced radiative cooling of solar cells by integration with heat pipe

Thermal management of solar cells is of vital importance to maintain adequate electrical efficiency. Lately, radiative cooling (RC) of solar cells has been researched extensively because of its passive nature and structural simplicity. However, commercial solar cells are usually encapsulated with highly emissive glass covers, and therefore the additional potential to reduce the cell temperature through RC is not significant. This study proposes a new system configuration to maximize the RC potential. It consists of a photovoltaic module for electricity generation, an RC module for heat removal to the sky, and a heat pipe for quick and efficient heat transfer between the two modules. A comparative analysis of temperature reduction and efficiency improvement between the proposed and previously studied systems is performed. The influence of input parameters (i.e., solar radiation, ambient temperature, wind speed, atmospheric emissivity, radiator length, and heat pipe resistance) on the system performance is also studied using COMSOL. Results show that in contrast to the conventional glass-coated module, the proposed system gives a maximum cell temperature reduction of 12.86 °C, which corresponds to a 7.25% relative rise in electrical efficiency. The new configuration's enhanced thermal performance supports it as an alternative to the glass-coated or ideally emissive photovoltaic modules. By addressing the challenge of limited radiative sky cooling, researchers can eventually move a step ahead and use this study for the thermal management of other devices and not just solar photovoltaics.

Comparison with experimental data of different theoretical approaches to high-energy electron bremsstrahlung including quantum coherence effects

The basic expressions for the differential nuclear bremsstrahlung cross section at high electron energy, as derived under different theoretical approaches and approximations to quantum coherence effects, are compared. The Baier-Katkov treatment is reformulated to allow introduction of the same value of the radiation length in all calculations. A dedicated Monte Carlo code is employed for obtaining photon energy spectra in the framework of the Baier-Katkov approach taking into account multiphoton emission, attenuation by pair production, and pile-up with photons from the background. The results of Monte Carlo simulations for both the Migdal and Baier-Katkov descriptions are compared to all available data that show the Landau-Pomeranchuk-Migdal suppression. The issue of the sensitivity of the experiments to the difference of the two approaches is investigated.

Radiative contribution to thermal grating decay

The decay of a spatially sinusoidal temperature perturbation (thermal grating) via thermal transport by both conduction and radiation is analyzed theoretically. The intrinsic non-radiative conduction is described by the heat diffusion equation while radiative transport is described by the radiation transport equation for a non-scattering absorbing medium. We solve the coupled equations analytically and obtain the thermal grating decay rate, which leads to an explicit expression for the radiative contribution to the effective thermal conductivity measured with the laser-induced transient thermal grating technique. We find that at a given thermal grating period, the radiative contribution to thermal transport is maximized when the absorption length of thermal radiation is about 1/4 of the period. We present the expression for an upper bound for the radiative contribution and discuss the results for representative materials. We conclude that in a typical transient grating measurement with the grating period in the micrometer range, the radiative contribution is negligible, but it may be significant if the grating period is in the millimeter or centimeter range. Our analysis also provides a Fourier-domain Green's function that can be used to find the temperature field produced by an arbitrary spatiotemporal distribution of heat sources.

Morphometrics Characterization of Thin-Tail Sheep in Lowland and Highland Areas

Breed characterization in the livestock is important for the breeding program in the future. This research aimed to characterize Thin-tail sheep in the highland and lowland areas of Jambi Province based on 7 body measurements and body indices using multivariate analysis. Data were collected from 160 sheep consisted of 80 rams and 80 ewes from each area (320 sheep in total with 1-2 years old). The research showed that the principal component analysis (PCA) in this study was explained 65.84%-72.30% by body measurements and 78.23%-84.99% by body indices of the total phenotypic variance of animals. The body measurement of cannon circumference (CC) and body indices of area index (AI), relative cannon index (RCI), dactyl thorax index (DTI), conformation index (CI), and index of body weight (IBW) were selected as the discriminating variable for Thin-tail sheep in different areas. However, this study’s canonical correlation (rc) values were 0.44 for body measurements and 0.47 for body indices. Therefore, about 67.5% of Thin-tail sheep from the lowland area and 57.5% of Thin-tail sheep from the highland area can be characterized with body measurements. Hence, about 61.2% of Thin-tail sheep from the lowland area and 65.6% of Thin-tail sheep from the highland area can be characterized with body indices. Temperature, humidity, rainfall, and length of radiation in the highland areas are lower than in the lowland areas. The cluster analysis in four Thin-tail sheep populations revealed two clusters, i.e., cluster 1 consisted of Kerinci and Sungai Penuh and cluster 2 consisted of Muaro Jambi and Batanghari. It was concluded that about 60% of Thin-tail sheep could be characterized through their body indices.

Synthesis Methods and Applications of Semiconductor Material ZnWO4 with Multifunctions and Multiconstructions

At present, nanostructures with excellent morphology have become a research hotspot. With the deepening of research and the rapid development of nanotechnology, nanosemiconductors have also made remarkable progress. In recent years, ZnWO4 in metal tungstates has been widely used in many fields, which is mainly due to its high crystal density, short radiation length, excellent optical properties, good radiation damage resistance, and non‐liquefaction. Therefore, herein, the synthesis methods and applications of ZnWO4 semiconductor materials in recent years are reviewed. First, the crystal structure and characteristics of ZnWO4 are described, and then the latest research progress of ZnWO4 semiconductor materials is summarized. The synthesis methods and contributions to photocatalysis, sensors, electronic materials, and luminescent materials are highlighted. The characteristics of ZnWO4 nanoarrays and their applications in supercapacitors are particularly emphasized, which provide a reference for the development of multifunctional nanoarrays. Finally, the challenges and countermeasures of ZnWO4 semiconductor materials are summarized and prospected. In a word, a new idea and strategy to design and assemble new types of ZnWO4 nanomaterials with multiconstructional systems and multifunctional properties for their practical applications is provided.

Dynamic Reconstruction for Facial Nerve Paralysis

Dynamic and static reconstruction procedures are employed for facial reanimation in patients suffering from facial nerve paralysis. Denervation and paralysis of the facial nerves causes considerable psychological and functional damage. Facial paralysis can affect facial expressiveness, communication, smile symmetry, eye protection, and speech competence. Due to their presumed poor prognosis, patients requiring facial nerve repair in a head and neck cancer practice are historically the least likely to receive a nerve graft. Dynamic reconstruction, on the other hand, is the gold standard in neurotology since patients are unlikely to die from their underlying condition. Even with malignant pathology, extended preoperative palsy, proximal nerve injury location, radiation, or long graft length, the current series supports the use of dynamic reconstruction. Dynamic facial reconstruction should be preformed in most cases unless there’s health risk of the method.

Error performance optimization utilizing the dynamic detection cycle in a SPAD-based free space optical communication system.

Afterpulsing is a critical non-ideal factor of the single photon avalanche diode (SPAD) at telecommunication wavelength, which limits the performance of a SPAD-based free space optical communication (FSO) system. Afterpulsing probability (AP) is highly dependent on the SPAD detection cycle. In a conventional SPAD-based system, the detection cycle is set to a relatively large constant time length to mitigate afterpulsing. However, it will limit the SPAD counting rate and degrade system performance. In order to improve system performance, a new scheme of the dynamic detection cycle is proposed to adapt to different operation conditions. Then, a multi-exponential model of AP is built and fitted with the test data of the single photon detector QCD-300. Furthermore, based on the joint model of the multi-exponential model of AP and bit error rate (BER) model of the SPAD-based FSO system, a simple and effective optimization algorithm is developed to optimize the detection cycle. And the optimization of the detection cycle under different operation conditions is also investigated. The results indicate that optimal detection cycle is dominated by signal light, background radiation, and SPAD gate length. Compared with a conventional scheme with a constant detection cycle, the proposed scheme with the dynamic detection cycle can improve system error performance effectively.

Calibration of cylindrical NaI(Tl) gamma-ray detector intended for truncated conical radioactive source

The computation of the solid angle and the detector efficiency is considering to be one of the most important factors during the measuring process for the radioactivity, especially the cylindrical γ-ray NaI(Tl) detectors nowadays have applications in several fields such as industry, hazardous for health, the gamma-ray radiation detectors grow to be the main essential instruments in radiation protection sector. In the present work, a generic numerical simulation method (NSM) for calculating the efficiency of the γ-ray spectrometry setup is established. The formulas are suitable for any type of source-to-detector shape and can be valuable to determine the full-energy peak and the total efficiencies and P/T ratio of cylindrical γ-ray NaI(Tl) detector setup concerning the truncated conical radioactive source. This methodology is based on estimate the path length of γ-ray radiation inside the detector active medium, inside the source itself, and the self-attenuation correction factors, which typically use to correct the sample attenuation of the original geometry source. The calculations can be completed in general by using extra reasonable and complicate analytical and numerical techniques than the standard models; especially the effective solid angle, and the detector efficiency have to be calculated in case of the truncated conical radioactive source studied condition. Moreover, the (NSM) can be used for the straight calculations of the γ-ray detector efficiency after the computation of improvement that need in the case of γ-γ coincidence summing (CS). The (NSM) confirmation of the development created by the efficiency transfer method has been achieved by comparing the results of the measuring truncated conical radioactive source with certified nuclide activities with the γ-ray NaI(Tl) detector, and a good agreement was obtained after corrections of (CS). The methodology can be unlimited to find the theoretical efficiencies and modifications equivalent to any geometry by essential sufficiently the physical selective considered situation.

Turbulent transport of radiation in the solar convective zone

ABSTRACTA turbulent transport of radiation in the solar convective zone is investigated. The mean-field equation for the irradiation intensity is derived. It is shown that due to the turbulent effects, the effective penetration length of radiation can be increased several times in comparison with the mean penetration length of radiation (defined as an inverse mean absorption coefficient). Using the model of the solar convective zone based on mixing length theory, where the mean penetration length of radiation is usually much smaller than the turbulent correlation length, it is demonstrated that the ratio of the effective penetration length to the mean penetration length of radiation increases 2.5 times in the vicinity of the solar surface. The main reasons for this are the compressibility effects that become important in the vicinity of the solar surface where temperature and density fluctuations increase towards the solar surface, enhancing fluctuations of the radiation absorption coefficient and increasing the effective penetration length of radiation.

Suppressed Transmission of Long-Range Surface Plasmon Polariton by TE-Induced Edge Plasmon.

Work on controlling the propagation of surface plasmon polaritons (SPPs) through the use of external stimuli has attracted much attention due to the potential use of SPPs in nanoplasmonic integrated circuits. We report that the excitation of edge plasmon by TE-polarized light passing across gapped-SPP waveguides (G-SPPWs) leads to the suppressed transmission of long-range SPPs (LRSPPs) propagating along G-SPPWs. The induced current density by highly confined edge plasmon is numerically investigated to characterize the extended radiation length of decoupled LRSPPs by the TE-induced edge plasmon. The suppressed transmission of LRSPPs is confirmed using the measured extinction ratio of the plasmonic signals which are generated from the modulated optical signals, when compared to the extended radiation length calculated for a wide range of the input power. It is also shown that LRSPP transmission is sensitive to the excited power of edge plasmon in the gap through the permittivity change near the gap. Such a control of SPPs through the use of light could be boosted by the hybridized edge plasmon mode and a huge field enhancement using nanogap, gratings or metasurfaces, and could provide opportunities for ultrafast nano-plasmonic signal generation that is compatible with pervasive optical communication systems.

Design of a Low-Crosstalk Sub-Wavelength-Pitch Silicon Waveguide Array for Optical Phased Array

In this work, a compact sub-wavelength-pitch silicon waveguide array with low crosstalk is proposed and analyzed. The crosstalk is suppressed by periodic silicon nano-blocks symmetrically arranged along the silicon strip waveguides. The silicon nano-blocks are properly designed to work in the resonant region as a high-reflection boundary so that the evanescent fields of the silicon waveguide, which directly contribute to the coupling between waveguides, can be truncated. Meanwhile, the nano-blocks periodically perturb the evanescent fields to form a weak-radiating grating, leading to a millimeter-long effective radiation length required for highly directive optical phased arrays. Simulation results show that the crosstalk between the waveguides in the proposed design is at least 10 dB lower than traditional waveguide array with identical sizes within the 1500-1590 nm bandwidth. Furthermore, the proposed design achieves an effective radiation length up to 1.47 mm, resulting in a theoretical narrow beam width of 0.052°. Combining both the low crosstalk and the long effective radiating length, our design offers a promising platform for high-performance two-dimensional scanning optical phased array with a large field of view and a narrow beam width.

Determination of the dependence between climatic factors and Covid-19 disease incidence

The purpose of research consists in definition and an estimation of climatic factors influence on disease incidence of Covid-19 on an example of Mykolaiv city. In research we used such scientific methods: theoretical methods: analysis, synthesis, monitoring, systematization, generalization. For research facility, were held by calculations based on software Microsoft Excel. The calculations were performed using the formula correlation. Results. The study examines the influence of climatic factors such as air temperature, humidity, solar radiation activity, wind speed, rainfall, and length of daylight. For the pair «Disease incidence – Temperature» the correlation coefficient is −0.74. For the pair «Disease incidence − Solar Radiation» correlation coefficient is −0.71. For the pair «Disease incidence – Daylight hours» correlation coefficient is −0.70. Humidity, as a derivative of air temperature, is evidenced by a comparison of decline periods and growth of these values. In the spring, along with the increase in temperature, the humidity dropped, and in the fall, when the air temperature dropped, the humidity increased. This factor also affected the spread of the virus in the second half of the year, when the humidity increased the virus began to spread faster. For the pair «Disease incidence – Humidity» correlation coefficient is +0.73 (average direct correlation). Other climatic factors, such as wind speed and rainfall, have not been shown to have a significant effect on the rate of disease spread. For the pair «Disease incidence − Wind speed» correlation coefficient is +0.32, which corresponds to a weak direct correlation. For the pair «Disease incidence − Rainfall» correlation coefficient is −0.30, which indicates a weak inverse correlation. Conclusion. The results of the study show that the reduction of disease incidence is observed at high temperatures, high activity of solar radiation, and prolonged daylight, which determines the conditions for the prevention of such diseases and will improve the quality of life to achieve sustainable development.