Suppression Factor Research Articles

External-cavity diode laser at 2.6 µm and its frequency stabilization with a scanning Fabry-Pérot cavity

We report on the construction of an external cavity diode laser at 2.6 µm wavelength and its frequency stabilization with an external scanning Fabry-Pérot cavity using Pound-Drever-Hall (PDH) frequency stabilization technique. We discuss the frequency noise characteristics of the laser using the PDH residual error signal analysis and the locking performance. We have achieved a 2.5 x 105 suppression factor in the frequency noise power spectral density at Fourier frequencies lower than 100 Hz when the laser is stabilized. The laser is employed to observe resonant excitation on the 5s5p3P0 →5s4d3D1 transition in cold 88Sr atoms trapped in a magneto-optical trap. We have observed an enhancement in the trapped atom number by a factor of 8.3 compared to the case when a single laser at 707 nm is employed for repumping.

Multimodal Consistency Suppression Factor for Fake News Detection

Recent multi-modal fake news detection methods often use the consistency between textual and visual contents to determine the truth or fake of a news information. Higher levels of textual-visual consistency typically lead to a greater likelihood of classifying a news item as real. However, a critical observation reveals that creators of most fake news intentionally select images that align with the textual content, thereby enhancing the credibility of the news. Consequently, high consistency between textual and visual contents alone cannot guarantee the authenticity of the information. To address this problem, we introduce a novel approach termed Multimodal Consistency-based Suppression Factor to modulate the significance of textual-visual consistency in information assessment. When the textual-visual matching is high, this suppression factor reduces the influence of consistency during the judgment process. Moreover, we use Contrastive Language-Image Pre-training (CLIP) model to extract features and measure the consistency level between modalities to guide multimodal fusion. In addition, we also use a method of compressing and fusing modal information based on Variational Autoencoder (VAE) to reconstruct CLIP features, learning the shared representation of different modal information of CLIP. Finally, extensive experiments were conducted on three publicly datasets, Weibo, Twitter and Weibo21, and the results confirmed that our method outperformed the state-of-the-art methods in the field, and had 0.8%, 2.6% and 4.1% effect improvement on the accuracy rate.

Evolution mapping II: describing statistics of the non-linear cosmic velocity field.

Abstract We extend the evolution mapping approach, introduced in the first paper of this series to describe non-linear matter density fluctuations, to statistics of the cosmic velocity field. This framework classifies cosmological parameters into shape parameters, which determine the shape of the linear matter power spectrum, PL(k, z), and evolution parameters, which control its amplitude at any redshift. Evolution mapping leverages the fact that density fluctuations in cosmologies with identical shape parameters but different evolution parameters exhibit similar non-linear evolutions when expressed as a function of clustering amplitude. We analyse a suite of N-body simulations sharing identical shape parameters but spanning a wide range of evolution parameters. Using a method for estimating the volume-weighted velocity field based on the Voronoi tesselation of simulation particles, we study the non-linear evolution of the velocity divergence power spectrum, Pθθ(k), and its cross-power spectrum with the density field, Pδθ(k). We demonstrate that the evolution mapping relation applies accurately to Pθθ(k) and Pδθ(k). While this breaks down in the strongly non-linear regime, deviations can be modelled in terms of differences in the suppression factor, g(a) = D(a)/a, similar to those for the density field. Such modelling describes the differences in Pθθ(k) between models with the same linear clustering amplitude to better than 1percnt accuracy at all scales and redshifts considered. Evolution mapping simplifies the description of the cosmological dependence of non-linear density and velocity statistics, streamlining the sampling of large cosmological parameter spaces for cosmological analysis.

Nuclear suppression of coherent J/ψ photoproduction in heavy-ion ultraperipheral collisions and leading twist nuclear shadowing

We determine the nuclear suppression factor SPb(x), where x=MJ/ψ2/Wγp2 with MJ/ψ the J/ψ mass and Wγp the photon-nucleon energy, for the cross section of coherent J/ψ photoproduction in heavy-ion ultraperipheral collisions at the Large Hadron Collider and Relativistic Heavy Ion Collider by performing the χ2 fit to all available data on the cross section dσAA→J/ψAA/dy as a function of the J/ψ rapidity y and the photoproduction cross section σγA→J/ψA(Wγp) as a function of Wγp. We find that while the dσAA→J/ψAA/dy data alone constrain SPb(x) for x≥10−3, the combined dσAA→J/ψAA/dy and σγA→J/ψA(Wγp) data allow us to determine SPb(x) in the wide interval 10−5<x<0.05. In particular, the data favor SPb(x), which decreases with a decrease of x in the 10−4<x<0.01 interval and can be both decreasing or constant for x<10−4. Identifying SPb(x) with the ratio of the gluon distributions in Pb and the proton Rg(x,Q02)=gA(x,Q02)/[Agp(x,Q02)], we demonstrate that the leading twist approximation for nuclear shadowing provides a good description of all the data on dσAA→J/ψAA/dy and σγA→J/ψA(Wγp) as well as on the experimental values for SPb(x) derived from σγA→J/ψA(Wγp). We also show that modern nuclear parton distributions reasonably reproduce SPb(x) as well. Published by the American Physical Society 2024

Growth orientation control in rapid solid-state crystal growth of (K,Na)NbO3 single crystals using plate-like NaNbO3 single crystal particles

The rolling-extended orientation technique and plate-like NaNbO3 (NN) single crystal particles prepared by a single-step molten salt synthesis, both of which have been developed to fabricate (K, Na)NbO3 (KNN) textured ceramics, were utilized to control the growth orientation of KNN single crystals synthesized by a rapid solid-stated crystal growth (RSSCG) method. As the seed crystals, two kinds of NN single crystal particles were synthesized using pure NaCl and KCl-NaCl mixed molten salts. Plate-like KNN single crystals of about 1 cm squares with the upper and lower faces almost parallel to the (100) (001) planes were obtained with a probability exceeding 50% when NN single crystal particles were synthesized from mixed salts and were subsequently thermal-treated again in Na2CO3-NaCl mixed molten salts under appropriate conditions to remove the Bi element, which is known as the suppression factor of the crystal growth. The average crystal growth rate was 0.6–1.2 mm h−1. Controlling the growth orientation of KNN single crystals produced by the SSCG method using seed crystals other than KTaO3 single crystals was successfully accomplished for the first time.

Effect of the Tesla Valve on the heat transfer performance and the suppression of pressure drop oscillation in a liquid cooling loop

The suppression of pressure drop oscillation within a liquid cooling loop is necessary to maintain the system stability and develop a steady heat transfer performance. The Tesla Valve is proposed as a means of eliminating this instability by suppressing the backward flow, which in turn facilitates a stable heat transfer process. The steady-state analysis is performed to identify the conditions that would induce flow instability. The calculated results indicate that the flow instability will appear when the heat flux (q) reaches a threshold value of 28 W/cm2. Furthermore, the impact of the Tesla Valve on the suppression of instability and the heat transfer coefficient is revealed by comparison with the dynamic features observed in a common liquid cooling loop. Two flow instability regimes, with and without backflow, are observed in the common liquid cooling loop. In the case of the former instability, a violent fluctuation in both the inlet temperature and the heat transfer coefficient is captured. This phenomenon can be effectively eradicated by the Tesla Valve. In the latter instability regime, the hydrodynamic characteristics of pressure drop remain significantly oscillatory, while the heat transfer performance returns stable. Furthermore, this specific form of instability cannot be eliminated by the prototype I of Tesla Valve when q ≥ 30.4 W/cm2. In addition, the liquid cooling loop with prototype III displays a superior heat transfer performance, yet results in an additional pressure drop of 8.1 kPa in comparison to prototype II. To assess the suppression mechanism and efficiency, the Suppression Factor (Fs) and Coefficient of Suppression Performance (Fc) are proposed. It can be found that the pressure drop oscillation instability can be thoroughly suppressed by the Tesla Valve when Fs > 1. Meanwhile, the greater the Fc, the more effective the suppression performance. However, the incorporation of the Tesla Valve shows a negligible effect on the heat transfer performance in the two-phase region.

Particle identification using plastic scintillators in the COMET Phase-I experiment

The COMET (COherent Muon to Electron Transition) Phase-I experiment aims to search for muon to electron conversion with a single event sensitivity of O (10−15). In COMET, a Cylindrical Trigger Hodoscope (CTH), consisting of segmented plastic scintillators, provides a primary trigger signal and timing measurement while suppressing backgrounds under the high rate environment. This paper studies the particle identification capability of CTH to suppress one of the serious backgrounds induced by cosmic-rays. We demonstrated that a background suppression factor greater than 10 is achievable with a signal efficiency higher than 90%.

Jet quenching of the heavy quarks in the quark-gluon plasma and the nonadditive statistics

Using the Plastino-Plastino (PP) equation, we calculate transport coefficients of the heavy-quarks traversing inside the quark-gluon plasma, and generalize their relationship with differential energy loss. The PP equation indicates anomalous diffusion of the probe particles and yields a quasi-exponential stationary distribution obtained also from the nonadditive statistics proposed by C. Tsallis. We estimate energy loss in a nonadditive quark-gluon medium, and calculate the jet quenching parameter (qˆ) for the PP dynamics. With the help of the estimate of qˆ, we calculate the nuclear suppression factor (RAA) of the heavy-quarks passing through a nonadditive quark-gluon plasma using the model proposed by Dokshitzer and Kharzeev. In many a case, the parameters in the analysis are fixed from the experimental results to minimize arbitrariness. There is a good agreement between the theoretical calculation and experimental RAA data, indicating that fast heavy-quarks may be subjected to anomalous diffusion inside the QGP.

Acute effects of a vigorous-intensity warm-up on response suppression and decision-making of football referees

ABSTRACT This study investigates the acute effect of physical exercise simulating a standard pre-competitive warm-up on the response suppression and decision-making of football referees. Thirty-four referees (n = 17 – regional level; n = 17 – national level) participated in the study. A Stop-Signal Task (SST) and a decision-making video test were used to evaluate the referees’ perceptual-cognitive functions. The findings revealed that the vigorous aerobic exercise acutely impacted basic cognitive functions, as indicated by decreased reaction time and decreased choice accuracy. However, higher-order cognitive functions such as response suppression and decision-making did not exhibit significant changes post-exercise. Based on these results, there is no evidence to suggest that a vigorous-intensity warm-up is likely to favour response suppression and decision-making factors in the initial phases of the game. National referees showed superior response suppression abilities (shorter stop-signal reaction times and lower probability of responding to the stop-signal) than regional referees, indicating that higher-level referees possess enhanced perceptual-cognitive skills, likely influenced by their experience. Further studies are required to determine whether these variables can be acutely improved through physical exercise. In this regard, our results suggest the need for alternative strategies in pre-competitive referee warm-ups if aiming to improve perceptual-cognitive skills in the initial phases of the game.

Anomalous diffusion of the heavy quarks through the fractional Langevin equation

The dynamics of heavy quarks within the hot QCD medium have been revisited, considering the influence of anomalous diffusion. This study has been conducted using the framework of the fractional Langevin equation involving the Caputo fractional derivative. We introduce a numerical scheme for the fractional Langevin equation and demonstrate that the mean-squared displacement of the particle exhibits anomalous diffusion, deviating from a linear relationship with time. Our analysis calculates various entities, such as mean-squared momentum, momentum spread, and the nuclear suppression factor RAA. Notably, our findings indicate that superdiffusion strongly suppresses the RAA compared to normal diffusion in the hot QCD medium. The possible impacts on other parameters are also discussed. Published by the American Physical Society 2024

Application of wavelet transform in anti-Compton phoswich detector for gamma spectrum

The response of an anti-Compton phoswich detector to gamma rays was investigated using Monte-Carlo method, and the pulses from different crystal cases, including gamma deposition only in the LaBr3(Ce) or CsI(Tl) crystal and coincidence in both crystals, were analyzed. A novel pulse discrimination method for gamma deposition events based on wavelet transform analysis, called SSD (Scale Shape Discrimination), was developed in this study. Compared to the traditional PSD (Pulse Shape Discrimination) method, SSD has the advantage of transforming one-dimensional pulses in the time-domain into two-dimensional time-frequency spectra, providing the more useful features for pulse discrimination. The performances of the Compton suppression and Full-energy peak loss using PSD and SSD methods was studied. The results show that the Compton suppression factor IPSD = 5.12 and ISSD = 5.32, and FEP loss factor PLPSD = 0.0554 and PLSSD = 0.0587. Meanwhile, the influences of the cutoff values for pulse discrimination on the results of I and PL with different method were analyzed.

Fusion and one-neutron stripping process for 6Li + 94Zr system around the Coulomb Barrier* *This research is supported by the National Nature Science Foundation of China (U2167204, 11975040, 1832130, 12375130), the Director's Foundation of Department of Nuclear Physics, China Institute of Atomic Energy 12SZJJ-202305. The Brazilian authors are grateful to the partial support from financial agencies FAPERJ, CNPq, and INTC-FNA

The complete and incomplete fusion cross section as well as one-neutron stripping process of 6Li + 94Zr system were measured at the energies around the Coulomb barrier by online γ-ray method. In addition to a 30% suppression factor when compared with the measured total fusion process, the complete fusion cross section in 6Li + 94Zr system was observed to be significantly lower than those in the nearby 6Li + 90, 96Zr system. The new experimental result implies that the coupling with breakup channel in the 6Li-induced fusion processes can be affected by the inner structure of the target, which is still not clear in any available model calculation. For the one-neutron stripping process, the direct production cross sections for each level in 95Zr were extracted and compared with the coupled reaction channel calculation, offering a unique opportunity to examine the single-particle nature of the produced excited states. Given the fact that an overall overestimation of the production cross section for 954-keV and 1618-keV levels was observed in the comparison, further investigation is highly demanded in order to understand the full reaction mechanism for the one-neutron stripping process induced by 6Li.

Vacancy Suppression and Resonant Level Rendering Extraordinary Power Factor in Sn0.99In0.01Te/Tourmaline Composite.

SnTe, as a potential medium-temperature thermoelectric material, reaches a maximum power factor (PF)usually above 750K, which is not conducive to continuous high-power output in practical applications. In this study, PF is maintained at high values between 18.5 and 25µWcm-1K-2 for Sn0.99In0.01Te-xwt% tourmaline samples within the temperature range of 323 to 873K, driving the highest PFeng of 1.2Wm-1K-1 and PFave of 22.5µWcm-1K-2, over 2.5 times that of pristine SnTe. Such an extraordinary PF is attributed to the synergy of resonant levels and Sn vacancy suppression. Specifically, the Seebeck coefficient increases dramatically, reaching 88µVK-1 at room temperature. Meanwhile, by Sn vacancy suppression, carrier concentration, and mobility are optimized to ≈1019cm-3 and 740cm2V-1s-1, respectively. With the tourmaline compositing, Sn vacancies are further suppressed and the thermal conductivity simultaneously decreases, with the minimum lattice thermal conductivity of 0.9W m-1 K-1. Finally, the zT value ≈0.8 is obtained in the Sn0.99In0.01Te sample. The peak of the power output density reaches 0.89W cm-2 at a temperature difference of 600K. Such SnTe alloys with high and "temperature-independent" PF will offer an option for realizing high output power in thermoelectric devices.

More accurate suppression of compton continuum based on list mode data acquisition technique

Compton suppression is a beneficial technique employed in gamma-spectroscopy to decrease the Compton continuum and enhance the detection efficiency for various radionuclide identification/measurement applications. However, for cascade gamma-emitters radionuclides the conventional approach of Compton suppression (i.e., surrounding HPGe with NaI(Tl)/plastic detectors) removes all coincident events and reduces the detection efficiency. In this study, to address this challenge, a new approach is proposed that uses serial geometry (i.e., NaI(Tl) detector + sample + HPGe detector), more accurate coincidence time window, and the recorded gamma-ray energy in the detectors. The approach is experimentally tested and compared with the conventional approach. The results showed that by the proposed approach for 60Co, a cascade gamma-emitter nuclide, the suppression factor (SF) is improved and only 8% of photo-peak events, compared to 25% in the conventional approach, are lost by the suppression procedure. This decrease in loss of the photo-peak events in the proposed Compton suppression approach improves the accuracy of the activity measurement of the cascade-emitter radionuclides.

Tension between neutrino masses and gauge coupling unification in natural grand unified theories

The natural grand unified theories (GUT) solve various problems of the supersymmetric GUT and give realistic quark and lepton mass matrices under the natural assumption that all terms allowed by the symmetry are introduced with O(1) coefficients. However, because of the natural assumption, it is difficult to achieve the gauge coupling unification without tuning, while keeping neutrino masses at realistic values. In this paper, we try to avoid this tension between the neutrino masses and the gauge coupling unification, by introducing suppression factors for several terms. These suppression factors can be understood by approximate symmetries in some of the solutions. We show that one of the most important results in the natural GUT scenario, that the nucleon decay mediated by superheavy gauge fields is enhanced due to a smaller unification scale while the nucleon decay mediated by superheavy colored Higgs is suppressed, may change in those models proposed in this paper. Published by the American Physical Society 2024

Further investigation on the fusion of 6Li with 209Bi target at near-barrier energies

Abstract The complete and incomplete fusion cross sections for 6Li+209Bi were measured via the in-beam γ-ray method around the Coulomb barrier. The cross sections of (deuteron captured) incomplete fusion (ICF) products were re-quantified experimentally for this reaction system. The results reveal that the ICF cross section is equivalent to that of complete fusion (CF) above the Coulomb barrier and dominant near or below the barrier. A theoretical calculation based on the Continuum Discretized Coupled Channel (CDCC) method is performed for the aforementioned CF and ICF cross sections, and the result is consistent with the experimental ones. The universal fusion function (UFF) is also compared with the measured CF cross section with different barrier parameters, demonstrating that the CF suppression factor is quite sensitive to the choice of potential, which can reflect both dynamic and static effects of breakup on the fusion process.

Modeling fuel break effectiveness in southern Spain wildfires

BackgroundFuel breaks aim to reduce the energetic progression of a wildfire, facilitating safe and efficient suppression. Changes in fire regimes are creating increasingly complex scenarios in which a higher percentage of wildfires exceed control capabilities, and a significant increase in firefighting costs is expected. Therefore, it is necessary to redefine fuel break networks incorporating science-based criteria. This change entails the improvement of the existing fuel breaks, the abandonment of those whose effectiveness does not justify the investment in their maintenance, and the development of new optimized designs. Fuel break effectiveness is understood as the probability of controlling a fire in the treated area. We analyzed 563 intersections between fires and fuel breaks that occurred during wildfires from 2011 to 2018 considering topographic, meteorological, fuel, design feature, suppression, and fire behavior factors. The main goal of this study is to quantitatively analyze the effectiveness of fuel breaks during wildfires in southern Spain and to develop models to predict potential fuel break effectiveness in fire containment capabilities by comparing machine learning techniques with a classic statistical approach.ResultsFuel breaks were effective in containing the fire in 46.9% of cases. The most influential factors in effectiveness were the type of suppression work executed on fuel breaks (aerial, ground, or combined firefighting), the flame length, and the intersection angle between the fire and fuel break. Although the most accurate results were achieved with an artificial neural network, a decision tree could be the easiest model for end-user operational application.ConclusionsThis study entails a change in effectiveness assessment to an empirical approach in real wildfires in Spain. Our findings can be used to support decision-making for optimizing fire containment capability and firefighter safety.

Muon g−2 and proton lifetime in SUSY SU(5) GUTs with split superpartners

We consider the interplay of the muon g−2 anomaly and the proton decay in the supersymmetry (SUSY) SU(5) grand unified theories (GUTs) with generation-independent scalar soft masses. In these scenarios, we introduce a number of 5+5¯ messenger fields with doublet-triplet splitting in general gauge mediation to transmit SUSY breaking to the visible sector by gauge loops. As a result, squarks and sleptons receive generation-independent soft SUSY breaking masses, which are split already at the messenger scale. Taking into account the perturbative unification of gauge couplings as well as the bounds from electroweak precision and vacuum stability bounds, we showed the parameter space in general gauge mediation to explain the muon g−2 anomaly with smuon and sneutrino loops while evading the strong bounds on squarks and gluinos from the Large Hadron Collider. We also obtained the dominant Higgsino contributions to the proton decay mode, p→K+ν¯, with general generation-independent sparticle masses for squarks and sleptons. Even for split scalar soft masses in our model, however, we found that the bounds from the proton decay are satisfied only if the effective Yukawa couplings of the colored Higgsinos are suppressed further by a factor of order 10−4–10−3. We illustrated how such a suppression factor is realized in orbifold GUTs in the extra dimension where the colored Higgsinos in the bulk are not coupled to the matter fields localized at the orbifold fixed points at the leading order. Published by the American Physical Society 2024

Prompt and nonprompt ψ(2S) production in pPb collisions at sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{\ extrm{NN}}} $$\\end{document} = 8.16 TeV

The production of ψ(2S) mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s_{\ extrm{NN}}} $$\\end{document} = 8.16 TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb−1. The prompt and nonprompt ψ(2S) production cross-sections and the ratio of the ψ(2S) to J/ψ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt ψ(2S) is observed to be more suppressed compared to pp collisions than the prompt J/ψ production, while the nonprompt productions have similar suppression factors.

Infrared small target detection based on variance difference weighted three-layer local contrast measure

Infrared (IR) small target detection technology is of paramount importance in the infrared search and track (IRST) system. The current methods typically exhibit strong performance in simple backgrounds, but they struggle to effectively suppress high-brightness background and strong noise. For the sake of diminish the false alarm rate of infrared small target detection algorithms under strong clutter interference, an infrared small target detection algorithm based on variance difference weighted three-layer local contrast measure (VDWTLCM) is proposed in this paper. The algorithm comprises two modules: the three-layer local contrast measure (TLCM) and the weighting function based on mean value of the variance difference (MVD). In the calculation module of TLCM, the image is processed pixel by pixel using a three-layer sliding window, while both the ratio form definition and the difference form definition are utilized to calculate the local contrast for each pixel, which can enhance the target and eliminate the high-brightness background. To calculate the MVD weighting function, a modified layered gradient kernel is first introduced to pre-process the IR image, aimed at achieving more effective clutter smoothing. And then the concept of variance difference is employed to further suppress the highlighted background edges. Ultimately, the target is extracted utilizing adaptive threshold segmentation. The experimental results demonstrate that, compared with the common infrared small target detection algorithms, the proposed algorithm improves the signal to clutter ratio gain (SCRG) by an average of 13.13 times and the background suppression factor (BSF) by an average of 10.02 times, and can achieve superior detection performance in different complex scenarios.