arXiv Physics @arxiv_physics@qoto.org

This study explores the efficacy of thermal splicing conditions between silica and zirconium-fluoride fibers, focusing on achieving mechanical strength between the two fibers. A comprehensive characterization of the thermal profile in the hot zone of the filament splicer was conducted using a fiber Bragg grating, providing valuable insights into its stability and overall performance. Results demonstrate mechanically strong joints and suggest a very narrow temperature window to achieve strong connection between the two materials. Moreover, we characterize the surface composition of the ZrF4 fiber using energy dispersive spectroscopy following splicing at ideal temperatures, as well as at higher and lower temperatures. This work paves the way towards future implementation of silica and fluoride fibers splicing using alternative splicing solutions such as CO2 laser system while raising interesting facts for further studies in the specific field.

We determine distributions and correlation properties of offshore wind speeds and wind speed increments by analyzing wind data sampled with a resolution of one second for 20 months at different heights over the sea level in the North Sea. Distributions of horizontal wind speeds can be fitted to Weibull distributions with shape and scale parameters varying weakly with the vertical height separation. Kullback-Leibler divergences between distributions at different heights change with the squared logarithm of the height ratio. Cross-correlations between time derivates of wind speeds are long-term anticorrelated and their correlations functions satisfy sum rules. Distributions of horizontal wind speed increments change from a tent-like shape to a Gaussian with rising increment lag. A surprising peak occurs in the left tail of the increment distributions for lags in a range $10-200\,{\rm km}$ after applying the Taylor's hypothesis locally to transform time lags into distances. The peak is decisive in order to obtain an expected and observed linear scaling of third-order structure functions with distance. This suggests that it is an intrinsic feature of atmospheric turbulence.

This paper uses the gyro-moment (GM) approach as a multi-fidelity tool to explore the effect of triangularity on tokamak edge turbulence. Considering experimental data from an L-mode DIII-D discharge, we conduct gyrokinetic (GK) simulations with realistic plasma edge geometry parameters at $ρ=0.95$. We find that employing ten GMs effectively captures essential features of both trapped electron mode (TEM) and ion temperature gradient (ITG) turbulence. By comparing electromagnetic GK simulations with adiabatic electron GK and reduced fluid simulations, we identify the range of validity of the reduced models. We observe that TEMs drive turbulent heat transport under nominal discharge conditions, hindering accurate transport level estimates by both simplified models. However, when TEMs are absent, and turbulence is ITG-driven, an agreement across the different models is observed. Finally, a parameter scan shows that the positive triangularity scenario destabilizes the TEM, therefore, the adiabatic electron model tends to show agreement with the electromagnetic simulations in zero and negative triangularity scenarios. On the other hand, the reduced fluid simulations exhibit limited sensitivity to triangularity changes, shedding light on the importance of retaining kinetic effects to accurately model the impact of triangularity turbulence in the tokamak edge. In conclusion, our multi-fidelity study suggests that a GM hierarchy with a limited number of moments is an ideal candidate for efficiently exploring triangularity effects on micro-scale turbulence.

Skipper CCDs are a mature detector technology that has been suggested for future space telescope instruments requiring sub-electron readout noise in the near-ultraviolet to the near-infrared. While modern skipper CCDs inherit from the radiation-tolerant p-channel detectors developed by LBNL, the effects of high doses of ionizing radiation on skipper CCDs (such as those expected in space) remains largely unmeasured. We report preliminary results on the performance of p-channel skipper CCDs following irradiation with 217-MeV protons at the Northwestern Medicine Proton Center. The total nonionizing energy loss (NIEL) experienced by the detectors exceeds 6 years at the Sun-Earth Lagrange Point 2 (L2). We demonstrate that the skipper amplifier continues to function as expected following this irradiation. Owing to the low readout noise of these detectors, controlled irradiation tests can be used to sensitively characterize the charge transfer inefficiency, dark current, and the density and time constants of charge traps as a function of proton fluence. We conclude with a brief outlook toward future tests of these detectors at other proton and gamma-ray facilities.

In this paper, we report new insight into a symmetry-breaking phenomenon that occurs for turbulent flow in periodic porous media composed of cylindrical solid obstacles with circular cross-section. We have used Large Eddy Simulation to investigate the symmetry-breaking phenomenon by varying the porosity (0.57-0.99) and the pore scale Reynolds number (37-1,000). Asymmetrical flow distribution is observed in the intermediate porosity flow regime for values of porosities between 0.8 and 0.9, which is characterized by the formation of alternating low and high velocity flow channels above and below the solid obstacles. These channels are parallel to the direction of the flow. Correspondingly, the microscale vortices formed behind the solid obstacles exhibit a bias in the shedding direction. The transition from symmetric to asymmetric flow occurs in between the Reynolds numbers of 37 (laminar) and 100 (turbulent). A Hopf bifurcation resulting in unsteady oscillatory laminar flow marks the origin of a secondary flow instability arising from the interaction of the shear layers around the solid obstacle. When turbulence emerges, stochastic phase difference in the vortex wake oscillations caused by the secondary flow instability results in flow symmetry breaking. We note that symmetry breaking does not occur for cylindrical solid obstacles with square cross-section due to the presence of sharp vertices in the solid obstacle surface. At the macroscale level, symmetry-breaking results in residual transverse drag force components acting on the solid obstacle surfaces. Symmetry-breaking promotes attached flow on the solid obstacle surface, which is potentially beneficial for improving transport properties at the solid obstacle surface such as convection heat flux.

We elucidate how different theoretical assumptions bring about radically different interpretations of the same experimental result. We do this by analyzing special relativity as it was originally formulated. Then, we examine the relationship of the theory with the result of the Michelson and Morley experiment. We point out that in diverse a historical context the same experiment can be thought of as providing different conceptualizations of phenomena. This demonstrates why special relativity prevailed over its rival theories. This theory made a new reinterpretation of the experiment by associating it with a novel phenomenon, namely, the invariance of the speed of light, a phenomenon that was not the one originally investigated. This leads us to an understanding of how this experiment could have been interpreted in a completely different historical context.

Circular Dichroism (CD) can distinguish the handedness of chiral molecules. However, it is typically very weak due to vanishing absorption at low molecular concentrations. Here, we suggest Thermal Circular Dichroism (TCD) for chiral detection, leveraging the temperature difference in the chiral sample when subjected to right and left-circularly polarized excitations. The TCD combines the enantiospecificity of circular dichroism with the higher sensitivity of thermal measurements, while introducing new opportunities in the thermal domain that can be synergistically combined with optical approaches. We propose a theoretical framework to understand the TCD of individual and arrays of resonators covered by chiral molecules. To enhance the weak TCD of chiral samples, we first use individual dielectric Mie resonators and identify chirality transfer and self-heating as the underlying mechanisms giving rise to the differential temperature. However, inherent limitations imposed by the materials and geometries of such resonators make it challenging to surpass a certain level in enhancements. To overcome this, we suggest nonlocal thermal and electromagnetic interactions in arrays. We predict that a combination of chirality transfer to Mie resonators, collective thermal effects, and optical lattice resonance could, in principle, offer more than 4 orders of magnitude enhancement in TCD. Our thermonanophotonic-based approach thus establishes key concepts for ultrasensitive chiral detection.

This paper reports on a measurement of electron-ion recombination in liquid argon in the ICARUS liquid argon time projection chamber (LArTPC). A clear dependence of recombination on the angle of the ionizing particle track relative to the drift electric field is observed. An ellipsoid modified box (EMB) model of recombination describes the data across all measured angles. These measurements are used for the calorimetric energy scale calibration of the ICARUS TPC, which is also presented. The impact of the EMB model is studied on calorimetric particle identification, as well as muon and proton energy measurements. Accounting for the angular dependence in EMB recombination improves the accuracy and precision of these measurements.

The spherical Couette system consists of two differentially rotating concentric spheres with a fluid filled in between. We study a regime where the outer sphere is rotating rapidly enough so that the Coriolis force is important and the inner sphere is rotating either slower or in the opposite direction with respect to the outer sphere. We numerically study the sudden transition to turbulence at a critical differential rotation seen in experiments at BTU Cottbus - Senftenberg, Germany and investigate its cause. We find that the source of turbulence is the boundary layer on the inner sphere, which becomes centrifugally unstable. We show that this instability leads to generation of small scale structures which lead to turbulence in the bulk, dominated by inertial waves, a change in the force balance near the inner boundary, the formation of a mean flow through Reynolds stresses, and consequently, to an efficient angular momentum transport. We compare our findings with axisymmetric simulations and show that there are significant similarities in the nature of the flow in the turbulent regimes of full 3D and axisymmetric simulations but differences in the evolution of the instability that leads to this transition. We find that a heuristic argument based on a Reynolds number defined using the thickness of the boundary layer as a length scale helps explain the scaling law of the variation of critical differential rotation for transition to turbulence with rotation rate observed in the experiments.

This study aims to determine the protective concrete shielding thickness requirements in concrete walls of positron emission tomography (PET) and computed tomography (CT) facilities. Consider the most commonly used PET radiotracer, the radioisotope F18, which emits two back-to-back 511 keV photons. Photon transmission measurements were carried out through an Israeli B30 strength ordinary concrete wall (3 meter high, 20 cm thick) using photons emitted from an F18 source into a cone having a 24 degree FWHM dose aperture angle. The source, positioned 3 meters from the wall, yielded a 0.64 m beam disk radius on the wall. Our measurement setup roughly simulates radiation emitted from a patient injected with F18. Dose rates were measured by an Atomtex Radiation Survey Meter, positioned at distances 0.05 to 3 meters from the far side of the wall. For a wide-beam, thick-shielding setup, there is a buildup effect, as photons having reduced energies may reach the detector from Compton scattering in the wall. In concrete, the Compton scattering cross section accounts for 99% of the total interaction cross section. The buildup factor B accounts for the increase of observed radiation transmission through shielding material due to scattered radiation. We measured a narrow-beam transmission coefficient T=3.0 +- 0.9 %, consistent with the theoretical value 2% calculated from NIST photon attenuation data without buildup. We measured a wide-beam transmission coefficient of 8.6 +- 1.8%; in good agreement with two available wide-beam Monte Carlo (MC) simulations. We confirm by experiment, complementing MC simulations, that for a 20 cm thick concrete wall, due to buildup, about four times thicker shielding is required to achieve a designated level of radiation protection, compared to that calculated using narrow-beam, thin-shielding transmission coefficients.

Nonlocal deformation sensing achieved by integrating atomic force microscopy indentation with nanodiamond-based orientation tracking features high precision and high spatial resolution, providing a useful technique for studying the mechanical properties of soft biological systems. However, this technique is currently limited to lifeless systems because it cannot differentiate the indentation-induced deformation from that associated with live activities or other external perturbations. Here we develop a dynamic nonlocal deformation sensing method using oscillatory nanoindentation and spectroscopic analysis to overcome this limitation. The method realizes both temporally and spatially resolved mechanical analysis, with tens of microsecond time-lag precision, nanometer vertical deformation precision, and sub-hundred nanometer lateral spatial resolution, leading to the disclosure of surface/interface effects in the mechanical response of viscoelastic materials and live cells. Neglecting surface tension would underestimate the liquid-like characteristics of the materials. This work demonstrates nanodiamond sensors as a useful tool for spatial-temporal mechanical analysis of soft, complex bio-relevant materials.

The classical Hodgkin-Huxley model describes the propagation of an axon potential (AP) in unmyelinated axons. In many cases the axons have a myelin sheath and the experimental studies have then revealed significant changes in the velocity of APs. In this paper, a theoretical model is proposed describing the AP propagation in myelinated axons. As far as the velocity of an AP is affected, the basis of the model is taken after Lieberstein, who included the possible effect of inductance that might influence velocity, into the governing equation. The proposed model includes the structural properties of the myelin sheath: the $μ$-factor (the ratio of the length of the myelin sheath and the Ranvier node) and g-ratio (the ratio of the inner-to-outer diameter of a myelinated axon) through parameter $γ$. It is demonstrated that the Lieberstein model can describe all the essential effects characteristic to the formation and propagation of an AP in an unmyelinated axon. Then a phenomenological model for a myelinated axon is described including the influence of the structural properties of the myelin sheath and the radius of an axon. The numerical simulation using the physical variables demonstrates the changes in the velocity of an AP as well as the changes in its profile. These results match well the known effects from experimental studies.

This work proposes the Least Squares with Virtual Displacements (LSVD) method to obtain the shear strength of n soil samples for the cohesionless, frictionless and mixed resistance conditions. Finding a common tangent line of more than two samples may not have an exact solution, especially if there are measurement errors. LSVD is an iterative method to find the best common tangent line or function to the n soil samples. There are soils that can be modeled with a linear failure envelope but the LSVD can be formulated in different forms, adapting itself to other criterion too, like the logarithmic failure envelope. The tested data is analyzed with LSVD and compared between other commonly used methods, like p-q method and CTPAC. The soils' samples were subjected to random noise to simulate errors from measurements to study the method's results. Also with that analysis a common reference point can be found to compare the methods given that all of them take different points of the Mohr Circles.

The knowledge of scintillation quenching of $α$-particles plays a paramount role in understanding $α$-induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ($^{222}$Rn, $^{218}$Po and $^{214}$Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.

Active Target Time Projection Chambers (AT-TPCs) are state-of-the-art tools in the field of low-energy nuclear physics, particularly suitable for experiments using low-intensity radioactive ion beams or gamma rays. The Fudan Multi-purpose Active Target Time Projection Chamber (fMeta-TPC) with 2048 channels has been developed to study $α$-clustering nuclei. {\fcb In this work, the focus is on the study of the photonuclear reaction with the Laser Compton Scattering (LCS) gamma source, especially for the decay of the highly excited $α$-cluster state.} The design of fMeta-TPC is described and a comprehensive evaluation of its offline performance is performed by ultraviolet (UV) laser and $^{241}$Am $α$ source. The result shows that the intrinsic angular resolution of the detector is within 0.30$^{\circ}$ and has an energy resolution of 6.85\% for 3.0 MeV $α$ particles. The gain uniformity of the detector is about 10\% (RMS/Mean), tested by the $^{55}$Fe X-ray source.

Modern optical systems send and receive ultra-short temporal pulses (USP). While ultra-broad band antennas do exist in the microwave region (e.g., log-periodic antennas, or, concentric loop antennas), their short temporal response is typically limited by the antenna's large dispersion, hence, resulting in a substantial pulse broadening. Here we show that loop antennas may exhibit USP attributes, below 400 ps (or, an equivalent coherent band pass exceeding 2.5 GHz) with only three loops, or, with a single, thick loop.

The emission of neutrons from heavy ion reactions is an important observable for studying the asymmetric nuclear equation of state and the reaction dynamics. A 20-unit neutron array has been developed and mounted on the compact spectrometer for heavy ion experiments (CSHINE) to measure the neutron spectra, neutron-neutron and neutron-proton correlation functions. Each unit consists of a $\rm 15\times 15\times 15~cm^3$ plastic scintillator coupled to a $ ϕ=52 ~\rm mm$ photomultiplier. The Geant4 simulation with optical process is performed to investigate the time resolution and the neutron detection efficiency. The inherent time resolution of 212 ps is obtained by cosmic ray coincidence test. The n-$γ$ discrimination and time-of-flight performance are given by $\rm ^{252}Cf$ radioactive source test and beam test. The neutron energy spectra have been obtained in the angle range $30^\circ \le θ_{\rm lab} \le 51^\circ$ in the beam experiment of $^{124}$Sn+$^{124}$Sn at 25 MeV/u with CSHINE.

The Thermo Scientific P385 Neutron Generator is a compact neutron source, producing 14 MeV neutrons through the deuterium-tritium (DT) fusion reaction. For practical use, it is important to measure and preferably understand the dependence of the neutron production rate on the accelerator current and voltage. In this study, we evaluated neutron production with a neutron spectrometer (BTI N-Probe), a He-3 detector surrounded by HDPE shells (Nested Neutron Spectrometer, NNS), and two ZnS fast neutron scintillators (EJ-410) for both P385 A3082 and A3083 sealed tubes. We also predicted the neutron yield using the TRIM code, which calculates the trajectory and the energy loss of deuterons and tritons within the target. Experimental and theoretical results showed a linear dependence on beam current and a $\sim$3.5 power law dependence on the operating voltage. A series of NNS measurements, neutron spectrum from N-Probe and MCNP calculation showed that the A3083 and A3082 tubes provide a maximum neutron yield of $\sim 8.2 \times 10^8$ n/s and $\sim 4.5 \times 10^8$ n/s, respectively. We showed that tritium decay was not a significant contributor to this difference.

In an era where Position, Navigation, and Timing (PNT) systems are integral to our technological infrastructure, the increasing prevalence of severe space weather events and the advent of deliberate disruptions such as GPS jamming and spoofing pose significant risks. These challenges are underscored by recent military operations in Ukraine, highlighting the vulnerability of Global Navigation Satellite Systems (GNSS). In response, we introduce the Cosmic Ray Navigation System (CRoNS). This innovative and resilient alternative utilizes cosmic muon showers for precise location pinpointing, especially in environments where GNSS is compromised or unavailable. CRoNS capitalizes on an economical, distributed network of compact muon sensors deployed across urban landscapes and potentially integrated into mobile devices. These sensors are tasked with continuously monitoring muon flux resulting from extensive air showers (EASs) triggered by the consistent high-energy particle flux entering Earth's atmosphere. A central AI unit synthesizes the collected data, determining EAS parameters to establish a dynamic reference coordinate system that could span cities and even nations. A notable advantage of CRoNS lies in its capability for reliable operation beneath the Earth's surface and in aquatic environments.

The primary and metastatic stages of BC consider different cancerous cell lines (MDAs), meaning the highest number of cells in this research (300,000) represents the metastatic stages of BC, and 50,000 represents the primary level of BC developments have been studied based on fluorescence-enhanced photodynamic characterizations. The ability to characterize the fluorescence caused by MDA with 50,000 cells compared to the dominant radiation of MDA with 300,000 cells is emphatic proof of the high potential of fluorescence technique in timely BC detections. 5-ALA induces an accumulation of protoporphyrin IX (PpIX) photosensitizer through a biosynthetic pathway, leading to red radiation of fluorescence measurements. The fluorescence signal reduction due to decreased cell viability and increased MDA's cellular death rate corresponds to the changes in lipid metabolism enzymes of MDAs cultured at different doses. Furthermore, statistical concerns have been studied using PCA multivariate component analysis to differentiate MDA cells administrated by 5-ALA.