Full Jet Research Articles

Study of a full coaxial atmospheric pressure plasma jet device and its application to the modification of polytetrafluoroethylene

Study of a full coaxial atmospheric pressure plasma jet device and its application to the modification of polytetrafluoroethylene

Topology optimisation for vat photopolymerization 3D printing of ceramics with flushing jet accessibility constraint

ABSTRACT For vat photopolymerization 3D printing technology with high-viscosity ceramic slurry, the cleaning of residual uncured slurry presents a challenging task for lattice-based porous structures. Hence, this study contributes a multi-scale topology optimisation method for lattice-solid hybrid structures dedicated to ceramic vat photopolymerization 3D printing. A novel flushing jet accessibility constraint is proposed, aiming to effectively remove the residual uncured slurry after finishing the vat photopolymerization. Specifically, a multi-material interpolation for graded lattices and solid materials is introduced to form the fundamental of topology optimisation. Then, a series of filtering and projection operations are developed to ensure the accessibility of flushing waters to every location that may have residual ceramic slurry. Accordingly, a multi-scale topology optimisation mathematical model is established and solved with the adjoint sensitivities. 2D and 3D numerical examples are conducted to evaluate the effectiveness of the proposed method. Furthermore, a 3D printing experiment is performed to validate the full water jet accessibility of the optimised structural solution and one pillow bracket part is carried out as a practical application demonstration.

Measurement of charged and full jet production and nuclear modification factor in pp and p–Pb collisions with ALICE

The study of jet production in small collision systems is essential for testing our understanding of perturbative and non perturbative QCD and cold nuclear matter (CNM) effects. In addition, studies at high multiplicity in small collision systems exhibit signatures of collectivity, which is still not fully understood within a unified picture across system size. Jet quenching in small systems is not observed within current measurement precision, calling for more precise jet measurements. Results of charged particle and fully reconstructed jet production in pp and p-Pb collisions are presented at √SNN = 5.02 and 8 TeV, along with the corresponding nuclear modification factor RpPb at √SNN = 5.02 TeV. These results are the most precise measurements of the RpPb by ALICE to date. To investigate whether jet energy is redistributed in CNM, the crosssection ratios for different jet resolution parameters (R) are compared between pp and p–Pb collisions, as well as within each collision system. Finally, comparisons between data and model predictions are discussed. This result extends previous LHC measurements to lower jet transverse momentum, constraining hard parton production and fragmentation mechanisms applied in model calculations, and the impact of the nuclear-modified parton distribution function on jet production. This measurement also provides new constraints on jet quenching in small collision systems.

Research on gas wave refrigeration application of full feedback periodic jet oscillator

Static gas wave refrigeration (SGWR) is a mechanic equipment with no moving parts which realize refrigeration by working on gas through pressure energy. This paper introduces full feedback jet oscillator as the jet distributor of the gas wave refrigerator and shows the switching mechanism of the oscillator in detail through dynamics description. The range of influence of wedge distance (distance between wedge tip and the nozzle) on the pressure retention rate and frequency at the oscillator outlet is discussed, and a SGWR experiment platform is set up to make comparison of the pressure waveform as well as cooling efficiency of the impulse jet from two oscillators with different wedge distance in the gas wave tube. The result shows that jet oscillator performance varies along with the wedge distance, thus influencing the cooling efficiency. To expand the efficient operation range, the principle of jet frequency changing and the impact of narrowing the oscillator structure on jet frequency are discussed in detail, the variation rule equation of the jet switching frequency is derived. Matching experiments of jet oscillator and size of gas wave tube have been conducted under conditions of specific frequency and variable frequency. It is concluded that there exists fluctuation value in gas wave tube refrigeration efficiency versus gas injection frequency curve, which can be up to 15% or more. Based on the present results, the jet frequency control method can make the gas wave tube operate at the refrigeration's peak frequency, thus improving SGWR refrigeration efficiency.

Jet quenching effect in relativistic heavy-ion collisions

One of the main goals of high-energy nuclear physics is to explore the fundamental properties of quark-gluon plasma (QGP), a new state of quantum chromodynamics (QCD) matter created in relativistic heavy-ion collisions, in which the energetic quarks and gluons, known as fast partons, created prior to the formation of the QGP, traverse the hot-dense medium and experience strong interactions with the constituents of the medium, and eventually lead to the attenuation of jet energy. Such a novel phenomenon, referred to as jet quenching, plays an essential role in probing the transport properties of the QGP. The objective of this paper is to review some of the latest experimental and theoretical progress of jet quenching, such as medium modification on the large <inline-formula><tex-math id="M11111">\begin{document}$ p_{\rm T} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="20-20230993_M11111.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="20-20230993_M11111.png"/></alternatives></inline-formula> hadrons, full jets, and jet substructures in heavy-ion collisions, as well as the challenges in the forefront theoretical investigations.

Studying hadronization at LHCb

LHCb is a fully instrumented forward spectrometer with particle identification and muon reconstruction covering the pseudorapidity (\etaη) range from 2 to 5. Its full jet reconstruction capability makes the LHCb experiment a suitable venue to explore jet substructure observables, particularly formation of hadrons and heavy quarkonia resonances inside jets. This contribution presents a brief overview of ongoing research program and discusses recent results on non-identified charged hadron distributions in Z-tagged jets and charmonium distributions within jets. Future works towards furthering the knowledge of hadronizion are also discussed.

Single inclusive jet production in pA collisions at NLO in the small-x regime

We present the first complete next-to-leading-order (NLO) prediction with full jet algorithm implementation for the single inclusive jet production in pA collisions at forward rapidities within the color glass condensate (CGC) effective theory. Our prediction is fully differential over the final state physical kinematics, which allows the implementation of any infra-red safe observable including the jet clustering procedure. The NLO calculation is organized with the aid of the observable originated power counting proposed in [1] which gives rise to the novel soft contributions in the CGC factorization. We achieve the fully-differential calculation by constructing suitable subtraction terms to handle the singularities in the real corrections. The subtraction contributions can be exactly integrated analytically. We present the NLO cross section with the jets constructed using the anti-kT algorithm. The NLO calculation demonstrates explicitly the validity of the CGC factorization in jet production. Furthermore, as a byproduct of the subtraction method, we also derive the fully analytic cross section for the forward jet production in the small-R limit. We show that in the small-R approximation, the forward jet cross section can be factorized into a semi-hard cross section that produces a parton and the semi-inclusive jet functions (siJFs). We argue that this feature holds for generic jet production and jet substructure observables in the CGC framework. Last, we show numerical analyses of the derived formula to validate our calculations. We justify when the small-R approximation is appropriate. Like forward hadron production, the obtained NLO result also exhibits the negativity of the cross section in the large jet transverse regime, which signals the need for the threshold resummation. A sketch of the threshold resummation in the CGC framework is presented based on the multiple emission picture and it is found to agree with the approach using the rapidity renormalization group equation developed in [2].

Studying the mechanisms for strange particle production with ALICE at LHC

The main goal of the ALICE experiment is to study the physics of strongly interacting matter, focusing on the properties of the quark-gluon plasma (QGP). The relative production of strange hadrons with respect to non-strange hadrons in heavy-ion collisions was historically considered as one of the signatures of QGP formation. However, the latest results in proton-proton (pp) and proton-lead (p-Pb) collisions have revealed an increasing trend in the yield ratio of strange hadrons to pions with the charged-particle multiplicity in the event, showing a smooth evolution across different collision systems and energies. We present the new studies which are performed with the aim of better understanding the production mechanisms for strange particles and hence the strangeness enhancement phenomenon in small collision systems. In one of the recent studies, the very forward energy transported by beam remnants (spectators) and detected by the Zero Degree Calorimeters (ZDC) is used to classify events. The contribution of the effective energy and the particle multiplicity on strangeness production is studied using a multi-differential approach in order to disentangle initial and final state effects. In the second study, the origin of strangeness enhancement with multiplicity in pp has been further investigated by separating the contribution of soft and hard processes, such as jets, to strange hadron production. Techniques involving full jet reconstruction or two-particle correlations have been exploited. The results indicate that the increased relative strangeness production emerges from the growth of the underlying event, being disconnected from initial state properties, and suggest that soft (out-of-jets) processes are the dominant contribution to strange hadron production.

Comparison of different fulljet nozzles used in laboratory type rain simulator in terms of some rainfall characteristics

Objective: The objective of this study was to determine and compare rain intensities, Christiansen coefficients, drop diameters and kinetic energies, by using Full Jet type nozzles at different pressures. Material and Methods: In this study, simulated rainfalls were applied on 17 cups (250 cm3), were placed on a platform, during 5 minutes at 30, 40, 50, 60 and 70 kPa pressures by using ½ HH-36 SQ, ½ HH-40 SS and ½ HH-50 WSQ nozzles with 3 replicated. The drop diameters were determined by the flour pellet method. Rainfall intensities, Christiansen coefficients, terminal velocities, drop diameter ratio, terminal velocity ratio, moment, kinetic energy, moment per unit area, kinetic energy per unit area ratios and kinetic energy for each nozzles were calculated. Results: It was found that average rain intensities were 97-210 mm h-1, average uniformity coefficients were 85-86 %, average drop diameters were 1.89-2.11 mm, average terminal velocities were 6.35-6.79 m s-1 for nozzles. Average kinetic energies for each nozzles were also calculated between 16.30-23.32 J m-2 mm-1. Conclusions: According to this study, it was determined that the most suitable nozzle for erosion studies is Fulljet ½ HH-50 WSQ.

Numerical Analysis on the Performance of High Concentration Photovoltaic Systems Under the Nonuniform Energy Flow Density

Photovoltaic panels can directly convert solar energy into electricity, but temperature will have a certain impact on the efficiency of photovoltaic cells. Especially under the condition of nonuniform energy flow density of high-power concentration, it is of great significance to maintain the temperature uniformity of cells. Therefore, based on the radiation under nonuniform heat flux density, four heat exchangers were proposed: single-channel serpentine flow, multi-channel flat plate, full jet, and single-jet nozzle. Taking into account the uniformity of the cell temperature, the single-jet nozzle and single-channel serpentine flow can better maintain the uniformity of the temperature field compared with other heat exchangers. Especially under high-concentration energy flow density, considering the quality of heat and electricity, the performance of the four-jet nozzles is the best from the perspective of exergy efficiency. Under the condition of four-jet nozzles, the electrical efficiency and thermal efficiency of the cell can be maintained at about 29 and 62.5%, respectively, and the exergy efficiency of the system can reach 31%.

Multi-nozzle spray cooling of a reactor pressure vessel steel plate for the application of ex-vessel cooling

Spray cooling is a versatile technology for various cooling applications involving high surface heat fluxes. Experimental facility was built to study heat transfer performance of an upward multi-nozzle array of water sprays impacting a surface of heated plate made of reactor vessel grade steel. The effect of inclination angles of the steel surface on the cooling performance was investigated to assess heat transfer in complex semispherical/semielliptical geometry of large reactor lower head and to address possible application of spray cooling in severe accident management (SAM) of light water reactors (LWRs) based on In-vessel melt retention with external reactor vessel cooling (IVR-ERVC). Joule heating of SA302B steel foil of 0.15 mm thickness and surface area of 96 cm2 enabled prototypic heat fluxes to be evacuated during reactor accident. A 2 × 3 array of full jet narrow-coned pressure-swirl spray nozzles was used to reproduce multi-nozzle cooling. The tests were conducted as a series of consequent steady states realized at stepwise increasing power and surface heat fluxes up to the maximum values of 29 kW and 2.97 MW/m2 limited in the specific facility design. Seven surface inclinations, between 0° and 90° were tested and no significant variations in spray cooling performance with the inclination of the heated surface was found. The results indicated a promising prospect of using a multi-nozzle array system for cooling of large surface area of reactor lower head. Much higher heat fluxes can be safely extracted by spray cooling in comparison with the critical heat fluxes that appeared at RPV water pool cooling at natural convection. The maximum value of heat flux at direct spray impact zones and its drop-off slightly from the center to the periphery of the spray cone was detected in the tests. The water flow rate and liquid subcooling significantly influenced maximum steel surface temperature but had no noticeable effects on surface temperature uniformity. The spray-to-spray interaction had no observable effects on local surface temperatures, however, the colliding zones where four spray cones have visible effects on local surface temperatures due to poor liquid momentum. The results also showed that more uniform liquid film distribution could be obtained for some inclinations because of improved liquid drainage, which in turn leads to maintaining low surface temperatures.

Recoil-free azimuthal angle for precision boson-jet correlation

The azimuthal decorrelation between a vector boson and a jet is an essential hard probe in high energy proton-proton and heavy-ion collisions. We overcome intrinsic limitations of previous studies by using a recoil-free axis, achieving unprecedented next-to-next-to-leading logarithmic accuracy with small nonperturbative corrections. This choice of axis also makes the observable robust in the presence of a large background. Furthermore, the azimuthal angle distribution is minimally changed when determined using only charged particle tracks, which offer superior angular resolution for precise measurements. Our effective field theory includes full jet dynamics, and we find contributions from linearly-polarized gluon transverse momentum distributions in the initial and final state.

Influence of the filter cloth and nozzles type on the in-situ cleaning procedure of filter presses

Exemplary representation of the contaminated surface and the resulting binary image with coordinate generation based on the effective radius of the cleaning nozzle and the shortest way of cleaning procedure (left to right). • The surface contamination is lower with smaller meshes within the same weave type. • Calendering of the fabric surface does not lead to less surface contamination. • Multifilament fabrics have the lowest surface contamination with the smallest amount of cleaning agent. • Mathematical description of the cleaning process by a regressive model possible. • Full jet nozzle to be preferred for surface cleaning. • Optimization of the dirt detection by variation with colour filters and light sources possible.

Counting on Short Gamma-Ray Bursts: Gravitational-wave Constraints of Jet Geometry

Abstract The detections of GW170817 and GRB 170817A revealed that at least some short gamma-ray bursts (sGRB) are associated with the merger of neutron-star compact binaries. The gamma-rays are thought to result from the formation of collimated jets, but the details of this process continue to elude us. One important feature of gamma-ray bursts is the emission profile of the jet as a function of viewing angle. We present two related methods to measure the effective angular width, , of sGRB jets using gravitational-wave (GW) and gamma-ray data, assuming all sGRBs have the same angular dependence for their luminosities. The first is a counting experiment that requires minimal knowledge about each event, beyond whether or not they were detected in gamma-rays. The second method uses GW and electromagnetic data to estimate parameters of the source. We additionally outline a model-independent method to infer the full jet structure of sGRBs using a nonparametric approach. Applying our methods to GW170817 and GW190425, we find weak constraints on the sGRB luminosity profile. We project that with 5 and 100 binary neutron star detections, the counting method would constrain the relative uncertainty in to within and , respectively. Incorporating GW parameter estimation provides only marginal improvements. We conclude that the majority of the information about jet structure comes from the relative sensitivities of GW and gamma-ray detectors as encoded in simple counting experiments.

Influence of surface roughness on heat transfer during quenching hot metals with different nozzles

The experimental work aims at investigating the influence of surface roughness on heat transfer by using different nozzles. Part of the rough surfaces are provided directly by the industry. These surfaces of casting products possess considerable roughness up to millimeters which can be either unstructured or with typical grooves in the casting direction. The understanding of its effect on cooling hot metals can help to shed light on the quenching process encountered in the industrial applications. This study will initially be carried out with individual nozzles, such as full cone and full jet nozzles, in order to identify the basic relations. Subsequently, a mold is also applied which can be regarded as a series of full jet nozzles. As for the experiments with mold, the plate is moving downwards with a preset velocity; meanwhile, the plate is fixed for experiments with full jet and full cone nozzle.

Jet quenching in the hadron gas: An exploratory study

The suppression of high momentum particles in heavy-ion collisions in comparison to elementary reactions is one of the main indications for the formation of a quark-gluon plasma. In recent studies, full jets are being reconstructed and substructure observables are gaining importance in assessing the medium modifications of hard probes. In this work, the effect of the late stage hadronic interactions are explored within the hadronic transport approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons). High momentum particles are incorporated in a radially expanding hadron gas to analyse the corresponding angular distributions, also refered to as `jet shape' observables. We find that the full hadron gas can be approximated with a pion gas with constant elastic cross-sections of 100 mb. In addition, the temperature and probe energy dependence of diffusion coefficients $\tilde{q}$ and $\tilde{e}$ quantifying the transverse and parallel momentum transfers are extracted. The species dependence and the importance of different interaction types are investigated. Parametrizations are presented that can be employed in future jet quenching calculations to include the effect of the hadronic phase.

CME Productive and Non-productive Recurring Jets Near an Active Region AR11176

We study the recurring jets near AR11176 during the period 2011 March 31 17:00 UT to April 1 05:00 UT using observations from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). Mini-filaments (mini-filament1 & 2) are found at the base of these recurring jets where mini-filament1 shows the partial signature of eruption in case of Jet1-3. However, the mini-filament2 shows a complete eruption driving a full blow-out jet (Jet4). The eruption of mini-filament2 triggers C-class flare and Jet4 eruption. The eruption of Jet4 triggers a coronal mass ejection (CME). The plane-of-sky velocity of recurring jets (Jet1-4) results in 160 km/s, 106 km/s, 151 km/s and 369 km/s. The estimated velocity of CME is 636 km/s. The continuous magnetic flux cancellation is observed at the base of the jet productive region which could be the cause of the eruption of mini-filaments and recurring jets. In the former case, the mini-filament1 shows partial eruption and first three jets (Jet1-3) are produced, but the rate of cancellation was rather low. However, in the latter case, mini-filament2 fully erupts (perhaps because of a higher cancellation rate), and this triggers a C-class flare and a CME-productive jet. At the base of first three jets (Jet1-3), the mini-filament1 causes to push the overlying dynamic complex thin loops resulting in the reconnection and drives the jet (Jet1-3) eruptions. The formation of the plasma blobs are observed during the eruption of the first jet (Jet1).

Jets with electrons from boosted top quarks

We propose a method to identify jets consisting of all the visible remnants of a boosted top quark decaying semileptonically with an electron in the final state. An overlap of electron shower with the b quark initiated shower, and the large nontrivial energy-momentum carried by the invisible neutrino in the top quark decay are the two obstacles to achieving this aim. Our method uses the distribution of energy in different parts of the detector to identify a jet containing an energetic electron, involves use of substructure of the jet to determine the momentum associated with the electron and then completes the identification of top jet with the construction of new variables which would reflect the top quark decay kinematics. The last part involves an ansatz of the existence of a massless, invisible four-momentum roughly collimated with the electron, whose four- momentum when combined with that of the the electron and the full jet, reconstructs to the W boson and the top quark respectively. We demonstrate the efficacy of this proposal using simulated data and show that our method not only reduces the backgrounds from light flavor jets, b jets from QCD, and hadronic top jets, it can also tell apart jets rich in electrons but not due to top quark decays.

Hopf-Zero singularities truly unfold chaos

We provide conditions to guarantee the occurrence of Shilnikov bifurcations in analytic unfoldings of some Hopf-Zero singularities through a beyond all order phenomenon: the exponentially small breakdown of invariant manifolds which coincide at any order of the normal form procedure. The conditions are computable and satisfied by generic singularities and generic unfoldings.The existence of Shilnikov bifurcations in the Cr case was already argued by Guckenheimer in the 80’s. About the same time, endowing the space of C∞ unfoldings with a convenient topology, persistence and density of the Shilnikov phenomenon was proved by Broer and Vegter in 1984. However, since the proof involves the use of flat perturbations, this approach is not valid in the analytic context. What is more, none of the mentioned approaches provides a computable criteria to decide whether a given unfolding exhibits Shilnikov bifurcations or not.Many people appeals to the appearance of Hopf-Zero singularities to explain the emergence of chaos in a huge number of applications. However, no one can refer to a specific theorem establishing the conditions that a given unfolding should satisfy to ensure that chaotic dynamics are exhibited. We fill this gap by providing an ultimate result about the appearance of Shilnikov bifurcations in analytic unfoldings of a certain class of Hopf-Zero singularities. These conditions are computable and satisfied by generic families. One of these conditions depends on the full jet of the singularity and comes from a beyond all order phenomenon. It can be related with Stokes constants. The other conditions only depend on the 2-jet of the family.

Nuclear modification of jet shape for inclusive jets and γ-jets at the LHC energies

With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jets and γ-jets in Pb+Pb collisions at 5.02 ATeV and 2.76 ATeV. The in-medium evolution of full jet shower is described by a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced splitting process. The dynamical evolution of bulk medium is simulated by solving relativistic hydrodynamic equation with source term which accounts for the energy and momentum deposited by hard jet shower to soft medium. Our study demonstrates that the hydrodynamic medium response to jet propagation significantly enhances the broadening of jet shape at large angles and is essential for the cone-size dependence of jet energy loss and nuclear modification factor of inclusive jet production. It is also found that the nuclear modification pattern of jet shape is sensitive to jet energy but has weak dependence on the flavor of the parton that initiates the jet. Our result can naturally explain the different nuclear modification patterns of jet shape functions for single inclusive jet and γ-jet events as observed by the CMS Collaboration, and can be tested in the future by measuring the jet shape function over a wider range of jet energies in heavy-ion collisions.