Heavy Targets Research Articles

Fast Visual Tracking With Robustifying Kernelized Correlation Filters

Robust visual tracking is a challenging work because the target object suffers appearance variations over time. Tracking algorithms based on correlation filter have presently attracted much attention because of their high efficiency and computation speed. However, these algorithms can easily drift for the noisy updates. Moreover, they are out of action and cannot re-track when trackers failure caused by heavy occlusion or target being out of view. In this paper, we propose a robust correlation filter that is constructed by considering all the extracted target appearances from the initial image to the current image. The numerator and denominator of the filter model are updated separately instead of linearly interpolated only by storing the current model. Strategies, such as reducing feature dimensionality and interpolating correlation scores, are investigated to reduce computational cost for fast tracking. Occlusion and fast motion problems can be effectively solved by the expansion of the search area. In addition, model updates occur under the condition of a confidence metric (i.e., peak-to-sidelobe ratio) threshold. Comprehensive experiments were conducted on object tracking data sets and the results showed that our method performs well compared to the other competitive methods. Moreover, it runs on a single central processing unit at a speed of 69.5 frames per second, which is suitable for real-time application.

Predicting Membrane Lifetime with Cerium Oxide in Heavy Duty Fuel Cell Systems

Stringent reliability and durability requirements for fuel cells in heavy duty vehicles demand highly durable ionomer membranes. Fuel cell membranes degrade chemically and mechanically during operation, which can lead to membrane thinning, pinhole and crack formation and eventual failure due to hydrogen leaks. The chemical portion of degradation can be suppressed with the use of radical scavenging agents such as cerium oxide. In order to implement extended durability solutions in actual field operation, however, aptly designed accelerated durability tests and empirical models are needed to predict membrane lifetime under various operating conditions, while also considering additive stability over time. Here, an empirical membrane lifetime model recently developed for transit bus applications is modified and demonstrated to predict membrane lifetime with cerium oxide incorporated into the membrane electrode assembly as a chemical stabilizer. The lifetime prediction approach utilizes laboratory scale experimental data from an accelerated membrane durability test complemented by measured cerium washout rates. Provided that the cerium washout rates were relatively low, the predicted membrane lifetime of cerium supported membranes was found to significantly exceed the ultimate 25,000 h heavy duty durability target.

SHiP project as a new facility at intensity frontier

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility suggested for SPS accelerator at CERN. The experiment is currently in Comprehensive Design Report preparation phase, aiming to become a part of European Strategy for Particle Physics update in 2019. In the initial phase of SHiP, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target producing 2 × 1020 protons on target in 5 years. A dedicated detector, based on a long vacuum tank followed by a spectrometer and particle identification detectors, will allow probing a variety of models with light long-lived exotic particles and masses below O(10) GeV/c2. The main focus will be the physics of the so-called Hidden Portals, i.e. search for Dark Photons, Light scalars and Heavy Neutrinos. The sensitivity to Heavy Neutrinos will allow for the first time to probe, in the mass range between the kaon and the charm meson mass, a coupling range for which Baryogenesis and active neutrino masses could be explained simultaneously. Another dedicated detector will allow the study of tau-neutrino physics.

A Novel Experimental Setup for Rare Events Selection and Its Potential Application to Super-heavy Elements Search

The paper presents a novel instrumentation for rare events selection which was tested in our research of short lived super heavy elements production and detection. The instrumentation includes an active catcher multi elements system and dedicated electronics. The active catcher located in the forward hemisphere is composed of 63 scintillator detection modules. Reaction products of damped collisions between heavy ion projectiles and heavy target nuclei are implanted in the fast plastic scintillators of the active catcher modules. The acquisition system trigger delivered by logical branch of the electronics allows to record the reaction products which decay via the alpha particle emissions or spontaneous fission which take place between beam bursts. One microsecond wave form signal from FADCs contains information on heavy implanted nucleus as well as its decays.

Monte Carlo transport code use for optimisation of neutron flux produced with 10-18 MeV electron beam energy

This manuscript describes how to calculate the neutron flux produced by irradiation of a heavy target with an electron beam energy from 10 MeV to 18 MeV. It also describes how to optimise the design of the photo-neutrons converter target. For this purpose, we investigate the optimal materials used as a neutron converter by performing several simulations with the MCNP-6 code using heavy materials (tantalum, lead, tungsten and tungsten-beryllium). We optimise the neutron flux by varying thickness and diameter of the target with different electron beam energy. The results show that the electron-based target was able to provide high-neutron flux with a small target geometry dimension. After all calculations, we concluded that the neutron flux produced using the optimal geometry found in this article, during the several simulations using the MCNP method knows a significant increase, and reaches the following values of 2.01 × 1011 n/cm²s, 2.28 × 1011 n/cm²s, 1.17 × 1010 n/cm²s and 1.51 × 1011 n/cm²s, respectively for lead, tantalum, tungsten and tungsten-beryllium targets.

The choice of the energy embedding law in the design of heavy ionic fusion cylindrical targets

The paper considers the numerical design of heavy ion fusion (FIHIF) targets, which is one of the branches of controlled thermonuclear fusion (CTF). One of the important tasks in the targets design for controlled thermonuclear fusion is the energy embedding selection whereby it is possible to obtain “burning” (the presence of thermonuclear reactions) of the working DT region. The work is devoted to the rapid ignition of FIHIF targets by means of an additional short-term energy contribution to the DT substance already compressed by massively more longer by energy embedding. This problem has been fairly well studied for laser targets, but this problem is new for heavy ion fusion targets. Maximum momentum increasing is very technically difficult and expensive on modern FIHIF installations. The work shows that the additional energy embedding (“igniting” impulse) reduces the requirements to the maximum impulse. The purpose of this work is to research the ignition impulse effect on the FIHIF target parameters.

Dynamics of complete and incomplete fusion of 6,7Li, 15N and 16O with a 209Bi target

The dynamics of complete and incomplete fusion of 6,7Li, 15N and 16O with a common target (209Bi) around the Coulomb barrier are analyzed within the context of the coupled channel formulation and the energy dependent Woods-Saxon potential (EDWSP) model. The calculated results are compared with experimental fusion cross-sections and it has been shown that complete fusion (CF) data of weakly bound projectile with a heavy target (209Bi) gets suppressed at above barrier energies. In the case of the 6Li + 209Bi (7Li + 209Bi) reaction, the CF data at above barrier energies is reduced by 34% (26%) with reference to the expectations of the coupled channel approach. However, the theoretical estimations due to the EDWSP model can minimize the suppression factor by 9% with respect to the reported value and consequently the portion of above barrier CF cross-section data of 6Li + 209Bi (7Li + 209Bi) reaction is suppressed by 25% (17%) when compared with the present model calculations. This fusion inhibition can be correlated with the low breakup threshold of projectile which in turn breaks up into two fragments in the entrance channel prior to fusion barrier. The total fusion (TF) data, which is sum of complete fusion (CF) data and incomplete fusion (ICF) data, is not suppressed when compared with the predictions of the theoretical approaches and thus breakup channel has very little influence on the total fusion cross-sections. Although the breakup fragments appeared in both reactions, the enhanced suppression effects observed for the lighter projectile can be correlated with its low binding energy associated with the $\alpha$ -breakup channel. Further the outcomes of the EDWSP model reasonably explained the ICF contribution appeared in the fusion of 6,7Li + 209Bi reactions. In contrast to this, the observed fusion dynamics of 15N + 209Bi and 16O + 209Bi reactions, wherein the collective excitations such as two phonon, three phonon vibrational states contribute to produce below barrier fusion enhancement, has been adequately explored by the adopted models, and henceforth ensures the stability of well bound nuclei against breakup effects.

Fusion dynamics of stable and weakly bound colliding systems

This work systematically analyzed the fusion dynamics of the projectile-target combinations involving stable and loosely bound systems within the view of the energy-dependent Woods–Saxon potential model (EDWSP model) and the coupled channel approach. The different projectiles are bombarded onto series of Sm-isotopes, which possess the dominance of the different kinds of the nuclear structure degrees of freedom and with the increase of the neutron richness, the Sm-isotopes gradually shift from spherical shape to a statically deformed shape. In the fusion of [Formula: see text] reaction, the impacts of vibrational degrees of freedom of the colliding nuclei are dominant while in the case of [Formula: see text] systems, the rotational states of the deformed target isotopes have a strong impression on the below-barrier fusion data. The heavier target isotopes ([Formula: see text] also exhibit the higher order deformation such as [Formula: see text], [Formula: see text]-deformation parameter in its ground state and couplings to such channels must be incorporated in theoretical calculations in order to achieve close agreement with the sub-barrier fusion data. However, in the case of the loosely bound systems, the projectile breakup channel significantly affects the fusion excitation functions in the domain of the Coulomb barrier. To ensure the role of the projectile breakup channel, the fusion of the different loosely bound projectiles ([Formula: see text] and [Formula: see text] with Sm-isotopes are investigated, wherein the above-barrier fusion data of these reactions are suppressed with reference to the coupled channel calculations. This hindrance is the result of the projectile breakup effects that occur as a consequence of the breakup of the projectile before reaching the fusion barrier due to its low binding energy. However, in the EDWSP model calculations the magnitude of the hindrance of the above-barrier fusion data of [Formula: see text] and [Formula: see text] reactions is reduced by a factor varying from 7% to 13% with respect to a value reported in the literature. In contrast to this, the sub-barrier fusion enhancement of [Formula: see text] and [Formula: see text] reactions is the result of the dominance of the nuclear structure degrees of freedom of the colliding systems.

Fusion hindrance at deep sub-barrier energies for the B11+Au197 system

Fusion cross sections for the $^{11}\mathrm{B}+^{197}\mathrm{Au}$ system have been measured at energies around and deep below the Coulomb barrier, to probe the occurrence of fusion hindrance in case of asymmetric systems. A deviation with respect to the standard coupled channels calculations has been observed at the lowest energy. The results have been compared with an adiabatic model calculation that considers a damping of the coupling strength for a gradual transition from sudden to adiabatic regime at very low energies. The data could be explained without inclusion of the damping factor. This implies that the influence of fusion hindrance is not significant within the measured energy range for this system. The present result is consistent with the observed trend between the degree of fusion hindrance and the charge product that reveals a weaker influence of hindrance on fusion involving lighter projectiles on heavy targets.

SHiP: a new facility with a dedicated detector for studying tau-neutrino properties and nucleon structure functions

SHiP is a new general purpose fixed target facility, whose Technical Proposal has been recently reviewed by the CERN SPS Committee, who recommended that the experiment proceeds further to a Comprehensive Design phase. In its initial phase, the 400 GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating 2 × 1020 pot in 5 years. A dedicated detector downstream of the target will allow to probe a variety of models with light long-lived exotic particles and masses below a few GeV/c2. Another dedicated detector will allow the study of neutrino cross-sections and angular distributions, which was the focus of the poster. ντ deep inelastic scattering cross sections will be measured with a statistics 1000 times larger than currently available, with the extraction of the F4 and F5 structure functions, never measured so far and allow for new tests of lepton non-universality with sensitivity to BSM physics. Moreover, ντ’s will be distinguished from ’s, thus providing the first observation of the . With νµ scattering it will be possible to reduce by about 50% the current uncertainty on the strange content of the nucleon in the range of the x variable between 0.05 and 0.3, complementary to LHC measurements. The detector will be based on several techniques developed for the OPERA experiment at LNGS.

Improved technique for preparation of deuterated-polyethylene targets

Abstract An improved method for preparation of self-supporting deuterated polyethylene targets using solvent casting technique is described. The improved method provides recommendations for solvent heating, solvent casting of the thin film, and subsequent heating treatment which is shown to greatly enhance the overall target strength and durability as needed for accelerator experiments. A detailed characterization using both optical and electron microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy demonstrates the improvements using the post-casting heating treatment. The effects of heavy ion-induced target degradation and recommendations for use under these conditions is also discussed.

Linear microfocus bremsstrahlung generated in light and heavy narrow targets in B-18 betatron

The first results of studying the properties of X- and G-ray beams generated at the grazing incidence of 18-MeV electrons with the 50 and 8-μm-thick Si crystals and a 13-μm-thick Ta foil of 4 mm in length along the electron beam are presented. The target has been placed in a goniometer inside the chamber of a B-18 betatron. The results exhibit strong changes in the angular distribution of radiation at the variation of the orientation of the target. This effect is not observed in the case of the normal incidence of electrons on the surface of a thin target. Images of a reference microstructure have been obtained with a high resolution of details of the microstructure owing to the smallness of the source of radiation. The dependence of the contrast of an image on the position of the microstructure in the radiation cone has been demonstrated, which is determined by the change in the effective size of the radiation source when the emission angle of the source is changed.

Validity of sum rules for the polarization transfer in electron bremsstrahlung

The polarization correlations, which describe the spin transfer from a high-energy spin-polarized electron to the photon in the elementary process of bremsstrahlung induced by strong potentials, obey a strict sum rule in the case of coplanar emission. The proof is carried out within the relativistic partial-wave approach. Further sum estimates are obtained by means of a variational principle under the sole condition that the transition amplitude is linear in the electron wavefunctions and in the photon field. Numerical sum rule results are given for light and heavy bare target atoms in the energy range 1–10 MeV.

Benchmarks of subcriticality in accelerator-driven system at Kyoto University Critical Assembly

Abstract Basic research on the accelerator-driven system is conducted by combining 235U-fueled and 232Th-loaded cores in the Kyoto University Critical Assembly with the pulsed neutron generator (14 MeV neutrons) and the proton beam accelerator (100 MeV protons with a heavy metal target). The results of experimental subcriticality are presented with a wide range of subcriticality level between near critical and 10,000 pcm, as obtained by the pulsed neutron source method, the Feynman-α method, and the neutron source multiplication method.

Vector boson production in pPb and PbPb collisions at the LHC and its impact on nCTEQ15 PDFs

We provide a comprehensive comparison of W^pm / Z vector boson production data in pPb and PbPb collisions at the LHC with predictions obtained using the nCTEQ15 PDFs. We identify the measurements which have the largest potential impact on the PDFs, and estimate the effect of including these data using a Bayesian reweighting method. We find this data set can provide information as regards both the nuclear corrections and the heavy flavor (strange quark) PDF components. As for the proton, the parton flavor determination/separation is dependent on nuclear corrections (from heavy target DIS, for example), this information can also help improve the proton PDFs.

Energy Production Demonstrator and Material Testing Station optimization for Megawatt proton beams

A simulation study of the Energy Production Demonstrator (EPD) concept – a solid heavy metal target irradiated by GeV-range intense proton beams and producing more energy than consuming – is carried out. Neutron production, fission, energy deposition, energy gain, testing volume and helium production are simulated using the MARS15 code for tungsten, thorium, and natural uranium targets in the proton energy range 0.5–120GeV. This study shows that the proton energy range of 2–4GeV is optimal for both a natU EPD and the tungsten-based testing station for proton accelerator facilities. Simulation-based conservative estimates not including breeding and fission of plutonium suggest the proton beam current sufficient to produce 1GW of thermal output power with the natU EPD while supplying a relatively small fraction of that power to operate the accelerator. The thermal analysis has been performed and has shown that the EPD with a parallel proton beam feeding the core has a potential problem due to a possible core meltdown. A scheme has been proposed with a beam steering on the outer surface of the target; its thermal analysis indicates that slicing the target in shorter parts and maintaining a temperature of 25°C on their surfaces would to avoid the target meltdown.

Four- and three-body breakup mechanism of 6Li elastic scattering

We investigate a breakup mechanism of 6Li elastic scattering on heavy targets (T = 209Bi or 208Pb) with the four-body version of the continuum-discretized coupled-channels method (four-body CDCC). Four-body CDCC successfully reproduces measured elastic cross sections with no adjustable parameter, and we can then clearly discuss the four-body dynamics. Our analysis shows that dα breakup (6Li + T → d + α + T) is much more essential than npα breakup (6Li + T → n + p + α + T) in 6Li scattering.

SHiP: a new facility with a dedicated detector for studying tau neutrino properties

SHiP (Search for Hidden Particles) is a new general purpose fixed target facility at the CERN SPS accelerator, with the aim of search for New Physics which has small coupling with standard particles by searching for long lived beyond standard model particles with masses below a few GeV/c2. The SHiP facility is a high intensity beam bump, the 400GeV proton beam extracted from the SPS will be dumped on a heavy target with the aim of integrating 2×1020 pot in 5 years. A dedicated detector, based on the OPERA-like ECC (Emulsion Cloud Chamber), will provide tau and anti-tau neutrino detection capability to study ντ and ν‾τ cross-sections with a statistics a few 100 times larger than the DONUT experiment. Moreover, the structure functions F4 and F5 which is only accessible by tau neutrino interactions can be measured first time. SHiP is the unique chance to study tau and anti tau neutrino properties.

Importance of the continuum–continuum couplings in the 6Li elastic breakup on different target masses

A theoretical study of Li6 breakup on target masses ranging from A=58 to 208 is performed. It is obtained that when continuum–continuum couplings are included in the potential coupling matrix, they substantially reduce the total and nuclear breakup cross sections, while the Coulomb breakup cross sections for the medium and heavy target masses are increased. When these couplings are excluded, we show that the total and nuclear breakup cross sections depend linearly on AT1/3, namely they decrease linearly as the mass of the target increases. In the same case, the Coulomb breakup cross section depends linearly with the charge of the target ZT (decreases as ZT increases). We found that this linearity is destroyed when these couplings are included. However, in this case, it is the Coulomb-nuclear interference that also depends linearly with the target charge (increase with ZT).

Optimization of breeding properties of the spallation neutron source target for ADS

One of the main components of an ADS (accelerator-driven reactor systems) is the spallation target, generating neutrons for power plant. Neutrons are generated due in spallation reactions induced on heavy nuclei by accelerator beam of high-energy protons with subsequent multiplication of neutrons in the cascade process of interactions of secondary intermediate-energy particles with target nuclei, subcritical core and blanket.On average, from 20 (for Hg and Pb targets) to 50 (for U target) neutrons are produced per 1-GeV proton in spallation reactions in the target containing nuclei of heavy elements (for example, Hg, Ta, W, U,).Heavy elements such as lead, bismuth, mercury, tantalum, and tungsten are considered as suitable materials for the targets. Lead-bismuth eutectic targets are successfully developed.It is demonstrated in the present paper that there exist optimal size of the target material allowing obtaining for the given incident particle energy maximum number of “spallation” neutrons. Results of calculations of energy spectrum of neutrons generated in the proton interactions with heavy targets for the energy range of incident protons from 0.8 to 1.4GeV.Implemented analysis of variation of neutron generation rate for cylindrical target with 10cm diameter and length from 1 to 120cm at impinging proton energies from 0.8 to 1.4GeV allowed calculating optimal target dimensions consisting of heavy nuclei for the nuclear power installations under design.Optimization of dimensions of neutron generating targets consisting of natural natBi, natHg, natPb и natW isotopes was implemented.