Projectile Fragmentation Research Articles

Estimation of Influence of Target Material Type on Penetration Capability of 12.7 mm Armor-Piercing Projectile

In the study an estimation of the influence of target material type on the penetration capability of the 12.7 mm API-T (armor-piercing incendiary with tracer) projectile is performed. The literature review contains 14 references regarding 12.7 mm ammunition studies. A relatively large number of metallic targets are taken into consideration in a computer simulation that assesses the influence of the target type on the penetration capabilities of the given projectile. By comparing the acquired findings with the data of other authors, the numerical model was first successfully validated. Simulation results indicate that bainitic steels are by far the most resilient steels. Because of their hardness, these steels displayed significant erosion of the penetrator tip and significant projectile fragmentation upon impact. Iron targets, as expected, performed worse than steel targets, with more penetration seen. Mild steel had a significantly deeper penetration compared to armor steel. The performance of other steels employed in the study was comparable. Numerical simulations have shown to be a very effective technique in ammunition and armor design, resulting in substantial time and cost savings (fewer experimental experiments). Furthermore, by utilizing simulations, researchers can estimate certain physical processes that would be challenging to detect in actual testing.

Influence of explosive type and constant γ in Mott’s stochastic model on terminal-ballistics parameters of high-explosive warheads using numerical simulations

The research examined the use of numerical simulations for high-explosive (HE) munitions. Lagrange and Euler solvers from Ansys Autodyn, whose brief theoretical synopsis is given, were utilized. Numerical program modeling of materials under dynamic loads (explosives and solid bodies) is also explained. The study also provides a brief summary of relevant research works that address numerical simulations of the fragmentation of HE projectiles (warheads). First, using data from other authors, the numerical model in this paper was effectively validated. The original research in the publication included an evaluation of the influence of explosive type on mass distribution, as well as velocity and the kinetic energy of fragments on cylindrical warheads, along with some recommendations and findings. Results show that ordered by values of initial fragment velocity are explosives: Trinitrotoluen (TNT), H6, Comp. B, Octol, PBX-9404-3, and LX-10-1. Explosives LX-10-1 and PBX-9404-3 showed similar performance because both explosives are HMX-based mixtures, with LX-10-1 having 0.5% more Octogen (HMX). The greatest (fastest) expansion of fragments (for the given time frame of 150 µs) is present in the most potent explosives (LX-10-1 and PBX-9404-3) since they have the largest detonation velocities. In the configurations with stronger explosives (Octol, LX-10-1, PBX-9404-3), the front and rear cover of the cylinder is more fragmented than in the case of weaker explosives. The highest number of fragments is obtained with PBX-9404-3 explosive, 142% higher than using TNT charge. Also, as part of the original research in the paper, an assessment of the influence of the constant γ in Mott’s stochastic fragmentation model on the mass distribution of fragments and their kinetic energy was made. Results indicate that constant γ has the greatest influence on the number of very small fragments, which can be used when calibrating this constant with experimental data. The masses of fragments are relatively uniform (for all γ values) up to the mass group of 50–100 g, above which the most massive fragments are obtained when γ = 5. Most of the fragments have relatively high energy where that is, fragments of mass 0.5–2 g have an average kinetic energy of 470–650 J, while fragments of masses 50–100 g have an average kinetic energy of 50–85 kJ. Described numerical simulations are a valuable tool for HE warhead designers, as they can minimize the time and expense associated with optimizing HE munition design and effectiveness evaluation when used in conjunction with available analytical techniques and experimentation procedures.

Discovery of Neutron-Rich Silicon Isotopes 45,46Si

Abstract New isotopes $^{45,46}$Si, which extend beyond the most neutron-rich Si isotopes confirmed thus far, have been discovered at the RI Beam Factory at the RIKEN Nishina Center. The isotopes were produced by the in-flight fragmentation reactions of $^{70}$Zn at 345 MeV/nucleon on a Be target. All the projectile fragments were analyzed and identified using the large-acceptance two-stage separator BigRIPS. Consequently, six $^{45}$Si events and one $^{46}$Si event were confirmed. The neutron-bound nature of odd-N$^{45}$Si may have a significant impact on the nuclear stability of neutron-rich proton $sd$-shell nuclei at approximately $N=40$.

Numerical Analysis of Debris Cloud Formation in UHMWPE Wavy Plates during Hypervelocity Impact

This paper presents and analyses the numerical results of hypervelocity impact against ultra-high molecular weight polyethylene (UHMWPE) plates with four different surface wave profiles. UHMWPE wavy plates (WP) are intended to be used in Whipple Shield bumper plate, which is of paramount importance for space vehicles against micro-meteorite and orbital debris (MMOD) impact protection. Numerical work was carried out as a hybrid combination of smoothed particle hydrodynamics (SPH) and finite element modelling (FEM). Circular plates were subjected to hypervelocity impact of a spherical aluminium projectile travelling at 3000 m/s. The outcomes of the simulations were analysed in terms of debris cloud generation, projectile fragmentation, and impact energy dissipation performance of wavy plates, and compared with a conventional flat counterpart. Results of this study indicate that surface wave profile has a clear positive influence in terms of hypervelocity impact protection performance.

Forensic-radiological diagnosis of gunshot wounds

Although gunshot wounds are less common in Germany than in other countries, aproportion of suicides and violent crimes are committed with firearms, which is why basic knowledge of diagnosis is important. Fundamentals regarding forensic assessment of gunshot wounds are discussed alongside typical radiological findings. In addition to analyzing our own cases and evaluating official statistics, this article is based on adiscussion of basic research and expert recommendations. The article describes the characteristics of the bullet entry and exit as well as special features of the bullet trajectory, particularly in bony injuries, and discusses their significance for radiological findings. Pitfalls in interpretation, such as changes in body position and the deflection of projectile (fragments) in the body, are presented, as are the advantages of supplementary radiological diagnostics (projectile search before initiation of dissection, simple detection of an air embolism, clarity of bullet trajectory reconstruction). This article is intended to provide an overview of not only typical types of weapons and projectiles but also their effects on the body of the victim, which must be documented by the examiner.

Penetration resistance of Al2O3 ceramic-ultra-high molecular weight polyethylene (UHMWPE) composite armor: Experimental and numerical investigations

To enhance the protective performance of ceramic composite armor, ballistic penetration experiments were conducted on Al2O3 ceramic-ultra-high molecular weight polyethylene (UHMWPE) composite armor with different thickness configurations. The damage and failure modes of hard projectiles and ceramic-fiber composite targets were analyzed. The recovered projectiles and ceramic fragments were sieved and weighed at multiple stages, revealing a positive correlation between the degree of fragmentation of the projectiles and ceramics and the overall ballistic resistance of the composite targets. Numerical simulations were performed using the LS-DYNA finite element software, and the simulation results showed high consistency with the experimental results, confirming the validity of the material parameters. The results indicate that the projectile heads primarily exhibited crushing and abrasive fragmentation. Larger projectile fragments mainly resulted from tensile and shear stress-induced failure. The failure modes of the composite targets included the formation of ceramic cones and radial cracks under high-velocity impacts. The UHMWPE laminated plates exhibited interlayer separation caused by tensile waves, permanent plastic deformation of the rear surface bulging, and perforation failure primarily due to shear forces.Through extended numerical simulations, while maintaining the same areal density and configuration of 9 mm Al2O3 ceramic + 12 mm UHMWPE laminated composite armor, the thickness configurations of the Al2O3 ceramic and UHMWPE laminated backplates were varied, and various thicknesses of UHMWPE laminates were simulated as the cover layer for the ceramic panels. The simulation results indicated that the composite armor configuration of 10 mm Al2O3 ceramic + 8 mm UHMWPE composite armor increased energy absorption by 13.48 %. When altering the cover layer thickness, a 4 mm UHMWPE + 9 mm Al2O3 + 8 mm UHMWPE composite armor demonstrated a 27.11 % improvement in energy absorption, showing a relatively significant enhancement.

Predicting 28Si projectile fragmentation cross sections with Bayesian neural network method* *Supported by the National Nature Science Foundation of China (11075100, 11347198, 11565001), the Natural Science Foundation of Shanxi Province, China (2011011001-2), the Shanxi Provincial Foundation for Returned Overseas Chinese Scholars (2011-058), and the Postgraduate Science and Technology Innovation Project of Shanxi Normal University (2023XBY004)

This study utilizes the Bayesian neural network (BNN) method in machine learning to learn and predict the cross-sectional data of 28Si projectile fragmentation for different targets at different energies and to quantify the uncertainty. The detailed modeling process of the BNN is presented, and its prediction results are compared with those of the Cummings, Nilsen, EPAX2, EPAX3, and FRACS models and experimental measurement values. The results reveal that, compared with other models, the BNN method achieves the smallest root-mean-square error (RMSE) and the highest agreement with the experimental values. Only the BNN method and FRACS model show a significant odd-even staggering effect; however, the results of the BNN method are closer to the experimental values. Furthermore, the BNN method is the only model capable of reproducing data features with low cross-section values at Z = 9, and the average ratio of the predicted to experimental values of the BNN is close to 1.0. These results indicate that the BNN method can accurately reproduce and predict the fragment production cross sections of 28Si projectile fragmentation and demonstrate its ability to capture key data characteristics.

Charge measurement with nuclear emulsions spectrometers for hadron therapy fragmentation cross section measurements with the FOOT experiment

Experimental data concerning projectile and target fragmentation is limited, increasing the uncertainty on the dose in the entrance channel in particle therapy treatments. The FOOT experiment measures nuclear fragmentation cross sections with two complementary detectors. The performance of the FOOT nuclear emulsion detectors in identifying the charge of nuclear fragments has recently been studied using 16O beams at 200 and 400MeV/n, directed at carbon and polyethylene targets. This work extends the previous analysis, comparing experimental data and FLUKA Monte Carlo predictions, focusing on the angular distribution and relative abundances of fragments with Z≤5 originating from the interactions of a 400MeV/n oxygen beam with a carbon target.

Investigation of projectile fragment emission in the fragmentation of 28Si on C target at 736 A MeV

The emission angular distributions, the transverse momentum distributions and the temperature parameters of projectile fragments produced in fragmentation of [Formula: see text]Si on C target at 736[Formula: see text]A[Formula: see text]MeV are measured. It is found that the scattering angle of primary silicon ions is smaller than the emission angle of their fragments. The average value and the width of the angular distribution and the transverse momentum distribution are increased with the decrease of the charge of projectile fragments. The cumulative squared transverse momentum distribution of projectile fragments can be well fitted by a single Rayleigh distribution, which indicates that the projectile fragments are emitted from a single temperature emission source. Most of the temperature parameters of projectile fragments emission source are in the range of 2–5[Formula: see text]MeV, which does not obviously depend on the charge of the projectile fragments.

The shape of the Tz = +1 nucleus 94Pd and the role of proton-neutron interactions on the structure of its excited states

Reduced transition probabilities have been extracted between excited, yrast states in the N=Z+2 nucleus 94Pd. The transitions of interest were observed following decays of the Iπ=14+, Ex=2129-keV isomeric state, which was populated following the projectile fragmentation of a 124Xe primary beam at the GSI Helmholtzzentrum für Schwerionenforschung accelerator facility as part of FAIR Phase-0. Experimental information regarding the reduced E2 transition strengths for the decays of the yrast 8+ and 6+ states was determined following isomer-delayed Eγ1−Eγ2−△T2,1 coincidence method, using the LaBr3(Ce)-based FATIMA fast-timing coincidence gamma-ray array, which allowed direct determination of lifetimes of states in 94Pd using the Generalized Centroid Difference (GCD) method. The experimental value for the half-life of the yrast 8+ state of 755(106) ps results in a reduced transition probability of B(E2:8→+6+) = 205−25+34 e2fm4, which enables a precise verification of shell-model calculations for this unique system, lying directly between the N=Z line and the N=50 neutron shell closure. The determined B(E2) value provides an insight into the purity of (g9/2)n configurations in competition with admixtures from excitations between the (lower) N=3pf and (higher) N=4gds orbitals for the first time. The results indicate weak collectivity expected for near-zero quadrupole deformation and an increasing importance of the T=0 proton-neutron interaction at N=48.

Plastic scintillator fiber detectors for heavy ion trajectory reconstruction for the Super-FRS at FAIR

At the FAIR facility, currently under construction at GSI (Darmstadt), a 1.5 AGeV uranium beam with intensities up to 2.5 × 1011 238U/spill will impinge on a graphite target at the entrance of the Super-FRS for the production of a wide range of rare isotopes by projectile fission and fragmentation. The next generation in-flight magnetic separator Super-FRS, operated up to a magnetic rigidity of 20 Tm with a large angular acceptance (Δθ = ± 40 mrad, Δϕ = ± 20 mrad) and momentum acceptance (Δ p/p = ± 2.5%), requires a new generation of tracking detectors with a position resolution of 0.2 mm (σx ) over large detector areas reaching up to 570 cm2. Besides gas detectors, planar detectors made of scintillating fibers are an option worth investigating not only because of the comparable material budget but especially for the fast response and high-rate capability. A one-dimensional prototype consisting of 128 fibers with active area of 25.6 × 100 mm2 coupled to Multi-Pixel-Photon Counters (MPPCs) and readout by FPGA TDC is described together with some recent 197Au beam test results.

A possible probe to neutron-skin thickness by fragment parallel momentum distribution in projectile fragmentation reactions

A possible probe to neutron-skin thickness by fragment parallel momentum distribution in projectile fragmentation reactions

Broken seniority symmetry in the semimagic proton mid-shell nucleus Rh95

Lifetime measurements of low-lying excited states in the semimagic (N=50) nucleus Rh95 have been performed by means of the fast-timing technique. The experiment was carried out using γ-ray detector arrays consisting of LaBr3(Ce) scintillators and germanium detectors integrated into the DESPEC experimental setup commissioned for the Facility for Antiproton and Ion Research () Phase-0, Darmstadt, Germany. The excited states in Rh95 were populated primarily via the β decays of Pd95 nuclei, produced in the projectile fragmentation of a 850 MeV/nucleon Xe124 beam impinging on a 4g/cm2Be9 target. The deduced electromagnetic E2 transition strengths for the γ-ray cascade within the multiplet structure depopulating from the isomeric Iπ=21/2+ state are found to exhibit strong deviations from predictions of standard shell model calculations which feature approximately conserved seniority symmetry. In particular, the observation of a strongly suppressed E2 strength for the 13/2+→9/2+ ground state transition cannot be explained by calculations employing standard interactions. This remarkable result may require revision of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations, and might also point to the need for including three-body forces in the Hamiltonian. Published by the American Physical Society 2024

Impact Disruption of Bjurböle Porous Chondritic Projectile

The ∼200 m s−1 impact of a single 400 kg Bjurböle L/LL ordinary chondrite meteorite onto sea ice resulted in the catastrophic disruption of the projectile. This resulted in a significant fraction of decimeter-sized fragments that exhibit power-law cumulative size and mass distributions. This size range is underrepresented in impact experiments and asteroid boulder studies. The Bjurböle projectile fragments share similarities in shape (sphericity and roughness at small and large scales) with asteroid boulders. However, the mean aspect ratio (3D measurement) and apparent aspect ratio (2D measurement) of the Bjurböle fragments is 0.83 and 0.77, respectively, indicating that Bjurböle fragments are more equidimensional compared to both fragments produced in smaller-scale impact experiments and asteroid boulders. These differences may be attributed either to the fragment source (projectile versus target), to the high porosity and low strength of Bjurböle, to the lower impact velocity compared with typical asteroid collision velocities, or potentially to fragment erosion during sea sediment penetration or cleaning.

Multiplicity correlation of fast target protons and projectile fragments for the events produced in the interaction of 84Kr nuclei with emulsion nuclei at 1 A GeV

It has become obvious that one crucial aspect in understanding high energy nuclear reactions is the fragmentation of colliding nuclei. The nuclear emulsion is a 4[Formula: see text] detector that makes it simple to identify and quantify the charges of projectile fragments. In this work, we study the multiplicity distribution and angle distributions of single, double charge projectile fragments, fast target protons (gray particle) as well as their correlation for the events produced in the interactions of [Formula: see text] with emulsion nuclei at 1[Formula: see text]A[Formula: see text]GeV. We also study the target-dependent angle distribution of gray particles. The results are compared with other experimental data as per availability. This analysis shows that multiplicity distributions have a remarkable link between the projectile and target fragmentation processes.

Projectile fragments from peripheral collisions of 25 MeV/nucleon 64Ni on 64Ni

We study the yields and the momentum distributions of projectile-like fragments from peripheral collisions of 64Ni (25 MeV/nucleon) on 64Ni. The experimental data were obtained in previous works with the BigSol separator system at the Cyclotron Institute of Texas A&M University. Projectile fragments were collected and analyzed at forward angles (1.5°-3.0°). The production cross sections and the momentum distributions (p/A) of the fragments were systematically studied and compared with the Deep-Inelastic Transfer (DIT) model and the Constrained Molecular Dynamics (CoMD) model followed by the deexcitation model GEMINI. Special attention is given to the possibility to produce neutron-rich rare isotopes of elements at the beginning of the astrophysical r-process. Moreover, efforts to reconstuct the excitation energy distributions are ongoing in hopes to shed light to the reaction mechanisms of peripheral collisions at this energy (25 MeV/nucleon).

Multinucleon transfer in 48Ti + 48Ti collisions at 11.5 MeV/nucleon

In this work, experimental data of projectile fragment distributions from a preliminary experimental study of the reaction of 11.5 MeV/nucleon 48Ti on 48Ti analyzed with the MARS recoil separator at the Cyclotron Institute of Texas A&M University are presented. Production cross sections, momentum distributions and excitation-energy distributions are extracted and compared with calculations with the Deep Inelastic Transfer (DIT) model and the Constrained Molecular Dynamics model (CoMD). Despite the limited extent of the present dataset, an overall agreement of the models with the data is found pointing at the prevailing nucleon-exchange character of the collisions at this energy.

Projectile Fragmentation Characteristics of the Events Produced from 84Kr+Emulsion Interaction at 1 a Gev

ABSTRACT: Projectile fragmentation is a rather well-isolated phenomenon within the complex context of highly energetic heavy-ion collisions with a multibaryon system. The projectile fragmentation study reveals the characteristics of the particles release out from the projectile spectator region. The goal of present investigation is to study the emission possibility of single event, double events and triple events for the single charge, double charge and multiple charge projectile fragments. The observation show that the emission possibility of single, double and triple events is depending on the types of the projectile fragments.

Increasing the rate capability for the cryogenic stopping cell of the FRS Ion Catcher

At the FRS Ion Catcher (FRS-IC), projectile and fission fragments are produced at relativistic energies, separated in-flight, energy-bunched, slowed down, and thermalized in the ultra-pure helium gas-filled cryogenic stopping cell (CSC). Thermalized nuclei are extracted from the CSC using a combination of DC and RF electric fields and gas flow. This CSC also serves as the prototype for the CSC of the Super-FRS, where exotic nuclei will be produced at unprecedented rates making it possible to go towards the extremes of the nuclear chart. Therefore, it is essential to efficiently extract thermalized exotic nuclei from the CSC under high beam rate conditions, in order to use the rare exotic nuclei, which come as cocktail beams. The dependence of the extraction efficiency on the intensity of the impinging beam into the CSC was studied with a primary beam of 238U and its fragments. Tests were done with two different versions of the DC electrode structure inside the cryogenic chamber, the standard 1 m long and a short 0.5 m long DC electrode systems. In contrast to the rate capability of 104 ions/s with the long DC electrode system, results show no extraction efficiency loss up to the rate of 2 × 105 ions/s with the new short DC electrode. This order of magnitude increase of the rate capability paves the way for new experiments at the FRS-IC, including studies of exotic nuclei with in-cell multi-nucleon transfer reactions. The results further validate the design concept of the CSC of the Super-FRS, which was developed to effectively manage beams of even higher intensities.

Production of Δ0 resonances in the target and projectile fragmentation regions in p+12C and d+12C collisions at 4.2 GeV/c per nucleon

Production of Δ0 resonances in the target and projectile fragmentation regions in p+12C and d+12C collisions at 4.2 GeV/c per nucleon