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At least 163 records · Page 9

Generation of ultra-high-pressure shocks by collision of a fast plasma projectile driven in the laser-induced cavity pressure acceleration scheme with a solid target

A novel, efficient method of generating ultra-high-pressure shocks is proposed and investigated. In this method, the shock is generated by collision of a fast plasma projectile (a macro-particle) driven by laser-induced cavity pressure acceleration (LICPA) with a solid target placed at the LICPA accelerator channel exit. Using the measurements performed at the kilojoule PALS laser facility and two-dimensional hydrodynamic simulations, it is shown that the shock pressure ∼ Gbar can be produced with this method at the laser driver energy of only a few hundred joules, by an order of magnitude lower than the energy needed for production of such pressure with other laser-based methods known so far.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Discovery of 98 Sn Produced by the Projectile Fragmentation of a 345-MeV/Nucleon 124 Xe Beam

We present the discovery of a new isotope of $^{98}$Sn beyond the double-magic N = Z = 50 nucleus $^{100}$Sn. $^{98}$Sn was identified among the projectile-fragmentation products of a $^{124}$Xe beam at 345 MeV/nucleon at the RI Beam Factory, RIKEN, Japan. Additionally, we have confirmed the production of $^{96}$In and $^{94}$Cd, previously reported as new isotopes at RIKEN. These highly proton-rich nuclei were separated and identified using the large-acceptance two-stage separator BigRIPS. Furthermore, we have determined the cross sections of $^{98}$Sn and its neighboring nuclei. These experimental values were compared to the semi-empirical cross-section formula EPAX3.1a, resulting in a reduction of the predicted cross sections by roughly a factor of 5.

07 ISOTOPE AND RADIATION SOURCES↗

Ionization of water molecules by fast charged projectiles

Single-ionization cross sections of water molecules colliding with fast protons are calculated from lowest-order perturbation theory by taking all electrons and molecular orientations consistently into account. Explicit analytical formulas based on the peaking approximation are obtained for differential ionization cross sections with the partial contribution from the various electron orbitals accounted for. The results, which are in very good agreement with total and partial cross sections at high electron and projectile energies, display a strong variation on molecular orientation and molecular orbitals.

74 ATOMIC AND MOLECULAR PHYSICS↗

Dynamical ternary decays of excited projectile-like fragments

We study neutron-proton equilibration in dynamically deformed nuclear systems by investigating the correlations between the three largest fragments produced in collisions of 70 Zn + 70 Zn at 35 MeV per nucleon. In this work, the rotation angle is interpreted as a measure of the duration of contact between the regions of the excited projectile-like fragment as it decays. In this work we address questions of whether there is a simultaneous or a double rupture scenario, sizing of the fragments, and alignment of the configuration.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Production of the most neutron-deficient Zn isotopes by projectile fragmentation of Kr 78

The cross sections for the production of three most neutron-deficient zinc isotopes, 54–56 Zn, in the projectile fragmentation of 78 Kr at 345 MeV/nucleon on a beryllium target, were measured. Although the results are smaller by over an order of magnitude from those obtained with a 58 Ni beam at 75 MeV/nucleon on a nickel target, the rates of reaction products are found to be larger in the case of high-energy fragmentation of 78 Kr. The experimental cross sections for the most neutron-deficient isotopes of even-Z nuclei between zinc and krypton were analyzed in the framework of the abrasion-ablation model. A very good agreement with the data was found when the nuclear masses predicted by a particular variant of the Hartree-Fock-Bogoliubov mass model were used. The prospects for the observation of more exotic isotopes in this region are discussed in context of 2p radioactivity.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Comparative analysis of properties of channels of deuteron and tritium production in {sup 16}Op collisions at a projectile momentum of 3.25 GeV/c per nucleon

The results of a comparative analysis of channels involving the inclusive production of deuterons and tritons in {sup 16}Op collisions at a projectile momentum of 3.25 GeV/c per nucleon are presented. The mechanisms governing proton, deuteron, and triton production in the fragmentation of oxygen nuclei are found to be independent. It is shown that the observed proton-multiplicity correlations are associated predominantly with the character of the primary event of a proton-nucleon collision in {sup 16}Op interactions. It is found that, in reactions involving triton production, the contributions of processes leading to an increase in the mean proton multiplicity (n → p + π{sup −} and np → pn) and processes leading to its decrease (p → n + π{sup +}) compensate each other.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Special features of isomeric ratios in nuclear reactions induced by various projectile particles

Calculations for (p, n) and (α, p3n) reactions were performed with the aid of the TALYS-1.4 code. Reactions in which the mass numbers of target and product nuclei were identical were examined in the range of A = 44–124. Excitation functions were obtained for product nuclei in ground and isomeric states, and isomeric ratios were calculated. The calculated data reflect well the dependence of the isomeric ratios on the projectile type. A comparison of the calculated and experimental data reveals, that, for some nuclei in a high-spin state, the calculated data fall greatly short of their experimental counterparts. These discrepancies may be due to the presence of high-spin yrast states and rotational bands in these nuclei. Calculations involving various level-density models included in the TALYS-1.4 code with allowance for the enhancement of collective effects do not remove the discrepancies in the majority of cases.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Study of hypervelocity projectile impact on thick metal plates

Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments: Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Crush Gun Impact of Unconfined Explosive with Flat-Faced Projectiles at Nominal Velocity of 60 m/s

A pneumatic gun apparatus was designed and built to deliver crushing impacts at velocities of 0-70 m/s. The apparatus is designed to halt the projectile (if desired) approximately 1 mm before impacting the sapphire imaging surface, preventing a complete “pinch” condition from attaining. The primary diagnostics include high-speed visible videography and infrared imaging to determine spatial temperature rise of the sample during impact.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Load Data for Mk279 Projectiles

This document details the resulting velocity of Mk279 Mod1 projectiles when fired from a RD24 barrel with between 15 and 110 grains of smokeless propellant to achieve velocities between 163 and 651m/s.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

INL CRMO XRF Report 2024-01: Provenance Determinations for 135 Haskett Projectile Points from Eastern Idaho

This report presents provenance determinations for 135 obsidian and fine-grained volcanic (FGV) Haskett projectile points from across eastern Idaho. These determinations were made using energy-dispersive X-ray fluorescence (ED-XRF) spectrometry at the Idaho National Laboratory (INL) Cultural Resource Management Office (CRMO) under the direction of Dr. Kyle Freund.

58 GEOSCIENCES↗

INL CRMO XRF Report 2025-03: Provenance Determinations for 854 Projectile Points from Idaho Falls District Bureau of Land Management Archaeological Collections

This report presents provenance determinations for 854 obsidian and fine-grained volcanic projectile points from Idaho Falls District Bureau of Land Management collections. Provenance determinations were made using energy dispersive X-ray fluorescence (ED-XRF) spectrometry at the Idaho National Laboratory (INL) Cultural Resource Management Office (CRMO) under the direction of Dr. Kyle Freund.

99 - GENERAL AND MISCELLANEOUS↗

INL CRMO XRF Report 2025-02: Provenance Determinations for 1,124 Projectile Points from Lands and Collections Managed by the U.S. Department of Energy-Idaho Operations Office (DOE-ID)

This report presents provenance determinations for 1,124 obsidian and fine-grained volcanic (FGV) projectile points from lands and collections managed by the U.S. Department of Energy-Idaho Operations Office (DOE-ID). These determinations were made using energy-dispersive X-ray fluorescence (ED-XRF) spectrometry at the Idaho National Laboratory (INL) Cultural Resource Management Office (CRMO) under the direction of Dr. Kyle Freund.

58 GEOSCIENCES↗

INL CRMO XRF Report 2025-05: Provenance Determinations for 23 Folsom and Midland Projectile Points from Eastern Idaho

This report presents provenance determinations for 23 obsidian and fine-grained volcanic Folsom and Midland projectile points from eastern Idaho. Provenance determinations were made using energy dispersive X-ray fluorescence (ED-XRF) spectrometry at the Idaho National Laboratory (INL) Cultural Resource Management Office (CRMO) under the direction of Dr. Kyle Freund.

58 GEOSCIENCES↗