98 research outputs found
OPERATIVE MANAGEMENT RESULTS OF THE FEMALE URINARY INCONTINENCE TREATED BY THE MARSHAL-MARCHETTI-KRANTZ TECHNIQUE
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Co-existing structures in 105Ru
New positive-parity states, having a band-like structure, were observed in
105Ru. The nucleus was produced in induced fission reaction and the prompt
gamma-rays, emitted from the fragments, were detected by the EUROBALL III
multi-detector array. The partial scheme of excited 105Ru levels is analyzed
within the Triaxial-Rotor-plus-Particle approach
In-beam fast-timing measurements in 103,105,107Cd
Fast-timing measurements were performed recently in the region of the
medium-mass 103,105,107Cd isotopes, produced in fusion evaporation reactions.
Emitted gamma-rays were detected by eight HPGe and five LaBr3:Ce detectors
working in coincidence. Results on new and re-evaluated half-lives are
discussed within a systematic of transition rates. The states in
103,105,107Cd are interpreted as arising from a single-particle excitation. The
half-life analysis of the states in 103,105,107Cd shows no change in
the single-particle transition strength as a function of the neutron number
Laboratory evidence for proton energization by collisionless shock surfing
Charged particles can be accelerated to high energies by collisionless shock waves in astrophysical environments, such as supernova remnants. By interacting with the magnetized ambient medium, these shocks can transfer energy to particles. Despite increasing efforts in the characterization of these shocks from satellite measurements at Earth’s bow shock as well as powerful numerical simulations, the underlying acceleration mechanism or a combination thereof is still widely debated. Here we show that astrophysically relevant super-critical quasi-perpendicular magnetized collisionless shocks can be produced and characterized in the laboratory. We observe the characteristics of super-criticality in the shock profile as well as the energization of protons picked up from the ambient gas to hundreds of kiloelectronvolts. Kinetic simulations modelling the laboratory experiment identified shock surfing as the proton acceleration mechanism. Our observations not only provide direct evidence of early-stage ion energization by collisionless shocks but also highlight the role played by this particular mechanism in energizing ambient ions to feed further stages of acceleration. Furthermore, our results open the door to future laboratory experiments investigating the possible transition to other mechanisms, when increasing the magnetic field strength, or the effect that induced shock front ripples could have on acceleration processes
Detailed characterization of a laboratory magnetized supercritical collisionless shock and of the associated proton energization
Collisionless shocks are ubiquitous in the Universe and are held responsible for the production of nonthermal particles and high-energy radiation. In the absence of particle collisions in the system, theory shows that the interaction of an expanding plasma with a pre-existing electromagnetic structure (as in our case) is able to induce energy dissipation and allow shock formation. Shock formation can alternatively take place when two plasmas interact, through microscopic instabilities inducing electromagnetic fields that are able in turn to mediate energy dissipation and shock formation. Using our platform in which we couple a rapidly expanding plasma induced by high-power lasers (JLF/Titan at LLNL and LULI2000) with high-strength magnetic fields, we have investigated the generation of a magnetized collisionless shock and the associated particle energization. We have characterized the shock as being collisionless and supercritical. We report here on measurements of the plasma density and temperature, the electromagnetic field structures, and the particle energization in the experiments, under various conditions of ambient plasma and magnetic field. We have also modeled the formation of the shocks using macroscopic hydrodynamic simulations and the associated particle acceleration using kinetic particle-in-cell simulations. As a companion paper to Yao et al. [Nat. Phys. 17, 1177-1182 (2021)], here we show additional results of the experiments and simulations, providing more information to allow their reproduction and to demonstrate the robustness of our interpretation of the proton energization mechanism as being shock surfing acceleration
Core-coupled states and split proton-neutron quasi-particle multiplets in 122-126Ag
Neutron-rich silver isotopes were populated in the fragmentation of a 136Xe
beam and the relativistic fission of 238U. The fragments were mass analyzed
with the GSI Fragment separator and subsequently implanted into a passive
stopper. Isomeric transitions were detected by 105 HPGe detectors. Eight
isomeric states were observed in 122-126Ag nuclei. The level schemes of
122,123,125Ag were revised and extended with isomeric transitions being
observed for the first time. The excited states in the odd-mass silver isotopes
are interpreted as core-coupled states. The isomeric states in the even-mass
silver isotopes are discussed in the framework of the proton-neutron split
multiplets. The results of shell-model calculations, performed for the most
neutron-rich silver nuclei are compared to the experimental data
Fast-timing measurements in 95,96Mo
Half-lives of the 19/2+ and 21/2+ states in 95Mo and of the 8+ and 10+ states
in 96Mo were measured. Matrix elements for yrast transitions in 95Mo and 96Mo
are discussed.Comment: Proceedings of XIX International School on Nuclear Physics, Neutron
Physics and Applications, Varna, Bulgaria, 2011, 5 pages, 6 figure
Single-particle isomeric states in 121Pd and 117Ru
Neutron-rich nuclei were populated in a relativistic fission of 238U. Gamma-rays with energies of 135 keV and 184 keV were associated with two isomeric states in 121Pd and 117Ru. Half-lives of 0.63(5) microseconds and 2.0(3) micrisecondss were deduced and the isomeric states were interpreted in terms of deformed single-particle states
Observation of Positive-Parity Bands in Pd and Pd: Enhanced -Softness
The neutron-rich nuclei Pd and Pd were produced as fission
fragments following the Si + Er reaction at 142 MeV. Using the
identification based on the coincidences with the complementary fission
fragments, the only positive-parity bands observed so far in Pd and
Pd emerged from this work. A band, built on top of the 5/2 ground
state exhibiting = 1 energy-level staggering, was observed in each
of these nuclei. Both nuclei of interest, Pd and Pd, are
suggested to lie in the transitional region of Pd isotopes of maximum
-softness. The ground states of both nuclei are predicted by TRS
calculations to be extremely -soft with shallow triaxial minima. The
first crossing in the new bands is proposed to be due to an alignment of
neutrons
Single-particle isomeric states in 121Pd and 117Ru
Neutron-rich nuclei were populated in a relativistic fission of 238U.
Gamma-rays with energies of 135 keV and 184 keV were associated with two
isomeric states in 121Pd and 117Ru. Half-lives of 0.63(5) microseconds and
2.0(3) micrisecondss were deduced and the isomeric states were interpreted in
terms of deformed single-particle states
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