Interaction Of Heavy Ion Beams Research Articles

Interaction of Heavy Ion Beams with Plasma Electrons: Role of Many-Electron Ionization Processes

Interaction of Heavy Ion Beams with Plasma Electrons: Role of Many-Electron Ionization Processes

Towards the integration of the NUMEN experiment

The most promising probe to establish the Majorana or Dirac nature of the neutrino is the neutrinoless double beta decay and the effective neutrino mass would be evaluated by the knowledge of the corresponding nuclear matrix elements. Also measurements of the Double Charge Exchange (DCE) interactions of heavy ion beams can get information on them. The NUMEN experiment based on the pre-existing large acceptance MAGNEX spectrometer and integrated with new challenging components aims at measuring DCE cross sections using ion beams of unprecedented intensity (1013 pps) on specific isotopes at INFN-LNS in Catania. Expected rate on the sensitive area of about 0.15 m2 reaches up to about 5 Mpps, demanding for adequate detectors in measuring position, direction, energy, mass and charge of the ions produced by interactions. Gamma detectors surround a scattering chamber containing the target.

High efficiency ISOL system to produce neutron deficient short-lived alkali RIBs on GANIL/SPIRAL 1 facility

The SPIRAL1 (Système de Production d’Ions Radioactifs Accélérés en Ligne) facility at GANIL (Grand Accélérateur National d’Ions Lourds) is developing new techniques to access nuclei in the neutron-deficient isotope region far from the stability-valley, with Z ranging from 30 to 60. The availability of different primary beams, ranging from carbon to uranium with energies up to 95 MeV/A, gives an opportunity to produce a large variety of radioactive ion beams. The production of neutron-deficient short-lived alkalis by fusion-evaporation reactions is the focus of this work. A simple and compact target ion source system (TISS) is designed to produce isotopes of 74Rb (τ1/2 = 64.8 ms) and 114Cs (τ1/2 = 570 ms). The efficiencies of the different processes involved in the production are evaluated. Radioactive recoils are produced through the interaction of heavy-ion beams, respectively 20Ne beam and 58Ni beam at an intensity of 1013 and 1012 pps, with a thin 58Ni target. High atom-to-ion transformation (ATI) efficiency should be obtained above 70% and 90% for 74Rb and 114Cs nuclei respectively. The expected intensities of the RIBs are estimated to be around 104 pps at the exit of the TISS.

Researches on a reactor core in heavy ion inertial fusion

AbstractIn this paper, a study on a fusion reactor core is presented in heavy-ion inertial fusion (HIF), including the heavy-ion beam (HIB) transport in a fusion reactor, an HIB interaction with a background gas, the reactor cavity gas dynamics, the reactor gas backflow to the beam lines, and an HIB fusion reactor design. The HIB has remarkable preferable features to release the fusion energy in inertial fusion: in particle accelerators HIBs are generated with a high driver efficiency of about 30–40%, and the HIB ions deposit their energy inside of materials. Therefore, a requirement for the fusion target energy gain is relatively low, that would be ~50 to operate an HIF fusion reactor with a standard energy output of 1 GW of electricity. In a fusion reactor, the HIB charge neutralization is needed for a ballistic HIB transport. Multiple mechanical shutters would be installed at each HIB port at the reactor wall to stop the blast waves and the chamber gas backflow, so that the accelerator final elements would be protected from the reactor gas contaminant. The essential fusion reactor components are discussed in this paper.

Track measurement in the high multiplicity environment at the CBM Experiment

In the Compressed Baryonic Matter (CBM) Experiment at FAIR, the Silicon Tracking System (STS) will perform track reconstruction and momentum determination of the charged particles created in interactions of heavy-ion beams with nuclear targets. The STS will consist of 8 tracking layers located at distances between 30 cm and 100 cm downstream of the target inside the 1 Tm magnetic dipole field. An ultra-low material budget is required to achieve momentum resolution of the order of Δp/p = 1%. Therefore, the front-end electronics is placed outside the physics aperture. The active volume of the STS is built from 300 μm thick double-sided silicon microstrip sensors mounted onto lightweight carbon fiber support ladders. The sensors will be read out through ultra-thin micro-cables with fast self-triggering electronics at the periphery of the stations where also other infrastructure such as cooling can be placed. In this paper, the development status of the detector system, highlighting the overview of the STS layout, tracking algorithm and performance simulations are presented.

Density enhancement of an RF plasma in a magnetic quadrupole

A new method for the effective confinement of a low pressure gas discharge has been proposed by Christiansen and Jacoby. The principal component is a magnetic quadrupole superimposed upon an RF-driven gas discharge plasma. It has been suggested to use the device as an ion source for accelerator applications and as a plasma target to investigate the interaction of heavy ion beams with a magnetically confined plasma. A complete experiment including a capacitively coupled radio frequency (CCRF) discharge and an electric quadrupole magnet was set up and investigated by applying spectroscopic diagnostic methods. The plasma parameters for the magnetically confined CCRF discharge were measured using a Ar : He gas mixture. The electron temperature and the electron density as a function of the gas pressure and the magnetic field could be determined. A maximum of the mean electron temperature was identified as due to collisionless heating. Further, an ion beam was extracted and the mean electron density derived. The confinement of the plasma at low pressures between 0.4 and 1 Pa has also been obtained with an electron density of 3 × 1017 m−3.

Heavy ion beam interaction with a direct-driven pellet

In heavy ion beam (HIB) inertial confinement fusion (ICF), key issues include beam illumination non-uniformity. In this study we simulate the HIB interaction with a direct-driven target. The main purposes of this study are to clarify the multi-HIB energy deposition non-uniformity onto a direct-driven target and to calculate the target hydrodynamics in HIF. The calculation results demonstrate that we can realize a rather low non-uniform energy deposition, for example, less than 2.0% even for a 32-HIBs irradiation system.

Calculations of atomic structures in the problems of interaction of heavy-ion beams with targets

The process of energy conversion in heavy-ion inertial confinement fusion is associated with the deceleration of heavy ions in a low-temperature plasma that is produced when the beam ionizes the target material. In order to calculate the deceleration of heavy ions in a target, it is necessary to determine the wave functions, energy levels, and oscillator strengths for atoms and for ions in different charge states. The models that have been developed thus far to calculate deceleration processes apply only to gas targets. In the present paper, a method is proposed that is based on the Hartree-Fock-Slater model and makes it possible to perform calculations for experiments with both low-density (gas) and high-density (solid) targets. The method applies to neutral atoms and also to ions in different charge states. Results are presented from calculations carried out for nitrogen, oxygen, aluminum, and silicon atoms and are compared with the results obtained by other authors and with the experimental data. It is shown that, for high-density targets, the method proposed provides better agreement with experiments than do the models developed earlier.

Attenuation curves in concrete of neutrons from 1 GeV/u C and U ions on a Fe target for the shielding design of RIB in-flight facilities

Experimental data on neutron emission from the interaction of heavy ion beams with matter are far less abundant than data on neutron production from protons. The aim of the present work is to extend the available computational shielding data to high-energy neutrons produced by heavy ion beams (uranium and carbon) of 1 GeV/u slowed down in a thick iron target. Source terms and attenuation lengths for neutron attenuation in a concrete shield were calculated starting from experimental neutron energy distributions measured at GSI in the angular range from 0° to 90°. A comparison is also made with previous calculations performed for different ions and energies and with earlier estimates made at GSI for neon beams with 0.8 and 2 GeV/u energy stopped in thick iron, lead and uranium targets.

Attenuation curves in concrete of neutrons from 1 GeV/u C and U ions on a Fe target for the shielding design of RIB in-flight facilities

Experimental data on neutron emission from the interaction of heavy ion beams with matter are far less abundant than data on neutron production from protons. The aim of the present work is to extend the available computational shielding data to high-energy neutrons produced by heavy ion beams (uranium and carbon) of 1 GeV/u slowed down in a thick iron target. Source terms and attenuation lengths for neutron attenuation in a concrete shield were calculated starting from experimental neutron energy distributions measured at GSI in the angular range from 0° to 90°. A comparison is also made with previous calculations performed for different ions and energies and with earlier estimates made at GSI for neon beams with 0.8 and 2 GeV/u energy stopped in thick iron, lead and uranium targets.

Fundamental studies of intense heavy-ion beam interaction with solid targets

Intense (10/sup 11/ particles/1 /spl mu/s /spl sim/300 MeV/u) heavy ion beams are generated in the heavy-ion synchrotron (SIS) of the GSI-Darmstadt facility. Large volumes of strongly coupled plasmas are produced by heavy ion beam interaction with solid targets, with plasma densities close to the solid state, pressures of about 100 kbar, and temperatures of up to 1 eV, with relevance for equation of state (EOS) of matter, astrophysics, and low-entropy shock compression of solids. The plasmas created by ion beam interaction with metallic converters and cryogenic crystals were studied by backlighting shadowgraphy and by time-resolved spectroscopy in the visible and vacuum ultraviolet ranges. Low entropy weak shock waves induced by the ion beams in the metal-plexiglass multilayered targets were visualized by time resolved schlieren measurements, revealing induced multiple shockwaves with pressures higher than 15 kbar in a plexiglass window and propagation velocities up to 35% higher than the speed of sound in plexiglass at room temperature. To get an insight into the plasma dynamics, both types of experiments are simulated by the BIG-2 two-dimensional hydrodynamic code.

Radiation from Autoionsing Levels Correlated with Single Excited States of Highly Charged Ions in Dense Cold Plasmas

The interaction of heavy ion beams and laser light with matter is of central importance for the inertial fusion and x-ray laser research. Recently developed techniques in x-ray spectroscopy have provided extremely unusual emission spectra near the target even in traditional experiments. It will be shown that reasonable interpretation and diagnostic can be achieved only incorporating new concepts in the dielectronic satellite line formation. Theoretical models are developed which provide good agreement with experimental results. Charge exchange processes are proposed for the formation of hollow atoms.

Experiments on the interaction of heavy ions with dense plasma at GSI-Darmstadt

One of the main objectives of the experimental plasma physics activities at the Gesellschaft für Schwerionenforschung (GSI) are the interaction processes of heavy ions with dense ionized matter. Gas-discharge plasma targets were used for energy loss and charge state measurements in a regime of electron density and temperature up to 10 19 cm −3 and 20 eV, respectively. An improved model of the charge exchange processes in fully ionized hydrogen plasma, taking into account multiple excited electronic configurations which subsequently ionize, has removed the discrepancies of previous theoretical descriptions. The energy loss of the ion beam in partially ionized plasmas such as argon was found to agree very well with our simple theoretical model based on the modified Bethe–Bloch theory. A new setup with a 100 J/5 GW Nd–glass laser now provides access to density ranges up to 10 21 cm −3 and temperatures of up to 100 eV. First results of interaction experiments with laser-produced plasma are presented. To fully exploit the experimental possibilities of the new laser-plasma setup both improved charge state detection systems and better plasma diagnostics are indispensable. Present developments and future possibilities in these fields are presented. This paper summarizes the following contributions: • Interaction of heavy-ion beams with laser plasma by C. Stöckl et al. • Energy Loss of Heavy Ions in a laser-produced plasma by M. Roth et al. • Charge state measurements of heavy ions passing a laser produced plasma with high time resolution by W. Süß et al. • Plasma diagnostics for laser-produced plasma by O. Iwase et al. • Future possibilities of plasma diagnostics at GSI by M. Geißel et al.

Experiments on the Interaction of Heavy-Ion Beams with Dense Plasmas

Gas discharge plasma targets were used for energy loss and charge state measurements of fast heavy ions 5 MeV/u ≤ Ekin ≤ 10 MeV/u in a regime of electron density and temperature up to 1019 cm−3 and 20 eV, respectively. Progress has been achieved in the understanding of charge exchange processes in fully ionized hydrogen plasma. An improved model that has taken excitation-autoionization processes into account has removed some of the discrepancies of previous theoretical descriptions. Furthermore, the energy loss of the ion beam serves as an excellent diagnostic tool for measuring the electron density in partially ionized plasmas such as argon. The experience with these methods will be used in the future to diagnose dense laser-produced plasmas. A setup with a 5-GW neodymium-glass laser, currently under construction, will provide access to density ranges up to 1021 cm−3 and temperatures > 100 eV.

Interaction of heavy ion beams with dense plasmas

The main objective of the experimental plasma physics activities at the Gesellschaft für Schwerionenforschung (GSI) is the interaction processes of heavy ions with dense ionized matter. Gas discharge plasma targets were used for energy loss and charge state measurements in a regime of electron density and temperature up to 1019 cm-3 and 20 eV, respectively. Progress has been achieved in the understanding of charge-exchange processes in fully ionized hydrogen plasma. An improved model taking excitation-autoionization processes into account has removed most of the discrepancies of previous theoretical descriptions. Furthermore, it was found that the energy loss of the ion beam serves as an excellent diagnostic tool for measuring the electron density in partially ionized plasmas such as argon. The experience with these methods will be used in the future to diagnose dense laser produced plasmas. A setup with a 100 J/5 GW Nd:glass laser, currently under construction, will provide access to density range up to 1021 cm-3 and temperatures of more than 100 eV. To reach electron densities near solid-state density (1023 cm-3), heavy ion heated frozen rare gas crystals were used. The first hydrodynamic motion of ion heated solid material was observed. Vacuum-ultraviolet (VUV) spectroscopy was applied to diagnose these strongly coupled nonideal plasmas.

Z-pinch used as a plasma lens for heavy ion beams

Focusing of a heavy ion beam by the azimuthal magnetic field of a z-pinch discharge was observed. The experiment was carried out with a device, which has been designed to generate controlled plasma states for the investigation of the interaction of heavy ion beams with hot matter. A focusing factor of 5 in beam diameter was detected with high speed photographic methods. The experimental results are in agreement with numerical calculations.

Heavy ion beam target coronal physics

Numerical calculations of the heavy ion beam interaction with the low density plasma (corona) surrounding a small fusion pellet are discussed. As heavy ions enter the coronal plasma, they lose some of their electrons, and these stripped electrons, called ‘drop-offs’, constitute an electron beam with approximately the velocity of the ions. The interaction among the heavy ions, the drop-off electrons and the background electrons is investigated. The coronal density and temperature profiles are determined from one-dimensional hydrodynamic calculations, assuming classical ion deposition. The electron-electron and ion-electron cold two-stream instabilities are examined with one-dimensional particle-in-cell calculations. The results suggest that a strong coupling among the heavy ions, the drop-off electrons and the background electrons can exist; this leads to the creation of a non-Maxwellian electron plasma and significant electron heating. The ion beam energy loss is sensitive to the emittance of the beam, to the saturation level of the electric fields generated and to the background density scale length; these effects are discussed. Estimates of ion energy coupling to the corona are made, including the possible impact of target charge buildup; also, the coronal coupling effect on target physics is addressed.

Heavy ion beam interaction with spherical shell and super-range planar targets

A simple model for the heavy ion beam driven implosion of uniform spherical shell targets is constructed. The model equation is obtained by averaging the fluid equation of conservation of energy over the thickness of the shell. The energy balance contains the thermal and kinetic energies of the region absorbing the beam energy. The driving power is considered as a constant. The model gives the dependence of the implosion properties on the ion energy and the results are in agreement with published simulation data. The dynamics of a plane slab heated by an intense ion beam with range smaller than the slab thickness is described by a modified version of the model. It yields the temporal behavior of the hydrodynamics efficiency and its dependence on the ratio between the payload and the absorber masses such as is observed in simulation results.