Energetic Heavy Ion Beams Research Articles

New geometry of wide-aperture quadrupole magnets for plasma experiments in the FAIR project

Abstract The experiments on matter under extreme conditions of density and temperature which are proposed by the HED@FAIR plasma physics collaboration at the new accelerator facility FAIR in Darmstadt, Germany require a strong final focusing system for energetic heavy ion beams. The main components of this system are four wide-aperture quadrupoles which have to provide a millimeter-size focal spot at the target. These superconducting magnets have 33 T/m central gradient with the inner aperture diameter of 240 mm and the magnetic length of 2 m. While designing the magnets, it has turned out that the magnet’s aperture shall be increased to 260 mm, and the design distance between the magnet’s centers of 2.5 m cannot be kept. Therefore it was necessary to reduce the physical length of the magnets and correspondingly, to compensate the integral field gradient by increasing the current. New requirements led to the development of a new magnets geometry which is presented along with parameters of the correction system and considerations about the magnet’s cooling system.

Fabrication of thin 130Te target foils for sub-barrier fusion studies

Abstract Thin 130Te target foils of thickness 139– 260 μ g /cm 2 have been prepared on 12C backing using resistive evaporation technique for sub-barrier fusion studies in heavy-ion induced nuclear reactions. The deposition thickness of both 12C and 130 Te has been measured using profilometer , and the thickness of a few target foils has been measured using α -transmission method. Target foils fabricated in the present work have been characterized using the Rutherford Backscattering Spectrometry (RBS), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS) for impurity and to estimate the thickness. 130 Te is known to be brittle with the low melting point, and it quickly degrades if bombarded with energetic heavy-ion beams. In the present work, 130Te target foils fabricated on carbon backing were bombarded with 70 MeV 32S and 114–155 MeV 35 , 37 Cl beams to vet the stability of the targets. It has been observed that 130Te target foils fabricated on 12C backing survived the bombardment with energetic 32S, and 35 , 37 Cl beams without any degradation for the entire duration of sub-barrier fusion measurement at different energies.

Effect of light, medium and heavy ion irradiations on the structural and electrical properties of ZnSe thin films

The effect of irradiations of energetic heavy ion beams on the structural and electrical properties of ZnSe thin films deposited on In2O3:Sn (ITO) coated glass substrate is given. The ZnSe thin films having a thickness of 100nm were deposited by physical vapour deposition on 200nm thick ITO coated glass. The ZnSe films were irradiated with 20MeV carbon, phosphorus and copper ion beams using the 5MV tandem accelerator at National Centre for Physics, Islamabad. The ion irradiations have shown the improvement in the structural properties in terms of increase in grain size and decrease in the lattice strain. The measurements of photo decay have shown that the decay of the photocurrent has been prolonged in the sample irradiated with carbon ion as compared to the phosphorous and copper irradiated sample.

Progress of RIBF accelerators

In order to greatly expand scientific opportunities with radioactive isotope (RI) beams, RIKEN has constructed a new heavy-ion accelerator facility, called “RI Beam Factory (RIBF).” Three new ring cyclotrons with K-values of 570 MeV, 980 MeV, and 2600 MeV, respectively, boost the energies of the output beams from the existing K540-MeV ring cyclotron up to 440 MeV/u for light ions and 345 MeV/u for very heavy ions. These energetic heavy-ion beams are converted into intense radioactive isotope (RI) beams via projectile fragmentation of stable isotopes or in-flight fission of uranium isotopes by a superconducting fragment separator, BigRIPS. The three ring cyclotrons were commissioned in 2006, and RI beams from uranium were first obtained in 2007. The beam intensities and available ion species are increasing at RIBF, owing to the continuous efforts that have been made since the first beam. So far, we have accelerated deuteron, helium, nitrogen, oxygen, aluminum, calcium, zinc, krypton, xenon, and uranium beams with the superconducting ring cyclotron (SRC). The extracted beam intensities reached 1000 pnA for the helium and oxygen beams, and the calcium beam intensity exceeded 400 pnA recently. The intensities of the xenon and uranium beams are also increasing they reached 24 and 3.6 pnA, respectively. This paper illustrates the construction, commissioning, and various improvements carried out for the RIBF accelerators, as well as the present accelerator performance.

Measurement of microdosimetric spectra with a wall-less tissue-equivalent proportional counter for a 290 MeV/u 12C beam

The frequency distribution of the lineal energy, y, of a 290 MeV/u carbon beam was measured to obtain the dose-weighted mean of y and compare it with the linear energy transfer (LET). In the experiment, a wall-less tissue-equivalent proportional counter (TEPC) in a cylindrical volume with a simulated diameter of 0.72 µm was used. The measured frequency distribution of y as well as its dose-mean value agrees within 10% uncertainty with the corresponding data from microdosimetric calculations using the PHITS code. The ratio of the measured dose-mean lineal energy to the LET of the 290 MeV/u carbon beam is 0.73, which is much smaller than the corresponding data obtained by a wall TEPC. This result demonstrates that a wall-less TEPC is necessary to precisely measure the dose-mean of y for energetic heavy ion beams.

Target design for studies of radiative properties in warm dense matter at GSI and FAIR - the WDM collaboration

Intense beams of energetic heavy ions from SIS-18 at GSI can heat extended volumes of condensed matter to a temperature of several eV. The matter at about solid density and a temperature near or above the Fermi temperature is referred to as ‘Warm Dense Matter’ (WDM). The knowledge of radiative properties and the equation of state of WDM is particularly limited because standard perturbative theoretical approaches are not applicable in this regime. The kilojoule PHELIX laser at GSI can be used to produce X-rays of several keV energy for scattering diagnostics of ion beam heated matter. In this paper special target configurations for compression and isochoric heating of matter with heavy ions are presented. The possibilities of X-ray scattering diagnostics of such targets are discussed. The target parameters achievable with the new FAIR facility are calculated.

High energy density matter research using intense heavy ion beams at the future FAIR facility at Darmstadt: the HEDgeHOB collaboration

This paper reports an overview of the extensive theoretical work that has been carried out over the past few years to explore the capabilities of intense beams of energetic heavy ions to study High Energy Density (HED) states in matter. This work has shown that an intense ion beam can be a very efficient driver for disparate experimental schemes suitable to study this important field of research. These include HIHEX [Heavy Ion Heating and EXpansion] that involves generation of required HED states by isochoric and uniform heating of matter by the ion beam that is followed by isentropic expansion. Another proposed experimental set up is named LAPLAS that stands for LAboratory PLAnetary Sciences. This latter experiment has been designed to generate physical conditions that are expected to exist in the interiors of the giant planets. This is achieved by a low-entropy compression of the sample material (hydrogen or ice). A third scheme involves a ramp (shockless) compression of a test material which will allow one to investigate the material properties, like yield strength, under dynamic conditions.

Survey of Theoretical Work for the Proposed HEDgeHOB Experimental Schemes: HIHEX and LAPLAS

AbstractThis paper presents a review of the theoretical work that has resulted in a scientific proposal on studies of High‐Energy‐Density (HED) states in matter using intense beams of energetic heavy ions that will be available at the future Facility for Antiprotons and Ion Research (FAIR) at Darmstadt [W.F. Henning, Nucl. Inst. Meth B 24 (2003) 725‐729]. The proposal is named HEDgeHOB that stands for High Energy Density Matter Generated by Heavy Ion Beams. Two experimental schemes have been worked out for the HEDgeHOB experimental proposal, namely, HIHEX and LAPLAS. The first scheme allows for studies of HED states by isochoric and uniform heating of matter by an intense heavy ion beam that is followed by isentropic expansion of the heated material. Numerical simulations have shown that using the beam parameters that will be available at the FAIR, one can access all the interesting physical states of HED matter including an expanded hot liquid state, twophase liquid‐gas region, critical point parameters and strongly coupled plasmas for all the materials of interest. The second scheme involves a low‐entropy compression of a test material like hydrogen that is enclosed in a cylindrical shell of a high‐Z material like gold or lead. The target can be driven by a hollow or a circular beam. This compression scheme relies on multiple shock reflection between the hydrogen‐gold (lead) boundary and the cylinder axis. The hydrodynamic stability of the LAPLAS target has also been analyzed that shows that the implosion is completely stable to Rayleigh‐Taylor and Richtmyer‐Meshkov instabilities. LAPLAS implosion using a hollow beam is suitable for studying the problem of hydrogen metallization whereas the one employing a circular focal spot leads to physical conditions that are expected to exist in the interiors of the giant planets. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The RIKEN RI Beam Factory Project: A status report

In order to greatly upgrade the capability of its existing heavy-ion accelerator facility, RIKEN is constructing a new radioactive isotope (RI) beam facility, called “RI Beam Factory”. This facility is of an in-flight RI beam separation scheme. Three new ring cyclotrons with K-values of 570MeV, 980MeV and 2500MeV, respectively, boost energies of the output beams from the existing K540-MeV ring cyclotron up to 440MeV/nucleon for light ions and 350MeV/nucleon for very heavy ions. The K2500-MeV ring cyclotron, SRC is the world’s first superconducting ring cyclotron. These energetic heavy-ion beams are converted into intense RI beams via projectile fragmentation of stable isotopes or in-flight fission of uranium isotopes by a superconducting fragment separator, BigRIPS. The combination of the SRC and the BigRIPS will greatly expand our knowledge of nuclear world into presently inaccessible region on the nuclear chart. The new ring cyclotrons and the Big RIPS will be commissioned in late 2006. Construction of a part of major experimental installations planned is expected to start in 2007.

Studies of thermophysical properties of high-energy-density states in matter using intense heavy ion beams at the future FAIR accelerator facilities: The HEDgeHOB collaboration

Intense beams of energetic heavy ions are believed to be a very efficient and novel tool to create states of High-Energy-Density (HED) in matter. This paper shows with the help of numerical simulations that the heavy ion beams that will be generated at the future Facility for Antiprotons and Ion Research (FAIR)[W.F. Henning, Nucl. Instr. Meth. B 214, 211 (2004)] will allow one to use two different experimental schemes to study HED states in matter. First scheme named HIHEX (Heavy Ion Heating and EXpansion), will generate high-pressure, high-entropy states in matter by volumetric isochoric heating. The heated material will then be allowed to expand isentropically. Using this scheme, it will be possible to study important regions of the phase diagram that are either difficult to access or are even unaccessible using traditional methods of shock compression. The second scheme would allow one to achieve low-entropy compression of a sample material like hydrogen or water to produce conditions that are believed to exist in the interiors of the giant planets. This scheme is named LAPLAS (LAboratory PLAnetary Sciences).

FAIR Experiments in Biophysics and Materials Research

Beams of energetic heavy ions are used in many different fields, for example, in biology for testing radiation damage in cells, in geochronology for dating of natural minerals, and in nanotechnology for fabricating nanostructures. One of the most prominent applications is the hadron tumor-therapy, which proves to be extremely successful as shown in clinical studies.When energetic ions penetrate into matter, the material along the path of the projectile undergoes complex processes: atoms are ionized, electron cascades develop, molecular bonds break, and atoms are shifted from their equilibrium positions. In many solids, mainly insulators, so-called ion tracks develop.

Proposal for the Study of Thermophysical Properties of High-Energy-Density Matter Using Current and Future Heavy-Ion Accelerator Facilities at GSI Darmstadt

The subject of high-energy-density (HED) states in matter is of considerable importance to numerous branches of basic as well as applied physics. Intense heavy-ion beams are an excellent tool to create large samples of HED matter in the laboratory with fairly uniform physical conditions. Gesellschaft für Schwerionenforschung, Darmstadt, is a unique worldwide laboratory that has a heavy-ion synchrotron, SIS18, that delivers intense beams of energetic heavy ions. Construction of a much more powerful synchrotron, SIS100, at the future international facility for antiprotons and ion research (FAIR) at Darmstadt will lead to an increase in beam intensity by 3 orders of magnitude compared to what is currently available. The purpose of this Letter is to investigate with the help of two-dimensional numerical simulations, the potential of the FAIR to carry out research in the field of HED states in matter.

Studies of heavy ion-induced high-energy density states in matter at the GSI Darmstadt SIS-18 and future FAIR facility

This paper presents numerical simulation results of heating and compression of matter using intense beams of energetic heavy ions. In this study we consider different beam parameters that include those which are currently available at the heavy ion synchrotron, SIS18 at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt and those which will be available in the near future as a result of the upgraded facility. In addition to this, we carried out detailed calculations considering parameters of high-intensity beam which will be generated at the GSI future Facility for Antiprotons and Ion Research (FAIR facility) that has been approved by the German Government. These simulations show that by using the above ion beam parameter range, it will be possible to carry out very useful studies on the thermophysical properties of high-energy density (HED) states in matter. This scheme would make it possible to investigate those regions of the phase diagram that are either very difficult to access or even are unaccessible using the traditional methods of shock waves. Moreover, employing a hollow ion beam which has an annular (ring shaped) focal spot, it would be possible to achieve a low entropy compression of a test material like hydrogen, which is enclosed in a cylindrical shell of a high-density material such as lead or gold. These experiments will enable one to study the interiors of Giant planets, Jupiter and Saturn as well as to investigate the problem of hydrogen metallization.

The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam–target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fur Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are considered to be the same as expected at the future SIS100 facility. The simulations show that due to multiple shock reflection between the cylinder axis and the lead–hydrogen boundary, one can achieve up to 20 times solid density in hydrogen while keeping the temperature as low as a few thousand K. The corresponding pressure is of the order of 10 Mbar. These values of the physical parameters lie within the range of theoretically predicted values for hydrogen metallization. We have also carried out a parameter study of this problem by varying the target and beam parameters over a wide range. It has been found that the results are very insensitive to such changes in the input parameters.

Influence of the equation of state of matter and ion beam characteristics on target heating and compression

The subject of high-energy density (HED) in matter is of considerable interest to many branches of physics. Intense beams of energetic heavy ions are a promising tool for creating large samples of HED matter which can be used to study the equation-of-state properties of such exotic states of matter experimentally. The Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, is a unique laboratory worldwide which has a heavy ion synchrotron facility, SIS18 (with a magnetic rigidity of 18 Tm), that delivers intense heavy ion beams. Using the beams generated at this present facility, interesting experimental work has been carried out in the field of HED matter (D. H. H. Hoffmann et al., Nucl. Instrum. Methods Phys. Res., Sect. B 161-162, 9 (2000)). The GSI is planning to significantly expand its accelerator capabilities with construction of a new synchrotron ring, SIS100, which will have a magnetic rigidity of 100 Tm. This new facility will deliver a uranium beam which will have orders of magnitude higher intensity than the existing facility and will also have the possibility of multibeam acceleration. This paper presents two-dimensional hydrodynamic simulations of different target geo- metries including solid as well as hollow cylinders that are irradiated with beams having different shapes of the focal spot which will be available at the SIS100 facility. These include a circular focal spot, an annular focal spot, and an elliptic focal spot, respectively. The purpose of this study is to determine the region of the physical parameters including density, temperature, and pressure that can be accessed using the SIS100 beam. This information, we hope, will be useful for designing experiments on the studies of thermophysical properties of matter including the designing of appropriate diagnostic tools.

Energy loss dynamics of intense heavy ion beams interacting with solid targets

At the Gesellschaft für Schwerionenforschung (GSI, Darmstadt) intense beams of energetic heavy ions have been used to generate high-energy-density (HED) state in matter by impact on solid targets. Recently, we have developed a new method by which we use the same heavy ion beam that heats the target to provide information about the physical state of the interior of the target (Varentsov et al., 2001). This is accomplished by measuring the energy loss dynamics (ELD) of the beam emerging from the back surface of the target. For this purpose, a new time-resolving energy loss spectrometer (scintillating Bragg-peak (SBP) spectrometer) has been developed. In our experiments we have measured energy loss dynamics of intense beams of 238U, 86Kr, 40Ar, and 18O ions during the interaction with solid rare-gas targets, such as solid Ne and solid Xe. We observed continuous reduction in the energy loss during the interaction time due to rapid hydrodynamic response of the ion-beam-heated target matter. These are the first measurements of this kind. Two-dimensional hydrodynamic simulations were carried out using the beam and target parameters of the experiments. The conducted research has established that the ELD measurement technique is an excellent diagnostic method for HED matter. It specifically allows for direct and quantitative comparison with the results of hydrodynamic simulations, providing experimental data for verification of computer codes and underlying theoretical models. The ELD measurements will be used as a standard diagnostics in the future experiments on investigation of the HED matter induced by intense heavy ion beams, such as the HI-HEX (Heavy Ion Heating and EXpansion) EOS studies (Hoffmann et al., 2002).

Strong pulsed magnetic quadrupole lens

Pulsed magnetic quadrupole lenses have been developed for focusing high energetic heavy ion beams. The quadrupoles were built using iron-free structures. Up to now a magnetic flux density above 14 T has been reached in a quadrupole of 22 mm aperture. The field properties of the quadrupoles are presented. In an experiment with a heavy ion beam the focusing properties were investigated. This development can be used for building a condensor system to increase the collection efficiency of a downstream ion optical devices for nuclear reaction products.

Catching energetic heavy-ion beams in gas

The stopping of argon beams at energies up to 100 MeV/u in a combination of an aluminum energy degrader and a helium gas cell was investigated. The transmission of ions through the gas was measured at different gas pressures. A Monte Carlo simulation was applied in order to calculate the spatial distribution of ions stopped in the gas. It was found that the width of the range distribution was not largely enhanced by the aluminum energy degrader.

Time-resolved energy loss spectroscopy of energetic heavy ion beams generating a dense plasma

At the Gesellschaft für Schwerionenforschung (GSI) Darmstadt, intense beams of energetic heavy ions have been used to generate hot dense plasmas by impact on solid targets. Recently, we have measured time evolution of the energy loss of intense beams (10 9–10 10 particles/pulse) of 190 MeV/u 238 U as well as of 300 MeV/u 86 Kr in cryogenic crystals of neon and xenon, respectively. For this purpose, a new time resolving energy loss spectrometer has been set up. We observed continuous reduction in the energy loss due to hydrodynamic motion of the ion beam heated target matter. These are the first measurements of this kind. Two-dimensional hydrodynamic simulations were also carried out using the above beam and target parameters. Good agreement has been found between the experimental results and the simulations.

Creation of strongly coupled plasmas using intense beams of 400 MeV/u uranium ions to be generated at the Gesellschaft für Schwerionenforschung (GSI) Darmstadt SIS-200

The heavy ion synchrotron, SIS-18 (that has an 18 Tm magnetic rigidity), at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt is a unique facility worldwide that delivers intense beams of energetic heavy ions. The GSI has plans to extend its accelerator capabilities by building a new synchrotron (SIS-200) with a much higher magnetic rigidity of 200 Tm. According to the preliminary design considerations, the SIS-200 will generate a uranium beam that will consist of at least 1012 particles and that will be delivered in a 50 ns long pulse. This beam will be used to study various interesting problems, including fragmentation of the projectile ions while passing through solid matter and creation of high-density, strongly coupled plasmas. For the former type of studies, a particle energy of 1 GeV/u has been considered to be appropriate, while for the latter case, a lower value of 400 MeV/u has been found to be most suitable. In this paper we present, with the help of two-dimensional numerical simulations, the hydrodynamic and thermodynamic response of a solid lead cylindrical target that is irradiated with the future SIS-200 beam, which has a particle energy of 400 MeV/u. The beam focal spot is assumed to be circular and the power deposition profile is considered to be Gaussian along the radial direction. Calculations have also been done using a beam that has a ring-shaped (annular) focal spot that interacts with solid as well as hollow lead cylinders, respectively. In all the above cases it has been assumed that the cylinder length is shorter than the range of 400 MeV/u uranium ions in solid lead so that the Bragg peak does not lie inside the target and the energy deposition is almost uniform along the particle trajectory. These simulations show that it will be possible to create extended volumes of high-density, strongly coupled plasmas using the future SIS-200 beam.