Light Ion Beams Research Articles

Mono and sequential ion irradiation induced damage formation and damage recovery in oxide glasses: Stopping power dependence of the mechanical properties

Simple and complex borosilicate glasses were irradiated with single and double ion beams of light and heavy ions over a broad fluence and stopping power range. As a result of the heavy ion irradiation (U, Kr, Au), the hardness was observed to diminish and saturate after a decrease by 35 ± 1%. Unlike slow and swift heavy ion irradiation, irradiation with light ions (He,O) induced a saturation hardness decrease of 18 ± 1% only. During double ion beam irradiation; where glasses were first irradiated with a heavy ion (gold) and then by a light ion (helium), the light ion irradiation induced partial damage recovery. As a consequence of the recovery effect, the hardness of the pre-irradiated glasses increased by 10–15% depending on the chemical composition. These results highlight that the nuclear energy loss and high electronic energy loss (≥4 keV/nm) result in significant and similar modifications whereas light ions with low electronic energy loss (≤1 keV/nm) result in only mild damage formation in virgin glasses and recovery in highly pre-damaged glasses. These results are important to understand the damage formation and recovery in actinide bearing minerals and in glasses subjected to self-irradiation by alpha decays.

Fabrication and analysis of polymer microstructures through ion microprobe techniques

ABSTRACTIn this work, we explored the capabilities of energetic focused beams of light ions for the fabrication and analysis of microstructures produced on commercial polyethylene terephthalate (PET) foils. To that end, single lines and multi‐structure patterns were drawn directly on the foils using Proton Beam Writing (PBW) techniques followed by chemical etching. The characterization of the microstructures was carried out with on‐axis Scanning Transmission Ion Microscopy (STIM) employing H+1, He+2, and Li+3 ions in the MeV range. Scanning Electron Microscopy (SEM) was employed as well. The results show that a polymer like PET can be patterned trough a proper combination of irradiation parameters and etching times. However, aspect ratios obtained in this way are quite poor. Moreover, STIM images obtained from different regions of the ion energy spectra reveal patterns and cavities seen neither by conventional STIM, where the whole energy spectrum is used, nor by SEM. Moreover, striking differences are observed when different ions are used for STIM analysis. The results suggest that heavier ions provide additional information of the structures under analysis when compared with usual STIM employing protons. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43253.

Status of the SPIRAL2 injector commissioning.

The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

72 - Calorimetry, ionometry and solid state dosimetry in scanned light-ion beams

72 CALORIMETRY, IONOMETRY AND SOLID STATE DOSIMETRY IN SCANNED LIGHT-ION BEAMS R. Thomas a, J. De Pooter b, A. Krauss c, N. Durny d, S. Rossomme e, A. Kacperek f, V. Vondracek g, L. Petrie h, A. Lourenco a,i, N. Lee a, D. Shipley a, H. Palmans a,j. a National Physical Laboratory, Teddington, UK; b VSL B.V., Delft, Netherlands; c Physikalisch-Technische Bundesanstalt, Braunschweig, Germany; d Slovensky Metrologicky Ustav, Bratislava, Slovakia; e Universite Catholique de Louvain, Louvain-la-Neuve, Belgium; f Clatterbridge Cancer Centre, Clatterbridge, UK; g Proton Therapy Centre, Prague, Czech Republic; h University of Surrey, Guildford, UK; i University College London, London, UK; j EBG MedAustron GmbH, Wiener Neustadt, Austria

Simulation Study of a Combined Pair Production – Compton Camera for In-Vivo Dosimetry During Therapeutic Proton Irradiation

Proton and light ion beams are applied to the therapeutic irradiation of cancer patients due to the favorable dose deposition of these particles in tissue. By means of accelerated ions, a high dose can be accurately deposited in the tumor while normal tissue is spared. Since minor changes in the patient’s tissue along the beam path can compromise the success of the treatment, an in-vivo monitoring of the dose deposition is highly desired. Cameras detecting the prompt $\gamma $ -rays emitted during therapy are under investigation for this purpose. Due to the energy spectrum of prompt $\gamma $ -rays with a range between a few keV and several MeV, it is reasonable to consider the utilization of electron-positron pair production events to reconstruct the origin of these prompt photons. The combined use as a pair production and Compton camera is expected to increase its efficiency. We evaluated if a pair production camera could be suitable in this context by means of Monte-Carlo simulations. Modelling of the pair production events taking place in a prototype detector dedicated to Compton imaging were performed. We analyzed the efficiency of the detector system regarding pair production and Compton events. The most crucial property of this pair production camera is the angular resolution. The results of this work indicate that the spatial resolution of the considered detection system used as pair production camera is, for principal reasons, insufficient for an application to range assessment in particle therapy. Furthermore, the efficiency of the pair production camera under study is one order of magnitude lower than the efficiency of the setup applied to the detection of Compton events.

ANURIB – Advanced National facility for Unstable and Rare Ion Beams

An ISOL post-accelerator type of RIB facility is being developed at Variable Energy Cyclotron Centre (VECC), Kolkata, India. In this scheme, Rare Ion Beams (RIBs) will be produced using light ion beams (p, α) from the K=130 cyclotron, the RIB of interest will be separated from the other reaction products and accelerated up to about 2 MeV /u using a number of linear accelerators. Recently, a few RIBs have been produced and accelerated using this facility. As an extention of this effort, another RIB facility – ANURIB will be developed in a new campus as a green-field project. ANURIB will have two driver accelerators – a superconducting electron LINAC to produce n-rich RIBs using photofission route and a 50 MeV proton cyclotron for producing p-rich RIBs. In this paper, the status of the RIB facility in the present campus and future plans with the ANURIB facility will be discussed.

Behavior of nitrided and carburized AISI 904 L stainless steels under severe light ion beam irradiation with plasma focus

Superaustenitic stainless steels have become of growing interest in industrial and technological fields, but there is not a complete understanding on their fundamental properties and their performances. For this paper, AISI 904 L superaustenitic samples were nitrided and carburized in order to study the expanded austenite stability under severe deuterium and helium ion bombardment. Surface treatments were conducted using pulsed plasma glow discharges in a low pressure atmosphere, and a dense plasma focus device was used to irradiate the samples. Characterization techniques used were focused ion beam/SEM, energy-dispersive X-ray spectroscopy, and grazing incidence X-ray diffraction. Our results showed in carburized samples lattice expansion growth with the time treatment, but in nitrided samples, an expanded austenite reduction with time treatment was observed due to the formation of nitride nanoagglomerates. Moreover, this ion impingement provoked surface melting and a severe collision cascade, and a damaged bead located under the craters composed solely of minor alloying atoms. Furthermore, nitrided samples were more stable following ion bombardment than the carburized ones. When helium ions were used, the loss of expansion (triggered by diffusion processes of N or C to deeper regions) was more pronounced in the expanded austenite, but when deuterium ions were used to bombard the sample, there was a crystallite development of stressed austenite, which provoked a diffraction peak arousal at 43.3°. Copyright © 2015 John Wiley & Sons, Ltd.

Generation of ultra-intense ion beams by a short-pulse laser

This paper summarizes briefly the main experimental and numerical results of the IPPLM team studies on the generation of ultra-intense ion beams by a short (≤1 ps) laser pulse. Basic laser-driven ion acceleration schemes capable of generating such ion beams are described including the target normal sheath acceleration (TNSA) scheme, the skin-layer ponderomotive acceleration (SLPA) scheme and the laser-induced cavity pressure acceleration (LICPA) scheme. It is shown that an efficient way for achieving high ion beam intensities and fluencies lies in using a short-wavelength laser driver of circular light polarization. In such a case, SLPA clearly dominates over TNSA, and dense and compact ion bunch is generated with high energetic efficiency. The LICPA scheme operating in the photon (radiation) pressure regime can be even more efficient than SLPA. As it is demonstrated by particle-in-cell simulations, the LICPA accelerator with a picosecond, circularly polarized laser driver of intensity ∼ 1021 W/cm2 can produce sub-picosecond light ion beams of intensity ∼ 1022 W/cm2 and fluence > 1 GJ/cm2 with the energetic efficiency of tens of percent. Laser-driven ion beams of such extreme parameters could open up new research areas in high-energy-density science, inertial fusion or nuclear physics.

Defocusing of an ion beam propagating in background plasma due to two-stream instability

The current and charge neutralization of charged particle beams by background plasma enable ballistic beam propagation and have a wide range of applications in inertial fusion and high energy density physics. However, the beam-plasma interaction can result in the development of collective instabilities that may have deleterious effects on ballistic propagation of an ion beam. In the case of fast, light-ion beams, non-linear fields created by instabilities can lead to significant defocusing of the beam. We study an ion beam pulse propagating in a background plasma, which is subjected to two-stream instability between the beam ions and plasma electrons, using PIC code LSP. The defocusing effects of the instability on the beam can be much more pronounced in small radius beams. We show through simulations that a beamlet produced from an ion beam passed through an aperture can be used as a diagnostic tool to identify the presence of the two-stream instability and quantify its defocusing effects. The effect can be observed on the Neutralized Drift Compression Experiment-II facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma.

Using neutral beams as a light ion beam probe (invited).

By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of (1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge and (2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fields appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g., Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally imposed 3D fields, e.g., magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. In addition, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.

Assessment of improved organ at risk sparing for meningioma: Light ion beam therapy as boost versus sole treatment option

PurposeTo compare photons, protons and carbon ions and their combinations for treatment of atypical and anaplastical skull base meningioma. Material and methodsTwo planning target volumes (PTVinitial/PTVboost) were delineated for 10 patients (prescribed doses 50Gy(RBE) and 10Gy(RBE)). Plans for intensity modulated photon (IMXT), proton (IMPT) and carbon ion therapy (12C) were generated assuming a non-gantry scenario for particles. The following combinations were compared: IMXT+IMXT/IMPT/12C; IMPT+IMPT/12C; and 12C+12C. Plan quality was evaluated by target conformity and homogeneity (CI, HI), V95%, D2% and D50% and dose-volume-histogram (DVH) parameters for organs-at-risk (OAR). If dose escalation was possible, it was performed until OAR tolerance levels were reached. ResultsCI was worst for IMXT. HI<0.05±0.01 for 12C was significantly better than for IMXT. For all treatment options dose escalation above 60Gy(RBE) was possible for four patients, but impossible for six patients. Compared to IMXT+IMXT, ion beam therapy showed an improved sparing for most OARs, e.g. using protons and carbon ions D50% was reduced by more than 50% for the ipsilateral eye and the brainstem. ConclusionHighly conformal IMPT and 12C plans could be generated with a non-gantry scenario. Improved OAR sparing favors both sole 12C and/or IMPT plans.

Simulation of secondary electron emission from a stepped surface in scanning ion microscopes

For the use of scanning ion microscopes in device metrology, secondary electron (SE) emission from step patterns formed on a silicon substrate is investigated by simulation. The entire surface of a step is irradiated by H, He, Ne, and Ga ions with energies of 10–50 keV to form the line profile of the SE yield. Because of their highly localized production of SEs, light-ion beams result in clearer peaks in the line profile than heavy-ion beams. The recoiling atoms and cascade electrons contribute to the height of the SE peak, but tend to broaden it as well. Both the peak height and width decrease with decreasing step height. The presence of an inclining side wall in the step largely decreases the peak height and increases the peak width. Reducing the ion energy decreases the height gradually, but produces no clear change in the width.

Influence of the patient size on secondary doses delivered in light ion beams

*Secondary radiation exposure of patients in light ion therapy is of concern due to possible normal tissue damage and risk of induction of secondary cancers. Neutrons, protons and heavier ions are generated by nuclear inelastic interactions of primary ions both in the beam line and in the patient. The patient is exposed to a complex radiation field and secondary doses can be deposited in normal tissues both close to and relatively far from the treated volume. The energy distribution of secondary particles and secondary doses delivered to different organs were studied by the MC code SHIELD-HIT10 using the anthropomorphic phantoms representing a 10-year-old child (CHILD-HIT) and an adult male (ADAM-HIT). Brain tumor irradiations were simulated with approximated scanned beams of 1 H, 7 Li and 12 C ions. The influence of patient size on the secondary dose distributions were studied using the same target definition and irradiation geometry with a lateral beam. For the scanned beams, the secondary organ absorbed doses normalized per absorbed dose to the treated volume (brain tumor) were in the range 1 nGy/Gy - 0.1 mGy/Gy and the absorbed doses in the CHILD-HIT phantom were higher than in ADAM-HIT by up to a factor of 5, depending on organ.

Properties of an energy degrader for light ions

The Ion Beam Applications (IBA) Company works on the development of a superconducting cyclotron able to deliver various light ion beams with a maximal energy of 400 MeV per nucleon (MeV/u) [1]. This accelerator named C400 is designed to equip a hadrontherapy centre such as the ARCHADE project in France [2]. Fully stripped ions from He up to O can be accelerated inside the C400. They are extracted with an electromagnetic septum at fixed energy. To modulate the energy of the beams delivered to the patients, use is made of an energy selection system similar to the one developed by IBA for Proton Therapy (PT) systems. Figure 1 shows the layout of the Energy Selection System (ESS) for proton therapy system. After the beam extraction, a set of quadrupoles is used to focus the beam in order to obtain a minimal beam size at the entrance of the energy degrader. The later consists of a graphite wheel with variable thickness to degrade the energy beam from 230 MeV down to a minimal energy of 70 MeV. Behind the degrader, a collimator is used to limit the emittance of the transmitted beam. After another set of quadrupoles to refocus the beam, two sets of 2 dipole magnets are installed to bend the beam towards the irradiation rooms. The first set of dipoles act as an energy analyzer and a momentum slit is placed in the middle of the two sets of dipoles to limit the energy spread of the transported beam to a maximal value E/E = 0.6%. A similar ESS is under design to transport ion beams extracted from the C400. Compared to protons, light ions exhibit less angular divergence because of their higher masses but suffer from ion fragmentation due to nucleus-nucleus interactions inside the degrader, leading to a smaller transmission efficiency through the degrader. Charged ion fragments with the same magnetic rigidity as

Effective source size, radial, angular and energy spread of therapeutic 11C positron emitter beams produced by 12C fragmentation

The use of positron emitter light ion beams in combination with PET (Positron Emission Tomography) and PET–CT (Computed Tomography) imaging could significantly improve treatment verification and dose delivery imaging during radiation therapy.The present study is dedicated to the analysis of the beam quality in terms of the effective source size, as well as radial, angular and energy spread of the 11C ion beam produced by projectile fragmentation of a primary point monodirectional and monoenergetic 12C ion beam in a dedicated range shifter of different materials. This study was performed combining analytical methods describing the transport of particles in matter and the Monte Carlo code SHIELD-HIT+.A high brilliance and production yield of 11C fragments with a small effective source size and emittance is best achieved with a decelerator made of two media: a first liquid hydrogen section of about 20cm followed by a hydrogen rich section of variable length.The calculated intensity of the produced 11C ion beam ranges from about 5% to 8% of the primary 12C beam intensity depending on the exit energy and the acceptance of the beam transport system. The angular spread is lower than 1 degree for all the materials studied, but the brilliance of the beam is the highest with the proposed mixed decelerator.

Practical Implementation of Light Ion Beam Treatments.

This article reviews Practical Implementation of Light Ion Beam Treatments. by Michael F. Moyers, Stanislav M. Vatnitsky , Madison, WI, 2012. 580 pp. Price: $175.00. ISBN 978-1-930524-55-2 (hardcover)/978-1-930524-59-0 (CD).

Reference dosimetry for light-ion beams based on graphite calorimetry

Developments in hadron therapy require efforts to improve the accuracy of the dose delivered to a target volume. Here, the determination of the absorbed dose under reference conditions was analysed. Based on the International Atomic Energy Agency TRS-398 code of practice, for hadron beams, the combined standard uncertainty on absorbed dose to water under reference conditions, derived from ionisation chambers, is too large. This uncertainty is dominated by the beam quality correction factors, [Formula: see text], mainly due to the mean energy to produce one ion pair in air, wair. A method to reduce this uncertainty is to carry out primary dosimetry, using calorimetry. A [Formula: see text]-value can be derived from a direct comparison between calorimetry and ionometry. Here, this comparison is performed using a graphite calorimeter in an 80-MeV A(-1) carbon ion beam. Assuming recommended TRS-398 values of water-to-graphite stopping power ratio and the perturbation factor for an ionisation chamber, preliminary results indicate a wair-value of 35.5 ± 0.9 J C(-1).

A new fission-fragment detector to complement the CACTUS-SiRi setup at the Oslo Cyclotron Laboratory

An array of Parallel Plate Avalanche Counters (PPAC) for the detection of heavy ions has been developed. The new device, NIFF (Nuclear Instrument for Fission Fragments), consists of four individual detectors and covers 60% of 2π. It was designed to be used in conjunction with the SiRi array of ΔE−E silicon telescopes for light charged particles and fits into the CACTUS array of 28 large-volume NaI scintillation detectors at the Oslo Cyclotron Laboratory. The low-pressure gas-filled PPACs are sensitive for the detection of fission fragments, but are insensitive to scattered beam particles of light ions or light-ion ejectiles. The PPAC detectors of NIFF have good time resolution and can be used either to select or to veto fission events in in-beam experiments with light-ion beams and actinide targets. The powerful combination of SiRi, CACTUS, and NIFF provides new research opportunities for the study of nuclear structure and nuclear reactions in the actinide region. The new setup is particularly well suited to study the competition of fission and γ decay as a function of excitation energy.

Development of a compact high current low emittance RF ion source

A 13.56MHz inductively coupled plasma based RF ion source is developed for production of high brightness focused ion beams of heavy gaseous elements for high speed milling and light ions for high speed imaging. In order to obtain ion beams with low emittance, no magnetic field of any kind is used in the ion source. However, to achieve the high plasma density, the plasma chamber volume is reduced to couple RF power as high as 8–12W/cm3 to the plasma. Measurements show that the normalized rms emittance of 0.6mA Ar1+ beam to be as low as 0.0075mm-mrad while it is 0.004mm-mrad for 1.2mA of ion beam from hydrogen plasma. With a simple parallel plate extraction system with an aperture of 2mm diameter, 80mA/cm2 of ion beam from hydrogen plasma could be extracted at 3.5kV extraction potential and 300W of RF power. The ion source has been operated with other heavy gases and results show that more than 1mA of xenon and krypton ion beam could easily be extracted at 5kV extraction potential and 200W of RF power. In this article, the capability of the ion source to produce high current, low emittance heavy as well as light ion beams is presented.

Surface Wear Studies in Some Materials Using α-induced Reactions

The radio-activity produced during the irradiation of 63,65 Cu, 59 Co, 93 Nb and 121,123 Sb targets with α-particles have been measured using activation technique. The yields of radioactive isotopic products 66,67,68 Ga, 61 Cu, 96g,m Tc and 123,124,126 I have been determined in the energy range ≈ 10-40 MeV using stacked foil technique. Radioactive counting of samples was performed with a high-resolution gamma-spectrometer. As light ion beams produce an extremely narrow layer of activities in the surface of a material, these reactions may be useful for thin layer activation study. 1. IntR oDUctIon The thin layer activation (TLA) technique has become a widely used sensitive tool to study the surface wear of micron order in metallic surfaces in various engineering components. It is known that reliability of industrial equipments, transport systems, power plants both nuclear as well as conventional etc., is considerable influenced by the process of wear, corrosion and erosion. As such, the development of effective methods for the detection, measurements and monitoring of these processes are quite important. This is an important aspects in the sense that dangerous accidents during operation of industrial installation, and production losses may be avoided due to machine break-down. The charged particle activation for measurement and monitoring of corrosion and wear is important particularly when the parts of the surface are not really accessible. In TLA method, radioactivities in thin layers of the metallic foils are induced by bombarding them with light charged particles like protons, deuterons and α-particles. The incident charged particles may produce radio-active residues in the target material through nuclear reactions. The yield of the radio-active residues as a function of the depth gives the profile of surface wear. The yield of a particular radio-isotope may be determined from the measured cross-sections for that reaction responsible for the formation of the residue. The cross-sections for the production of