Production Of Radioactive Ion Beams Research Articles

LSTAR — An isobar separator for expanding radioactive ion beam production at the Cyclotron Institute, Texas A&M University

A new isobar separator, LSTAR (Light-ion guide Separator for Texas A&M’s Radioactive ion beams), has been designed to purify the exotic beams produced by a He-driven light-ion guide (He-LIG) system at Texas A&M University, primarily for the TAMUTRAP experiment. The main purpose of TAMUTRAP is to probe for physics beyond the standard model by searching for possible scalar or tensor currents in the weak interaction using nuclear β decay. The proton-rich isotopes of interest for this program will be produced at low yields, requiring efficient reduction of contaminant species to avoid overloading of TAMUTRAP’s radiofrequency quadrupole cooler-buncher. The layout, ion-optics, and specifications of LSTAR will be presented.

Production study of Fr, Ra and Ac radioactive ion beams at ISOLDE, CERN

The presented paper discusses the production of radioactive ion beams of francium, radium, and actinium from thick uranium carbide (UCx\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{x}$$\\end{document}) targets at ISOLDE, CERN. This study focuses on the release curves and extractable yields of francium, radium and actinium isotopes. The ion source temperature was varied in order to study the relative contributions of surface and laser ionization to the production of the actinium ion beams. The experimental results are presented in the form of release parameters. Representative extractable yields per μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}C are presented for 222-231\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{222-231}$$\\end{document}Ac, several Ra and Fr isotopes in the mass ranges 214≤\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le$$\\end{document}A≤\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le$$\\end{document}233 and 205≤\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le$$\\end{document}A≤\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le$$\\end{document}231 respectively. The release efficiency for several isotopes of each of the studied elements was calculated by comparing their yields to the estimated in-target production rates modeled by CERN-FLUKA. The maximal extraction efficiency of actinium was calculated to be 2.1(6)% for a combination of surface ionization using a Ta ion source and resonant laser ionization using the two-step 438.58 nm, and 424.69 nm scheme.

Radioactive ion-beam development at SPIRAL1

SPIRAL1 at GANIL is a facility dedicated to the production of radioactive ion beams (RIBs) and their post-acceleration. A major upgrade allowed this facility to produce RIBs of condensable elements. It does so by using both a hot 1+ ion source and an ECR Charge Breeder where the latter is used to increase the ion charge state for post-acceleration. The SPIRAL1 team is pursuing R&D on both fronts in order to expand the offer of RIBs. Several 1+ sources have been or will be tested in 2023: (1) MonoNaKe, a surface ion source, is being modified to ionize short-lived lithium isotopes (2) TULIP, dedicated to ionize short lived fusion-evaporation residues has been tested online for the second time (3) the FEBIAD source has produced radioactive Cr ions for the first time. The SPIRAL1 Charge Breeder (SP1CB) is now fitted with a fixed frequency amplifier (Klystron) and a variable frequency amplifier (travelling wave tube). Using one amplifier, the other, or both, enables several heating modes, giving better control on the charge state distribution at the output of SP1CB.

Study of the radionuclide deposition in the radioactive ion line of the Selective Production of Exotic Species (SPES) facility

SPES (Selective Production of Exotic Species) is a second generation facility for the production of radioactive ion beams that is going to be commissioned at the Laboratori Nazionali di Legnaro of INFN at Legnaro, Padua, Italy. Radioactive neutron-rich isotopes are expected to be produced by nuclear fission induced by a 40 MeV, 200 μA primary proton beam impinging on a 238UCx target. The expected reaction rate is about 1013 fission/s. Radioactive ion beams are produced using the isotope separation on-line technique. The production of such an amount of radioactive species raises radiological issues throughout the life cycle of the facility. A study of the radioactive contamination of the components of the radioactive ion beam line is performed with the FLUKA Monte Carlo simulation code, under realistic hypotheses for the produced isobaric beams. The present results complete previous studies focused on the radiological impact of the production target irradiation, the residual activation of the primary proton beam line and the radioactive contamination of the ion source complex. The overall ambient dose equivalent rate due to the different radiation sources is calculated at several positions inside the production bunker and at different times after a typical one-year operating period of the facility with the 238UCx target at full power. The obtained results and the developed methodology provide the guidelines and the needed tools to plan ordinary and extraordinary interventions as well as final decommissioning of the SPES facility.

Nuclear physics midterm plan at LNS

The next years will see the completion of several new facilities at Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud (LNS) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics and applications. These include a new line for high-intensity cyclotron beams, a new facility for in-flight production of radioactive ion beams, the PANDORA plasma trap for multidisciplinary studies and a high-power laser for basic science and applied physics. The nuclear physics community has organized a workshop to discuss the new physics opportunities that will be possible in the middle term (5–7 years) by employing state-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.

Recent results on the new fragment in-flight separator at INFN-LNS

A project for an upgrade of the Superconducting Cyclotron is underway at INFN-LNS. One of the goals of this project is the production of RIBs (Radioactive Ion Beams) of high intensity. To reach this purpose, a dedicated facility consisting of a new fragment separator FRAISE (FRAgment In-flight SEparator) is ongoing, exploiting primary beams with a power up to ≈ 2-3 kW. The high intensity achievable with FRAISE requires the use of appropriate diagnostics and tagging systems that can operate also in a strong radioactive environment. In this framework, a R&D program has been started to develop the FRAISE facility as well as the diagnostics and the tagging systems.

Production and mechanical characterization of Titanium Carbide ISOL target disks fabricated by direct ink writing

Titanium carbide boasts a large variety of high-temperature applications from aerospace to electronics and is also employed as Isotope Separation On-Line target for the production of Radioactive Ion Beams, which are employed in numerous research and technological fields, ranging from nuclear physics to medical applications. High working temperature, open and tailored porosity and resistance to thermal stresses are fundamental characteristics for this kind of targets. In this work, an extrusion-based additive manufacturing technique (Direct Ink Writing) was used for the fabrication of complex three-dimensional macro-porous structures in the shape of disks with dimensions compatible for their use as targets. An ink containing a suspension of TiC powders with solid loading of 47.5 vol% was prepared and its rheological properties were investigated. Afterwards, single filaments with an average diameter of 0.36 mm were produced and characterized with four-point bending tests to determine the bulk material tensile strength and Young's modulus. TiC targets were then manufactured and their mechanical properties were characterized with the Ball on Three Balls approach, a biaxial flexural test suitable for disk-shaped samples. For both flexural tests, a Finite Element model was developed representatively reproducing the experimental results. The calculated tensile strength values for both filaments and disks were analyzed with Weibull's statistical approach to provide reference stress limit, corresponding to a survival probability of 99.9%.

Production of innovative radionuclides for medical applications at the CERN-MEDICIS facility

Since its commissioning in December 2017, the CERN-MEDICIS facility has been providing non-conventional radionuclides for research in nuclear medicine. Benefitting from decades of experience in the production of radioactive ion beams and in the mass separation process from the ISOLDE facility at CERN, MEDICIS quickly became a worldwide key player in the supply of novel medical isotopes dedicated to research in the fields of cancer imaging, diagnostics, and radiation therapy.After a few years of operation, successful collections have been performed on a large panel of radionuclides such as 128Ba, 149,152,155Tb, 153Sm, 165,167Tm, 169Er, 175Yb, 191Pt, and 225,227Ac. Several milestones have been achieved on the output of the facility, such as the collection of 0.5 GBq of 175Yb, and a total separation efficiency higher than 50% reached for 167Tm in 2020. These collections led to notable recent in-vitro and preclinical results in targeted radionuclide therapy achieved with high molar activity 175Yb and 153Sm products.Constant developments are ongoing, such as innovative target designs, molecular formation to improve the release of some specific isotopes, laser development in the dedicated MELISSA laboratory, study of new implantation foil materials, and post-collection radiochemistry.

Understanding radioactive ion beam production at ISAC through yield measurements and simulations

The high-intensity proton beam of the TRIUMF 500 MeV cyclotron offers unique opportunities to produce rare isotopes by irradiating a variety of targets. In particular, the ISAC (Isotope Separation and ACceleration) facility provides the infrastructure to deliver customized rare ion beams for fundamental research in nuclear physics, astrophysics, material science, and nuclear medicine. A continuous effort is made to develop new radioactive ion beams (RIB) and improve their intensity or purity, properties that depend strongly on the type of target, operating conditions, the ion source, and beam transport efficiency. Yield data and theoretical production rates based on FLUKA and Geant4 simulations are collected in the TRIUMF Isotope Database, providing a valuable resource for RIB development and experiment planning. This paper introduces the newly upgraded TRIUMF Isotope Database and presents examples on how its resources can be used to plan experiments and understand the origin of certain RIB. In particular we discuss the collection of 155Tb which is an important component of medical isotope research at TRIUMF.

Radioactive Ion Beams: Production and Experiments at INFN-LNL

In this contribution the main mechanisms and techniques for the production of Radioactive Ion Beams are reviewed. In particular, the in-flight facility EXOTIC at INFN-LNL will be described and the results of a recent measurement of interest for the cosmological 7Li problem will be presented.

Laser photo-ionization study of nat Ag using opto-galvanic signal at SPES offline laser lab

Resonant Ionization Laser Ion Source (RILIS) is one of the most advancing techniques for the production of radioactive ion beams (RIBs) in ISOL facilities. SPES project at INFN-LNL is a second generation ISOL facility which aims to produce several isotopes in a couple of years. Within the framework of this project, resonant photo-ionization schemes of several elements are studied in the offline laser lab, to be later implemented in the SPES Laser Ion Source. Silver is one of the elements being studied for the stated purpose. In this article, we report a resonant photo-ionization scheme of silver tested with a hollow cathode lamp (HCL). Evidence of high lying Rydberg states around 60945.32 cm−1 has also been observed by studying the fast opto-galvanic signal detected.

Thermal and Structural Characterization of a Titanium Carbide/Carbon Composite for Nuclear Applications

In the framework of ISOL (isotope separation on-line) facilities, porous carbides are among the most employed target materials for the production of radioactive ion beams for research. As foreseen by the ISOL technique, a production target is impinged by an energetic particle beam, inducing nuclear reactions from such an interaction. The resulting radionuclides are subsequently released, thanks to the high target working temperature (1600-2000 °C); ionized; and extracted into a beam. Since the target microstructure and porosity play a fundamental role in the radionuclide release efficiency, custom-made target materials are often specifically produced, resulting in unknown thermal and structural properties. Considering that such targets might undergo intense thermal stresses during operation, a thermal and structural characterization is necessary to avoid target failure under irradiation. In the presented work, a custom-made porous titanium carbide that was specifically designed for application as an ISOL target was produced and characterized. The thermal characterization was focused on the evaluation of the material emissivity and thermal conductivity in the 600-1400 °C temperature range. For the estimation of a reference material tensile stress limit, the virtual thermoelastic parameter approach was adopted. In particular, for the aforementioned temperature range, an emissivity between 0.7 and 0.8 was measured, whereas a thermal conductivity between 8 and 10 W/mK was estimated.

Depth dose measurements in water for 11C and 10C beams with therapy relevant energies

Owing to the favorable depth-dose distribution and the radiobiological properties of heavy ion radiation, ion beam therapy shows an improved success/toxicity ratio compared to conventional radiotherapy. The sharp dose gradients and very high doses in the Bragg peak region, which represent the larger physical advantage of ion beam therapy, make it also extremely sensitive to range uncertainties. The use of β+-radioactive ion beams would be ideal for simultaneous treatment and accurate online range monitoring through PET imaging. Since all the unfragmented primary ions are potentially contributing to the PET signal, these beams offer an improved image quality while preserving the physical and radiobiological advantages of the stable counterparts. The challenging production of radioactive ion beams and the difficulties in reaching high intensities, have discouraged their clinical application. In this context, the project Biomedical Applications of Radioactive ion Beams (BARB) started at GSI (Helmholtzzentrum für Schwerionenforschung GmbH) with the main goal to assess the technical feasibility and investigate possible advantages of radioactive ion beams on the pre-clinical level. During the first experimental campaign 11C and 10C beams were produced and isotopically separated with the FRagment Separator (FRS) at GSI. The β+-radioactive ion beams were produced with a beam purity of 99% for all the beam investigated (except one case where it was 94%) and intensities potentially sufficient to treat a small animal tumors within few minutes of irradiation time, ∼106 particle per spill for the 10C and ∼107 particle per spill for the 11C beam, respectively. The impact of different ion optical parameters on the depth dose distribution was studied with a precision water column system. In this work, the measured depth dose distributions are presented together with results from Monte Carlo simulations using the FLUKA software.

Remote handling systems for the Selective Production of Exotic Species (SPES) facility

The SPES (Selective Production of Exotic Species) facility, currently under development at Legnaro National Laboratories of INFN, aims at the production of intense RIB (Radioactive Ion Beams) employing the Isotope Separation On-Line (ISOL) technique for interdisciplinary research. The radioactive isotopes of interest are produced by the interaction of a multi-foil uranium carbide target with a 40 MeV 200 μA proton beam generated by a cyclotron proton driver. The Target Ion Source (TIS) is the core of the SPES project, here the radioactive nuclei, mainly neutron-rich isotopes, are stopped, extracted, ionized, separated, accelerated and delivered to specific experimental areas. Due to efficiency reasons, the TIS unit needs to be replaced periodically during operation. In this highly radioactive environment, the employment of autonomous systems allows the manipulation, transport, and storage of the TIS unit without the need for human intervention. A dedicated remote handling infrastructure is therefore under development to fulfill the functional and safety requirement of the project. This contribution describes the layout of the SPES target area, where all the remote handling systems operate to grant the smooth operation of the facility avoiding personnel exposure to a high dose rate or contamination issues.

Design and radiological study of the 225Ac medical target at the TRIUMF-ARIEL proton-target station

At the Advanced Rare Isotope Laboratory (ARIEL) at TRIUMF, two targets will be irradiated in series with up to 100 µA of a 500 MeV proton beam. Whilst the upstream target will be used for radioactive ion beam production via the isotope separation on-line (ISOL) method, the downstream target will make use of the transmitted beam for medical isotope production, especially for targeted radiation therapy.The medical target design was optimized to meet both requirements for in-target 225Ac production as well as to operate within the ARIEL proton station via FLUKA and ANSYS simulations. To host the medical target, a module was specially designed and integrated into the shielding envelope.In addition, three failure scenarios are also considered, featuring maximum credible incidents that highlight the overall shielding performance. An evaluation of the dosimetry impact throughout the final stage of the medical target life cycle was also carried out. The latter entailed the reproduction of residual ambient dose rates when a dismantled target is retrieved from the hotcell and sent for processing in a shielded container. Overall, the simulation work led to the validation of the medical target design and its operation within the scope of ARIEL.

Charge breeder of Electron Cyclotron Resonance type: A new application to produce intense metal ion beams for accelerators

Metal ion beams are more and more requested by physicists (Nuclear Physics, Material Physics) for their experiments. At GANIL, they are produced by Electron Cyclotron Resonance (ECR) Ion Sources for the two accelerator machines: ECR4 & ECR4M (Sortais et al., 1989) [1] for the Cyclotrons and PhoenixV3 for the Linac (Thuillier et al., 2016) [2]. One of the challenges is to produce these beams with high global efficiency: today, total ionization efficiency varies between ∼1% and ∼28% regarding the method carried out. A new alternative would be the 1＋/N＋ method studied intensively for the past twenty years in the framework of Radioactive Ion Beam (RIB) production. In this article, the primary results leading to the proof of principle of that technique applied to the production of metal ion beams is presented.

A concept for the extraction of the most refractory elements at CERN-ISOLDE as carbonyl complex ions

We introduce a novel thick-target concept tailored to the extraction of refractory 4d and 5d transition metal radionuclides of molybdenum, technetium, ruthenium and tungsten for radioactive ion beam production. Despite the more than 60-year old history of thick-target ISOL mass-separation facilities like ISOLDE, the extraction of these most refractory elements as radioactive ion beam has so far not been successful. In ordinary thick ISOL targets, their radioisotopes produced in the target are stopped within the condensed target material. Here, we present a concept which overcomes limitations associated with this method. We exploit the recoil momentum of nuclear reaction products for their release from the solid target material. They are thermalized in a carbon monoxide-containing atmosphere, in which volatile carbonyl complexes form readily at ambient temperature and pressure. This compound serves as volatile carrier for transport to the ion source. Excess carbon monoxide is removed by cryogenic gas separation to enable low pressures in the source region, in which the species are ionized and hence made available for radioactive ion beam formation. The setup is operated in batch mode. Initially, we investigate the feasibility of the approach with isotopes of more than 35s half-life. At the cost of reduced efficiency, the concept could also be applied to isotopes with half-lives of at least one to 10s. We report parameter studies of the key processes of the method, which validate this concept and which define the parameters for the setup. This would allow for the first time the extraction of radioactive molybdenum, tungsten and several other transition metals at thick-target ISOL facilities.

Radioactive and Stable Ion Beam production at GANIL

GANIL Facilities deliver ion beams from Proton to Uranium up to 95MeV/A. The Cyclotron facility combined with the SPIRAL1 facility provides Stable Ion Beams (SIB) since 1983 and Radioactive Ion Beams (RIB) since 2001 for Physics experiments. R&D of new stable and radioactive beams are continuously under progress matching physicist requirements. During the last ten years, the SPIRAL1 facility was upgraded to extend its capabilities to deliver RIBs of condensable elements. After a new one delivered in 2019, off-line R&D’s have been done on the Target Ions Source System and also on the Charge Breeder to improve efficiencies and achieve an operational and reliable facility.In parallel, the commissioning of the LINAC-SPIRAL2 facility started in 2019 with a proton beam production. In 2020, a 16 kW proton beam was delivered for the first time on the Neutron For Science physics area, and a 4 mA beam of 4He2+ was produced with the PhoenixV3 ECR ion source to mimic a deuteron beam. In this article, an overview of GANIL ion sources, beam properties and future developments are described.

Anomalous Ionization Regime in a Forced Electron Beam Induced Arc Discharge Ion Source for Singly Charged Radioactive Ion Beam Production

At TRIUMF’s ISAC facility, 1+ Radioactive Ion Beams (RIBs) of noble gases, halogens, and molecules are created using a Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source. Reported ionization efficiencies for FEBIADs range from 10% to 25% for 40Ar+, while TRIUMF-FEBIAD ionization efficiency seems to be < 1% with a 90% emittance <15 μm. As RIB ion sources aim for a high ionization efficiency, an experimental and numerical campaign was conducted to investigate the comparably low efficiencies observed. The experimental results for 40Ar+ indicate that up to a 10% ionization efficiency is possible by operating the source at different parameters. The measurements agree with theoretical estimations; however, certain combinations of parameters produce an anomalously high electron current which enhances the ionization efficiency threefold. Present investigations aim to characterize and model the anomalous electron current because, if proven reliable, the argon ionization efficiency could reach 30% with no significant impact on beam emittance.

Charge breeders: Development of diagnostic tools to probe the underlying physics.

Charge breeders were developed more than 20 years ago in the context of radioactive ion beam (RIB) production. The main goal is to boost the charge state of a singly charged RIB to a higher value matching the A/Q of a post-accelerator. In that way, the RIB produced at some tens of keV can efficiently be accelerated to energies in a range of few MeV/u up to several tens of MeV/u, which is of interest for nuclear structure and nuclear astrophysics experiments. Two families of charge breeders have been developed: one based on Electron Cyclotron Resonance Ion Sources (ECRISs) suitable for Continuous Wave (CW) operation and another built around Electron Beam Ion Sources (EBISs) used for pulsed post-accelerators. For many years, experimental studies have been carried out to enhance the charge breeding process and improve the extracted beam quality, i.e., purity, intensity, emittance, and time structure. The evolution of the charge breeders is also closely related to the emergence of new facilities delivering even more exotic beams. Diagnostic tools, such as Faraday cups, beam profile monitors, and emittance scanners, are mandatory to tune the machines and evaluate their performances. However, to go beyond that, a better understanding of plasma physics (in ECRIS) and electron-ion interactions (in EBIS), as well as the 1+ beam characteristics, for instance, energy spread transverse emittance, is needed. Therefore, simulation codes modeling the physics phenomena in both type of charge breeders were developed to support the understanding of experimental outputs and to gain insights into non-observable parameters. Nevertheless, more sophisticated diagnostic tools are required to improve the charge breeding performance and to extend the potential applications toward new RIB facilities. This Review will present the two kinds of charge breeders and their technical evolutions. It will review the diagnostic tools and simulation codes employed for operation and evaluation of the internal physics processes.