Abstract
At the SPES (Selective Production of Exotic Species) facility, intense Radioactive Ion Beams (RIBs) are produced by the interaction of a 40 MeV proton beam with a multi-foil uranium carbide ...target employing the Isotope Separation On-Line (ISOL) technique. The Target Ion Source (TIS) unit constitutes the core of the isotope production process. TIS units are replaced on a periodic basis during operation to maintain high performance. An automated storage system has been designed to accept highly radioactive TIS units and house them during a cooling period prior to decommissioning. The system is conceived to meet strict functional and safety requirements. Its peculiar design allows for improved reliability and availability during critical operations, as well as minimization of staff exposure to ionizing radiation during maintenance tasks. This contribution describes the design and control architecture of the Temporary Storage System (TSS). The equipment is part of a structured framework of remote manipulation, consisting of various machines interlocked with the Access Control System (ACS) and the Machine Protection System (MPS).
Thorium carbide to be tested as target material for the production of
Ac with the ISOL method, was produced via carbothermal reduction of ThO
nanoparticles by graphite and graphene oxide, ...respectively. The use of graphene oxide (GO) as carbon source resulted in a reduced reactivity compared to graphite, confirmed by the presence of unreacted ThO
mainly in the core of the samples. The reacted ThO
or ThC
-GO showed a faster reactivity in air, mainly observed as ThC
amorphization. The specific surface area of the ThC
-GO samples was almost doubled compared to ThC
-graphite samples. The effect of these microstructural features was analysed in terms of thermal diffusivity and calculated thermal conductivity that were both reduced in ThC
-GO samples, however the difference with ThC
-graphite samples decreased at increasing temperature. The present study shows that the use of unreduced GO inhibits the solid-state reaction between ThO
and C; on the other hand, the high reactivity of the ThC
so produced is expected to be beneficial for the
Ac production with the ISOL method, affording a high release efficiency. It is expected that the use of reduced GO could represent a good solution for highly efficient ThC
targets.
The Isotope Separation On-Line (ISOL) method for the production of Radioactive Ion Beams (RIB) is attracting significant interest in the worldwide nuclear physics community. Within this context the ...SPES (Selective Production of Exotic Species) RIB facility is now under construction at INFN LNL (Istituto Nazionale di Fisica Nucleare Laboratori Nazionali di Legnaro). This technique is established as one of the main techniques for high intensity and high quality beams production. The SPES facility will produce n-rich isotopes by means of a 40 MeV proton beam, emitted by a cyclotron, impinging on a uranium carbide multi-foil fission target. The aim of this work is to describe the most important results obtained by the study of the on-line behavior of the SPES production target assembly. This target system will produce RIBs at a rate of about 1013 fissions per second, it will be able to dissipate a total power of up to 10 kW, and it is planned to work continuously for 2 week-runs of irradiation. ISOL beams of 24 different elements will be produced, therefore a target and ion source development is ongoing to ensure a great variety of produced isotopes and to improve the beam intensity and purity.
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
UC
target. The expected reaction rate is about 10
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
UC
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.
Radionuclides for radiopharmaceuticals can be produced in cyclotrons or nuclear reactors. Each of these production modes has serious issues, such as high target costs, production of long-lived wastes ...and contaminants, expensive separation. For this reason, new methods are under consideration for the production of highly pure radionuclides. The ISOL (Isotope Separation On-Line) method is the major technique for the production of radioactive ion beams for nuclear physics applications. The SPES-ISOLPHARM project at INFN-LNL (Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Legnaro) is a feasibility study for the production of medical isotopes exploiting the ISOL method. The ongoing activities concerning a recent experiment focused on
111
Ag, a study performed in collaboration with Padova and Trento Universities, is presented.
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•Theory of pH-static titrations for metal + ligand complexation kinetics was given.•pH static titrations represent a kinetic method alternative to spectrophotometry.•The kinetics of ...Sr2++DOTA reaction at various pH and temperatures was studied.•Other used methods for kinetic measurements can give wrong results.
The theory of pH-static (or pH-stat) titrations in kinetic measurements of metal ion + ligand complex formation was resumed, and equations required to fit the experimental data were derived. This method was applied to study the kinetics of Sr2++DOTA reaction (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). pH-static titrations were performed at various pH (from 4.00 to 6.00) and temperatures (5, 15, and 25 °C) and at a constant ionic strength of (Na)Cl 0.15 mol/L. The complex formation involved either a rapidly formed intermediate species which then gave the final complex, or the direct metal + ligand reaction. The corresponding equilibrium constant βos and kinetic constants kos (first order) and k (second order) were obtained. Both k and kos increased by increasing pH and temperature. Kinetic data were recorded by pH-static titrations also for Ni2++DOTA reaction, and other kinetic results were obtained by using a more commonly employed method, proposed by Kasprzyk and Wilkins S. P. Kasprzyk and R. G. Wilkins, Inorg. Chem., 1982, 21, 3349, which however appears to be theoretically incorrect. The comparison between the kinetic results for Sr2++DOTA and Ni2++DOTA reactions obtained by pH-static titrations, by the Kasprzyk/Wilkins method, and by the well-established spectrophotometric method (literature data), indicated that the Kasprzyk/Wilkins method should be used with caution as sometimes its systematic errors can be statistically relevant with respect to the typical precision of kinetic data.
The SPES laser ion source has been tested at ISOLDE Offline 2, CERN. A two-step single resonance photo-ionization scheme has been used to ionize gallium atoms in the SPES tantalum hot-cavity ion ...source. The ion beam time structure, laser enhancement of ion yield, and ionization efficiency are investigated in relation to the ion source temperature and ion load. From the time structures, it is inferred that a significant fraction of the extracted ions are generated in the transfer line rather than just in the hot cavity. The effect of the electrostatic axial field on the movement of ions inside the ion source is discussed. Generally, there is an inverse relationship between total ion load and the laser enhancement factor. This dependency is enhanced at lower operating temperature of the ion source. This is explained by the influence of thermionic electron emission and ion density on the transverse laser-ion confinement, and therefore the survival of ions as they drift towards the extraction region of the ion source. At 2200 °C, the nominal temperature for on-line operation of the ion source, the ratio of laser-ionized to surface-ionized gallium was stable around 55 during the measurement campaign, and independent of the total extracted ion current up to the measured value of 1.1 μA. A resonance laser ionization efficiency value of 27.2% for gallium has been measured.
Radio Pharmaceutical Therapy (RPT) comes forth as a promising technique to treat a wide range of tumors while ensuring low collateral damage to nearby healthy tissues. This kind of cancer therapy ...exploits the radiation following the decay of a specific radionuclide to deliver a lethal dose to tumor tissues. In the framework of the ISOLPHARM project of INFN, 111Ag was recently proposed as a promising core of a therapeutic radiopharmaceutical. In this paper, the production of 111Ag via neutron activation of 110Pd-enriched samples inside a TRIGA Mark II nuclear research reactor is studied. The radioisotope production is modeled using two different Monte Carlo codes (MCNPX and PHITS) and a stand-alone inventory calculation code FISPACT-II, with different cross section data libraries. The whole process is simulated starting from an MCNP6-based reactor model producing the neutron spectrum and flux in the selected irradiation facility. Moreover, a cost-effective, robust and easy-to-use spectroscopic system, based on a Lanthanum Bromo-Chloride (LBC) inorganic scintillator, is designed and characterized, with the aim of using it, in the future, for the quality control of the ISOLPHARM irradiated targets at the SPES facility of the Legnaro National Laboratories of INFN. natPd and 110Pd-enriched samples are irradiated in the reactor main irradiation facility and spectroscopically characterized using the LBC-based setup and a multiple-fit analysis procedure. Experimental results are compared with theoretical predictions of the developed models, showing that inaccuracies in the available cross section libraries prevent an accurate reproduction of the generated radioisotope activities. Nevertheless, models are normalized to our experimental data allowing for a reliable planning of the 111Ag production in a TRIGA Mark II reactor.
•111Ag proposed in ISOLPHARM-INFN project as a promising core of radiopharmaceutical.•Temporary 111Ag production via neutron activation inside a TRIGA Mark II reactor.•Spectroscopic characterization of the production with a dedicated LBC-based setup.•Monte Carlo model and benchmark with experimental data to plan the 111Ag production.•Future 111Ag production with high-specific activity at the Italian SPES-ISOL facility.
Accelerator-based techniques with electromagnetic mass separation are considered among the most innovative and promising strategies to produce non-conventional radionuclides for nuclear medicine. ...Such approach was successfully used at CERN, where the dedicated MEDICIS facility was built, and at TRIUMF, where the ISAC radioactive beam facility was used to produce unconventional α-emitters. In such framework, the Legnaro National Laboratories of the Italian Institute of Nuclear Physics (INFN-LNL) proposed the ISOLPHARM project (ISOL technique for radioPHARMaceuticals), which will exploit radionuclides producible with the SPES (Selective Production of Exotic Species) ISOL (Isotope Separation On-Line) facility to develop novel radiopharmaceuticals. The ISOL technique utilizes the irradiation with a primary beam of particles/nuclei of a production target where radionuclides are produced. A radioactive ion beam is subsequently extracted from the production target unit, and transported up to an analyzing magnet, where non-isobaric contaminants are filtered out. The so-obtained purified radioactive beam is dumped onto an implantation substrate, referred as collection target. Then, the desired nuclides can be chemically harvested from the collected isobars, and the isotopically pure atom collection can be employed to radiolabel high specific activity radiopharmaceuticals. Metallic deposition targets in the form of coated metal foils were mostly used at TRIUMF and CERN. At ISOLPHARM, a different approach is under investigation which foresees the use of soluble cold-pressed collection targets, possibly facilitating the chemical purification process of the collected radionuclides. In this study, the production and characterization of some of the ISOLPHARM collection targets is presented, in particular, soluble salts (NaCl and NaNO3) and organic materials widely used for pharmaceutical tablets production are considered. All such materials proved to be potentially suitable as collection targets, since solid samples were easily produced and resulted compatible with the vacuum conditions required for the ion implantation process. Furthermore, some of the selected substrates were used for proof-of-concept deposition tests with stable silver, to prove their suitability as ISOLPHARM deposition substrates for silver-111, a promising candidate for radiotherapy. Such tests highlighted possible scenarios useful for the development of new alternative materials, as the use of insoluble organic targets.
•ISOL based techniques for the production of medical radionuclides require the use of an implantation target.•Generally, implantation targets are metallic foil, ISOLPHARM at INFN-LNL proposes saline or organic substrates.•NaCl, NaNO3, cellulosic and dextrates substrates were produced by direct compression.•All samples were characterized in terms of density, mechanical strength, disaggregation and vacuum compatibility.•Implantation depth calculations and tests with the deposition of Ag + ions were performed.
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