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.

New solid state laser system for SPES: Selective Production of Exotic Species project at Laboratori Nazionali di Legnaro

The Selective Production of Exotic Species project is under construction at Laboratori Nazionali di Legnaro-INFN. The aim of the collaboration is to produce highly pure Radioactive Ion Beams (RIBs) from fission fragments of a uranium carbide (UC_x) target activated by a cyclotron proton beam. In order to select a specific atomic species, the main tool to be applied is the resonant laser ionization technique. We have just completed the installation of a dedicated all solid state laser system whose elements are tunable to transitions of all the elements/isotopes of interest for the project. The new laser system is based on three Titanium:sapphire laser sources, independently pumped by three Nd:YLF pump lasers, and it can be coupled to two high harmonic generation (second harmonic generation, third harmonic generation, and fourth harmonic generation) setups. The power, wavelength, and position of the laser beams are continuously monitored and stabilized by using automated active systems to improve the beam production stability of RIBs. This paper presents the main features of the laser system and examples of application of a laser ion source, including a first demonstration of photoionization of stable silver, one of the most requested elements for RIB application.

Exploiting within-breed variability in the autochthonous Reggiana breed identified several candidate genes affecting pigmentation-related traits, stature and udder defects in cattle

Autochthonous cattle breeds constitute important reservoirs of genetic diversity. Reggiana is an Italian local cattle breed reared in the north of Italy for the production of a mono‐breed Parmigiano–Reggiano cheese. Reggiana cattle usually have a classical solid red coat colour and pale muzzle. As part of the strategies designed for the sustainable conservation of this genetic resource, we investigated at the genome‐wise level the within‐breed detected variability of three pigmentation‐related traits (intensity of red coat colour, based on three classes – light/diluted, normal and dark; spotted patterns/piebaldism that sometime emerge in the breed; muzzle colour – pink/pale, grey and black), stature, presence/absence and number of supernumerary teats and teat length. A total of 1776 Reggiana cattle (about two‐thirds of the extant breed population) were genotyped with the GeneSeek GGP Bovine 150k SNP array and single‐marker and haplotype‐based GWASs were carried out. The results indicated that two main groups of genetic factors affect the intensity of red coat colour: darkening genes (including EDN3 and a few other genes) and diluting genes (including PMEL and a few other genes). Muzzle colour was mainly determined by MC1R gene markers. Piebaldism was mainly associated with KIT gene markers. Stature was associated with BTA6 markers upstream of the NCAPG–LCORL genes. Teat defects were associated with TBX3/TBX5, MCC and LGR5 genes. Overall, the identified genomic regions not only can be directly used in selection plans in the Reggiana breed, but also contribute to clarifying the genetic mechanisms involved in determining exterior traits in cattle.

Single-marker and haplotype-based genome-wide association studies for the number of teats in two heavy pig breeds

The number of teats is a reproductive‐related trait of great economic relevance as it affects the mothering ability of the sows and thus the number of properly weaned piglets. Moreover, genetic improvement of this trait is fundamental to parallelly help the selection for increased litter size. We present the results of single‐marker and haplotypes‐based genome‐wide association studies for the number of teats in two large cohorts of heavy pig breeds (Italian Large White and Italian Landrace) including 3990 animals genotyped with the 70K GGP Porcine BeadChip and other 1927 animals genotyped with the Illumina PorcineSNP60 BeadChip. In the Italian Large White population, genome scans identified three genome regions (SSC7, SSC10, and SSC12) that confirmed the involvement of the VRTN gene (as we previously reported) and highlighted additional loci known to affect teat counts, including the FRMD4A and HOXB1 gene regions. A different picture emerged in the Italian Landrace population, with a total of 12 genome regions in eight chromosomes (SSC3, SSC6, SSC8, SSC11, SSC13, SSC14, SSC15, and SSC16) mainly detected via the haplotype‐based genome scan. The most relevant QTL was close to the ARL4C gene on SSC15. Markers in the VRTN gene region were not significant in the Italian Landrace breed. The use of both single‐marker and haplotype‐based genome‐wide association analyses can be helpful to exploit and dissect the genome of the pigs of different populations. Overall, the obtained results supported the polygenic nature of the investigated trait and better elucidated its genetic architecture in Italian heavy pigs.

Development of implantation substrates for the collection of radionuclides of medical interest produced via ISOL technique at INFN-LNL

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.

Study of the radioactive contamination of the ion source complex in the Selective Production of Exotic Species (SPES) facility

The Isotope Separation On-Line (ISOL) technique is today established as one of the primary methods to produce high-intensity and high-quality radioactive beams. This technique produces, for a given amount of the desired isotope, many orders of magnitude of other radioactive species. Due to the activation generated by interactions of the primary beam, intense neutron fields, and deposition of the produced radioactive ions inside beam line elements, an ISOL facility in operation becomes an intense radioactive source. Therefore, the biological hazard imposes severe radiological safety challenges to the design, operation, maintenance, and final decommissioning of such facilities. A challenging component is the ion source complex, where the ion extraction electrode provides the extraction of radioactive ions from the ion source and the first acceleration to the extracted beam. The radioactive contamination of this sub-component is studied, by means of the FLUKA code, in the case of the Selective Production of Exotic Species facility, which is in the advanced construction phase at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Padua, Italy. The developed model includes isotope production by the interactions of a 40 MeV energy proton beam on a ²³⁸UC_x target, selection of radioactive isotopes that are able to stick on the electrode tip, time evolution of the deposited isotopes during the operation and cooling periods before maintenance interventions, and evaluation of the ambient dose equivalent rate generated by the contamination of the electrode tip. Based on these results, the possibility of manual interventions for maintenance and emergency vs the use of remote handling systems is discussed.

Effect of graphite and graphene oxide on thorium carbide microstructural and thermal properties

Thorium carbide to be tested as target material for the production of 225Ac with the ISOL method, was produced via carbothermal reduction of ThO2 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 ThO2 mainly in the core of the samples. The reacted ThO2 or ThC2-GO showed a faster reactivity in air, mainly observed as ThC2 amorphization. The specific surface area of the ThC2-GO samples was almost doubled compared to ThC2-graphite samples. The effect of these microstructural features was analysed in terms of thermal diffusivity and calculated thermal conductivity that were both reduced in ThC2-GO samples, however the difference with ThC2-graphite samples decreased at increasing temperature. The present study shows that the use of unreduced GO inhibits the solid-state reaction between ThO2 and C; on the other hand, the high reactivity of the ThC2 so produced is expected to be beneficial for the 225Ac 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 ThC2 targets.

Haplotype-based genome-wide association studies reveal new loci for haematological and clinical-biochemical parameters in Large White pigs

We report haplotype-based GWASs for 33 blood parameters measured in 843 Italian Large White pigs. In the single-trait analysis, a total of 30 QTL for number of basophils, six erythrocyte traits (haemoglobin, haematocrit, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, mean corpuscular volume and red blood cell count) and two clinical-biochemical traits (alkaline phosphatase and Ca²⁺ contents) were identified. In the multiple-trait analysis, a total of five QTL affected three different clusters of traits. Only four of these QTL were already reported in the single-marker and multi-marker GWASs we previously carried out on the same pig population. QTL on SSC11 and SSC17 showed effects on multiple traits. These results further dissected the genetic architecture of parameters that could be used as proxies in breeding programmes for more complex traits. In addition, these results might help to better define the pig as an animal model for several blood-related biological functions.

The ISOLPHARM project: A New ISOL production method of high specific activity beta-emitting radionuclides as radiopharmaceutical precursors

The ISOLPHARM project explores the feasibility of exploiting an innovative technology to produce extremely high specific activity beta-emitting radionuclides as radiopharmaceutical precursors. This technique is expected to produce radiopharmaceuticals that are virtually mainly impossible to obtain in standard production facilities, at lower cost and with less environmental impact than traditional techniques. The groundbreaking ISOLPHARM method investigated in this project has been granted an international patent (INFN). As a component of the SPES (Selective Production of Exotic Species) project at the Istituto Nazionale di Fisica Nucleare–Laboratori Nazionali di Legnaro (INFN–LNL), a new facility will produce radioactive ion beams of neutron-rich nuclei with high purity and a mass range of 80–160 amu. The radioactive isotopes will result from nuclear reactions induced by accelerating 40 MeV protons in a cyclotron to collide on a target of UC[Formula: see text]. The uranium in the target material will be [Formula: see text]U, yielding radioactive isotopes that belong to elements with an atomic number between 28 and 57. Isotope separation on line (ISOL) is adopted in the ISOLPHARM project to obtain pure isobaric beams for radiopharmaceutical applications, with no isotopic contaminations in the beam or subsequent trapping substrate. Isobaric contaminations may potentially affect radiochemical and radionuclide purity, but proper methods to separate chemically different elements can be developed.

Radiation resistance of elastomeric O-rings in mixed neutron and gamma fields: Testing methodology and experimental results

Materials and components employed in the presence of intense neutron and gamma fields are expected to absorb high dose levels that may induce deep modifications of their physical and mechanical properties, possibly causing loss of their function. A protocol for irradiating elastomeric materials in reactor mixed neutron and gamma fields and for testing the evolution of their main mechanical and physical properties with absorbed dose has been developed. Four elastomeric compounds used for vacuum O-rings, one fluoroelastomer polymer (FPM) based and three ethylene propylene diene monomer rubber (EPDM) based, presently available on the market have been selected for the test. One EPDM is rated as radiation resistant in gamma fields, while the other elastomers are general purpose products. Particular care has been devoted to dosimetry calculations, since absorbed dose in neutron fields, unlike pure gamma fields, is strongly dependent on the material composition and, in particular, on the hydrogen content. The products have been tested up to about 2 MGy absorbed dose. The FPM based elastomer, in spite of its lower dose absorption in fast neutron fields, features the largest variations of properties, with a dramatic increase in stiffness and brittleness. Out of the three EPDM based compounds, one shows large and rapid changes in the main mechanical properties, whereas the other two feature more stable behaviors. The performance of the EPDM rated as radiation resistant in pure gamma fields does not appear significantly better than that of the standard product. The predictive capability of the accelerated irradiation tests performed as well as the applicable concepts of threshold of radiation damage is discussed in view of the use of the examined products in the selective production of exotic species facility, now under construction at the Legnaro National Laboratories of the Italian Istituto Nazionale di Fisica Nucleare. It results that a careful account of dose rate effects and oxygen penetration in the material, both during test irradiations and in operating conditions, is needed to obtain reliable predictions.