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225 Ac is a radio-isotope that can be linked to biological vector molecules to treat certain distributed cancers using targeted alpha therapy. However, developing 225 Ac-labelled radiopharmaceuticals remains a challenge due to the supply shortage of pure 225 Ac itself. Several techniques to obtain pure 225 Ac are being investigated, amongst which is the high-energy proton spallation of thorium or uranium combined with resonant laser ionization and mass separation. As a proof-of-principle, we perform off-line resonant ionization mass spectrometry on two samples of 225 Ac, each with a known activity, in different chemical environments. We report overall operational collection efficiencies of 10.1(2)% and 9.9(8)% for the cases in which the 225 Ac was deposited on a rhenium surface and a ThO 2 mimic target matrix respectively. The bottleneck of the technique was the laser ionization efficiency, which was deduced to be 15.1(6)%.

The radionuclides 43Sc,  44g/mSc, and 47Sc can be produced cost-effectively in sufficient yield for medical research and applications by irradiating  natTi and  natV target materials with protons. Maximizing the production yield of the therapeutic 47Sc in the highest cross section energy range of 24–70 MeV results in the co-production of long-lived, high-γ-ray-energy 46Sc and 48Sc contaminants if one does not use enriched target materials. Mass separation can be used to obtain high molar activity and isotopically pure Sc radionuclides from natural target materials; however, suitable operational conditions to obtain relevant activity released from irradiated  natTi and  natV have not yet been established at CERN-MEDICIS and ISOLDE. The objective of this work was to develop target units for the production, release, and purification of Sc radionuclides by mass separation as well as to investigate target materials for the mass separation that are compatible with high-yield Sc radionuclide production in the 9–70 MeV proton energy range. In this study, the in-target production yield obtained at MEDICIS with 1.4 GeV protons is compared with the production yield that can be reached with commercially available cyclotrons. The thick-target materials were irradiated at MEDICIS and comprised of metallic  natTi,  natV metallic foils, and  natTiC pellets. The produced radionuclides were subsequently released, ionized, and extracted from various target and ion source units and mass separated. Mono-atomic Sc laser and molecule ionization with forced-electron-beam-induced arc-discharge ion sources were investigated. Sc radionuclide production in thick  natTi and  natV targets at MEDICIS is equivalent to low- to medium-energy cyclotron-irradiated targets at medically relevant yields, furthermore benefiting from the mass separation possibility. A two-step laser resonance ionization scheme was used to obtain mono-atomic Sc ion beams. Sc radionuclide release from irradiated target units most effectively could be promoted by volatile scandium fluoride formation. Thus, isotopically pure  44g/mSc, 46Sc, and 47Sc were obtained as mono-atomic and molecular ScF 2+ ion beams and collected for the first time at CERN-MEDICIS. Among all the investigated target materials,  natTiC is the most suitable target material for Sc mass separation as molecular halide beams, due to high possible operating temperatures and sustained release.

Samarium-153 ( 153 Sm) is a highly interesting radionuclide within the field of targeted radionuclide therapy because of its favorable decay characteristics. 153 Sm has a half-life of 1.93 d and decays into a stable daughter nuclide ( 153 Eu) whereupon β − particles [E = 705 keV (30%), 635 keV (50%)] are emitted which are suitable for therapy. 153 Sm also emits γ photons [103 keV (28%)] allowing for SPECT imaging, which is of value in theranostics. However, the full potential of 153 Sm in nuclear medicine is currently not being exploited because of the radionuclide's limited specific activity due to its carrier added production route. In this work a new production method was developed to produce 153 Sm with higher specific activity, allowing for its potential use in targeted radionuclide therapy. 153 Sm was efficiently produced via neutron irradiation of a highly enriched 152 Sm target (98.7% enriched, σ th = 206 b) in the BR2 reactor at SCK CEN. Irradiated target materials were shipped to CERN-MEDICIS, where 153 Sm was isolated from the 152 Sm target via mass separation (MS) in combination with laser resonance enhanced ionization to drastically increase the specific activity. The specific activity obtained was 1.87 TBq/mg (≈ 265 times higher after the end of irradiation in BR2 + cooling). An overall mass separation efficiency of 4.5% was reached on average for all mass separations. Further radiochemical purification steps were developed at SCK CEN to recover the 153 Sm from the MS target to yield a solution ready for radiolabeling. Each step of the radiochemical process was fully analyzed and characterized for further optimization resulting in a high efficiency (overall recovery: 84%). The obtained high specific activity (HSA) 153 Sm was then used in radiolabeling experiments with different concentrations of 4-isothiocyanatobenzyl-1,4,7,10-tetraazacyclododecane tetraacetic acid ( p -SCN-Bn-DOTA). Even at low concentrations of p -SCN-Bn-DOTA, radiolabeling of 0.5 MBq of HSA 153 Sm was found to be efficient. In this proof-of-concept study, we demonstrated the potential to combine neutron irradiation with mass separation to supply high specific activity 153 Sm. Using this process, 153 SmCl 3 suitable for radiolabeling, was produced with a very high specific activity allowing application of 153 Sm in targeted radionuclide therapy. Further studies to incorporate 153 Sm in radiopharmaceuticals for targeted radionuclide therapy are ongoing.

Photocathodes are key elements in high-brightness electron sources and ubiquitous in the operation of large-scale accelerators, although their operation is often limited by their quantum efficiency and lifetime. Here, we propose to overcome these limitations by utilizing direct-laser nanostructuring techniques on copper substrates, improving their efficiency and robustness for next-generation electron photoinjectors. When the surface of a metal is nanoengineered with patterns and particles much smaller than the optical wavelength, it can lead to the excitation of localized surface plasmons that produce hot electrons, ultimately contributing to the overall charge produced. In order to quantify the performance of laser-produced plasmonic photocathodes, we measured their quantum efficiency in a typical electron gun setup. Our experimental results suggest that plasmon-induced hot electrons lead to a significant increase in quantum efficiency, showing an overall charge enhancement factor of at least 4.5 and up to 25. A further increase in their efficiency was observed when combined with semiconductor thin-films deposited over the laser processed surfaces, pointing at potential pathways for further optimization. We demonstrate that simple laser-produced plasmonic photocathodes outperform standard metallic photocathodes, and can be directly produced at the electron gun level in vacuum environments and without any disruptive intervention. This approach could lead to unprecedented efficient and continuous operation of electron sources, and is useful in many applications across scientific disciplines requiring high average and peak current electron beams.

CERN-MEDICIS is an off-line isotope separator facility for the extraction of radioisotopes from irradiated targets of interest to medical applications. The beamline, between the ion source and the collection chamber, consists of ion extraction and focusing elements, and a dipole magnet mass spectrometer recovered from the LISOL facility in Louvain-la-Neuve. The latter has been modified for compatibility with MEDICIS, including the installation of a window for injecting laser light into the ion source for resonance photo-ionization. Ion beam optics and magnetic field modeling using SIMION and OPERA respectively were performed for the design and characterization of the beamline. The individual components and their optimal configuration in terms of ion beam extraction, mass separation, and ion transport efficiency is described, along with details of the commissioning and initial performance assessment with stable ion beams.

Thulium-167 is a promising radionuclide for nuclear medicine applications with potential use for both diagnosis and therapy (“theragnostics”) in disseminated tumor cells and small metastases, due to suitable gamma-line as well as conversion/Auger electron energies. However, adequate delivery methods are yet to be developed and accompanying radiobiological effects to be investigated, demanding the availability of 167 Tm in appropriate activities and quality. We report herein on the production of radionuclidically pure 167 Tm from proton-irradiated natural erbium oxide targets at a cyclotron and subsequent ion beam mass separation at the CERN-MEDICIS facility, with a particular focus on the process efficiency. Development of the mass separation process with studies on stable 169 Tm yielded 65 and 60% for pure and erbium-excess samples. An enhancement factor of thulium ion beam over that of erbium of up to several 10 4 was shown by utilizing laser resonance ionization and exploiting differences in their vapor pressures. Three 167 Tm samples produced at the IP2 irradiation station, receiving 22.8 MeV protons from Injector II at Paul Scherrer Institute (PSI), were mass separated with collected radionuclide efficiencies between 11 and 20%. Ion beam sputtering from the collection foils was identified as a limiting factor. In-situ gamma-measurements showed that up to 45% separation efficiency could be fully collected if these limits are overcome. Comparative analyses show possible neighboring mass suppression factors of more than 1,000, and overall 167 Tm/Er purity increase in the same range. Both the actual achieved collection and separation efficiencies present the highest values for the mass separation of external radionuclide sources at MEDICIS to date.

The β − -particle-emitting erbium-169 is a potential radionuclide toward therapy of metastasized cancer diseases. It can be produced in nuclear research reactors, irradiating isotopically-enriched 168 Er 2 O 3 . This path, however, is not suitable for receptor-targeted radionuclide therapy, where high specific molar activities are required. In this study, an electromagnetic isotope separation technique was applied after neutron irradiation to boost the specific activity by separating 169 Er from 168 Er targets. The separation efficiency increased up to 0.5% using resonant laser ionization. A subsequent chemical purification process was developed as well as activity standardization of the radionuclidically pure 169 Er. The quality of the 169 Er product permitted radiolabeling and pre-clinical studies. A preliminary in vitro experiment was accomplished, using a 169 Er-PSMA-617, to show the potential of 169 Er to reduce tumor cell viability.

A photoinjector, PHIN (PHotoINjector), has been realized at CERN by a joint effort of several institutes within the European Coordinated Accelerator Research in Europe program. The test facility has been installed and commissioned at CERN with the aim to demonstrate the beam parameters needed for the CLIC Test Facility 3 (CTF3). This beam is unique with respect to its long bunch train and high average charge per bunch requirements. The nominal beam for CTF3 consists of 1908 bunches each having a 2.33 nC charge and a bunch frequency of 1.5 GHz. Thus, a total charge of ∼4.4μC has to be extracted and accelerated. The stability of the intensity and the beam parameters along this exceptionally high average current train is crucial for the correct functioning of the CLIC drive beam scheme. Consequently, extensive time-resolved measurements of the transverse and longitudinal beam parameters have been developed, optimized, and performed. The shot-to-shot intensity stability has been studied in detail for the electron and the laser beams, simultaneously. The PHIN photoinjector has been commissioned between 2008 and 2010 during intermittent operations. This paper reports on the obtained results in order to demonstrate the feasibility and the stability of the required beam parameters.

The radionuclides [sup.43] Sc, [sup.44g/m] Sc, and [sup.47] Sc can be produced cost-effectively in sufficient yield for medical research and applications by irradiating [sup.nat] Ti and [sup.nat] V target materials with protons. Maximizing the production yield of the therapeutic [sup.47] Sc in the highest cross section energy range of 24–70 MeV results in the co-production of long-lived, high-γ-ray-energy [sup.46] Sc and [sup.48] Sc contaminants if one does not use enriched target materials. Mass separation can be used to obtain high molar activity and isotopically pure Sc radionuclides from natural target materials; however, suitable operational conditions to obtain relevant activity released from irradiated [sup.nat] Ti and [sup.nat] V have not yet been established at CERN-MEDICIS and ISOLDE. The objective of this work was to develop target units for the production, release, and purification of Sc radionuclides by mass separation as well as to investigate target materials for the mass separation that are compatible with high-yield Sc radionuclide production in the 9–70 MeV proton energy range. In this study, the in-target production yield obtained at MEDICIS with 1.4 GeV protons is compared with the production yield that can be reached with commercially available cyclotrons. The thick-target materials were irradiated at MEDICIS and comprised of metallic [sup.nat] Ti, [sup.nat] V metallic foils, and [sup.nat] TiC pellets. The produced radionuclides were subsequently released, ionized, and extracted from various target and ion source units and mass separated. Mono-atomic Sc laser and molecule ionization with forced-electron-beam-induced arc-discharge ion sources were investigated. Sc radionuclide production in thick [sup.nat] Ti and [sup.nat] V targets at MEDICIS is equivalent to low- to medium-energy cyclotron-irradiated targets at medically relevant yields, furthermore benefiting from the mass separation possibility. A two-step laser resonance ionization scheme was used to obtain mono-atomic Sc ion beams. Sc radionuclide release from irradiated target units most effectively could be promoted by volatile scandium fluoride formation. Thus, isotopically pure [sup.44g/m] Sc, [sup.46] Sc, and [sup.47] Sc were obtained as mono-atomic and molecular ScF[sub.2] [sup.+] ion beams and collected for the first time at CERN-MEDICIS. Among all the investigated target materials, [sup.nat] TiC is the most suitable target material for Sc mass separation as molecular halide beams, due to high possible operating temperatures and sustained release.

The radionuclides Sc, 44g/mSc, and Sc can be produced cost-effectively in sufficient yield for medical research and applications by irradiating natTi and natV target materials with protons. Maximizing the production yield of the therapeutic Sc in the highest cross section energy range of 24-70 MeV results in the co-production of long-lived, high-γ-ray-energy Sc and Sc contaminants if one does not use enriched target materials. Mass separation can be used to obtain high molar activity and isotopically pure Sc radionuclides from natural target materials; however, suitable operational conditions to obtain relevant activity released from irradiated natTi and natV have not yet been established at CERN-MEDICIS and ISOLDE. The objective of this work was to develop target units for the production, release, and purification of Sc radionuclides by mass separation as well as to investigate target materials for the mass separation that are compatible with high-yield Sc radionuclide production in the 9-70 MeV proton energy range. In this study, the in-target production yield obtained at MEDICIS with 1.4 GeV protons is compared with the production yield that can be reached with commercially available cyclotrons. The thick-target materials were irradiated at MEDICIS and comprised of metallic natTi, natV metallic foils, and natTiC pellets. The produced radionuclides were subsequently released, ionized, and extracted from various target and ion source units and mass separated. Mono-atomic Sc laser and molecule ionization with forced-electron-beam-induced arc-discharge ion sources were investigated. Sc radionuclide production in thick natTi and natV targets at MEDICIS is equivalent to low- to medium-energy cyclotron-irradiated targets at medically relevant yields, furthermore benefiting from the mass separation possibility. A two-step laser resonance ionization scheme was used to obtain mono-atomic Sc ion beams. Sc radionuclide release from irradiated target units most effectively could be promoted by volatile scandium fluoride formation. Thus, isotopically pure 44g/mSc, Sc, and Sc were obtained as mono-atomic and molecular ScF 2+ ion beams and collected for the first time at CERN-MEDICIS. Among all the investigated target materials, natTiC is the most suitable target material for Sc mass separation as molecular halide beams, due to high possible operating temperatures and sustained release.