A review of electrodeposition methods for the preparation of alpha-radiation sources

Validation of electrodeposited 241Am alpha-particle sources for use in liquified gas detectors at cryogenic temperatures

This paper describes a procedure for the validation of alpha-particle sources (exempt unsealed sources) to be used in experimental setups with liquefied gases at cryogenic temperatures (down to -196 °C) and high vacuum. These setups are of interest for the development and characterization of neutrino and dark matter detectors based on liquid argon, among others. Due to the high purity requirements, the sources have to withstand high vacuum and cryogenic temperatures for extended periods. The validation procedure has been applied to 241Am sources produced by electrodeposition.

Detection of Polonium-210 in Environmental, Biological and Food Samples: A Review

Ingestion of polonium-210 from environmental media and food can cause serious health hazards (e.g., gastrointestinal symptoms, tumours, etc.) and has been a public health concern worldwide since the 2006 poisoning of Agent Litvinenko 210Po in Russia. With the development of uranium mining and applications of nuclear technology in recent decades, the radioactive hazards posed by 210Po to living organisms and the environment have become increasingly prominent. In order to strengthen the monitoring of environmental 210Po and protect both the environment and human health, a series of explorations on the methods of 210Po determination have been ongoing by researchers across the globe. However, previous reviews have focused on individual sample types and have not provided a comprehensive account of environmental, food, and biological samples that are closely related to human health. In this work, the sources, health hazards, chemical purification, and detection methods of trace 210Po in different sample types are systematically reviewed. In particular, the advantages and disadvantages of various pretreatment methods are compared, and relevant domestic and international standards are integrated, which puts forward a new direction for the subsequent establishment of rapid, simple, and efficient measurement methods.

Radionuclide metrology: confidence in radioactivity measurements

Radionuclides, whether naturally occurring or artificially produced, are readily detected through their particle and photon emissions following nuclear decay. Radioanalytical techniques use the radiation as a looking glass into the composition of materials, thus providing valuable information to various scientific disciplines. Absolute quantification of the measurand often relies on accurate knowledge of nuclear decay data and detector calibrations traceable to the SI units. Behind the scenes of the radioanalytical world, there is a small community of radionuclide metrologists who provide the vital tools to convert detection rates into activity values. They perform highly accurate primary standardisations of activity to establish the SI-derived unit becquerel for the most relevant radionuclides, and demonstrate international equivalence of their standards through key comparisons. The trustworthiness of their metrological work crucially depends on painstaking scrutiny of their methods and the elaboration of comprehensive uncertainty budgets. Through meticulous methodology, rigorous data analysis, performance of reference measurements, technological innovation, education and training, and organisation of proficiency tests, they help the user community to achieve confidence in measurements for policy support, science, and trade. The author dedicates the George Hevesy Medal Award 2020 to the current and previous generations of radionuclide metrologists who have devoted their professional lives to this noble endeavour.

Radiochemical Determination of Long-Lived Radionuclides in Proton-Irradiated Heavy Metal Targets: Part II Tungsten

In this study, proton-irradiated tungsten targets, up to 2.6 GeV, were investigated for the purpose of the experimental cross-section measurements. Radiochemical separation methods were applied to isolate the residual long-lived alpha-emitters ¹⁴⁸Gd, ¹⁵⁴Dy, and ¹⁴⁶Sm and the beta-emitters ¹²⁹I and ³⁶Cl from proton-irradiated tungsten targets. The molecular plating technique has been applied to prepare ¹⁴⁸Gd, ¹⁵⁴Dy, and ¹⁴⁶Sm samples for alpha-spectrometry. Production cross-sections of ¹²⁹I and ³⁶Cl were determined by means of accelerator mass spectrometry. The results are compared with theoretical predictions, obtained with the INCL++-ABLA07 codes, showing good agreement for ³⁶Cl and ¹⁴⁸Gd, while a factor of 4 difference was observed for ¹⁵⁴Dy, similar to the results obtained for tantalum targets.

A new Rule of Thumb to evaluate alpha sources prepared by electro precipitation using X-ray Fluorescence

This report studies the feasibility of using X-ray Fluorescence for the characterization of alpha sources in a short time and proposes a new Rule of Thumb for the sake of simplicity. An uranium deposit of 0.012 ± 0.001 mgcm^-2 which XRF spectrum shows a low intensity U-Lα peak at 13.61 keV, provides good resolution in alpha spectrometry. By this method, long data acquisition times in alpha spectrometry of poorly prepared sources are avoided without the need for expensive equipment.

NiCo2O4 Nano-/Microstructures as High-Performance Biosensors: A Review

Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity, selectivity, wide concentration range, low detection limits, and excellent recyclability. Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area, high permeability, short electron, and ion diffusion pathways. Because of the rapid development of non-enzyme biosensors, the current state of methods for synthesis of pure and composite/hybrid NiCo2O4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein. Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies. Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides, viz. NiO and Co3O4, is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+ (0.58 V/0.49 V) and Co3+/Co2+ (0.53 V/0.51 V). Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene, reduced graphene oxide, carbon nanotubes (single and multi-walled), carbon nanofibers; conducting polymers like polypyrrole (PPy), polyaniline (PANI); metal oxides NiO, Co3O4, SnO2, MnO2; and metals like Au, Pd, etc. Various factors affecting the morphologies and biosensing parameters of the nano-/micro-structured NiCo2O4 are also highlighted. Finally, some drawbacks and future perspectives related to this promising field are outlined.

Alpha-particle emission probabilities of 231Pa derived from first semiconductor spectrometric measurements

The nuclide ²³¹Pa is a member of the ²³⁵U decay chain. It is a complex alpha emitter with 25 identified alpha emissions. Formerly published alpha-particle emission probabilities were derived from measurements taken with magnetic spectrometers. This work presents the first measurements made with semiconductor detectors. High-resolution alpha-particle spectrometry was carried out at CIEMAT and JRC using ion-implanted planar silicon detectors. Alpha-particle emission probabilities of 23 transitions were derived from deconvolutions of the spectra. For the major lines, uncertainties are lower than 1%, a significant improvement to existing data. The new data set will allow a more accurate evaluation of the decay scheme of ²³¹Pa.

Electro-Precipitation of Actinides on Boron-Doped Diamond Thin Films for Solid Sources Preparation for High-Resolution Alpha-Particle Spectrometry

In this work, we investigate a novel approach to prepare high-performance alpha-particle solid sources fabricated on diamond thin support layers, offering the properties of diamond such as a low-Z material with corrosion and mechanical hardness. As-prepared solid sources onto boron-doped-diamond (BDD) substrate exhibited high performance of the autoradiography and spectroscopic resolution at the level of other more conventional materials such as stainless steel. A straightforward precipitation process in the Na2SO4 or NaNO3 simple electrolytes under mild experimental conditions with a low current of several mA.cm−2 were successfully developed onto BDD substrates for deposition of single 241Am as well as 239Pu, 241Am, and 244Cm mixed radionuclides. The results demonstrate that solid sources deposited onto such BDD substrates can match the performance of those prepared onto stainless steel substrates with excellent uniformity and high-resolution spectroscopy, together combining the robustness, chemical resilience, and X-ray transparence of the diamond. Alpha-particle spectra exhibiting a low full width at half maximum (FWHM) of 12.5 keV at the energy of 5.485 MeV (241Am) could be practically obtained for BDD substrates.

Determination of 226Ra at low levels in environmental, urine, and human bone samples and 223Ra in bone biopsy using alpha-spectrometry and metrological traceability to 229Th/225Ra or 226Ra

²²⁶Ra is a natural radioelement emitting α and γ radiations. It can be highly concentrated in TENORM materials from the petroleum or fertilizer industries. In Switzerland, ²²⁶Ra is currently a radioactive inheritance problem from the watch industry. Furthermore, ²²³Ra is a radium isotope used in nuclear medicine to treat bone metastasis. There exist several methods to measure radium using alpha or gamma spectrometry or using ²²²Rn emanation technique. The limitations of these methods are due to the required detection limits and the nature of the samples. When using alpha spectrometry to reach very low detection limits, critical technical hitches often arise because of the difficulties in separating radium from barium, in removing organics eluted from the separating chromatography column, and in plating radium. Moreover, overall chemical recovery of radium is often not reproducible, depending on the studies. Here we propose a method that separates radium from other alkaline-earth cations using cation exchange chromatography and selective complex formation by EDTA and DCTA. Radium is completely free of the ²²⁹Th tracer and its daughter products, particularly ²²⁵Ac. Organics from the column are removed in a further purification step so that radium can be plated with acceptable yields in a HCl/HNO₃/ethanol solution. We successfully applied the method to soil, water, urine and human bone samples and further extended it to the determination of ²²³Ra in a bone biopsy, using ²²⁶Ra as an internal tracer.

Bimetallic Au@M (M = Ag, Pd, Fe, and Cu) Nanoarchitectures Mediated by 1,4-Phenylene Diisocyanide Functionalization

Hybridization with gold has attracted a lot of attention in many application areas such as energy, nanomedicine, and catalysts. Here, we demonstrate electrochemical hybridization of two different metals by using bare and 1,4-phenylene diisocyanide (PDI) functionalized gold nanoislands (GNIs) supported on a Si substrate. As pristine GNIs are not tightly locked on the Si surface, bimetallic Au@M (M = Ag, Pd, Fe, and Cu) core-shell type nanostructures are produced by an electric-field-induced clustering of GNIs and metal deposition. On the other hand, upon functionalization of GNIs by PDI, 3D island growth on the functionalized GNI template is observed as PDI acts as a protector against the electric-field-induced clustering. Depth-profiling X-ray photoelectron spectroscopy reveals no discernible difference in the interfacial electronic structures of hybrid metals prepared by using pristine and PDI-functionalized GNI templates. This work demonstrates a new approach to produce a secured template and to manipulate growth of hybrid nanoparticles on this template supported on a Si substrate by using electrodeposition and organic functionalization.

Investigation of key factors in preparation of alpha sources by electrodeposition

The electrodeposition for alpha source preparation, using several electrolyte solution-cathode material combinations, is investigated and evaluated. The investigated factors focused on the electrodeposition time, the applied current, electrolyte volume and anode-cathode distances for the conventional electrodeposition cell (with no external stirring or cooling system). The conditions (temperature and the solution pH) during the electrodeposition process were also studied and discussed. The optimized parameters for each system are provided, and evaluated for the usage in determination of actinides (uranium, plutonium, americium and curium radioisotopes) in various samples.

Evaluation of several electrolyte mixture-cathode material combinations in electrodeposition of americium radioisotopes for alpha-spectrometric measurements

Three different types of electrolytes, subsequently modified and adjusted, in combination with three cathode materials used as source backings were analysed for electrodeposition of americium isotopes for alpha-spectrometric measurements. The obtained results are discussed in terms of electrodeposition yield and source quality (source homogeneity and spectral resolution, FWHM). The optimal conditions for source preparation are provided.

Analysis of the 148Gd and 154Dy Content in Proton-Irradiated Lead Targets

This work presents the determination of the ¹⁴⁸Gd and ¹⁵⁴Dy content in Pb targets irradiated by 220-2600 MeV protons. It includes the chemical separation of lanthanides, followed by the preparation of proper samples, by molecular plating technique, for α-spectrometry measurements. The experimental cross section results were compared with theoretical predictions, calculated with the INCL++-ABLA07 code. The comparisons showed a satisfactory agreement for ¹⁴⁸Gd (less than within a factor two), while measured ¹⁵⁴Dy cross sections are higher than the theoretical values.

Automated setup for spray assisted layer-by-layer deposition

The design for a setup allowing the layer-by-layer (LbL) assembly of thin films consisting of various colloidal materials is presented. The proposed system utilizes the spray-assisted LbL approach and is capable of autonomously producing films. It provides advantages to existing LbL procedures in terms of process speed and applicability. The setup offers several features that are advantageous for routine operation like an actuated sample holder, stainless steel spraying nozzles, or an optical liquid detection system. The applicability is demonstrated by the preparation of films containing semiconductor nanoparticles, namely, CdSe∕CdS quantum dots and a polyelectolyte. The films of this type are of potential interest for applications in optoelectronic devices such as light-emitting diodes or solar cells.