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Recommended half-lives and specific well-defined emission energies and absolute emission probabilities are important input parameters that should be well-defined to assist in ensuring the diagnostic and therapeutic efficacy of individual radionuclides when applied in the field of nuclear medicine. Bearing in mind the nature of these requirements, approximately one hundred radionuclides have been considered and re-assessed as to whether their decay data are either adequately quantified, or require further in-depth measurements to improve their existing status and merit full re-evaluations of their decay schemes. The primary aim of such a review is to provide sufficient information on the existing and future requirements for such atomic and nuclear data.

An IAEA coordinated research project that began in 2012 and ended in 2016 was primarily dedicated to the compilation, evaluation and recommendation of cross-section data for the production of medical radionuclides. One significant part of this work focused on diagnostic positron emitters. These particular studies consist of 69 reactions for direct and indirect or generator production of 44Sc(44Ti), 52mMn(52Fe), 52gMn, 55Co, 61Cu, 62Cu(62Zn), 66Ga, 68Ga(68Ge), 72As(72Se), 73Se, 76Br, 82Rb(82Sr), 82mRb, 86Y, 89Zr, 90Nb, 94mTc, 110mIn(110Sn), 118Sb(118Te), 120I, 122I(122Xe), 128Cs(128Ba), and 140Pr(140Nd) medical radionuclides. The resulting reference cross-section data were obtained from Pade fits to selected and corrected experimental data, and integral thick target yields were subsequently deduced. Uncertainties in the fitted results were estimated via a Pade least-squares method with the addition of a 4% assessed systematic uncertainty. Experimental data were also compared with theoretical predictions available from the TENDL-2015 and TENDL-2017 libraries. All of the numerical reference cross-section data with their corresponding uncertainties and deduced integral thick target yields are available on-line at the IAEA-NDS medical portal www-nds.iaea.org/medicalportal and also at the IAEA-NDS web page www-nds.iaea.org/medical/positron_emitters.html .

International audience; Increasing interest in the treatment of human disease by means of targeted radionuclide-based therapies requires an accurate understanding of achievable yields and quantification of realisable degrees of purity. Important studies within a more extensive Coordinated Research Project of the International Atomic Energy Agency (IAEA CRP) have included in-depth assessments and evaluations of all available measured cross-section data for ten nuclear reactions leading to the formation of $^{131}$Cs, $^{131}$Ba, $^{225}$Ac, $^{225}$Ra, $^{227}$Th, $^{227}$Ac, $^{230}$U and $^{230}$Pa for various on-going and proposed therapeutic applications in nuclear medicine. Equivalent studies were also undertaken of possible reactions to produce the $^{178}$W/low-spin $^{178m}$Ta generator system that has been clinically applied in diagnosis by means of SPECT - these particular cross-section studies and recommendations are included in this paper for completeness. All available measured data have been critically reviewed and assessed to produce statistically consistent datasets. Selected datasets have been fitted by a least-squares method with Padé approximations of variable order to evaluate the production cross sections and corresponding uncertainties. New measurements have been made in some instances, and reported data have been adjusted to accommodate new nuclear decay or monitor reaction data which altered the original reported quantities adversely. Insufficient measured data are available in many cases to permit a reliable evaluation of cross sections, and these instances are discussed. Recommended therapeutic radionuclide production reaction data and their uncertainties are available on the Web page of the IAEA Nuclear Data Section at www-nds.iaea.org/radionuclides/ and also at the IAEA medical portal www-ds.iaea.org/medportal/

An IAEA coordinated research project was launched in December 2012 to establish and improve the nuclear data required to characterise charged-particle monitor reactions and extend data for medical radionuclide production. An international team was assembled to undertake work addressing the requirements for more accurate cross-section data over a wide range of targets and projectiles, undertaken in conjunction with a limited number of measurements and more extensive evaluations of the decay data of specific radionuclides. These studies are nearing completion, and are briefly described below.

Experimental nuclear spectroscopic data for known nuclides of mass number 62 (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge) have been evaluated and presented together with adopted properties of levels and {gamma} rays. New high-spin data are available for {sup 62}Ga, and {sup 62}Zn. Results of in-beam {gamma}-ray studies for {sup 62}Cu producing high-spin states are in conflict in terms of gamma-ray placements and branching ratios. In the opinion of the evaluators, a detailed study of high-spin structures in {sup 62}Cu is needed to obtain a consistent and confident level scheme. Precise studies of superallowed {beta} decay of {sup 62}Ga to {sup 62}Zn by several groups have extended the decay scheme. No significant new data, since the 2000 NDS for A = 62 (2000Hu18), have been reported for {sup 62}Co, {sup 62}Ni and {sup 62}Cu. No data are yet available for excited states in {sup 62}Ti and {sup 62}V, and those for {sup 62}Cr and {sup 62}Ge are scarce. The level lifetime data are available in very few cases. The radioactive decay schemes of {sup 62}Ti and {sup 62}Ge are unknown, and those for {sup 62}V, {sup 62}Cr and 92-ms {sup 62}Mn are scantily known. The datamore » presented here supersede those in the earlier NDS publications.« less

X- and γ ‐ray emission probabilities from the β − decay of 233Pa were measured with planar (LEPS) and coaxial Ge detectors. A 233Pa source was produced after radiochemical separation from a 237Np sample in which the parent (237Np) and daughter (233Pa) nuclides were in secular equilibrium. The results are compared with previous measurements and data evaluations.

Recommended nuclear decay data for specific actinides are important in fuel-cycle studies for thermal and fast reactors and inventory studies for safeguards. Therefore, a programme of work was initiated in 2005 to improve the actinide decay data library of the International Atomic Energy Agency through the efforts of a Coordinated Research Project (CRP). The proposed contents of the new database are described, including the agreement to include additional actinides and a significant number of natural decay chain radionuclides. This work is on-going, and is estimated for completion in 2009/10.

The Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA) offers cost-free nuclear data services to scientists worldwide. Most major experimental, evaluated, and bibliographic databases are made available through the Internet, as well as on CD-ROM and other media. These databases are used in a wide range of applications, including fission-, fusion-energy, and non-energy applications and basic research studies. The most important nuclear reaction and nuclear structure databases and selected special purpose libraries are overviewed. Multinational data networks and highly-focused Coordinated Research Projects (CRPs) are organised and sponsored under the auspices of the IAEA for the development and assembly of databases through the participation of recognized specialists from Member States. Further information concerning the various services can be found through the IAEA-NDS Web address http://www-nds.iaea.org, while mirror sites at IPEN, Brazil, and BARC, India, can be accessed through the addresses http://www-nds.ipen.br/ and http://www-nds.indcentre.org.in/, respectively.

Decay data constitute an important feature of nuclear physics that plays a significant role in the various work programmes of members and associates of the International Committee for Radionuclide Metrology (ICRM). At the invitation of the ICRM, a review has been undertaken with the joint aims of emphasising decay-data achievements over the previous 10 years, and highlighting inadequacies that remain to be addressed in the future.

Gamma-ray emission probabilities from the β − decay of 233 Pa were measured with planar (LEPS) and coaxial Ge detectors. A 233 Pa source was produced after radiochemical separation from a 237 Np sample in which the parent ( 237 Np) and daughter ( 233 Pa) nuclides were in secular equilibrium. Absolute γ ‐ ray emission probabilities per 100 α decays of the parent nuclide 237 Np were also measured in conjunction with the α - and γ ‐ ray spectroscopy techniques.

A Co-ordinated Research Project (CRP) entitled "Updated Decay Data Library for Actinides" was initiated in 2005 by the International Atomic Energy Agency (IAEA), with the primary aim of improving the quality of recommended decay data for actinides and their decay chains. Participants have attended two Research Coordination Meetings, and agreed on a list of important nuclides and evaluation methodologies to be adopted in work programmes dedicated to the preparation of a new database. Specific measurements were also proposed to address discrepancies between existing data, and some of these experimental studies are described in detail within this paper.

The Working Party on international nuclear data Evaluation Cooperation (WPEC) is a collaborative effort between the major OECD nuclear data projects: ENDF/B (USA), JENDL (Japan) and JEFF (Europe), and the IAEA- supported non-OECD projects CENDL (China) and BROND (Russian Federation). Nuclear data challenges and problems that are common to all projects are considered in various WPEC subgroups that are normally of limited time span. The achievements of these subgroups during the course of 2005/06 are reviewed in this paper. Among the recent accomplishments are improved criticality predictions through revised U evaluations, the completion of new cross-section standards, and the creation of a new fission product library. Problems that are currently being addressed are the processing and inclusion of covariance data in the libraries, improvements in decay data to assist in decay heat calculations, assembly of a well-structured High Priority Request List, validation of the new fission product cross-section library, and the assessment of nuclear data needs for GEN-IV.

The α -decay half-life of Cm 246 has been measured to be T 1 / 2 = 4706 (40) yr by means of the alpha-counting of ingrowth activity following the decay of a mass separated source of the Cf 250 parent nuclide. The α -decay emission probabilities of Cm 246 and Cf 250 have also been determined with high precision and have been compared with results from previous measurements. A new α -decay branch of Cm 246 to the 4 + level of the ground-state band of the Pu 242 daughter nucleus has been identified and characterized.

Representative decay data studies are described and reviewed, ranging from various measurement programmes to the maintenance of evaluated decay‐data libraries. Gross beta‐decay measurements are essential to address the decay‐data requirements for short‐lived fission products, well‐defined half‐lives are required in assessments of the storage of long‐lived radionuclides in waste depositories, and improved decay data continue to be demanded in safeguards, to improve detector‐calibration standards, and for medical and analytical applications. Such needs require the measurement of good quality decay data, along with multinational evaluations of decay schemes by means of agreed procedures.

The Nuclear Data Section (NDS) of the International Atomic Energy Agency (IAEA) provides a wide range of atomic and nuclear data services to scientists worldwide, with particular emphasis placed on the needs of developing countries. Highly focused Co-ordinated Research Projects and multinational data networks are sponsored under the auspices of the IAEA for the development and assembly of databases through the organised participation of specialists from Member States. More than 100 data libraries are readily available cost-free through the Internet, CD-ROM and other media. These databases are used in a wide range of applications, including fission- and fusion-energy, non-energy applications and basic research studies. Further information concerning the various services can be found through the web address of the IAEA Nuclear Data Section: and a mirror site at IPEN, Brazil that is maintained by NDS staff:.

A Co-ordinated Research Project (CRP) was established in 1998 by the IAEA Nuclear Data Section (Update of X-ray and γ -ray Decay Data Standards for Detector Calibration and Other Applications), in order to improve further the recommended decay data used to undertake efficiency calibrations of γ -ray detectors. Participants in this CRP reviewed and modified the list of radionuclides most suited for detector efficiency calibration, and also considered the decay-data needs for safeguards, waste management, dosimetry, nuclear medicine, material analysis and environmental monitoring. Overall, 62 radionuclides were selected for decay-data evaluation, along with four parent–daughter combinations and two natural decay chains. γ -ray emissions from specific nuclear reactions were also included to extend the calibrant energy well beyond 10 MeV. A significant number of these decay-data evaluations have been completed, and an IAEA-TECDOC report and database are in the process of being assembled for planned completion by the end of 2003.

Specific inadequacies have been identified within the decay-data files of the Joint Evaluated File (JEF-2.2) prepared by the NEA Data Bank for nuclear applications. Reevaluations have been made of the decay data for specific fission products judged to be of particular importance in reactor operation. Emphasis has been placed on a select number of short-lived radionuclides (half-life less than 3 hours) that are judged to be important in the nuclear power and reprocessing industries. The evaluation methodology is described, and the requirements for new measurements are outlined for individual nuclides.

The rate constants for the reactions between thermal Ps atoms and a series of iron (III) compounds including some complexes which can be considered as model compounds for biologically active systems have been determined.

A single-stage impactor has been used to calibrate a Polytec HC-15/1 optical aerosol analyser so that this instrument can be used to study water droplets from approximately 1 to 20 μm aerodynamic diameter. The resulting calibration data were in good agreement with calculations based on Mie light scattering theory, and gave a conversion factor of 2.0 ± 0.2 between polystyrene latex microspheres and water droplets of the same aerodynamic diameter. Monodisperse water droplets were sampled by a Polytec HC-70/2 analyser, calibrated using the conversion factor of 2.0. The measured count median diameter agreed closely with that predicted from the well-defined operating conditions of the vibrating orifice aerosol generator. Size measurements of a polydisperse water-droplet spray were also undertaken with both a Malvern laser diffractometer and a Polytec HC-15 analyser; good agreement was achieved between the two techniques.

Aerosols encountered in the nuclear industry require physical and chemical characterization to determine their transport properties and guarantee their cleanup and control. Such data are also necessary when assessing the consequences of hypothetical severe reactor accidents in which relatively high concentrations of aerosol could be generated containing fission product radionuclides. The concentrations of individual elements and chemical compounds within the airborne particles can be measured, and depth profiling has been used to study aerosol formation mechanisms. The various analytical techniques used to measure the chemical properties of nuclear-based aerosols are high-lighted. The merits and disadvantages of each method are discussed, and guidelines are provided for future developments.

Evidence is presented which supports the reversible formation of molecular complexes between Ps atoms and a series of nitrobenzene derivatives and p-benzoquinone in solution. The activation energy for the forward reaction step I (Ps + M (II) reversible PsM (I)) is generally very small; E/sub A/ approximately 1 kcal/mol. $delta$H/sub EQ/, the enthalpy of the overall process, ranges from almost zero, in the case of very unreactive substrates, such as toluene or heptane, to -8 kcal/mol for dinitrobenzene or p-benzoquinone. The reactivities of the various substrate molecules toward Ps follow trends as observed in conventional molecular complex formation. Furthermore an attempt was made to assess the role of the solvent upon the stability of the molecular complexes. (auth)

An experimental assessment has been made of the performance of an inertial spectrometer to measure the aerodynamic diameter of aerosol particles. These studies have included a determination of the optimum operating conditions for good size resolution, and the calibration of the instrument with monodisperse aerosol particles. Sampling conditions had to be chosen with care in order to ensure that the instrument operated correctly and separated particles on the basis of their aerodynamic size. When the instrument was upright, the calibration curves agreed closely with those of the manufacturer. However, when the spectrometer was inverted, the calibration curves were slightly displaced due to the change in direction of the gravitational force with respect to the other forces acting on the particles as they passed through the spectrometer.

151 Eu Mossbauer spectrometry has been used to study the after-effects of electron-capture decay of 151Gd and β-decay of 151Sm in inorganic and organic lanthanide compounds doped with these nuclides. No charge state other than 151EuIII was observed following nuclear decay in lanthanide oxides and fluorides doped with 151Gd or 151Sm. However, both the bivalent state. l51EuII, and the tervalent state. 151EuIII, were observed following the electron-capture decay of 151Gd-doped organic lanthanide compounds. The effects of varying temperature, the organic ligand, and the lanthanide matrix element were investigated. The presence of water of crystallisation was not essential for the production and stabilization of 151EuII in lanthanide oxalates. The presence of a conjugated organic ligand in 151Gd-doped compounds suppressed the formation of 151EuII.

151 Eu Mossbauer spectra of a number of europium(III) complexes, including aminopolycarboxylates, β-diketones, and 1,10-phenanthroline complexes, have been investigated. Isomer shifts of these complexes fall within a remarkably small range, indicating that their bonding is predominantly ionic in character, with the possibility of a small covalent contribution.

The relative transition energies and intensities of the components resulting from quadrupole splitting in 151Eu Mo¨ssbauer spectra are presented as functions of the asymmetry parameter. It is shown that the integrated area of the absorption peak is independent of the electric field gradient.