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Excited-state lifetimes were measured by direct fast-timing methods in three N = 125 isotones — 209Po, 211Rn, and 213Ra — near doubly magic 208Pb. These nuclei have a single neutron hole and successively add pairs of protons relative to 208Pb. The first-excited state to ground-state transition, 5 / 2 1 − → 1 / 2 1 − , has almost identical energy in each isotone and can be associated with the single neutron-hole transition ν f 5 / 2 − 1 → ν p 1 / 2 − 1 . The extent to which the protons act as spectators is assessed based on the measured transition rates, which show a systematic increase along the isotone chain, and by comparisons with large-basis shell-model calculations. The shell model accounts for some of the increased transition strength but consistently underestimates the experimental values. It also fails to explain the near-constant transition energies. These results suggest emerging collectivity beyond the shell-model valence space and show that the near-constant transition energies are not a consequence of a pure neutron-hole transition, but rather the outcome of complex nucleon-nucleon correlations that increase quadrupole collectivity.

Auger emitting radioisotopes are of great interest in targeted radiotherapy because, once internalised in the tumour cells, they can deliver dose locally to the radiation sensitive targets, while not affecting surrounding cells. Geant4 is a Monte Carlo code widely used to characterise the physics mechanism at the basis of targeted radiotherapy. In this work, we benchmarked the modelling of the emission of Auger electrons in Geant4 deriving from the decay of 123I, 124I, 125I radionuclides against existing theoretical approaches. We also compared Geant4 against reference data in the case of 131Cs, which is of interest for brachytherapy. In the case of 125I and 131Cs, the simulation results are compared to experimental measurements as well. Good agreement was found between Geant4 and the reference data. As far as we know, this is the first study aimed to benchmark against experimental measurements the emission of Auger electrons in Geant4 for radiotherapy applications.

The level structure of I124 (Z=53, N=71) has been studied via the Sn122(Li7,5n)I124 reaction with a beam energy of 54 MeV. Through in-beam and out-of-beam ?-ray spectroscopy, the sophisticated low-lying levels including isomeric states and numerous collective states have been established for the first time. A positive-parity collective band built on the 10+ state at 1297 keV is interpreted as being associated with the combination of a proton and a neutron in the same intruder h11/2 orbital, namely the ph11/2?h11/2 configuration. This band shows a typical quadrupole vibrational character. In contrast, the negative parity bands based on the pg7/2?h11/2 configuration show a soft triaxial rotation. An isomeric 8- state at 689 keV with a half-life of 14 ns can be explained as a K isomer due to a proton with an ?p=9/2 in the g9/2 orbital coupled to a neutron with an ?n=7/2 in the h11/2 orbital. The excited states based on this pg9/2?h11/2 configuration show a coupled rotational structure. Another coupled rotational band built on the 6+ state at 714 keV is thought to be based on the pg9/2?d3/2 configuration.

The E0 transition depopulating the first-excited 0 + state in 24Mg has been observed for the first time, and the E0 transition strength determined by electron-positron pair and γ-ray spectroscopy measurements performed using the Super-e pair spectrometer. The E0 transition strength is ρ 2 × 10 3 = 380 ( 70 ) . A two-state mixing model implies a deformation of the first-excited 0 + state of β 2 ≈ 1 and a change in the mean-square charge radius of Δ 〈 r 2 〉 ≈ 1.9 fm 2 , which suggests a significant shape change between the ground state and first-excited 0 + state in 24Mg. The observed E0 strength gives direct evidence of shape coexistence and superdeformation in 24Mg, bringing this nucleus into line with similar behaviour in nearby N = Z nuclei. This result agrees with recent theoretical work on the cluster nature of 24Mg and has potential ramifications for nuclear reactions of astrophysical importance.

Background: High-spin isomers at $\ensuremath{\approx}9$ MeV excitation energies have been reported in several $N=83$ isotones near $Z=64$. Spin and parity assignments of ${J}^{\ensuremath{\pi}}=49/{2}^{+}$ remain tentative for a number of these states in the odd-$A$ nuclei.Purpose: To study the decay of the ($49/{2}^{+}$) high-spin isomer in $^{145}\mathrm{Sm}$, make firm spin and parity assignments to the isomer and states populated in its decay, and investigate the structure of the nucleus.Methods: The $^{145}\mathrm{Sm}$ isomer was populated in the $^{124}\mathrm{Sn}(^{26}\mathrm{Mg},5n)$ reaction. $\ensuremath{\gamma}$-ray and conversion-electron data were collected using the Solenogam array.Results: A revised lifetime of ${t}_{1/2}=3.52(16)\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$ was measured for the high-spin isomer. Several new states have been added to the level scheme, and a new state at 8815 keV is proposed as the isomer, based on decay-property systematics, transition strengths, and spin and parity assignments. Firm spin and parity assignments have been made to states up to and including the isomer and the new level scheme is interpreted using shell-model calculations performed with the KShell program.Conclusions: The interpretation of the $49/{2}^{+}$ isomer as a deformed excitation of the core neutrons remains unchanged, although there has been a significant revision of the level scheme below the isomer, and hence significant reinterpretations of the lower-lying states.

New 125 I atomic decay emission data of medical interest are presented. The calculations are based on two atomic structure codes that implement the multi-configuration Dirac-Hartree-Fock method. Radiative and non-radiative ransition rates are calculated in this method and then used to generate the atomic deexcitation cascade. Subshell transition rates, level widths and fluorescence yields are compared to the Evaluated Atomic Data Library. Coster-Kronig and Auger electron emission yields are also compared with results from other authors. The comparison with the experimental electron emission spectrum shows that the new calculations can reproduce very well the structure of the K-LL Auger electron peaks and improve the description of the M Auger peaks below 300 eV. The 125 I dose-point kernel is also simulated using the new data, resulting in higher values below 10 nm when compared those obtained with the Evaluated Atomic Data Library.

Excited states in $^{174}\mathrm{Re}$ have been populated in fusion-evaporation reactions at the Australian National University, and $\ensuremath{\gamma}$-ray spectroscopy has been used to determine the level structure and to deduce the underlying nucleon configurations. The half-life of the bandhead of the ${K}^{\ensuremath{\pi}}={8}^{\ensuremath{-}}$ band has been measured to be 2.7(4) ns. A band built on an isomeric state of spin-parity (${14}^{\ensuremath{-}}$) and a half-life of 53(5) ns has been observed here for the first time, and has been determined to have a four-quasiparticle structure. Contrasting reduced-hindrance values for its decay are discussed in terms of deformation and configuration changes, as indicated by configuration-constrained potential energy surface calculations.

Stellar carbon synthesis occurs exclusively via the $3\alpha$ process, in which three $\alpha$ particles fuse to form $^{12}$C in the excited Hoyle state, followed by electromagnetic decay to the ground state. The Hoyle state is above the $\alpha$ threshold, and the rate of stellar carbon production depends on the radiative width of this state. The radiative width cannot be measured directly, and must instead be deduced by combining three separately measured quantities. One of these quantities is the $E0$ decay branching ratio of the Hoyle state, and the current $10$\% uncertainty on the radiative width stems mainly from the uncertainty on this ratio. The $E0$ branching ratio was deduced from a series of pair conversion measurements of the $E0$ and $E2$ transitions depopulating the $0^+_2$ Hoyle state and $2^+_1$ state in $^{12}$C, respectively. The excited states were populated by the $^{12}$C$(p,p^\prime)$ reaction at 10.5 MeV beam energy, and the pairs were detected with the electron-positron pair spectrometer, Super-e, at the Australian National University. The deduced branching ratio required knowledge of the proton population of the two states, as well as the alignment of the $2^+_1$ state in the reaction. For this purpose, proton scattering and $\gamma$-ray angular distribution experiments were also performed. An $E0$ branching ratio of $\Gamma^{E0}_{\pi}/\Gamma=8.2(5)\times10^{-6}$ was deduced in the current work, and an adopted value of $\Gamma^{E0}_{\pi}/\Gamma=7.6(4)\times10^{-6}$ is recommended based on a weighted average of previous literature values and the new result. The new recommended value for the $E0$ branching ratio is about 14% larger than the previous adopted value of $\Gamma^{E0}_{\pi}/\Gamma=6.7(6)\times10^{-6}$, while the uncertainty has been reduced from 9% to 5%., Comment: Accepted for publication as a Regular Article in Phys. Rev. C on July 29 2020

The cascading 3.21 and 4.44 MeV electric quadrupole transitions have been observed from the Hoyle state at 7.65 MeV excitation energy in $^{12}\mathrm{C}$, excited by the $^{12}\mathrm{C}(p,{p}^{\ensuremath{'}})$ reaction at 10.7 MeV proton energy. From the proton-$\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ triple coincidence data, a value of ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{rad}}/\mathrm{\ensuremath{\Gamma}}=6.2(6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ was obtained for the radiative branching ratio. Using our results, together with ${\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\pi}}^{E0}/\mathrm{\ensuremath{\Gamma}}$ from Eriksen et al. [Phys. Rev. C 102, 024320 (2020)] and the currently adopted ${\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\pi}}(E0)$ values, the radiative width of the Hoyle state is determined as ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{rad}}=5.1(6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }\mathrm{eV}$. This value is about 34% higher than the currently adopted value and will impact models of stellar evolution and nucleosynthesis.

Excited states in $^{58,60,62}$Ni were populated via inelastic proton scattering at the Australian National University as well as via inelastic neutron scattering at the University of Kentucky Accelerator Laboratory. The Super-e electron spectrometer and the CAESAR Compton-suppressed HPGe array were used in complementary experiments to measure conversion coefficients and $\delta(E2/M1)$ mixing ratios, respectively, for a number of $2^+ \rightarrow 2^+$ transitions. The data obtained were combined with lifetimes and branching ratios to determine $E0$, $M1$, and $E2$ transition strengths between $2^+$ states. The $E0$ transition strengths between $0^+$ states were measured using internal conversion electron spectroscopy and compare well to previous results from internal pair formation spectroscopy. The $E0$ transition strengths between the lowest-lying $2^+$ states were found to be consistently large for the isotopes studied.

We report for the first time two distinctive features in the odd–odd nucleus 120I: a pair of doublet bands and a high-spin isomer built on the π h 11 / 2 ν h 11 / 2 configuration. For producing the excited states of 120I, a fusion-evaporation reaction 118Sn(6Li, 4n) at E = l a b 48 MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with Z = 53 . The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the π h 11 / 2 ν h 11 / 2 configuration. In contrast, the high-spin isomer with a half-life of 49(2) ns at spin-parity J π = 25 + can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the 114Sn core: three protons ( g 7 / 2 ) 1 ( d 5 / 2 ) 1 ( h 11 / 2 ) 1 and three neutrons ( h 11 / 2 ) 3 . This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of 114Sn with Z = 50 and N = 64 .

The first-excited state g factor of 26 Mg has been measured relative to the g factor of the Mg 24 ( 2 1 + ) state using the high-velocity transient-field technique, giving g = + 0.86 ± 0.10 . This new measurement is in strong disagreement with the currently adopted value, but in agreement with the sd -shell model using the USDB interaction. The newly measured g factor, along with E ( 2 1 + ) and B ( E 2 ) systematics, signal the closure of the ν d 5 / 2 subshell at N = 14 . The possibility that precise g -factor measurements may indicate the onset of neutron pf admixtures in first-excited state even–even magnesium isotopes below 32 Mg is discussed and the importance of precise excited-state g -factor measurements on sd shell nuclei with N ≠ Z to test shell-model wavefunctions is noted.

The E0 transition strength in the 2 2 + → 2 1 + transitions of 58,60,62Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the δ ( E 2 / M 1 ) mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, δ ( E 2 / M 1 ) mixing ratios and γ-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the E0 strengths. These are the first 2 + → 2 + E0 transition strengths measured in nuclei with spherical ground states and the E0 component is found to be unexpectedly large; in fact, these are amongst the largest E0 transition strengths in medium and heavy nuclei reported to date.

The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely 67Ga, 80mBr, 89Zr, 90Nb, 99mTc, 111In, 117mSn, 119Sb, 123I, 124I, 125I, 135La, 195mPt and 201Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKS using appropriate geometric reduction factors. The number of Auger and Coster-Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKS in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions., 27 pages, 4 figures, 3 tables

This research was made possible by an Australian Research Council Discovery Grant DP140103317. J.T.H.D. acknowledges support of the Australian Government Research Training Program.

The emergence of nuclear collectivity near doubly-magic $^{132}$Sn was explored along the stable, even-even $^{124-130}$Te isotopes. Preliminary measurements of the $B(E2;4^{+}_{1}\rightarrow2^{+}_{1})$ transition strengths are reported from Coulomb excitation experiments primarily aimed at measuring the $g$ factors of the $4^{+}_{1}$ states. Isotopically enriched Te targets were excited by 198-205 MeV $^{58}$Ni beams. A comparison of transition strengths obtained is made to large-scale shell-model calculations with successes and limitations discussed., Comment: 5 pages, 3 figures, Submitted to Proceedings HIAS 2019, EPJ Web of Conferences

Background: The even cadmium isotopes near the neutron midshell have long been considered among the best examples of vibrational nuclei. However, the vibrational nature of these nuclei has been questioned based on $E2$ transition rates that are not consistent with vibrational excitations. In the neighboring odd-mass nuclei, the $g$ factors of the low-excitation collective states have been shown to be more consistent with a deformed rotational core than a vibrational core. Moving beyond the comparison of vibrational versus rotational models, recent advances in computational power have made shell-model calculations feasible for Cd isotopes. These calculations may give insights into the emergence and nature of collectivity in the Cd isotopes.Purpose: To investigate the nature of collective excitations in the $A\ensuremath{\approx}100$ region through experimental and theoretical studies of magnetic moments and electromagnetic transitions in $^{111}\mathrm{Cd}$.Method: The spectroscopy of $^{111}\mathrm{Cd}$ has been studied following Coulomb excitation. Angular correlation measurements, transient-field $g$-factor measurements and lifetime measurements by the Doppler-broadened line shape method were performed. The structure of the nucleus was explored in relation to particle-vibration versus particle-rotor interpretations. Large-scale shell-model calculations were performed with the SR88MHJM Hamiltonian.Results: Excited-state $g$ factors have been measured, spin assignments examined, and lifetimes determined. Attention was given to the reported $5/{2}^{+}$ 753-keV and $3/{2}^{+}$ 755-keV states. The $3/{2}^{+}$ 755-keV level was not observed; evidence is presented that the reported $3/{2}^{+}$ state was a misidentification of the $5/{2}^{+}$ 753-keV state.Conclusions: It is shown that the $g$ factors and level structure of $^{111}\mathrm{Cd}$ are not readily explained by the particle-vibration model. A particle-rotor approach has both successes and limitations. The shell-model approach successfully reproduces much of the known low-excitation structure in $^{111}\mathrm{Cd}$.

The level structure of the odd-odd iodine nucleus I122 has been studied by the Sn120 (Li7, 5n)I122 reaction at Elab=58 MeV. Two chopped beams from the 14UD (Unit Doubled) tandem heavy-ion accelerator at the Australian National University were used; one was a nanosecond (ns) pulsed-beam with separation of 1.7 microseconds (μs) and the second one was a 60-μs beam separated by 880μs. Through in-beam and out-of-beam γ-ray spectroscopy, the complex proton-neutron multiplet states, including isomers with half-lives of a few tens of ns to a few tens of μs, have been identified. Collective states based on the proton h11/2 orbital exhibit two kinds of structure depending upon the coupled neutron orbital: a quadrupole vibration when involving the h11/2 orbital and a γ-soft deformed rotation when involving the g7/2 orbital. With spherical shell model and deformed shell-model calculations, the observed level structures are explained.

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 .

Auger electrons emitted after nuclear decay have potential application in targeted cancer therapy. For this purpose it is important to know the Auger electron yield per nuclear decay. In this work we measure the ratio of the number of conversion electrons (emitted as part of the nuclear decay process) and the number of Auger electrons (emitted as part of the atomic relaxation process after the nuclear decay) for the case of $^{125}$I. Results are compared with Monte-Carlo type simulations of the relaxation cascade using the BrIccEmis code. With the appropriate choice of parameters this program describes the observed spectra quite well over the whole energy range., 11 pages, 11 figures

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/

Transient-field $g$-factor measurements in inverse kinematics were performed for the first-excited states of the stable, even isotopes of Ge and Se. The $g$ factors of $^{74}$Ge and $^{74}$Se were measured simultaneously using a cocktail beam, which eliminates most possible sources of systematic error in a relative $g$-factor measurement. The results are $g(^{74}{\rm Se})/g(^{74}{\rm Ge})=1.34(7)$, $g(^{70}{\rm Ge})/g(^{74}{\rm Ge}) = 1.16(15)$, $g(^{72}{\rm Ge})/g(^{74}{\rm Ge})=0.92(13)$, $g(^{76}{\rm Ge})/g(^{74}{\rm Ge})=0.88(5)$, $g(^{76}{\rm Se})/g(^{74}{\rm Se})=0.96(7)$, $g(^{78}{\rm Se})/g(^{74}{\rm Se})=0.82(5)$, $g(^{80}{\rm Se})/g(^{74}{\rm Se})=0.99(7)$ and $g(^{82}{\rm Se})/g(^{74}{\rm Se})=1.19(6)$. The measured $g$-factor ratios are in agreement with ratios from previous measurements, despite considerable variation in previous reported absolute values. The absolute values of the $g$ factors remain uncertain, however the Rutgers parametrization was used to set the transient-field strength and then compare the experimental $g$ factors with shell-model calculations based on the JUN45 and jj44b interactions. Modest agreement was found between experiment and theory for both interactions. The shell model calculations indicate that the $g(2^+_1)$ values and trends are determined largely by the balance of the spin carried by orbital motion of the protons., 13 pages; 12 figures. Published as Phys. Rev. C 100, 044317 (2019). URL: https://link.aps.org/doi/10.1103/PhysRevC.100.044317

The study of electric monopole (E0) transitions between two 0 + states is important because the monopole strength carries vital information about the nuclear structure due to its direct link with the mean squared charge radius r 2 and quadrupole deformation parameter β . Therefore, the measurement of internal conversion electrons (ICE) or internal pair formation (IPF) is crucial for E0 transition studies. Transitions between 0 + states do not change angular momentum. Hence, single-photon emission is forbidden, but can decay by conversion electrons or pair formation and two-photon emission which is mostly negligible. In order to implement E0 studies at iThemba LABS, an electron spectrometer that uses a solenoidal magnetic field acting as a lens and a Si(Li) detector has been refurbished and characterized using calibration sources of ICE. Figures of merit have been extracted and compared with simulations. The spectrometer coupled with an array of LaBr3:Ce detectors and Low Energy Photon Spectrometers (LEPS) was successfully implemented for in-beam experiments. Measurements of internal conversion coefficients (ICC) and monopole strengths extracted from in-beam measurements of 72As, 72Ge, and 72Se are presented.

A new detector array, Solenogam, has been developed at the Australian National University Heavy Ion Accelerator Facility. Coupled initially to the SOLITAIRE 6.5 T, gas-filled, solenoidal separator, and later to an 8 T solenoid, the system enables the study of long-lived nuclear states through γ -ray and conversion-electron spectroscopy in a low-background environment. The detector system is described and results from the commissioning experiments are presented.

Electric monopole (E0) transitions are a highly sensitive probe of the charge distribution of an atomic nucleus. A large E0 transition strength (ρ2(E0)) is a clear indicator of nuclear shape coexistence. In the region between doubly magic 40Ca and 56Ni, E0 transitions have never been observed in the Ti or Cr isotopes, nor in the heavier iron isotopes (56,58Fe). We have performed the first measurements of the E0 transitions in 52Cr via conversion-electron and pair-conversion spectroscopy using the Super-e spectrometer at the Australian National University Heavy Ion Accelerator Facility. We present the first spectra obtained for 52Cr, including the first observation of the E0 transition from the first-excited 0+ state in 52Cr, in both electron-positron pairs and conversion-electron spectroscopy. The preliminary values for the E0 strength in the 1531keV 2+ → 2+ transition in 52Cr is ρ2(E0) × 103 = 470(190), and for the 1728-keV 23+ → 21+ transition, it is ρ2(E0) 103 = 1800(1200). The large E0 strengths observed are consistent with shape coexistence in this region. However, despite the relatively precise observation of the conversion-electron and electron-positron pair intensities, the E0 strengths have large uncertainties. More precise determinations of relevant spectroscopic quantities, such as the state lifetimes and transition mixing ratios for mixed M1 + E2 transitions, are needed to determine the E0 strength more precisely.

A new tabulation of electronic factors is reported for electron conversion for elements of Z from 5 to 126 and electronic factors for electron-positron pair conversion for elements of even Z from 4 to 100. The electronic factors for electron conversion, ${\Omega}_{CE}$(E0), were calculated using a modified version of the CATAR program developed by Pauli and Raff with a relativistic-Hartree-Fock-Slater approach (Pauli and Raff, 1975). The electronic factors for electron-positron pair conversion, ${\Omega}_{IPF}$(E0), were calculated using the model developed by Wilkinson (1969). The data tables presented here cover all atomic shells up to R2 and transition energies from 1 keV to 6000 keV and from 1100 keV to 8000 keV for pair conversion. A comparison with previous electronic factor tabulations is presented. Ratios of experimental {\Omega}(E0) values for 83 E0 transitions in 8$\leq$Z$\leq$98 are compared to this tabulation. Two examples of how to use the tabulation to extract E0 strengths are also included.

The Evaluated Nuclear Structure Data File (ENSDF) includes the most extensive and comprehensive set of nuclear structure and decay data evaluations performed by the international network of Nuclear Structure and Decay Data evaluators (NSDD) under the auspices of the IAEA. In this report we describe some of the recent NSDD activities and provide future perspectives., 評価済み核構造データファイル(Evaluated Nuclear Structure Data File: ENSDF)は、原子核構造と崩壊に関する様々な実験データを全ての核種について集めて、それらの実験データの評価値を与えてある世界唯一のデータファイルである。ENSDFは定期的に更新されており、そのための評価作業は各国の評価者で分担している。評価作業を速やかに行うために、IAEAの援助の下に評価者の国際的なネットワークが組織されている。この発表では、ネットワークの最近の活動のうち、ENSDFの処理コードの開発、測定が必要とされているデータのリストの作成、インターネット版核図表の利用の拡充などについて報告する。また、核構造・崩壊データの需要が増大しているにもかかわらず、評価者が減っている問題についても述べる。

The level structures of $^{212}\mathrm{Ra}$ and $^{213}\mathrm{Ra}$ have been established via time-correlated $\ensuremath{\gamma}$-ray spectroscopy following the $^{204}\mathrm{Pb}$($^{12}\mathrm{C},4n$)$^{212}\mathrm{Ra}$ and $^{204}\mathrm{Pb}$($^{13}\mathrm{C},4n$)$^{213}\mathrm{Ra}$ reactions. In $^{212}\mathrm{Ra}$, levels up to $\ensuremath{\sim}6.2\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ were identified and firm spin-parity assignments were achieved to a ${J}^{\ensuremath{\pi}}={19}^{+}$ isomer with a mean life of 31(3) ns. For $^{213}\mathrm{Ra}$ the corresponding values were $\ensuremath{\sim}4.5\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ in excitation energy and ${J}^{\ensuremath{\pi}}=33/{2}^{+}$. Two isomeric states with ${J}^{\ensuremath{\pi}}=23/{2}^{+}, \ensuremath{\tau}=27(3)$ ns and ${J}^{\ensuremath{\pi}}=33/{2}^{+}, \ensuremath{\tau}=50(3)$ ns were discovered in $^{213}\mathrm{Ra}$. The experimental data were compared with semiempirical shell-model calculations, which allowed dominant configurations to be assigned to most of the observed levels.

The KLL Auger spectrum of rubidium following the electron capture decay of $^{83}$Sr and $^{85}$Sr isotopes was experimentally studied in detail for the first time using one $^{83}$Sr source and three $^{85}$Sr sources in different host matrices. Energies, relative intensities, and natural widths of all the nine well-resolved basic spectrum components were determined and compared with both predictions and experimental data for krypton. Results of our multiconfiguration Dirac-Fock calculations demonstrated an influence of the "atomic structure effect" on absolute energies of the KLL transitions following the creation of initial vacancies by the electron capture decay. Environmental effects on the KLL Auger spectrum were distinctly observed only for the absolute transition energies., Comment: arXiv admin note: substantial text overlap with arXiv:1810.00102

International audience; Evaluated cross sections of beam-monitor reactions are expected to become the de-facto standard for cross-section measurements that are performed over a very broad energy range in accelerators in order to produce particular radionuclides for industrial and medical applications. The requirements for such data need to be addressed in a timely manner, and therefore an IAEA coordinated research project was launched in December 2012 to establish or improve the nuclear data required to characterise charged-particle monitor reactions. An international team was assembled to recommend 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. Least-square evaluations of monitor-reaction cross sections including uncertainty quantification have been undertaken for charged-particle beams of protons, deuterons, 3 He- and 4 He-particles. Recommended beam monitor reaction data with their uncertainties are available at the IAEA-NDS medical portal www-nds.iaea.org/medical/monitor_reactions.html .

This research was supported in part by the Australian Research Council Grants No. DP120101417, No. DP130104176, No. DP140102986, No. DP140103317, No. DP170101673, No. LE150100064, and No. FT100100991, and by The Australian National University Major Equipment Committee Grant No. 15MEC14.

Spectroscopic information on the decay properties of high- K isomers in deformed and transitional nuclei has been evaluated and collated. Assigned multi-quasiparticle configurations are included. Factors that control the transitions strengths, such as various contributions to K mixing, are outlined. The systematics of K -forbidden transitions for different multipolarities are discussed for selected cases in terms of the hindrances, F W , and of the reduced hindrance factor per degree of K forbiddenness, f ν , where ν = | Δ K − λ | , Δ K is the K -value difference between the initial and final state and λ is the transition multipole order. With the improved statistics for E 1 , M 1 and E 2 transitions, a factorization into the product of the underlying multipolarity-dependent transition strength and a ν -dependence, due to K forbiddenness ( f 0 ), is possible. This suggests a weaker dependence on K forbiddenness than is commonly assumed.

The low-energy electron spectra emitted in the radioactive decay of the $^{83}$Rb and $^{83}$Sr isotopes were measured with a combined electrostatic electron spectrometer. Radioactive sources used were prepared by ion implantation of $^{83}$Sr into a high purity polycrystalline platinum foil at 30 keV and by vacuum-evaporation deposition of $^{83}$ Rb on the same type of foil. From the measured conversion electron spectra, the electron binding energies (referenced to the Fermi level) for the K, L$_1$ , L$_2$ , L$_3$ , M$_1$ , M$_2$, and M$_3$ shell/subshells of krypton in the platinum host were determined to be 14 316.4(12), 1 914.3(9), 1 720.3(9), 1 667.6(9), 281.5(9), 209.6(13), and 201.2(15) eV, respectively, and those for the evaporated layer were observed to be lower by 0.7(1) eV. For both host matrices, values of 2.3(2), 4.6(2), 1.7(2), 1.3(2), and 3.2(3) eV were obtained for the krypton K, L$_1$ , L$_2$ , L$_3$ , and M$_1$ natural atomic level widths, respectively. The absolute energies of 10 838.5(9) and 10 839.5(10) eV were measured for the KL$_2$L$_3$ ($^{1}$D$_2$) Auger transition in krypton implanted in Pt and generated in the evaporated rubidium layer, respectively. A value of 601.0(8) eV was measured for the energy difference of the KL$_2$L$_3$ ($^{1}$D$_2$) transitions in Rb and Kr in the Pt host. Multiconfiguration Dirac-Fock calculations of the krypton KLL transition energies and intensities were also performed.

Excited states in Re186 with spins up to J=12 were investigated in two separate experiments using W186(d,2n) reactions at beam energies of 12.5 and 14.5 MeV. Two- and threefold γ-ray coincidence data were collected using the CAESAR and CAGRA spectrometers, respectively, each composed of Compton-suppressed high-purity germanium detectors. Analysis of the data revealed rotational bands built on several two-quasiparticle intrinsic states, including a long-lived Kπ=(8+) isomer. Configuration assignments were supported by an analysis of in-band properties, such as gK-gR values. The excitation energies of the observed intrinsic states were compared with results from multi-quasiparticle blocking calculations, based on the Lipkin-Nogami pairing approach, that included contributions from the residual proton-neutron interactions.

Using the 168Er(10B,5n) reaction at a beam energy of 68 MeV, new data have been obtained for the population and decay of a T1/2 = 148 ns, Kπ = 21/2− three-quasiparticle isomer at 1717 keV in 173Ta. Revised decay energies and intensities have been determined, together with newly observed members of a rotational band associated with the isomer. By comparison with other isomers in the A ≈ 180 deformed region, the 173Ta isomer properties help to specify the key degrees of freedom that determine K-forbidden transition rates. In particular, when all three quasiparticles are of the same nucleon type, there is a strong dependence of the E2 reduced hindrance factor on the isomer excitation energy.

Doubly magic nuclei and their near neighbours serve as an ideal testing ground for the nuclear shell model, and, consequently, enable us to define effective nuclear interactions. Collective states in nuclei near $^{56}$Ni can be attributed to multiparticle-multihole excitations from the $1f_{7/2}$ to the $2p_{3/2}$, $1f_{5/2}$ and $2p_{1/2}$ orbits across the $N$, $Z$ = 28 shell gap. These features are usually associated with shape coexistence. Properties of excited $0^{+}$ states, as well as $E0$ and $E2$ transition strengths are sensitive probes of the underlying nuclear structure. The aim of this work is to identify and characterize excited $0^{+}$ states and corresponding $E0$ transitions in $^{54,56,58}$Fe to search for shape coexistence around the $N$, $Z$ = 28 shell closure. In order to obtain experimental information, $E0$ transitions between the lowest excited $0^{+}$ states and ground states were measured for the stable even-even iron isotopes using the superconducting electron spectrometer ,"Super-e", at the Australian National University. Additional information on angular distributions, angular correlations, and $\gamma - \gamma$ coincidences was obtained with the CAESAR detector array (at ANU) under the same experimental conditions. In order to deduce $E0$ strengths, the experimental data were evaluated with lifetime information from Doppler-shift attenuation measurements following inelastic neutron scattering, carried out at the University of Kentucky.

We present a microscopic model for electric monopole ($E0$) transition matrix elements by combining a configuration interaction model for orbital occupations with an energy-density functional model for the single-particle potential and radial wave functions. The configuration interaction model is used to constrain the orbital occupations for the diagonal and off-diagonal matrix elements. These are used in an energy-density functional calculation to obtain a self-consistent transition density. This density contains the valence contribution, as well as the polarization of the protons by the valence protons and neutrons. We show connections between $E0$ matrix elements and isomer and isotope shifts of the charge radius. The spin-orbit correction to the charge density is important in some cases. This model accounts for a large part of the data over a wide region of the nuclear chart. It also accounts for the shape of the observed electron scattering form factors. The results depend on the Skyrme parameters used for the energy-density functional and might be used to provide new constraints for them.

Electron capture on $^{20}$Ne is thought to play a crucial role in the final evolution of electron-degenerate ONe stellar cores. Recent calculations suggest that the capture process is dominated by the second-forbidden transition between the ground states of $^{20}$Ne and $^{20}$F, making an experimental determination of this transition strength highly desirable. To accomplish this task we are refurbishing an intermediate-image magnetic spectrometer capable of focusing 7 MeV electrons, and designing a scintillator detector surrounded by an active cosmic-ray veto shield, which will serve as an energy-dispersive device at the focal plane., 4 pages, 1 figure, NIC-XIV

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.

To benchmark a Monte Carlo model of the Auger cascade that has been developed at the Australian National University (ANU) against the literature data. The model is applicable to any Auger-electron emitting radionuclide with nuclear structure data in the format of the Evaluated Nuclear Structure Data File (ENSDF). Sch\"onfeld's algorithms and the BrIcc code were incorporated to obtain initial vacancy distributions due to electron capture (EC) and internal conversion (IC), respectively. Atomic transition probabilities were adopted from the Evaluated Atomic Data Library (EADL) for elements with atomic number, Z = 1-100. Atomic transition energies were evaluated using a relativistic Dirac-Fock method. An energy-restriction protocol was implemented to eliminate energetically forbidden transitions from the simulations. Calculated initial vacancy distributions and average energy spectra of 123I, 124I and 125I were compared with the literature data. In addition, simulated kinetic energy spectra and frequency distributions of the number of emitted electrons and photons of the three iodine radionuclides are presented. Some examples of radiation spectra of individual decays are also given. Good agreement with the published data was achieved except for the outer-shell Auger and Coster-Kronig transitions. Nevertheless, the model needs to be compared with experimental data in a future study., Comment: 44 pages, 4 figures and 9 tables

The emergence and evolution of collective excitations in complex nuclei remains a central problem in the quest to understand the nuclear many-body problem. Nuclear quadrupole collectivity is usually investigated via electric quadrupole observables. Here, however, we measure the $g$ factors of low-excitation states in $^{111}\mathrm{Cd}$ and $^{113}\mathrm{Cd}$ and show that they are sensitive to the nature of the collectivity in these nuclei in ways that the electric quadrupole observables are not. The particle-vibration model, which assumes spherical core excitations, cannot explain the $g$ factors, whereas a particle-rotor model with a small, nonzero core deformation does. The contrast of the two models is made stark by the fact that they begin from the same limiting $g$-factor values: It is shown that when an odd nucleon occupies a spherical orbit with angular momentum $j=1/2$, or a deformed orbit with $j=1/2$ parentage, the particle-vibration model and the particle-rotor model both reduce to the same $g$-factor value in their respective limits of zero particle-vibration coupling or zero deformation.

Purpose DNA ligands labelled with

Purpose DNA ligands labelled with 125I induce cytotoxic DNA double-strand breaks (DSB), suggesting a potential for Auger endoradiotherapy. Since the 60-day half-life of 125I is suboptimal for therapy, we have investigated another Auger-emitter 124I, with shorter half-life (4.18 days), and the additional feature of positron-emission, enabling positron emission tomography (PET) imaging. The purpose of this study was to compare the two radionuclides on the basis of DNA DSB per decay. Materials and methods Using a 124I- (or 125I)-labelled minor groove binding DNA ligand, we investigated DNA breakage using the plasmid DNA assay. Biodistribution of the conjugate of the labelled ligand with transferrin was investigated in nude mice bearing a K562 human lymphoma xenograft. Results The probability of DSB per decay was 0.58 and 0.85 for 124I and 125I, respectively, confirming the therapeutic potential of the former. The crystal structure of the ligand DNA complex shows the iodine atom deep within the minor groove, consistent with the high efficiency of induced damage. Biodistribution studies, including PET imaging, showed distinctive results for the conjugate, compared to the free ligand and transferrin, consistent with receptor-mediated delivery of the ligand. Conclusions Conjugation of 124I-labelled DNA ligands to tumor targeting peptides provides a feasible strategy for Auger endoradiotherapy, with the advantage of monitoring tumor targeting by PET imaging.

Excited states in 62 Ni were populated with a (p, p') reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ 2 (E0), were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of popu- lated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 0 + to 0 + transition has been measured to be 77 +23 −34 × 10 −3 and agrees with previously reported values. Upper limits have been placed on the 0 + to 0 + and 0 + to 0 + transitions. The measured ρ 2 (E0) value of the 2 + to 2 + transition in 62 Ni has been measured for the first time and found to be one of the largest ρ 2 (E0) values measured to date in nuclei heavier than Ca. The low-lying states of 62 Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not sufficient to explain the large ρ 2 (E0) value for the 2 + to 2 + transition.

Solenogam is a recoil spectrometer designed and constructed for use at the Australian National University (ANU) Heavy-Ion Accelerator Facility (HIAF). The design enables the study of nuclear excitations populated by the decay of long-lived states such as isomers and radioactive ground states. Solenogam is comprised of high-sensitivity γ -ray and electron detector arrays coupled to a new 8-T solenoid. While the installation of the 8-T solenoid proceeds, off-line measurements have been made to characterise Solenogam’s performance. Gamma-electron coincidences in the electron capture decay of 182 Re into 182 W were used to investigate conversion coeffcients and γ -e – angular correlations. The measured conversion coeffcients show good agreement with theoretical calculations and have been used to extract E 0/ E 2 mixing ratios for a number of J → J transitions. The angular correlations measured by the array are in qualitative agreement with theoretical calculations. However, the magnitudes of the correlations are attenuated by approximately 40% for reasons unknown at present. These results are the first full use of the Solenogam system for γ -e – coincidence measurements and have proven that the system is capable of highly-sensitive internal conversion analysis of complex decays.