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Abstract Routine measurements of the last years at the 6 MV AMS system showed a good isobar suppression for all light isotopes, measured with the Degrader-Foil-Method, especially 36Cl and 10Be. However, the efficiency is reduced due to the charge state distribution generated by the degrader-foil. For measurements injecting atomic 26Al, the ionization efficiency becomes the bottleneck, which leads to a relatively low ion source output. In the case of AlO−, the output is expected about one order of magnitude higher. However, to use AlO− the isobar interference of 26Mg will become an issue. It has to be suppressed in several steps, e.g. by different dE/dx methods like TOF, degrader-foil or gas-filled magnet. In order to minimize the efficiency losses generated by the degrader-foil method, the 120°-magnet at the 6 MV AMS system was modified to enable a gas-filled operation, and therefore focus the beam to a mean charge state. A constraint for all modification of the detection beam line was that the operation of the degrader-foil method is not affected. In this paper, we report on the performed construction work, as well as test measurements for 27Al at 40 MeV ion energy. Isobar separation for 36Cl and 36S was measured as a function of the gas pressure. We compare measured data with Monte Carlo simulations performed with a computer code developed by our group. In addition, we will present a new dedicated gas ionization chamber designed for particle detection directly after the gas-filled magnet. [ABSTRACT FROM AUTHOR]

We present an analysis of the spectator mechanism of Δ-isobar production in the pion photoproduction on nuclei with the emission of two nucleons. The reaction mechanism is studied within the framework of the ΔN-correlation model, which considers the isobar and nucleon of the ΔN-system produced in the nucleus at the virtual NN→ΔN transition to be in a dynamic relationship. The two-particle transition operator for nuclei is obtained by the S-matrix approach. We consider the properties of the spectator mechanism of isobar production using the example of the reaction 16O(γ,π−pn)14O. Numerical estimates of the cross-section are obtained in the kinematic region, where it is possible to expect the manifestation of bound isobar-nuclear states. [ABSTRACT FROM AUTHOR]

Secondary ion mass spectrometry (SIMS) provides spatially resolved trace analysis of solid materials, but can be complicated by unresolved abundant molecular isobars. By adding a 300-kV single-stage accelerator mass spectrometer (SSAMS) as a detector for a Cameca ims 4f SIMS, one can measure more abundant positive ions from the SIMS while removing molecular isobars, thus improving very low abundance trace element and isotope analysis. This paper describes important features and capabilities of such an integrated system at the Naval Research Laboratory using charge state +1 ions. Transmission loss is compared to molecule destruction as gas flow to the molecule-destruction cell increases. As most measurements tolerate more modest abundance sensitivities than for 14 C analysis, a lower gas flow is acceptable, so good transmission of 20–50% for ions of interest can be maintained for a broad range of ion masses. This new instrument has measured isotope ratios for uranium, lead, rare earths, and other elements from particulates and localized regions, with molecule destruction enabling the measurement at low SIMS mass resolving power and thus high transmission, as examples will show. This new and world-unique instrument provides improved capabilities for applications in nuclear and other forensics, geochemistry, cosmochemistry, and the development of optical, electronic, multifunctional, and structural materials. [ABSTRACT FROM AUTHOR]

The Fuente de Piedra lake is a hypersaline wetland of great extension (13.5 km 2 ) and rich in aquatic birds and other species. It became therefore the third Spanish wetland to be included in the Ramsar convention and has been a “nature reserve” since 1984. The lake has an endorheic basin (150 km 2 ) with variable-density flows dominated by complex hydrogeological conditions. The traditional conceptualization of endorheic basins in semiarid climates considered that the brine in this hydric system was exclusively of evaporative origin and was placed only in the lake and its surrounding discharge area in the basin. Previous geophysical and hydrochemical studies identified different types of waters and brines. In this work, natural tracers (Cl − , Br − , Na + , Mg 2+ ) and environmental isotopes ( 18 O, 2 H, 14 C, 13 C and 3 H) were employed to a) discriminate different types of brines according to their degree of evaporation and genesis, and b) to estimate residence times of brine waters and identify recharge areas of the different flow subsystems. A conceptual model of the hydrogeological system of the lake basin and its links to a regional karst system is proposed. [ABSTRACT FROM AUTHOR]

The isotopic structure of the well-established s-wave resonances in the presence of a hypnotized narrow resonance N(1670)1/2 in the amplitude is discussed. Two sets of results coming out of fitting two different sets of the data are discussed. [ABSTRACT FROM AUTHOR]

The 2015 update of the discovery of nuclide project is presented. Twenty new nuclides were observed for the first time in 2015. An overall review of all previous assignments was made in order to apply the discovery criteria consistently to all elements. In addition, a list of isotopes published so far only in conference proceedings or internal reports is included. [ABSTRACT FROM AUTHOR]

A general principle is proposed for introducing multicomponent potentials by summing the separative power of the elements that divide the partial flows of binary mixtures consisting of pairs or sets of isotopes. It is shown that under different assumptions about the character of the separation process this method can be used to determine the well-known as well as new forms of separation potentials. A computational experiment is used to determine the potentials that best correspond to the separative processes in R- cascades and optimal cascades with minimum total flow and prescribed external concentration of the target isotope. [ABSTRACT FROM AUTHOR]

The mass, isotope, and isobar distributions of limiting temperatures for finite nuclei are investigated by using a thermodynamics approach together with the Skyrme energy density functional. The relationship between the width of the isotope (isobar) distribution of limiting temperatures and the stiffness of the density dependence of the symmetry energy clearly is observed. The nuclear symmetry energy with smaller slope parameter Lsym causes a wider isotope (isobar) distribution of limiting temperatures. The widths of the isotope (isobar) distributions of limiting temperatures could be useful observables for exploring the information of the density dependence of the nuclear symmetry energy at finite temperatures. [ABSTRACT FROM AUTHOR]

We present the results and analysis of our investigation of the role of break-up processes on the fusion of a 12C6+ beam with a 52Cr target near, at, and above the Coulomb barrier. In this experiment the excitation functions of evaporation residues produced via (12C, 2n), (12C, pxn), (12C, αxn), and (12C, αpxn) channels in a 12C + 52Cr reaction were measured at several beam energies ranging from ≈51 to 87 MeV by employing the recoil catcher technique followed by off-line γ-ray spectrometry. The measured excitation functions were compared with theoretical values obtained using the pace4 statistical model code. Further, for a (12C, p2n) channel the measured excitation function was compared with the predictions of the alice-91 code, which was chosen as it takes into account pre-equilibrium emissions. For non-α-emitting channels, the experimentally measured excitation functions-after correcting them for possible contributions from higher charge isobaric precursor decays-were, in general, found to be in good agreement with theoretical predictions. However, for α-emitting channels, the measured excitation functions had significantly more production cross sections than what pace4 predicted. This enhancement may be attributed to incomplete fusion processes. An attempt was made to estimate the incomplete fusion fraction in order to compare the relative importance of complete and incomplete fusion processes. The incomplete fusion fraction was found to be sensitive to the projectile energy and mass asymmetry of the entrance channel. We also discuss the results in terms of the impact of the frozen α-cluster structure of the 12C isotope on various fusion reactions. [ABSTRACT FROM AUTHOR]

Large-scale shell model calculations have been carried out for odd-odd 58-62Mn isotopes in two different model spaces. The first set of calculations has been carried out in full fp shell valence space with two recently derived fp shell interactions namely GXPF1A and KB3G treating 40Ca as core. The second set of calculations has been performed in the fpg9/2 valence space with the fpg interaction treating 48Ca as core and imposing a truncation by allowing up to a total of six particle excitations from the 0 f7/2 orbital to the upper fp orbitals for protons and from the upper fp orbitals to the 0 g9/2 orbital for neutrons. For low-lying states in 58Mn , KB3G and GXPF1A both predict good results and for 60Mn , KB3G is much better than GXPF1A. For negative-parity and high-spin positive-parity states in both isotopes the fpg interaction is required. Experimental data on 62Mn is sparse and therefore it is not possible to make any definite conclusions. More experimental data on negative-parity states is needed to ascertain the importance of 0 g9/2 and higher orbitals in neutron-rich Mn isotopes. [ABSTRACT FROM AUTHOR]

Dipole magnetic moments of several long isotopic chains are analyzed within the self-consistent finite Fermi system theory with exact account for the pairing and quasiparticle continuum. The momentum dependence of the spin-isospin Landau-Migdal amplitude g′ is taken into account. This dependence was introduced previously to describe high-energy electron magnetic scattering. New moment data for nuclei far from the $ \beta$ -stability valley are included in the analysis. For a number of semi-magic isotopes of the tin and lead chains a good description of the data is obtained, with an accuracy of 0.1- 0.2 $ \mu_{{N}}^{}$ . A chain of non-magic isotopes of copper is also analyzed in detail. [ABSTRACT FROM AUTHOR]

Low energy quadrupole excitations of the 84-110Mo nuclei are studied in the frame of the general Bohr collective model. The potential energy and inertial functions are calculated using the ATDHFB method starting from the Skyrme effective interaction. Obtained energies of the 21, 41, 22 and 02 levels and B(E2) values for the 21 → 0g.s transitions are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

In a series of experiments performed at the velocity filter SHIP, new or improved decay data of neutron-deficient isotopes of elements from mendelevium ( Z = 101) to hassium ( Z = 108) were obtained. In particular, evidence for $ \alpha$ -decay or electron capture from isomeric states in 265Hs and 258Db was found. [ABSTRACT FROM AUTHOR]

In this study, the nuclear low-lying states and corresponding energies for A=18 nuclei have been calculated within the nuclear shell model framework. The 18O and 18F isobars are selected as A=18 nuclei. The nuclear shell model calculations for these isobars have been performed in both m-scheme and JT-scheme methods. In the calculations two different two-body effective interactions have been used: Delta and Wildenthal interactions. The calculated results have been compared with the experimental data and found to be in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: Subsurface soils near Clyde Forks, Ontario, Canada, can have naturally high concentrations of mercury (Hg) from local geological sources. To investigate Hg in local aquatic food webs, Hg was measured in fish dorsal muscle (mainly yellow perch [YP] and pumpkinseed sunfish [PS]) and surface sediments from 10 regional lakes. Water chemistry, along with fork length, weight, and stable isotopes (δ 15N, δ 13C, δ 34S) in fish were also measured. No lake sediments had elevated (>0.3μg/g dw) Hg, and average Hg concentrations in fish were not sufficiently high (<1μg/g dw) to be of concern for fish-eating wildlife. Variance in fish Hg was best explained by dietary carbon source (δ 13C), and certain lake variables (e.g., pH for YP). PS with more pelagic feeding habits had higher δ 34S and Hg than those with more littoral feeding habits. Potential biological linkages between fish Hg and δ 34S, a parameter that may be related to the lake sulphate-reducing bacteria activity, requires further investigation. [Copyright &y& Elsevier]

Abstract  Two promising isotope ratios, the δ18O of the water fraction, as extracted by azeotropic distillation, and the 87Sr/86Sr of the ash fraction were tested for their applicability to determine the geographic origin. In two sampling phases, in total 78 fresh poultry breast meat and 72 dried beef samples, independent from each other and originating from different countries, were analysed. The δ18O was measured with isotope ratio mass spectrometry and the isotope abundance ratio of 87Sr/86Sr with a multicollector inductively coupled plasma mass spectrometer. With δ18O it was possible to distinguish (p 18O and, if so, it seems to reduce the initial between-country differences. The 87Sr/86Sr ratio did not give sufficient indications for differentiation by geographic origin in either poultry meat or dried beef in the smaller, first phase, data set and was therefore not further tested. [ABSTRACT FROM AUTHOR]

Abstract: We solve a problem of Belousov which has been open since 1967: to characterize the loop isotopes of F-quasigroups. We show that every F-quasigroup has a Moufang loop isotope which is a central product of its nucleus and Moufang center. We then use the loop to reveal the structure of the associated F-quasigroup. [Copyright &y& Elsevier]

Abstract: A compartment model, ACGEO, has been developed for the Korean reference Repository System (KRS) for an HLW disposal by utilizing AMBER, a general compartment modeling tool. ACGEO is a flexible and adaptable tool, by which a transient calculation of both a nuclide release and transport in the near- and the far-field of a repository system with various and complex shapes can be carried out. It is expected to be used for the treatment of nuclide transport of a decay chain for safety assessment, as well as for design feedback on the KRS both on a deterministic and a probabilistic bases. Some illustrative cases are also investigated in which the influence of varying the near-field system features on the release of selected nuclides for an HLW repository are examined, in order to demonstrate the usability of ACGEO for feedback to a refined repository concept and for establishing an appropriate safety margin for an HLW repository. [Copyright &y& Elsevier]

Abstract: The 1994 evaluation of A = 140 (1994Pe19) was updated using data available prior to Feb. 1, 2006. The A = 140 mass chain contains 16 nuclei from Te to Ho. Compared to 1994Pe19, the volume of data increased by almost a factor of two, of which about half came from three nuclides: 140La (two (n,γ) E = th datasets), 140Nd (a very rich high-spin dataset), and 140Eu (studied by a combination of techniques covering three new reaction and decay datasets). The main difficulty of this evaluation came from discrepant data for the same three nuclides. For 140La one of the datasets presented many unresolved multiplet levels which were discrepant with the other dataset, and were partially resolved here by the evaluator. For 140Nd the new dataset and the older ones had discrepant γ energies which were recalibrated by the evaluator. The two new high-spin dataset of 140Eu had discrepant Jπ assignments for many levels, which were resolved based on a more recent paper which had accurately established the low Jπ values. [Copyright &y& Elsevier]

Abstract: The experimental results from various decays and reactions for the A = 122 mass chain have been compiled and evaluated. The nuclides covered in this evaluation are from 122Rh to 122Ce. Adopted values for the level and decay properties are tabulated. Inconsistencies and discrepancies are noted. This evaluation replaces that of Nuclear Data Sheets, NDS 71 461 (1994), (1994Ta10). [Copyright &y& Elsevier]

Abstract: The occurrence of iron–cyanide complexes in the environment is of concern, since they are potentially hazardous. In order to determine the source of iron–cyanide complexes in contaminated soils and wastes, we developed a method based on the stable isotope ratios 13C/12C and 15N/14N of the complexed cyanide-ion (CN−). The method was tested on three pure chemicals and two industrials wastes: blast-furnace sludge (BFS) and gas-purifier waste (GPW). The iron–cyanide complexes were converted into the solid cupric ferrocyanide, Cu2[Fe(CN)6]·7H2O, followed by combustion and determination of the isotope-ratios by continuous flow isotope ratio mass spectrometry. Cupric ferrocyanide was obtained from the materials by (i) an alkaline extraction with 1M NaOH and (ii) a distillate digestion. The [Fe(CN)6]4− of the alkaline extraction was precipitated after adding Cu2+. The CN− of the distillate digestion was at first complexed with Fe2+ under inert conditions and then precipitated after adding Cu2+. The δ 13C-values obtained by the two methods differed slightly up to 1–3‰ for standards and BFS. The difference was larger for alkaline-extracted GPW (4–7‰), since non-cyanide C was co-extracted and co-precipitated. Therefore the distillate digestion technique is recommended when determining the C isotope ratios in samples rich in organic carbon. Since the δ 13C-values of BFS are in the range of −30 to −24‰ and of −17 to −5‰ for GPW, carbon seems to be a suitable tracer for identifying the source of cyanide in both wastes. However, the δ 15N-values overlapped for BFS and GPW, making nitrogen unsuitable as a tracer. [Copyright &y& Elsevier]

Abstract: The Vistula is a large lowland, temperate river receiving high loads of pollutants from a densely populated catchment. On the other hand, the river is to a relatively small extent affected by channelisation and damming. This study is the first attempt to characterise stable isotope aspects of dissolved inorganic carbon in the Vistula which is a major source of pollution to the Baltic Sea. Isotopic composition of DIC and other chemical properties were measured biweekly at the upper reach and monthly at the mouth of the river. Two longitudinal samplings were performed in hydrological summer and winter conditions. Short-term and short-range observations were carried out in an anthropogenically influenced urban reach at Cracow. Most water samples from the Vistula and its tributaries analysed in this study had δ 13CDIC values around the range −12‰ to −11‰, typical for European lowland rivers fed by groundwaters on carbonate areas. Variablity of δ 13CDIC in this river system is limited, except for the impoundments and the specific hydrological conditions. The few impoundments that exist on the Vistula intensify the photosynthesis/respiration cycle as well as the exchange of CO2 with the atmosphere. Enhanced contribution of biogenic carbon during floods is reflected by lowering of δ 13CDIC. Low flows facilitate photosynthetic assimilation and evasion of CO2 into the atmosphere resulting in positive shifts of δ 13CDIC. Principal Component Analysis confirmed that δ 13CDIC variability at the fixed cross-section in Cracow reflected releases and withdrawals of CO2 from the riverine DIC pool. The apparent δ 13CDIC variability depends to some extent on the spatio-temporal context of observations. Diurnality can be very pronounced in the impounded, anthropogenically influenced reaches in warm periods. Interpretation of the observed riverine δ 13CDIC patterns can be difficult as the spatial and temporal variabilities combine resulting in convoluted isotopic signals. Isotopic investigations into the nature of riverine carbon cycling should be supplemented by discharge records and by observations of the parameters influenced by the photosynthesis/respiration cycle (dissolved oxygen, pH, pCO2) and of those conservative with respect to biological processes (electrical conductivity, stable isotope composition of water). [Copyright &y& Elsevier]

Abstract: Combined investigations of ostracod communities, pollen, and stable isotopes were carried out on Lateglacial limnic high-resolution sediment sequence from Miesenheim in Germany. The pollen data confirm the presence of Meiendorf Interstadial, the first interstadial after the Pleniglacial. The former shallow lake was formed at the end of the Pleniglacial and partly dried out between the Bølling and the Allerød. Lake Laach tephra (12,880 warve yr BP) marks the top of this profile. The intensive colonization with ostracods at the beginning of the Meiendorf Interstadial is characterized by great instability of their populations. Only ostracods from the upper littoral zones of lakes, ponds or temporary pools were found. The stable isotope data (δ 18O, δ 13C) of the valves of the Cypridopsis vidua, Herpetocypris reptans, and Candona candida reflect the different microhabitats of these three species and show a general climatic development during the Meiendorf Interstadial with two summer temperature peaks, one at the beginning and a weaker one in the second half of the Meiendorf Interstadial. [Copyright &y& Elsevier]

In order to increase the resolving capability of isobar identification in low energy accelerator mass spectrometry (AMS) measurements, we have developed a new gas-filled time-of-flight (GF-TOF) detector system. The principle and the design of this system and the results from off-line and on-line tests (with α particles of 241Am and AgCl sample), respectively, are described. [Copyright &y& Elsevier]

The beta-decay of 232Fr to excited states in 232Ra has been studied using gamma-gamma coincidence detection combined with the isotope separator on-line technique at the ISOLDE PSB facility at CERN. Earlier findings are confirmed and three new gamma lines are reported. In addition to the beta-decay characteristics of 232Fr, the K = 0 ground-state band in 232Ra is identified. A yield survey of neutron-rich Fr isotopes, important also for the EURISOL project, is incorporated. [ABSTRACT FROM AUTHOR]

The article discusses that France's nuclear regulator has ordered ITER, an international fusion energy project, to hold off assembling its doughnut-shaped reactor, called a tokamak. France's Nuclear Safety Authority (ASN) sent a letter halting work until ITER can respond to safety concerns. Fusing hydrogen isotopes under extreme temperatures generates energy. But no fusion reactor has produced more heat than it consumes.