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Estimating the state thermal storage devices is key to use them efficiently to reduce the uncertainty of renewable sources. Although stratified storage tanks are one of the most efficient and cost-effective storage systems, they lack accurate state estimation methods. In this paper, we propose a general methodology for estimating the state of thermally stratified storage tanks of different topologies and capacity. The method is based on a simple moving horizon estimation technique and a 1-D smooth model that can integrate buoyancy effects into a smooth equation. The novelty of the proposed approach is that it is the first state estimation approach that considers both buoyancy and mixing effects. This distinction is paramount to an adequate estimation of the temperature distribution in the storage tank which can then be used for different aims, namely as a basis for model predictive controls. Besides the novel state estimation approach, the paper has three more contributions: (i) it shows how a model for seasonal storage devices can be further extended to smaller stratified tanks with different topologies; (ii) it modifies such a model so that the model equations can be integrated into a single dynamical equation; (iii) it proposes the most complete case study to date for modeling and estimating temperature distribution inside small stratified storage tanks. The analysis of the proposed approach is done in several stages. First, to validate the applicability of the model to small tanks and multiple topologies, we perform a model identification and parameter estimation for three different stratified tanks. Second, we test the accuracy of the proposed state estimation approach in those three stratified tanks employing the estimated parameters in the first experimental study and the models also previously defined. Finally, to further validate the models, we perform a simulation for each of the three tanks and we compare the accuracy of the simulation against real data. As we show, both the state estimation approach and the model are satisfactorily accurate as they display average mean errors below 2 °C.

This chapter discusses mainly the technical implementation of PEBs. First, the chapter presents how the EXCESS project parties are planning to implement the PEB concept in four different geographical areas in Europe, as cooling and heating demands vary between regions. The demo locations are Helsinki in Finland, Granada in Spain, Hasselt in Belgium and Graz in Austria. After demo case presentations, the roles of digitalisation in PEBs and business models for energy transformation are addressed. Finally, lessons learned from implementing demo cases are discussed.

In this paper, the influence of the addition of fins and the use of two different heat transfer fluids (water and a commercial silicone) have been experimentally tested and compared in four latent heat thermal energy storage systems, based on the shell-and-tube heat exchanger concept, using paraffin RT58 as phase change material. Three European institutions were involved under the framework of the MERITS project. A common approach (temperature and power profiles), and five different key performance indicators have been defined and used for the comparison: energy charged, average power, 5-min peak power, peak power to energy ratio, and time. For the same heat transfer fluid, results showed that finned designs (4.7-9.4 times more heat transfer surface) showed an improvement of up to 40%. On the contrary, for the same design, water (which has a specific heat 3 times higher and a thermal conductivity 4.9 times higher than silicone Syltherm 800), yielded results up to 44% higher. The research leading to these results has received funding from the European Commission Seventh Framework Programme (FP/2007–2013) under grant agreement No ENER/FP7/295983 (MERITS) and under Grant agreement N°PIRSES-GA-2013-610692 (INNOSTORAGE), and from the European Union's Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The work is partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER) and ULLE10-4E-1305). The authors would like to thank the Catalan Government for the quality accreditation given to the research group GREA (2014 SGR 123). Jaume Gasia would like to thank the Departament d’Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for his research fellowship (2017FI_B 00092).

Sorption heat storage has the potential to store large amounts of thermal energy from renewables and other distributed energy sources. This article provides an overview on the recent advancements on long-term sorption heat storage at material- and prototype- scales. The focus is on applications requiring heat within a temperature range of 30–150 °C such as space heating, domestic hot water production, and some industrial processes. At material level, emphasis is put on solid/gas reactions with water as sorbate. In particular, salt hydrates, adsorbents, and recent advancements on composite materials are reviewed. Most of the investigated salt hydrates comply with requirements such as safety and availability at low cost. However, hydrothermal stability issues such as deliquescence and decomposition at certain operating conditions make their utilization in a pure form challenging. Adsorbents are more hydrothermally stable but have lower energy densities and higher prices. Composite materials are investigated to reduce hydrothermal instabilities while achieving acceptable energy densities and material costs. At prototype-scale, the article provides an updated review on system prototypes based on the reviewed materials. Both open and closed system layouts are addressed, together with the main design issues such as heat and mass transfer in the reactors and materials corrosion resistance. Especially for open systems, the focus is on pure adsorbents rather than salt hydrates as active materials due to their better stability. However, high material costs and desorption temperatures, coupled with lower energy densities at typical system operating conditions, decrease their commercial attractiveness. Among the main conclusions, the implementation within the scientific community of common key performance indicators is suggested together with the inclusion of economic aspects already at material-scale investigations. This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES.

The structure of low-spin states originating from shape-coexisting configurations in $^{68}_{40}$Ni$_{28}$ was directly probed via the two-neutron transfer reaction $^{66}$Ni$(t,p)^{68}$Ni in inverse kinematics using a radioactive ion beam on a radioactive target. The direct feeding to the first excited 0$^+$ state was measured for center-of-mass angles 4°–16° and amounts to an integral of 4.2(16)% relative to the ground state. The observed difference in feeding of the 0$^+$ states is explained by the transfer of neutrons, mainly in the $pf$ shell below $N=40$ for the ground state, and across $N=40$ in the $g_{9/2}$ orbital for the 0$_2^+$, based on second-order distorted-wave Born approximation calculations combined with state-of-the-art shell-model two-nucleon amplitudes. However, the direct feeding to the 2$_1^+$ state [29(3)%] is incompatible with these calculations.

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of $ 0^{+}_{1,2}$01,2+, $ 2^{+}_{1,2}$21,2+and $ 4^{+}_{1}$41+states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions. The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of $ 0^{+}_{1,2}$01,2+, $ 2^{+}_{1,2}$21,2+and $ 4^{+}_{1}$41+states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions. ispartof: The European Physical Journal A - Hadrons and Nuclei vol:55 issue:8 pages:130-130 status: published

In this research, latent heat storage tanks are modelled with a water flow with a finite total heat capacity. Because of the finite heat capacity of the water flow, the Phase Change Material (PCM) will not melt uniformly. This is in contrast to the case were large water flows induce a constant wall temperature for the PCM. In this paper, we show that increased charging efficiencies can be obtained for high flow lengths and reduced PCM layer thicknesses. Additionally, both storage and charging performance increase for lower water volume fractions. Further, we show that multiple stage design enables improved charging performance and reduced pumping power requirements. ispartof: pages:1-8 ispartof: Proceedings of the 16th International Heat Transfer Conference, IHTC-16 pages:1-8 ispartof: International Heat Transfer Conference location:China date:10 Aug - 15 Aug 2018 status: published

Single-neutron states in the Z=30, N=49isotope 79Zn have been populated using the 78Zn(d,p)79Zn transfer reaction at REX-ISOLDE, CERN. The experimental setup allowed the combined detection of protons ejected in the reaction, and of γrays emitted by 79Zn. The analysis reveals that the lowest excited states populated in the reaction lie at approximately 1MeV of excitation, and involve neutron orbits above the N=50shell gap. From the analysis of γ-ray data and of proton angular distributions, characteristic of the amount of angular momentum transferred, a5/2+configuration was assigned to a state at 983keV. Comparison with large-scale-shell-model calculations supports a robust neutron N=50shell-closure for 78Ni. These data constitute an important step towards the understanding of the magicity of 78Ni and of the structure of nuclei in the region. publisher: Elsevier articletitle: Single-neutron orbits near 78Ni: Spectroscopy of the isotope 79Zn journaltitle: Physics Letters B articlelink: http://dx.doi.org/10.1016/j.physletb.2014.12.006 content_type: article copyright: Copyright © 2014 The Authors. Published by Elsevier B.V. ispartof: Physics Letters B vol:740 pages:298-302 status: published

A detailed $\alpha$-decay spectroscopy study of $^{180}\mathrm{Tl}$ has been performed at ISOLDE (CERN). $Z$-selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of $^{180}\mathrm{Tl}$. Fine-structure $\alpha$ decays to excited levels in the daughter $^{176}\mathrm{Au}$ were identified and an $\alpha$-decay scheme of $^{180}\mathrm{Tl}$ was constructed based on an analysis of $\alpha$-$\gamma$ and $\alpha$-$\gamma$-$\gamma$ coincidences. Multipolarities of several $\gamma$-ray transitions deexciting levels in $^{176}\mathrm{Au}$ were determined. Based on the analysis of reduced $\alpha$-decay widths, it was found that all $\alpha$ decays are hindered, which signifies a change of configuration between the parent and all daughter states.

The use of structural thermal storage is often suggested as a key technology to improve the penetration of renewable energy sources and mitigate potential production and distribution capacity issues. Therefore, a quantitative assessment of the energy flexibility provided by structural thermal energy storage is a prerequisite to instigate a large scale deployment of thermal mass as active storage technologies in an active demand response (ADR) context. In the first part of the work, a generic, simulation-based and dynamic quantification method is presented for the characterization of the ADR potential, or energy flexibility, of structural thermal energy storage. The quantification method is based on three ADR characteristics – i.e. available storage capacity, storage efficiency and power-shifting capability – which can be used to quantify the ADR potential in both design and operation. In the second part of the work, the methodology is applied to quantify the ADR characteristics for the structural thermal energy storage capacity for the different typologies of the Belgian residential building stock. Thereby an in-depth analysis demonstrates the relation between the building properties and its energy flexibility as well as the dependence of the energy flexibility on the dynamic boundary conditions. ispartof: Applied Energy vol:198 pages:192-202 status: published

13 pags., 6 figs. 3 tabs.-- Open Access funded by Creative Commons Atribution Licence 3.0, The bound states of Be have been studied by removing single neutrons from Be nuclei. A 2.8 MeV u beam of Be was produced at ISOLDE, CERN and directed on to both proton and deuteron targets inducing one-neutron removal reactions. Charged particles were detected to identify the two reaction channels (d, t) and (p, d), and the individual states in Be were identified by gamma detection. All bound states but one were populated and identified in the (d, t) reaction. The combination of REX-ISOLDE and MINIBALL allowed for a clean separation of the high-lying states in Be. This is the first time these states have been separated in a reaction experiment. Differential cross sections have been calculated for all the reaction channels and compared to DWBA calculations. Spectroscopic factors are derived and compared to values from the litterature. While the overall agreement between the spectrocopic factors is poor, the ratio between the ground state and the first excited state is in agreement with the previous measured ones. Furthermore, a significant population of the state is observed, which which may indicate the presence of multi-step processes at our beam energy., This work was supported by the Danish Research Council, by the European Union Seventh Framework through ENSAR (Contract No. 262010) and a Marie Curie Actions Grant under Contract No. PIEF-GA-2008-219175, by the BMBF under Contracts No. 06MT7178, No. 06MT9156, No. 05P09PKCI5, No. 05P12PKFNE, No. 06DA9036I, No. 05P12RDCIA, No. 05P15PKCIA and Verbundprojekt 05P2015, by the Spanish MINNECO under Contracts No. FPA2012-34332 and No. FPA2015-, by the FWO-Vlaanderen (Belgium), by GOA/10/010 (BOF KU Leuven), by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12), by the United Kingdom Science and Technology Facilities Council, and by Maier-Leibnitz-Laboratorium, Garching.

Sorption thermal energy storage (STES) has the potential to have higher energy densities and lower thermal losses compared to conventional thermal storage technologies, and it can contribute to increase the energy grid flexibility and the penetration of intermittent and distributed energy sources. However, STES is a technology still under research, and system-scale investigations are necessary to determine its potential in future energy systems. In this regard, the objective of this work is to investigate the STES potential in a reference energy system interacting with different energy markets. The system consists of a geothermal doublet supplying thermal energy to an organic Rankine cycle (ORC) and to a district heating network that satisfies the thermal energy demand of a residential neighborhood. A techno-economic optimization of the energy system is carried out using mixed integer linear programming. The optimization aims at finding the optimal STES size and system operational behavior that maximizes the yearly profits from selling the ORC energy to the energy markets. Among the main results, it is found that the STES integration increased the overall system profits by 41% in the scenario where the ORC interacted with the UK day ahead market (2017 data), and with two UK balancing services: the capacity market, and the short term operating reserve. In conclusion, this work highlights how a thermal storage technology still under research could become an asset under specific market conditions. Future policy mechanisms can benefit from similar analyses and foster the integration of new technologies into the energy grid. © 2019 The Author(s)

The integration of buildings in a Smart Grid, enabling demand-side management and thermal storage, requires robust reduced-order building models that allow for the development and evaluation of demand-side management control strategies. To develop such models for existing buildings, with often unknown the thermal properties, data-driven system identification methods are proposed. In this paper, system identification is carried out to identify suitable reduced-order models. Therefore, grey-box models of increasing complexity are identified on results from simulations with a detailed physical model, deployed in the integrated district energy assessment simulation (IDEAS) package in Modelica. Firstly, the robustness of identified grey-box models for day-ahead predictions and simulations of the thermal response of a dwelling, as well as the physical interpretation of the identified parameters, are analyzed. The influence of the identification dataset is quantified, comparing the added value of dedicated identification experiments against identification on data from in use buildings. Secondly, the influence of the data used for identification on model performance and the reliability of the parameter estimates is quantified. Both alternative measurements and the influence of noise on the data are considered.

The νg9/2, d5/2, s1/2 orbitals are assumed to be responsible for the swift onset of collectivity observed in the region below 68 Ni. Especially the single-particle energies and strengths of these orbitals are of importance. We studied such properties in the nearby

In-gas-cell laser ionization spectroscopy studies on the neutron deficient 97–101Ag isotopes have been performed with the LISOL setup. Magnetic dipole moments and mean-square charge radii have been determined for the first time with the exception of 101Ag, which was found in good agreement with previous experimental values. The reported results allow tentatively assigning the spin of 97,99Ag to 9 2 and confirming the presence of an isomeric state in these two isotopes, whose collapsed hyperfine structure suggests a spin of 1 2 . The effect of the N = 50 shell closure is not only manifested in the magnetic moments but also in the evolution of the mean-square charge radii of the isotopes investigated, in accordance with the spherical droplet model predictions.

The neutron-deficient ${}^{\mathrm{196,198}}$Pb isotopes have been studied in Coulomb-excitation experiments employing the Miniball γ-ray spectrometer and radioactive ion beams from the REX-ISOLDE post-accelerator at CERN. The reduced transition probabilities of the first excited 2+ states in 196Pb and 198Pb nuclei have been measured for the first time. Values of $B(E2)={18.2}_{-4.1}^{+4.8}$ W.u. and $B(E2)={13.1}_{-3.5}^{+4.9}$ W.u., were obtained, respectively. The experiment sheds light on the development of collectivity when moving from the regime governed by the generalised seniority scheme to a region, where intruding structures, associated with different deformed shapes, start to come down in energy and approach the spherical ground state. journal_title: Journal of Physics G: Nuclear and Particle Physics article_type: paper article_title: Collectivity in ${}^{\mathrm{196,198}}$Pb isotopes probed in Coulomb-excitation experiments at REX-ISOLDE copyright_information: © 2017 IOP Publishing Ltd date_received: 2016-10-31 date_accepted: 2017-03-17 date_epub: 2017-05-03 ispartof: Journal of Physics G, Nuclear and Particle Physics vol:44 issue:6 status: published

International audience; The ${\beta }^{+}$/EC decay of ${}^{\mathrm{182,184}}$Tl to excited states in the daughter nuclei ${}^{\mathrm{182,184}}$Hg has been investigated at the CERN on-line isotope mass separator facility. In both Tl nuclei two β-decaying states were observed. In the case of (184)Tl, narrow-band laser spectroscopy could be used to disentangle the decay of both isomers. In (182)Hg a precise energy of 335 (1) keV for the ${0}_{2}^{+}$ state was measured together with its feeding from a tentatively proposed ${2}_{3}^{+}$ state at 973 keV. Large conversion coefficients for the ${2}_{2}^{+}\to {2}_{1}^{+}$ transition in ${}^{\mathrm{182,184}}$Hg were measured to be 7.2 (13) and 14.2 (36), respectively, evidencing a strong E0 component.

Sorption heat storage can potentially store thermal energy for long time periods with a higher energy density compared to conventional storage technologies. A performance comparison in terms of energy density and storage capacity costs of different sorption system concepts used for seasonal heat storage is carried out. The reference scenario for the analysis consisted of satisfying the yearly heating demand of a passive house. Three salt hydrates (MgCl2, Na2S, and SrBr2), one adsorbent (zeolite 13X) and one ideal composite based on CaCl2, are used as active materials in solid sorption systems. One liquid sorption system based on NaOH is also considered in this analysis. The focus is on open solid sorption systems, which are compared with closed sorption systems and with the liquid sorption system. The main results show that, for the assumed reactor layouts, the closed solid sorption systems are generally more expensive compared to open systems. The use of the ideal composite represented a good compromise between energy density and storage capacity costs, assuming a sufficient hydrothermal stability. The ideal liquid system resulted more affordable in terms of reactor and active material costs but less compact compared to the systems based on the pure adsorbent and certain salt hydrates. Among the main conclusions, this analysis shows that the costs for the investigated ideal systems based on sorption reactions, even considering only the active material and the reactor material costs, are relatively high compared to the acceptable storage capacity costs defined for different users. However, acceptable storage capacity costs reflect the present market condition, and they can sensibly increase or decrease in a relatively short period due to for e.g. the variation of fossil fuels prices. Therefore, in the upcoming future, systems like the ones investigated in this work can become more competitive in the energy sector. This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES.

States in the N = 28 nucleus Ar-46 have been studied by a two-neutron transfer reaction at REX-ISOLDE (CERN). A beam of radioactive Ar-44 at an energy of 2.16 AMeV and a tritium-loaded titanium target were used to populate Ar-46 by the H-3(Ar-44, p) two-neutron transfer reaction. Protons emitted from the target were identified in the T-REX silicon detector array. The excitation energies of states in Ar-46 have been reconstructed from the measured angles and energies of recoil protons. Angular distributions for three final states were measured and based on the shape of the differential cross section an excited state at 3695 keV was identified as J(pi) = 0(+). The angular differential cross section for the population of different states are compared to calculations using a reaction model employing both sequential and direct transfer of two neutrons. Results are compared to shell-model calculations using state-of-the-art effective interactions.

Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z=82 and the neutron midshell at N=104. Purpose: Evidence for shape coexistence has been inferred from α-decay measurements, laser spectroscopy, and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of Rn202 and Rn204 were studied by means of low-energy Coulomb excitation at the REX-ISOLDE in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first excited 21+ state was extracted for both Rn202 and Rn204, corresponding to B(E2;21+→01+)=29-8+8 and 43-12+17 W.u. respectively. Additionally, E2 matrix elements connecting the 21+ state with the 41+ and 22+ states were determined in Rn202. No excited 0+ states were observed in the current data set, possibly owing to a limited population of second-order processes at the currently available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Grey-box modelling is a system identification technique that combines parameter estimation methods to quantify the model parameters and physical knowledge to define the model structure. Consequently, the potential of grey-box modelling lies, in addition to the application of reduced-order models in e.g. control strategies or district simulations, in the characterization of the thermal properties of buildings. Nevertheless, the quality of the obtained model is governed by the dynamic information that is available in the training data. Thereby, the required accuracy of the models, and thus the requirements of the training data, differ from application to application. This paper analyses how the significant difference in dynamic behavior of a slow floor heating system compared to a highly responsive radiator heating system results in a variation of the time constants of the building that are excited by the system and therefore identifiable in the system identification process. The performance of grey-box models for prediction and simulations are contrasted for cases with radiators and floor heating and the physical interpretability of the model parameters is demonstrated. publisher: Elsevier articletitle: Impact of the Heat Emission System on the Identification of Grey-box Models for Residential Buildings journaltitle: Energy Procedia articlelink: http://dx.doi.org/10.1016/j.egypro.2015.11.740 content_type: article copyright: Copyright © 2015 The Authors. Published by Elsevier Ltd. ispartof: pages:3300-3305 ispartof: Proceedings of 6th International Building Physics Conference vol:78 pages:3300-3305 ispartof: International Building Physics Conference location:Turin date:14 Jun - 17 Jun 2015 status: published

The quasi-SU(3) sequence of the positive parity $\ensuremath{\nu}{g}_{9/2},{d}_{5/2},{s}_{1/2}$ orbitals above the $N=40$ shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe $(Z=26)$ and Cr $(Z=24)$ isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of $^{68}\mathrm{Ni} (Z=28,\phantom{\rule{0.16em}{0ex}}N=40)$ through the $^{66}\mathrm{Ni}(d,p)^{67}\mathrm{Ni}$ one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball $\ensuremath{\gamma}$-array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-$\ensuremath{\mu}\mathrm{s}$ isomer at 1007 keV in $^{67}\mathrm{Ni}$. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the $\ensuremath{\nu}{g}_{9/2}$ (1007 keV) and $\ensuremath{\nu}{d}_{5/2}$ (2207 keV and 3277 keV) positive-parity neutron states and negative parity $(\ensuremath{\nu}pf)$ states have been observed at low excitation energy. The extracted relative spectroscopic factors, based on a distorted-wave Born approximation analysis, show that the $\ensuremath{\nu}{d}_{5/2}$ single-particle strength is mostly split over these two excited states. The results are also compared to the distribution of the proton single-particle strength in the $^{90}\mathrm{Zr}$ region $(Z=40,N=50)$.

The low-energy structure of the neutron-rich nucleus Ni-68 has been investigated by measuring the beta decay of the low-spin isomer in Co-68 selectively produced in the decay chain of Mn-68. A revised level scheme has been built based on the clear identification of beta-gamma-E0 delayed coincidences. Transitions between the three lowest-lying 0(+) and 2(+) states are discussed on the basis of measured intensities or their upper limits for unobserved branches and state-of-the-art shell model calculations.

Sub-barrier Coulomb-excitation was performed on a mixed beam of $^{62}$Mn and $^{62}$Fe, following in-trap $\beta^{-}$ decay of $^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418~keV, which has been tentatively associated to a $(2^{+},3^{+})\rightarrow1^{+}_{g.s.}$ transition. This fixes the relative positions of the $\beta$-decaying $4^{+}$ and $1^{+}$ states in $^{62}$Mn for the first time. Population of the $2^{+}_{1}$ state was observed in $^{62}$Fe and the cross-section determined by normalisation to the $^{109}$Ag target excitation, confirming the $B(E2)$ value measured in recoil-distance lifetime experiments., Comment: 9 pages, 10 figures

Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po196,198,200,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po200,202, the transitional and diagonal matrix elements of the 2+1 state are determined. In Po196,198 multistep Coulomb excitation is observed, populating the 4+1,0+2, and 2+2 states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po196 onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure., We acknowledge the support of the ISOLDE Collaboration and technical teams and, especially, the support of RILIS and REX. This work was supported by FWO-Vlaanderen (Belgium), by GOA/2010/010 (BOF KU Leuven), by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12), by the European Commission within the Seventh Framework Programme through I3-ENSAR (Contract No. RII3-CT-2010-262010), by the German BMBF under Contract Nos. 05P12PKFNE, 06DA9036I 05P12RDCIA, and 05P12RDCIB, by the UK Science and Technology Facilities Council, by the Spanish MINECO under Project No. FIS2011-28738-C02-02, by Narodowe Centrum Nauki (Polish Center for Scientific Research) Grant No. UMO-2013/10/M/ST2/00427, by the Academy of Finland (Contract No. 131665), and by the European Commission through the Marie Curie Actions call PIEFGA-2008-219174 (J.P.).

4 pags., 2 figs. -- INPC 2013 – International Nuclear Physics Conference, The investigation of the excitation energies of the 21+ –states in the neutron-rich Cd isotopes shows an irregular behaviour when approaching the neutron shell-closure at N = 82. The energy of the 21+–state in 128Cd is lower than the one in 126Cd. The transition strength B(E2, 0gs+ → 21+) in the even isotopes 122−128Cd was measured in Coulomb excitation experiments with the high-purity germanium detector array MINIBALL at REXISOLDE (CERN). The values for 122,124Cd coincide with beyond-mean-field calculations with a resultant prolate deformation, whereas 126,128Cd are better described by shell-model calculations., This project is supported by BMBF (No. 06 DA 9036I, No. 05 P12 RDCIA, No. 05 P12 RDCIB and No. 05 P12 PKFNE), HIC for FAIR, EU through EURONS (No. 506065) and ENSAR (No. 262010) and the MINIBALL and REX-ISOLDE collaborations.

The isotopes 122,124,126Cd were studied in a “safe” Coulomb-excitation experiment at the radioactive ion-beam facility REX-ISOLDE at CERN. The reduced transition probabilities B(E2; 0+g.s. →2+1) and limits for the quadrupole moments of the first 2+ excited states in the three isotopes were determined. The onset of collectivity in the vicinity of theZ=50 andN=82 shell closures is discussed by comparison with shell model and beyond mean-field calculations. ispartof: Physical Review C, Nuclear Physics vol:89 issue:1 pages:1-10 status: published

Seidlitz, M., et all ; 10 pags. ; 9 figs. ; 1 tab. ; PACS number(s): 21.60.Cs, 23.20.Js, 25.70.De, 29.38.Gj, Nuclear shell evolution in neutron-rich Na nuclei around N=20 was studied by determining reduced transition probabilities, i.e., B(E2) and B(M1) values, in order to map the border of the island of inversion. To this end Coulomb-excitation experiments, employing radioactive 29,30Na beams with a final beam energy of 2.85 MeV/nucleon, were performed at REX-ISOLDE, CERN. De-excitation γ rays were detected by the MINIBALL γ-ray spectrometer in coincidence with scattered particles in a segmented Si detector. Transition probabilities to excited states were deduced. The measured B(E2) values agree well with shell-model predictions, supporting the idea that in the Na isotopic chain the ground-state wave function contains significant intruder admixture already at N=18, with N=19 having an almost pure two-particle-two-hole deformed ground-state configuration. © 2014 American Physical Society., This work has been supported by the German BMBF under Contracts No. 06K-167, No. 06KY205I, No. 06DA9036I, No. 06MT9156, No. 05P09PKCI5, No. 05P12PKFNE, No. 05P12RDCIA, and No. 05P12RDCIB, by the FWOVlaanderen (Belgium), by the IAP Belgian Science Policy (BriX network (P7/12)), by the UK Science and Technology Funding Council, by the EUROpean Nuclear Structure Integrated Infrastructure Initiative (EURONS, RII3-CT-2004- 506065), and by the European Nuclear Science and Applications Research (ENSAR) under Project No. 262010.

The bound states of Be-12 have been studied through a Be-11(d, p) Be-12 transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of Be-11 was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in Be-12. The gamma-ray detection enabled a clear identification of the four known bound states in Be-12, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from distorted wave Born approximation (DWBA) calculations and have been compared to previous experimental and theoretical results.

A detailed $\ensuremath{\beta}$-decay study of ${}^{61}$Mn is presented, yielding extended information on the level structure of ${}^{61}$Fe. Pure beams were obtained at ISOLDE, CERN, after selective laser ionization and mass separation of fission products from the bombardment of a UC${}_{x}$ target by 1.4-GeV protons. The $\ensuremath{\beta}$ and $\ensuremath{\gamma}$ information was detected by two MiniBall clusters and three $\ensuremath{\Delta}$$E$ plastic scintillators. The new ${}^{61}$Mn decay scheme reveals 48 $\ensuremath{\gamma}$ transitions, distributed over 20 excited states. A comparison to the decay scheme of ${}^{59}$Mn and excited states in ${}^{59}$Fe is made. Shell-model calculations with two different interactions are performed in order to compare the nuclear structure of the two neighboring odd-$A$ iron isotopes. Tentative spin and parities of several excited states in ${}^{61}$Fe are assigned on the basis of $\ensuremath{\beta}$-decay feeding patterns in both ${}^{59,61}$Fe and of results from the theoretical shell-model calculations.

Detailed $\ensuremath{\alpha}$-decay studies of ${}^{179}$Tl${}^{g}$ and its daughter products ${}^{175}$Au${}^{g}$ and ${}^{171}$Ir${}^{g}$ were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the $\ensuremath{\alpha}$-decay properties of ${}^{175}$Au${}^{g}$ was performed as follows: ${E}_{\ensuremath{\alpha}}$ $=$ 6433(4) keV, ${T}_{1/2}$ $=$ 207(7) ms, and $\ensuremath{\alpha}$-decay branching ratio 90(7)$%$. First determination of the $\ensuremath{\alpha}$-decay branching ratios for ${}^{179}$Tl${}^{g}$ and ${}^{171}$Ir${}^{g}$ was also made: ${b}_{\ensuremath{\alpha}}$(${}^{179}$Tl${}^{g}$) $=$ 60(2)$%$ and ${b}_{\ensuremath{\alpha}}$(${}^{171}$Ir${}^{g}$) $=$ 15(2)$%$. The spins of the ground states in ${}^{175}$Au and ${}^{171}$Ir are established as 1/2${}^{+}$.

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two γ rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2− states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code GOSIA2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes. ispartof: Physical Review C, Nuclear Physics vol:87 issue:1 status: published

The Miniball germanium detector array has been operational at the REX (Radioactive ion beam EXperiment) post accelerator at the Isotope Separator On-Line facility ISOLDE at CERN since 2001. During the last decade, a series of successful Coulomb excitation and transfer reaction studies have been performed with this array, utilizing the unique and high-quality radioactive ion beams which are available at ISOLDE. In this article, an overview is given of the technical details of the full Miniball setup, including a description of the γ-ray and particle detectors, beam monitoring devices and methods to deal with beam contamination. The specific timing properties of the REX-ISOLDE facility are highlighted to indicate the sensitivity that can be achieved with the full Miniball setup. The article is finalized with a summary of some physics highlights at REX-ISOLDE and the utilization of the Miniball germanium detectors at other facilities. © The Author(s) 2013. ispartof: European Physical Journal A, Hadrons and Nuclei vol:49 issue:3 pages:1-32 status: published

We report on the study of excited states in 92,94,96Kr populated via projectile Coulomb excitation at safe energies. The radioactive ion beams at energies of 2.85 MeV/u were delivered by the REX-ISOLDE facility at CERN and impinged on self-supporting 194,196Pt targets. The emitted γ -rays were detected by the Miniball detector-array. A detailed description of the experimental techniques used for extracting diagonal and transitional matrix elements and of the theoretical framework is given. The present experiment reveals the moderate evolution of the collective structure in the considered neutron-rich Kr isotopic chain, which is supported by the interacting boson model combined with the self-consistent mean-field method using a microscopic Gogny energy-density functional. The theory also suggests possible shape coexistence in the exotic nucleus 96Kr. ispartof: Nuclear Physics A vol:899 pages:1-28 status: published

There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on 220Rn and 224Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model. An experimental study of certain short-lived isotopes of radon and radium has found clear octupole deformation in the nuclei of the latter — that is, these nuclei are pear-shaped; the results enable discrimination between differing theoretical approaches to octupole correlations. The atomic nucleus is a many-body quantum system with a shape determined by the number of nucleons that it contains and the interactions between them. Most of the several thousand known stable and radioactive atomic nuclei, with differing numbers of protons and neutrons, are spherical or rugby-ball shaped. But there is circumstantial evidence that some heavy, unstable nuclides are distorted into a pear shape through the phenomenon of octupole deformation. Samples of these rare atomic species can be accelerated to 8% of the speed of light in the REX-ISOLDE facility at CERN, and now Coulomb excitation experiments on beams of the short-lived isotopes radium-224 and radon-220 have demonstrated clear octupole deformation in the former. The results make it possible to discriminate between the various theoretical models of octupole-deformed nuclei, and are also relevant to the pursuit of physics beyond the Standard Model.

The ${}^{64}$Co $\ensuremath{\beta}$-decay feeding levels in the well-studied ${}^{64}$Ni nucleus were investigated. Whereas the previously known ${}^{64}$Co decay scheme merely contained 2 $\ensuremath{\gamma}$ rays, the decay scheme established in this work contains $18,$ of which 5 are observed in this work and 6 were previously observed in an ($n$,$\ensuremath{\gamma}$) study but not placed in the ${}^{64}$Ni level scheme. Surprisingly, one additional level---placed at an excitation energy of $3578.7$ keV---could be determined. The observed $\ensuremath{\beta}$-decay paths involve allowed $\ensuremath{\nu}{f}_{5/2}\ensuremath{\rightarrow}\ensuremath{\pi}{f}_{7/2}$ and $\ensuremath{\nu}{p}_{1/2}\ensuremath{\rightarrow}\ensuremath{\pi}{p}_{3/2}$ transitions. Three strongly fed levels around 4 MeV are interpreted to possess possible proton-intruder character.

A set of B(E2) values for the low-lying excited states in the radioactive isotope Sn-109 were deduced from a Coulomb excitation experiment. The 2.87-MeV/u radioactive beam was produced at the REX-ISOLDE facility at CERN and was incident on a secondary Ni-58 target. The B(E2) values were determined using the known 2(+) -> 0(+) reduced transition probability in Ni-58 as normalization with the semiclassical Coulomb excitation code GOSIA2. The transition probabilities are compared to shell-model calculations based on a realistic nucleon-nucleon interaction and the predictions of a simple core-excitation model. This measurement represents the first determination of multiple B(E2) values in a light Sn nucleus using the Coulomb excitation technique with low-energy radioactive beams. The results provide constraints for the single-neutron states relative to Sn-100 and also indicate the importance of both single-neutron and collective excitations in the light Sn isotopes. (Less)