Suchergebnisse

R. Lica et al. -- 14 pags., 7 figs., tab. -- Open Access funded by Creative Commons Atribution Licence 3.0 ; Neutron-rich Ba isotopes are expected to exhibit octupolar correlations, reaching their maximum in isotopes around mass A = 146. The odd-A neutron-rich members of this isotopic chain show typical patterns related to non-axially symmetric shapes, which are however less marked compared to even-A ones, pointing to a major contribution from vibrations. In the present paper we present results from a recent study focused on Cs β-decay performed at the ISOLDE Decay Station equipped with fast-timing detectors. A detailed analysis of the measured decay half-lives and decay scheme of Ba is presented, giving a first insight in the structure of this neutron-rich nucleus. ; The IDS collaboration acknowledges financial support from: Istituto Nazionale di Fisica Nucleare, the Italian 'Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale (PRIN)' contract number 2001024324 01302, the European Union's seventh framework through ENSAR, contract no. 262010, the European Unions Horizon 2020 Framework research and innovation programme under grant agreement no. 654002 (ENSAR2), the FATIMA-NuPNET network via the PRI-PIMNUP-2011-1338 project, the Spanish MINECO projects reference numbers FPA2013-41467-P and FPA2015-646969-P, the German BMBF under contract 05P15PKCIA and 'Verbundprojekt 05P2015', the FWO-Vlaanderen (Belgium) and the IAP Belgian Science Policy (BriX network P7/12). VCh and ZP acknowledge support by the polish grant of Narodowe Centrum Nauki nr 2015/18/M/ST2/00523. ; Peer Reviewed

7 pags., 4 figs. -- Presented at the XXXVI Mazurian Lakes Conference on Physics, Piaski, Poland, September 1–7, 2019. ; Beta decay is a primary source of information of the structure of a nucleus. An accurate measurement of the half-life of a nucleus is essential for the proper determination of the reduced Gammow-Teller transition probability B(GT). In this work, we present an experiment using a compact set-up of Si-telescope detectors to measure the half-life of the B nucleus. Three independent measurements have been analysed, obtaining the values 771.9(17) ms, 773.9(18) ms, and 770.9(27) ms. The value of the half-life obtained as the weighted averaged with the previous published measures is 771.17(94) ms which is a factor 3.2 of improvement in the uncertainty of the half-life. ; Work partially supported by the Spanish research grant FPA2015-64969-P, FPA2017-83946-C2-1-P and FPA2017-87568-P (MINECO/FEDER/EU) and the grant ENSAR2 from the H2020 program of the European Union under grant agreement No. 654002.

6 pags., 6 figs. -- 27th International Nuclear Physics Conference (INPC2019) 29 July - 2 August 2019, Glasgow, UK ; The main goal of this work is to study the structure of the highest energy states in 8Be populated following the ß+-decay and the electron capture (EC) of 8B. With this aim, two experiments were performed at ISOLDE-CERN in 2017 and 2018. The first experiment had the aim to resolve the 2+ doublet at 16.6 and 16.9 MeV, in order to study their isospin mixing. The second experiment aimed to determine a value or give an experimental upper limit to the branching ratio of the exotic EC-p decay. In this paper, we present the experimental setups and we discuss the analysis and present the preliminary results obtained so far. ; Work partially supported by the Spanish research grant FPA2015-64969-P and FPA2017-87568- P (MINECO) and the grant ENSAR2 from the H2020 program of the European Union under grant agreement No 654002.

12 pags., 5 figs., 3 tabs. ; The β decay of Hg207 into the single-proton-hole nucleus Tl207 has been studied through γ-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the πs1/2-1, πd3/2-1, and πh11/2-1 shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s1/2-coupled) are identified and three more states (d3/2-coupled) are tentatively assigned using spin-parity inferences, while further h11/2-coupled states may also have been observed for the first time. Comparisons are made with state-of-the-art large-scale shell model calculations and previous observations made in this region, and systematic underestimation of the energy of the octupole vibrational states is noted. We suggest that in order to resolve the difference in predicted energies for collective and noncollective t=1 states (t is the number of nucleons breaking the Pb208 core), the effect of t=2 mixing may be reduced for octupole-coupled states. The inclusion of mixing with t=0,2,3 excitations is necessary to replicate all t=1 state energies accurately. ; The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 654002. Support from the European Union Seventh Framework through ENSAR Contract No. 262010, the Science and Technology Facilities Council (UK), the MINECO Projects No. FPA2015-64969-P and No. FPA2017-87568-P (Spain), FWOVlaanderen (Belgium), GOA/2015/010 (BOF KU Leuven), the Excellence of Science Programme (EOS-FWO), the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12), the German BMBF under Contract No. 05P18PKCIA + "Verbundprojekt 05P2018," the Polish National Science Centre under Contracts No. UMO-2015/18/M/ST2/00523 and No. UMO-2019/33/N/ST2/03023, the National Science Foundation (US) Grant No. PHY-1811855 and the Romanian IFA project CERN-RO/ISOLDE is acknowledged. P.H.R. and S.M.J. acknowledge support from the UK Department for Business, Energy and Industrial Strategy via the National Measurement Office.

11 pags., 10 figs., 5 tabs.-- Open Access funded by Creative Commons Atribution Licence 4.0 ; The structure of Si34 was studied through γ spectroscopy separately in the β- decays of Mg34 and Al34 at the ISOLDE facility of CERN. Different configurations in Si34 were populated independently from the two recently identified β-decaying states in Al34 having spin-parity assignments Jπ=4- dominated by the normal configuration π(d5/2)-1 - ν(f7/2) and Jπ=1+ by the intruder configuration π(d5/2)-1 - ν(d3/2)-1(f7/2)2. The paper reports on spectroscopic properties of Si34 such as an extended level scheme, spin and parity assignments based on log(ft) values and γ-ray branching ratios, absolute β feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of Si34. Large scale shell-model calculations using the SDPF-U-MIX interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of SDPF-U-MIX, the N=20 shell gap, the level of mixing between normal and intruder configurations for the 01+, 02+, and 21+ states, and the absence of triaxial deformation in Si34. ; This work was partially supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS-UEFISCDI project number PN-II-RU-TE- 2014-4-1455, by the Romanian IFA Grant CERN/ISOLDE, by Research Foundation Flanders (FWO-Belgium), by GOA/2015/010 (BOF KU Leuven), and by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12). Support from the U.K. Science and Technology Facilities Council, the European Union Seventh Framework through ENSAR (Contract No. 262010), the MINECO (Spain) grants FPA2017-87568-P, FPA2015-64969-P, FPA2014-57196, FPA2015-65035-P, Programme "Centros de Excelencia Severo Ochoa" SEV-2016- 0597, the MEYS project SPIRAL2-CZ,EF16-013/0001679, the National Research, Development and Innovation Fund of Hungary via Project No. K128947, the European Regional Development Fund (Contract No. GINOP-2.3.3-15-2016- 00034), the German BMBF under contract 05P18PKCIA (ISOLDE), and "Verbundprojekt 05P2018" is also acknowledged. I.K. was supported by the National Research, Development and Innovation Office of Hungary (NKFIH), Contract No. PD 124717. ; Peer Reviewed

12 pags., 11 figs., 3 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N = 90. To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z = 56 isotopic chain accessible at present, Ba-148,Ba-150, has been studied via beta decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive-and negative-parity low-spin excited states of 150Ba and presents an extension of the beta-decay scheme of Cs-148. Employing the fast timing technique, half-lives for the 2(1)(+) level in both nuclei have been determined, resulting in T-1/2 = 1.51(1) ns for Ba-148 and T-1/2 = 3.4(2) ns for Ba-150. The systematics of low-spin states, together with the experimental determination of the B(E2 : 2(+) -> 0(+)) transition probabilities, indicate an increasing collectivity in Ba148-150, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character. ; The IDS Collaboration acknowledges financial support from Istituto Nazionale di Fisica Nucleare, the Italian "Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale" (PRIN), contract 2001024324 01302; the European Union seventh framework through ENSAR, contract 262010; the European Unions Horizon 2020 Framework research and innovation program under grant agreement 654002 (ENSAR2); the FATIMA-NuPNET network via the PRI-PIMNUP-2011-1338 project; the Romanian IFA grant CERN/ISOLDE and Romanian PN-II-RU-TE-2014-4-2003; the Spanish MINECO projects, reference numbers FPA2013- 41467-P, FPA2015-64969-P, FPA2015-65929, and FIS2015- 63770; Spanish grants FIS-2014-53434-P MINECO and Programa Ramon y Cajal 2012 No. 11420, MINECO grant IJCI-2014-19172, and the MINECO project FPA2014-52823- C2-1-P; the German BMBF under contract 05P15PKCIA, contract 05P15PKFNA, and "Verbundprojekt 05P2015," the FWO-Vlaanderen (Belgium); and the IAP Belgian Science Policy (BriX network P7/12). V.Ch. and Z.P. acknowledge support by the Polish grant of Narodowe Centrum Nauki, no. 2015/18/M/ST2/00523. ; Peer Reviewed

13 pags., 7 figs., 3 tabs. ; A new β-decaying state in Bi214 has been identified at the ISOLDE Decay Station at the CERN-ISOLDE facility. A preferred Iπ=(8-) assignment was suggested for this state based on the β-decay feeding pattern to levels in Po214 and shell-model calculations. The half-life of the Iπ=(8-) state was deduced to be T1/2=9.39(10) min. The deexcitation of the levels populated in Po214 by the β decay of this state was investigated via γ-γ coincidences and a number of new levels and transitions was identified. Shell-model calculations for excited states in Bi214 and Po214 were performed using two different effective interactions: the H208 and the modified Kuo-Herling particle interaction. Both calculations agree on the interpretation of the new β-decaying state as an Iπ=8- isomer and allow for tentative assignment of shell-model states to several high-spin states in Po214. ; This work has been supported by the Research Foundation Flanders (FWO, Belgium), by GOA/2015/010 (BOF KU Leuven), the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (BriX network P7/12), by the ENSAR2: European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 654002, by the U.K. Science and Technology Facilities Council, by the Slovak Research and Development Agency (Contract No. APVV-18-0268), by the Slovak grant agency VEGA (Contract No. 1/0651/21), by RFBR according to the research project N 19-02-00005, by the Romanian IFA Grant CERN/ISOLDE, by the Spanish Funding Agency (AEI) under the project PID2019-104390GB-I00, by the German BMBF under Grant No. 05P18PKCIA and by the Spanish Ministerio de Ciencia e Innovación grant PID2019-104714GB-C21. M.S. acknowledges funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 771036 (ERC CoG MAIDEN). ; Peer reviewed

10 pags., 8 figs., 1 tab.-- Open Access funded by Creative Commons Atribution Licence 4.0 ; Excited states in Sn133 were investigated through the ß decay of In133 at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for In133, allowing us to study separately, and in detail, the ß-decay branch of In133J¿=(9/2+) ground state and its J¿=(1/2-) isomer. Thanks to the large spin difference of the two ß-decaying states of In133, it is possible to investigate separately the lower and higher spin states in the daughter, Sn133, and thus to probe independently different single-particle and single-hole levels. We report here new ¿ transitions observed in the decay of In133, including those assigned to the deexcitation of the neutron-unbound states. ; We acknowledge the support of the ISOLDE Collaboration and technical teams. This work was supported in part by the Polish National Science Center under Contract No. UMO-2015/18/E/ST2/00217 and under Contract No. UMO-2015/18/M/ST2/00523, by the Spanish MINECO via FPA2015-65035-P project, by the Portuguese FCT via CERN/FIS-NUC/0004/2015 and CERN-FIS-PAR-0005-2017 projects. The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 654002.