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10th Conference on Nuclear Physics in Astrophysics, NPA-X 2022, Geneva, Switzerland, 5 Sep 2022 - 9 Sep 2022; The European physical journal / Web of Conferences 279, 04003 (2023). doi:10.1051/epjconf/202327904003, Published by EDP Sciences, Les Ulis

10 pags., 8 figs., 4 tabs., The nature of the and excited states in is studied using the transfer reaction in inverse kinematics at 10A MeV at TRIUMF ISAC-II, in particular to assess whether either of them can be considered as an excited halo state. The angular distributions for both states are extracted using deuteron- coincidences and analyzed using a transfer model taking into account one-step and two-step processes. A good fit of the angular distributions is obtained considering only the one-step process, whereby an inner neutron of is removed, leaving the halo neutron intact. Higher-order processes however cannot be rejected. The small spectroscopic factors extracted suggest that the structure of both states is not uniquely halo-like, but rather display a more complex configuration mixing cluster and halo structures. Further insights are limited, as this experiment specifically probed the halo-like (but not cluster-like) configuration in both states., This work was partially supported by the U.S. Department of Energy (DOE) through Grants/Contracts No. DE-FG03-93ER40789 (Colorado School of Mines), No. DEFG02-96ER40978 (Louisiana State), No. DE-SC0021422 (Michigan State), No. DE-AC05-00OR22725 (Oak Ridge National Laboratory), the National Nuclear Security Administration (NNSA) under the Stewardship Science Academic Alliances program through U.S. DOE Cooperative Agreements No. DE-FG52-08NA28552, and the National Science Foundation under Grant No. PHY-1811815 (Michigan State). This work is also supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Innovation (CFI), the British Columbia Knowledge and Development Fund (BCKDF), the Italian National Institute for Nuclear Physics (INFN), the Spanish Ministry of Science and Innovation and FEDER funds under Projects RTI2018-098117-B-C21 and PGC2018-096994-BC21, and the Spanish Agency of Research (AEI) via Project No. PID2019-104714GB-C21.

6 pags., 4 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0, The C-12(alpha,gamma)O-16 reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced a width, gamma(11), of the bound 1(-) level in O-16 is particularly important to determine the cross section. The magnitude of gamma(11) is determined via sub-Coulomb a-transfer reactions or the beta-delayed a decay of N-16, but the latter approach is presently hampered by the lack of sufficiently precise data on the beta-decay branching ratios. Here we report improved branching ratios for the bound 1(-) level [b(beta,11) = (5.02 +/- 0.10) x 10(-2)] and for beta-delayed alpha emission [b(beta alpha) = (1.59 +/- 0.06) x 10(-5)]. Our value for b(beta alpha) is 33% larger than previously held, leading to a substantial increase in gamma(11). Our revised value for gamma(11) is in good agreement with the value obtained in a-transfer studies and the weighted average of the two gives a robust and precise determination of gamma(11), which provides significantly improved constraints on the C-12(alpha,gamma) cross section in the energy range relevant to hydrostatic He burning., This work has been supported by the European Research Council under the ERC starting Grant Long Beamtime Experiments in Nuclear Astrophysics, No. 307447, the Horizon 2020 Research and Innovation Programme under Grant Agreement No. 654002, the Spanish Ministry of Economy and Competitiveness through Projects No. FPA2015-64969- P, FPA2015-65035-P, and FPA2017-87568-P, the Romanian Institutul de Fizica Atomica Grant CERN/ISOLDE, the United Kingdom Science and Technology Facilities Council, the Fonds voor Wetenschappelijk Onderzoek- Vlaanderen (Belgium) and GOA/2010/010 (Bijzonder OnderzoeksFonds KU Leuven), the German Federal Ministry of Education and Research under Contract No. 05P15PKCIA (ISOLDE) and Verbundprojekt 05P2015. B. J. acknowledges support from The Royal Society of Arts and Sciences in Gothenburg and OSK from the Villum Foundation through Project No. 10117.

(c) Consejo Superior de Investigaciones Científicas Licencia Creative Commons 3.0 España (by-nc), Presentamos un estudio de la situación de las científicas del área de Ciencia y Tecnologías Físicas en el CSIC, El estudio incluye datos numéricos en cuanto a presencia porcentual de mujeres en las distintas escalas y comisiones de evaluación, así como testimonios personales, reflexiones y consideraciones generales. Se pone de manifiesto el bajo porcentaje de investigadoras en esta Área, Se concluye el estudio con una serie de recomendaciones.

Riisager, Karsten et al., We have observed β−β−-delayed proton emission from the neutron-rich nucleus 11Be by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3±0.9)⋅10−6(8.3±0.9)⋅10−6 the strength of this decay mode, as measured by the BGTBGT-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the 11Be halo neutron into a single-proton state., We acknowledge support from the European Union Seventh Framework through ENSAR (contract No. 262010), from Austrian Science Fund (FWF) P22164-N20, from Spanish MINECO through projects FPA2010-17142 and FPA2012-32443, and CPAN ConsoliderCSD-2007-00042.

The bound states of 12Be have been studied through a 11Be(d ,p)12Be transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be 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 12Be. The gamma-ray detection enabled a clear identification of the four known bound states in 12Be, 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. © 2013 American Physical Society., Spanish MICINN under Contracts No. FPA2010-17142 and No. FPA2012-34332.

5 p.: gráf., A measurement of the final state distribution of the 8B decay, obtained by implanting a 8B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyväskylä[O. S. Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fits. Combined with the IGISOL data, this leads to an improvement of the overall errors and the extension of the neutrino spectrum at high energy. The new unperturbed neutrino spectrum represents a benchmark for future measurements of the solar neutrino flux as a function of energy., Supported by FWO-Vlaanderen(Belgium), the IUAP-Belgian State Belgian Science Policy (BriX network P6/23), the Dutch FOM program 114 (TRI P), the European Union—Research Infrastructure Action under the FP6 ‘‘Structuring theEuropean Research Area’’ Program, and the Spanish projects FPA2009-07387, FPA2010-17142 and CSD2007-00042.

We report on the observation of α decay from a state in 10B at 11.48 MeV. The only observed decay branch is to the first T=1 state in 6Li at 3.56 MeV. The apparent absence of an α-decay branch to the (T=0) ground state in 6Li suggests that the 11.48-MeV state should be assigned isospin T=1. The spin and parity of the 11.48-MeV state could not be directly determined from the present study apart from J=0 being ruled out by the observed angular correlation. We conjecture that the 11.48-MeV state is the analog of the 10.15-MeV, (4 +) state in 10Be, constitutes the third member of a rotational band built on the 0 + state at 7.65 MeV, and has pronounced molecular structure. © 2012 American Physical Society., Support of the Spanish CICYT research Grant No. FPA2009-07387 and the MICINN Consolider Project No. CSD 2007-00042 as well as the support of the European Union VI Framework through RII3-EURONS/JRA4-DLEP (Contract No. 506065). OSK acknowledges support from the Villum Kann Rasmussen Foundation.

8 páginas, 8 figuras.-- et al., Experimental results of the elastic scattering of 6He on 208Pb at ELAB=22 MeV, measured at the CRC facility (Louvain-la-Neuve, Belgium), are presented, including results on the 4He production channel. These data were taken with full angular coverage and high angular resolution. Both experimental cross sections are compared with continuum discretized coupled channels and distorted-wave Born approximation calculations, where direct breakup and transfer to the continuum processes are considered. The elastic data confirm the absence of the Coulomb rainbow, while the distribution of α particles indicates that such production is mostly generated by transfer to the continuum., This work has been supported by the Spanish MICINN under projects FPA2005-04460, FPA200502379, FPA2006-13807-c02-01, FPA2007-63074, FPA2009-07653, FPA2009- 07387 and FPA2010 22131-C02-01, by the Junta de Andalucía project FQM-4964, by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042) and Programme Multi-Dark (CSD2009-00064), by the European Community-Access to Research Infrastructure action of the Improving Human Potential Program Contract, No. HPRI-CT-1999-00110, and by the Belgian Program P5/07 on interuniversity attraction poles of the Belgian-state Federal Services for Scientific, Technical and Cultural Affairs. L. Acosta acknowledges financial support by the Universidad de Huelva.

12 páginas, 9 figuras, 3 tablas.-- et al., The reaction 8Li + 2H has been studied in inverse kinematics at the incident energy of 3.15 MeV/nucleon, using the REX-ISOLDE post-accelerator. The reaction channels corresponding to (d,p), (d,d), and (d,t) reactions populating ground states and low-lying excited states in 7 -9Li have been identified and the related angular distributions extracted and compared with coupled-channels, distorted-wave Born approximation (DWBA), and coupled-reaction-channels calculations. For the inelastic and (d,t) channels we find that higher order effects are very important and hence one needs to go beyond the simple DWBA to extract reliable structure information from these processes. © 2011 American Physical Society., The financial support of the Swedish Research Council for this work under Grant No. 2008-4158 is gratefully acknowledged, as well as support by the Lars Hierta Memorial Foundation. T. Nilsson acknowledges support through the Royal Swedish Academy of Sciences Research program by a grant from the Knut and Alice Wallenberg Foundation. This work is partially supported by the Spanish Ministerio de Ciencia e Innovacion under Projects No. FPA2006-13807- ´ C02-01, No. FPA2009-08848, No. FPA2009-07653, No. FPA2009-07387, and No. FPA2010-17142 and by the European Union Sixth Framework through RII3-EURONS (Contract No. 506065).

Comunicación presentada al "International scientific meeting on nuclear physics: basic concepts in nuclear physics: theory, experiments and applications" celebrado del 4 al 10 de julio del 2009 en La Rábida (España).-- et al., We measured the scattering of the halo nucleus Li-11 and its core Li-9 on the lead target at TRIUMF at energies below and around to the Coulomb barrier. We report here on our preliminary analysis of the inclusive breakup reaction.

The β decays of N12 and B12 have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2 + strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the N12 Q-value window suggests the presence of additional 0+ and 2 + components in the C12 structure at energies above 12.7 MeV. © 2010 The American Physical Society., Supported by the Academy of Finland (Project No. 44875), by the Spanish Agency CICYT (Nos. FPA2005-02379 and FPA2007-62216) and MEC Consolider Project No. CSD2007-00042, by the Belgian IAP P6/23 project and FWO-Vlaanderen, by the European Union sixth Framework Programme “EURONS”(No. 506065), and by the Swedish Research Council and the Knut and Alice Wallenberg Foundation. T.N. is a Royal Swedish Academy of Sciences Research Fellow supported by a grant from the Knut and Alice Wallenberg Foundation. The work at KVI was performed as part of Program 48 (TRIµP) of the Stichting voor Fundamenteel Onderzoek der Materie (FOM).

The reaction 3He+11B→d+12C* has been used to populate resonances in C12 up to an excitation energy of 15 MeV. The subsequent breakup to three α particles has been measured in complete kinematics. Dalitz plots are used to visualize and analyze the data. The Dalitz plot intensity distribution exhibits zero points characteristic of the total spin and parity of the 3α system allowing us to determine the spin and parity of a state in C12 at 13.35 MeV whose quantum numbers were hitherto not well established. The Dalitz plot intensity distributions of the 2- state at 11.83 MeV and the 1 + state at 12.71 MeV are compared with the predictions of a recent three-body calculation as well as with simpler models. All are able to reproduce the gross structures seen in the Dalitz plot, but none give an accurate description of the detailed profile of the distributions. © 2010 The American Physical Society., support of the Spanish CICYT research grant FPA2007-62170 and the MICINN Consolider Project CSD 2007-00042 as well as the support of the European Union VI Framework through RII3-EURONS/JRA4-DLEP (Contract No. 506065)

The triple-α-particle breakup of states in the triple-α continuum of C12 has been investigated by way of coincident detection of all three α particles of the breakup. The states have been fed in the β decay of N12 and B12, and the α particles measured using a setup that covers all of the triple-α phase space. Contributions from the breakup through the Be8(0+) ground state as well as other channels-interpreted as breakup through excited energies in Be8-have been identified. Spins and parities of C12 triple-α continuum states are deduced from the measured phase-space distributions for breakup through Be8 above the ground state by comparison to a fully symmetrized sequential R-matrix description of the breakup. At around 10 MeV in C12, the breakup is found to be dominated by 0+ strength breaking up through the ghost of the Be8(0+) ground state with L=0 angular momentum between the first emitted α particle and the intermediate Be8 nucleus. For C12 energies above the 12.7 MeV 1+ state, however, L=2 breakup of a C12 2+ state through the Be8(2+) excited state dominates. Furthermore, the possibility of a 2+ excited state in the 9-12 MeV region of C12 is investigated. © 2009 The American Physical Society., Supported by the Academy of Finland under the Finnish Center of Excellence Programme 2000–2005 (Project No. 44875, Nuclear and Condensed Matter Physics Programme at JYFL); by the European Union Fifth Framework Programme “Improving Human Potential—Access to Research Infrastructure,” Contract No. HPRI-CT-1999-00044; by the Spanish CICYT Agency under project number FPA2007-62170 and the MICINN Consolider project CSD2007-00042; and by the EU-RI3 (Integgrated Infrastructure Initiative) under Contract No. 506065.

Absolute branching ratios to unbound states in C12 populated in the β decays of N12 and B12 are reported. Clean sources of N12 and B12 were obtained using the isotope separation on-line (ISOL) method. The relative branching ratios to the different populated states were extracted using single-alpha as well as complete kinematics triple-alpha spectra. These two largely independent methods give consistent results. Absolute normalization is achieved via the precisely known absolute branching ratio to the bound 4.44 MeV state in C12. The extracted branching ratios to the unbound states are a factor of three more precise than previous measurements. Branching ratios in the decay of Na20 are also extracted and used to check the results. © 2009 The American Physical Society., Supported by the Academy of Finland (Project No. 44875), by the Spanish Agency CICYT (Nos. FPA2007–62170 and FPA2007–62216), by the European Union Sixth Framework Programme “EURONS” (No. 506065), by the Swedish Research Council, and the Knut and Alice Wallenberg foundation.

New experimental data from the scattering of 6He + 208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of α particles. The energy and angular distribution of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the α particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound states of the final nucleus.

17 pages, 9 figures, 6 tables.-- PACS nrs.: 21.10.Tg; 21.10.Re; 21.10.Ky; 27.90.+b., Lifetimes of excited states in 229Th, populated in the β decay of 229Ac, have been measured using the advanced time-delayed βγ γ (t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new γ lines have been introduced into the β-decay scheme of 229Ac based on results of γγ coincidence measurements. Reduced transition probabilities have been determined for more than 70 γ transitions in 229Th. Average |D0| values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest Kπ =1/2±, 3/2±, and 5/2± parity partner bands, respectively. Excited states in 229Th and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2+ isomeric state is predicted to be about 10 h. Potential energy surfaces on the (β2, β3) plane for the lowest single quasiparticle configurations in 229Th have been calculated using the Strutinsky method., This work has been supported in part by Grant No. 1 P03B 059 27 from the Polish Committee for Scientific Research(KBN) (for theoretical calculations), the Swedish Research Council, the research plan MSM0021620834 provided by the Ministry of Education of the Czech Republic, and the Spanish CICYT under Project No. FPA2002-04181-C04-02. Support by the European Commission through the HPRI-CT-1999-00018 project and by the ISOLDE Collaboration are also acknowledged. Fast timing detectors and electronics have been provided by the Fast Timing Pool of Electronics. One of us (E.R.) would like to thank the OSIRIS group for its generous hospitality and for financial support during her stay in Studsvik.

5 pages, 10 figures.-- PACS nrs.: 21.10.Tg; 23.20.Lv; 27.30.+t.-- Issue title: "ENAM 2004, Fourth International Conference on Exotic Nuclei and Atomic Masses" (Pine Mountain, Georgia, Sep 12-16, 2004)., The fast timing βγγ(t) method was applied to investigate the level lifetimes in 30,31,32Mg. Levels in Mg have been populated in β and β-delayed neutron emission of Na, at the ISOLDE facility. From the γγ coincidences a number of new states have been identified and new level schemes were constructed for 30 31,32Mg. The following preliminary half lives have been determined: T-1/2 = 3.9(4) ns for the 1789 keV state in 30Mg, T-1/2 = 133(8) ps and 10.5(8) ns for the 221 keV and 461 keV states in 31Mg, respectively, and T-1/2 = 16(4) ps for the 885 keV level in 32Mg. The 1789 keV level was established as a candidate for the intruder 0(+) configuration in 30Mg with a possible strong E0 branch to the ground state.

10 pages, 2 tables, 10 figures.--PACS nrs.: 21.10.-k; 24.30.-v; 27.30.+t, An excitation function for resonance elastic scattering of alpha particles on O-18 and Ne-18 was measured using the method of inverse geometry with a very thick target. Spectroscopic information was obtained for 23 levels in the excitation energy region from 11.9 to 13.7 MeV in Ne-22. Twelve of them are new. General features of a-cluster bands in Ne-22 are analyzed in the framework of the potential model with a deep potential well. Predictions for the 11(-) level in Ne-22, as well as for the isotopic shift of the cluster levels in Mg-22, are given. Evidence is presented that new perspectives on the study of nuclear structure and nuclear spectroscopy can be obtained in complimentary measurements of alpha-cluster states in mirror Nnot equalZ nuclei., This work was supported by NSF Grant Nos. PHY99-01133 and PHY02-030099, RFBR Grant No. 00-02-17401, U.S. DOE Grant No. DE-FG03-93ER40773, and European Community-Access to Research Infrastructure action of the Improving Human Potential Programme, Contract No.HPRI-CT-1999-00110.

4 pages, 1 table, 3 figures.--PACS nrs.: 27.10.+h; 21.10.Pc; 25.60.Gc, The one-proton knockout channel from He-6 (240 MeV/u) impinging on a carbon target has been investigated. The triton fragments originating from this channel were detected in coincidence with the two neutrons. A broad structure, peaked at 3 MeV above the t+2n threshold, is observed in the t+n+n-relative energy spectrum. It is shown that this structure is mainly due to a I-pi=1/2(+) resonance as expected for the H-5 ground state, and from the observed angular and energy correlations, being used for the first time in H-5 studies, that the neutrons to a large extent occupy the p shell., This work was supported by the BMBF under Contracts No. 06 DA 925 I, No. 06 OF 838, and No. 06 MZ 864 I, and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts No. DARIC, No. OF ELZ, No. MZ KRAK, and partly supported by the Polish Committee of Scientific Research under Contract No. KBN/2P03B/144/10, CICYT under Contract No. AEN99-1046-C02-02 (M. J.G. B., O.T.), RFBR under Contract No. 01-02-16685, and EC under Contract No. ERBCHGE-CT92-0003. One of us (B. J.) acknowledges support from the Alexander von Humboldt Research Foundation.

4 pages, 2 figures.--PACS nrs.: 21.45.+v; 23.40.–s; 27.20.+n., Using beta decays of a clean source of N-13 produced at the IGISOL facility, we have measured the breakup of the C-12 (12.71 MeV) state into three alpha particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed., This research was supported by the Academy of Finland under the Finnish Centre of Excellence Programme 2000-2005 (Project No. 44875, Nuclear and Condensed Matter Physics Programme at JYFL), by the Spanish Agency CICYT under Contract No. AEN99-1046-C02-02, and by the European Union Fifth Framework Programme ‘‘Improving Human Potential–Access to Research Infrastructure.’’

4 pages, 3 figures.-- PACS nrs.: 27.20.+n, 24.30.Gd, 25.60.Dz, 25.60.Gc., The two-neutron halo nucleus Be-14 has been investigated in a kinematically complete measurement of the fragments (Be-12 and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra were measured, and the contributions from electromagnetic dissociation (EMD) were deduced. Comparison with three-body model calculations suggests that the halo wave function contains a large nu(2s(1/2))(2) admixture. The EMD invariant mass spectrum exhibited enhanced strength near threshold consistent with a nonresonant soft-dipole excitation., The authors are grateful to the support provided by the technical and operations staff of LPC and GANIL. Discussions with Ian Thompson and Pierre Descouvemont are also acknowledged.

11 pages, 1 table, 2 figures., The process of β-delayed two-proton emission has attracted much interest over the past two decades, since it was hoped that the study of this process would provide information on correlations inside nuclei. At ISOLDE Ar-31 has been extensively studied in three experiments during the past decade. We review these studies by comparing the new physics results that have emerged from the different experiments and by highlighting the technical development leading to these results. The β-delayed two-proton emission is, in most cases, simply an extension of β-delayed single proton emission to high lying states that are unstable to proton emission, thus no sign of correlations has been seen., We would like to thank our many co-workers in the IS339 collaboration at ISOLDE and also the staff at ISOLDE for providing excellent beams for research.

12 pages, 6 figures, 2 tables., The positron-neutrino correlation in the 0(+) --> 0(+) β-decay of Ar-32 was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the super-allowed decay. Our result is consistent with the standard model prediction; for vanishing Fierz interference we find a = 0.9989 ± 0.0052 ± 0.0039. Our result leads to improved constraints on scalar weak interactions. The positron-neutrino correlation in Ar-33 decay was measured in the same experiment; for vanishing Fierz interference we find a = 0.944 ± 0.002 ± 0.003. The Ar-32 and Ar-33 correlations, in combination with precision measurements of the half-lives, super-allowed branching ratios and beta endpoint energies, will determine the isospin impurities of the super-allowed transitions. These will provide useful tests of isospin-violation corrections used in deducing |V-ud| which currently indicates non-unitarity of the KM matrix., This work was supported in part by the USA National Science Foundation and the Warren Foundation (at the University of Notre Dame) and by the Department of Energy (at the University of Washington).

23 pages, 10 figures.-- PACS nrs.: 23.40.Hc; 27.30.+t.-- Printed version published on Sep 11, 2000., We have measured the beta-decay of Ar-31 with a high granularity setup sensitive to multiparticle decay branches. Two-proton emission is observed from the isobaric analog state in Cl-31 to the four lowest states in P-29 and furthermore from a large number of states fed in Gamow-Teller transitions. The mechanism of two-proton emission is studied via energy and angular correlations between the two protons. In all cases the mechanism is found to be sequential yielding information about states in S-30 up to 8 MeV excitation energy. Improved data on the beta-delayed one-proton branches together with the two-proton data provide precise information about the beta-strength distribution up to 15 MeV excitation energy., This work was supported in part by the Spanish agency CICYT under contract number AEN96-1679. I. Piqueras thanks the Svenska Institutet for a Guest Scholarship.

5 pages, 3 figures, 1 table.-- PACS nrs.: 21.10.Hw; 23.40.Bw; 23.90.+w; 27.30.+t., The beta-delayed proton emission from the lightest Ar-isotopes has been recorded with a high-granularity, large solid-angle Si-detector set-up. Proton energy shifts due to beta-recoil have been measured. We demonstrate how this allows the spin of Ar-31 to be determined as 5/2. The method can be applied at decay rates as low as 1 s(-1).

36 pages, 5 tables, 9 figures.-- PACS nrs.: 23.20.−g; 21.10.Tg; 21.10.Re; 27.90.+b., The structure of Ra-229 has been studied in the β- decay of Fr-229. Spins and parities have been determined from the conversion electron measurements, while half-lives for the 137.5, 142.7, 168.8, 213.0 and 479.0 keV levels have been measured in the ps and ns ranges via the fast timing βγγ(t) method. Our data confirm the previous results and enrich the knowledge of the structure of this nucleus by 25 new states and several strong transitions. Structural similarities are established between Ra-229 and its N = 141 isotone Th-231. The experimental results are compared with the theoretical predictions of the quasiparticle-phonon model with inclusion of Coriolis coupling. The reduced transition probabilities, and especially the moderately fast B(E1) rate for the 137.5 keV transition connecting the band-heads of the K-π = 5/2(±) parity doublet bands, reveal the presence of significant octupole correlations in Ra-229., This work was partially supported by the Spanish CICYT "Plan National de Altas Energias" (under contracts AEN96-1662 and AEN96-1679), the Margit & Folke Pehrzon Foundation, the Swedish Natural Science Research Council, Czech Republic Grant Agency (under contract 202/96/ 1744) and the Polish Scientific Research Committee (under grant KBN-2-P03B-OOl-11).

4 pages, 1 table, 4 figures.-- PACS nrs.: 23.20.En, 13.30.Ce, 23.40.Bw, 24.80.+y.-- Erratum to this paper in: Phys. Rev. Lett. 83(15): 3101-3101 (1999)., Erratum available at: http://digital.csic.es/handle/10261/12896, The positron-neutrino correlation in the O+ -> O+ decay of Ar-32 was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the superallowed decay. Our result is consistent with the standard model prediction. For vanishing Fierz interference we find a = 0.9989 ± 0.0052 ± 0.0039, which yields improved constraints on scalar weak interactions., This work was supported in part by the DOE (at the University of Washington) and by the NSF and the Warren Foundation (at the University of Notre Dame).

7 pages, 1 table, 3 figures.-- PACS nrs.: 25.60.Gc; 27.20.+n., The longitudinal momentum distribution of Be-7 fragments after fragmentation of B-8 and the one-proton removal cross section (σ(-1p)) in a carbon target were measured at 1440 MeV/u with the fragment separator FRS used as an energy-loss spectrometer. The results show a narrow momentum distribution with a FWHM value of 91 ± 5 MeV/c and a large cross-section, σ(-1p) = 98 ± 6 mb. Both these results support the interpretation of a spatially extended proton orbit forming a halo in the B-8 ground state. The momentum distribution and the: one-proton removal cross section are shown to be reproduced with a three-body wave function for B-8 where the target is treated as a black disc in the breakup process., This work was supported by the German Federal Minister for Education and Research BMBF under Contracts 06 DA 820, 06 OF 474, and 06 MZ 476 and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts DARIK, OF ELK, and MZ KRK. It was partly supported by the Polish Committee of Scientific Research under Contract PB2/P03B/113/09, EC under Contract ERBCHGE-CT92-0003, CICYT under Contract AEN96-1679 (MJGB, LMF), and by Deutsche Forschungsgemeinschaft (DFG)under Contract 436 RUS 130/127/1 and Le-439/1. One of us (B.J.) acknowledges the support through an Alexander von Humboldt Research Award.

3 pages, 2 figures, 1 table.-- PACS nrs.: 23.90.+w, 23.40.Hc, 24.30.Gd, 27.30.+t., We have remeasured the decay of Ar-31 with a setup sensitive to multiparticle decay branches and obtained a new limit of 1.1 x 10(-3) (99% C.L.) on the β-delayed three-proton branch between the isobaric analog state in Cl-31 and the ground state of Si-28. This a factor of 17 below the previously reported first observation of β-delayed three-proton emission in Ar-31. The limit on a possible β3p branch to the first excited state in Si-28 is 2.9 x 10(-4).

11 pages, 2 tables, 6 figures.-- PACS nrs.: 27.20.+n; 25.60.Gc; 25.70.De; 29.30.Hs., The three-body breakup He-6 --> He-4 + n + n is studied experimentally, using a secondary He-6 ion beam of 240 MeV/nucleon incident on carbon and lead targets. integrated cross sections for one- and two-neutron knockout and differential cross sections dσ/dE* and dσ/dΘ for inelastic nuclear or electromagnetic excitations into the He-6 continuum are presented. The E1-strength distribution is deduced from electromagnetic cross sections and is found to exhaust (10 ± 2)% of the energy-weighted Thomas-Reichr-Kuhn sum rule or (40 ± 8)% of the cluster sum rule for excitation energies below 5 MeV. Both the energy-weighted and non-energy-weighted dipole cluster sum rules are almost exhausted integrating the strength up to 10 MeV, a fact from which the root-mean-square distance between the a core and the two valence neutrons of r(α-2n) = (3.36 ± 0.39) fm is derived. The known I(π) = 2(+) (1.80 MeV) resonance in He-6 is observed in nuclear inelastic scattering; model-dependent values of the quadrupole deformation parameter δ(2) = (1.7 ± 0.3) fm or B (E2,0(+) --> 2(+)) = (3.2 ± 0.6)e(2) fm(4) are derived. No clear signature could be obtained for predicted higher-lying 2(+) resonances, but low-lying continuum strength of multipolarity other than dipole, likely of monopole and quadrupole multipolarity, is indicated by the data. Two-body correlations in the decaying He-4 + n + n system are investigated. The astrophysical relevance of the data with regard to the two-neutron capture process He-4(2n, γ) He-6 is briefly discussed., This work was supported by the German Federal Minister for Education and Research (BMBF) under Contracts No. 06 DA 820, 06 OF 474 and 06 MZ 864 and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts No. DARIK, No. OF ELK, MZ KRK and partly supported by the Polish Committee of Scientific Research under Contract No. PB2/P03B/113/09, EC under Contract No. ERBCHGECT92-0003, and the Spanish CICYT under Contract No. AEN92-0788-C02-02 (M.J.G.B.), and by Deutsche Forschungsgemeinschaft (DFG) under Contract No. 436 RUS 130/127/1. One of us (B.J.) acknowledges support through an Alexander von Humboldt Senior Research Scientist Award.

52 pages, 11 figures, 10 tables.-- PACS nrs.: 23.20.−g; 23.20.Lv; 25.45.Hi; 25.55.−e; 27.90.+b., Levels in Fr-225 have been studied by gamma-ray and conversion-electron spectroscopy following the beta-decay of Rn-225 and by the Ra-226(t,alpha)Fr-225 single-proton-pickup reaction. Multipolarities were obtained for ~ 50 gamma-transitions, and a level scheme was established in which definite spin-parity values were determined for over 20 of the 48 levels. Although low-lying rotational bands of both parities exist for K = 1/2 and K = 3/2, there is no experimental evidence to claim these are parity doublets. E1 strengths connecting the K-π = 3/2(±) bands are intermediate between those for nuclides which are reflection symmetric and those claimed to be octupole deformed. The (t,α) cross sections are in better agreement with those predicted for the reflection-symmetric case than with those from an octupole-deformed description. These observations may be confirming theoretical predictions that octupole correlations are important in Fr-225, but that there is no large stable octupole deformation., This work was performed under the auspices of the Natural Sciences and Engineering Research Council of Canada, the German Bundesministerium ftir Forschung und Technologie, the Norges Almenvitenskapelige Forskningsrhd, the Polish Committee for Scientific Research, the US Department of Energy by Lawrence Livermore National Laboratory under Contract W-7045-ENG-48 and the Spanish CICYT under contract AEN94-0833-C02-02.

4 pages, 2 tables, 1 figure.-- PACS nrs.: 23.40.Hc, 21.10.Pc, 21.60.Cs, 23.20.Lv., New values for the γ ray intensities following the β decay of Li-11 are presented. Special emphasis is put on the determination of the Gamow-Teller transition Li-11 --> Be-11 (1/2(-), 320 keV) to the only bound excited state in Be-11. We show that a shell-model calculation can simultaneously reproduce the half-life of Li-11 and the newly measured branching ratio to the 1/2(-) state provided the Li-11 ground state wave function contains about 50% of s-wave neutron components., Financial support for this study from the Spanish CICyT (Contract AEN94-0833-C02-02) and DGICyT (Contract PB93-263) and Bundesministerium für Forschung und Technologie (contract No. 06DA665I) is gratefully acknowledged.

4 pages, 4 figures, 2 tables.-- PACS nrs.: 21.10.Pc, 25.40.Ny, 27.20.+n., Resonances in the unbound nucleus N-11 have been studied, using the resonance scattering reaction C-10+p. The data give evidence for three states above the C-10+p threshold with energies 1.30, 2.04, and 3.72 MeV. These states can be interpreted, in a potential-model analysis, as the ground state and the first two excited states with spin-parity 1/2(+), 1/2(-), and 5/2(+) arising from the shell-model orbitals 1s(1/2), Op(1/2), and Od(5/2). A narrow state superposed on a broad structure found at higher energy could be interpreted as the mirror state of the 3/2(-) in Be-11 shifted down in energy. This shift would suggest a large radius of the potential., We acknowledge financial support from the European Community under Contract No. CHGE-CT94-0056 (Human Capital and Mobility, Access to the GANIL large scale facility) and from the Russian Foundation RFFI.

4 pages, 3 figures.-- PACS nrs.: 25.60.+v, 21.10.Pc, 25.70.Mn, 27.20.+n., Reactions of the halo systems Be-11 and Li-11 (at 460 and 280 MeV/nucleon) with a carbon target demonstrate that (n + Li-9) has an (unbound) l = 0 ground state very close to the threshold. The neutron halo of Li-11 has appreciable (1s(1/2))(2) and (0p(1/2))(2) components., This work was supported by the German Federal Minister for Research and Technology (BMFT) under Contracts No. 06 DA 641 1, No. 06 Bü 103, and No. 06 MZ 465 and by GSI via Hochschulzusammenarbeitsvereinbarugen under Contracts No. DA RICK, BO FRE, F ELE, MZ Krak, and partly supported by the Polish Committee of Scientific Research under Contraet No. PB1158/P3/92/02.

4 pages, 3 figures, 2 tables., Extremely neutron-rich nuclei exhibit a number of interesting features of which the most well-known is the neutron halo phenomenon found in 11Li. See e.g. ref. [1] for a recent review. A much less investigated nucleus is 8He, although it is the nucleus with the highest A/Z-ratio that is still stable against particle emission. In the first experiment where evidence for an anomalously large matter radius in 11Li was seen [2], similar effects were also found in 6He and 8He. The extended neutron distribution has previously mainly been probed in dissociation experiments [3] at 800 MeV/u. We present here further information on reactions involving 8He.

4 pags.; 6 figs.; 1 tab.; Open Access funded by Creative Commons Atribution Licence 4.0, © 2015 The Authors. We have observed β+-delayed α and pα emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of βpα emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd–even effects., We acknowledge support from the European Union Seventh Framework through ENSAR (contract no. 262010) and by the Spanish research agency under number FPA2012-32443.

Forty-eight transition probabilities for lines belonging to the 4p-ns (n=6,7,8,9) transition arrays of Ar(I) have been determined by means of emission-line-intensity measurements. The single-photon delayed-coincidence method has been used to obtain the lifetime values of the ns(3/2)2 (n=6,7,8,9) levels. With the taking into account of these lifetimes together with theoretical calculation in jK coupling for the lines beyond the experimental range, the relative transition probabilities were put on an absolute scale. The lifetime values obtained in the present work are original in the literature excepting the 7s (3/2)2-level lifetime. Four transition probabilities are also the first values found in the literature.

23 pages, 4 tables, 10 figures., The structure of excited states in Sn-132, fed in the β-decay of In-132, has been investigated. Absolute intensities were deduced from γ-singles measurements. From multi-spectrum analysis of γ-lines the half-life of In-132 was determined to be 186 ± 22 ms. A level scheme based on γγ and βγ coincidences is presented. The conversion electron spectrum has been studied and internal conversion coefficients deduced for two low-energy transitions. The total decay energy of In-132 was determined, from γ-gated β-spectra, to be Q(β) = 13.6 ± 0.4 MeV. A lower limit of 6.968 MeV for the neutron separation energy in Sn-132 was deduced from the β-delayed neutron spectrum. The experimental results on the level structure of the doubly closed shell nucleus Sn-132 show that the shell model is applicable even far from the valley of stability.

20 pages, 7 tables, 8 figures., The beta-delayed proton and alpha spectra from 17Ne have been studied with Si-detectors. The Gamow-Teller strength in the decay of 17Ne has been extracted and compared with a two-particle-one-hole shell-model calculation. The experimental strength is quenched by a factor of 0.82 with respect to the calculated one. Furthermore, the decay scheme has been improved and is discussed in some detail. The proton emitting levels in 17F are very broad and the line shapes are strongly influenced by phase-space effects. Interference between peaks corresponding to the same intermediate spin is a prominent feature emerging clearly with the good resolution and statistics of the present work., Supported by the German Federal Minister for Research and Technology (BMFT) under the contract number 06DA454.