Suchergebnisse

5 pages, 2 tables, 3 figures.--PACS nrs.: 23.40.Hc; 27.20.+n. ; The beta decay of O-13 has been studied at the IGISOL facility of the Jyvaskyla accelerator centre (Finland). By developing a low-energy isotope-separated beam of O-13 and using a modern segmented charged-particle detector array an improved measurement of the delayed proton spectrum was possible. Protons with energy up to more than 12 MeV are measured and the corresponding log(ft) values extracted. A revised decay scheme is constructed. The connection to molecular states and the shell model is discussed. ; This work 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 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 FPA2002-04181-C04-02, and by the EU-RI3 (Integrated Infrastructure Initiative) under contract no 506065. ; Peer reviewed

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.'' ; Peer reviewed

12 pages, 5 figures, 3 tables.-- PACS nrs.: 23.40.Hc; 27.20.+n.-- Printed version published Sep 15, 2008.-- ArXiv pre-print available at: http://arxiv.org/abs/0806.3025 ; The β-delayed charged particle emission from Li-11 has been studied with emphasis on the three-body nαHe-6 and five-body 2α3n channels from the 10.59 and 18.15 MeV states in Be-11. Monte Carlo simulations using an R-matrix formalism lead to the conclusion that the He-A resonance states play a significant role in the break-up of these states. The results exclude an earlier assumption of a phase-space description of the break-up process of the 18.15 MeV state. Evidence for extra sequential decay paths is found for both states. ; This work has been supported by the Spanish CICYT, under the projects FPA2002-04181-C04-02, FPA2005-02379 and theMEC Consolider project CSD2007-00042, the European Union Sixth Framework through RII3-EURONS (contract No. 506065) and the Swedish Knut and Alice Wallenberg Foundation. M. Madurga acknowledges the support of the Spanish MEC under the FPU program, FPU AP-2004-0002. ; Peer reviewed

5 pages, 1 table, 3 figures.-- PACS nrs.: 23.40.Hc; 27.20.+n; 21.10.Hw.-- Printed version published Jun 29, 2009.-- ArXiv available at: http://arxiv.org/abs/0904.4212v1 ; Coincidences between charged particles emitted in the β-decay of 11Li were observed using highly segmented detectors. The breakup channels involving three particles were studied in full kinematics allowing for the reconstruction of the excitation energy of the 11Be states participating in the decay. In particular, the contribution of a previously unobserved state at 16.3 MeV in 11Be has been identified selecting the α + 7He → α + 6He + n channel. The angular correlations between the α particle and the center of mass of the 6He + n system favors spin and parity assignment of 3/2− for this state as well as for the previously known state at 18 MeV. ; This work has been supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), under the projects FPA2007-62170 and CSD2007-00042, the European Union Sixth Framework through RII3-EURONS (contract No. 506065) and the Swedish Knut and Alice Wallenberg Foundation. ; Peer reviewed

4 pages, 3 figures, 1 table.-- PACS nrs.: 21.10.Tg; 23.40.−s; 27.40.+z. ; The Advanced-Time-Delayed method was used to measure lifetimes of the states in Ar-41 populated in the β decay of Cl-41. The nuclei Cl-41 were produced at ISOLDE by 1.4-GeV proton bombardment of a thick UCx target and mass-separated as molecular ions, XeCl+. Our measured half-life of the 167.1-keV state, T(1/2) = 315(15) ps, is significantly lower than the previously measured value of 410(30) ps. We have also determined T(1/2) = 260(80) ps and T(1/2) ≤ 46 ps for the 515.9- and 1867.7-keV states, respectively. These are the shortest lifetimes measured so far with the ultrafast timing method using the new LaBr3(Ce) crystals for γ-ray detection. ; This work was performed as part of an undergraduate research project (ERW) at the Physics Department of the University of Notre Dame. Fast-timing detectors and electronics were provided by the Fast Timing Pool of Electronics. This study was supported in part by the NSF PHY04-57120, Swedish Research Council, BMBF Grant No. 06KY205I, the Alexander von Humboldt Foundation (WBW), Foundation for Polish Science (AK), the European Union Sixth Framework through RII3-EURONS (Contract No. 506065), and the EURTD project TARGISOL (HPRI-CT-2001-50033). ; Peer reviewed

Background: Neutron-rich nuclei with protons in the fp shell show an onset of collectivity around N=40. Spectroscopic information is required to understand the underlying mechanism and to determine the relevant terms of the nucleon-nucleon interaction that are responsible for the evolution of the shell structure in this mass region. Methods: We report on the lifetime measurement of the first 2+ and 4+ states in 70,72 ,74Zn and the first 6+ state in 72Zn using the recoil distance Doppler shift method. The experiment was carried out at the INFN Laboratory of Legnaro with the AGATA demonstrator, first phase of the Advanced Gamma Tracking Array of highly segmented, high-purity germanium detectors coupled to the PRISMA magnetic spectrometer. The excited states of the nuclei of interest were populated in the deep inelastic scattering of a 76Ge beam impinging on a 238U target. Results: The maximum of collectivity along the chain of Zn isotopes is observed for 72Zn at N=42. An unexpectedly long lifetime of 20-5.2+1.8 ps was measured for the 4+ state in 74Zn. Conclusions: Our results lead to small values of the B(E2;41+→21+)/B(E2;21+→01+) ratio for 72,74Zn, suggesting a significant noncollective contribution to these excitations. These experimental results are not reproduced by state-of-the-art microscopic models and call for lifetime measurements beyond the first 2+ state in heavy zinc and nickel isotopes. © 2013 American Physical Society. ; This work has been partly financed by the European Union Seventh Framework Program FP7/2007-2013 under Grant Agreement No. 262010 ENSAR, the Polish MNiSW under Grant No. DPN/N190/AGATA/2009, the Spanish Ministerio de Ciencia e Innovacion under Contract No. FPA2011-29854-C04, and ´ the BMBF under Grant Nos. 05P12RDFN8 and 06DA9040I. ; Peer Reviewed

6 pags., 3 figs., 1 tab. ; The structure and B(E1) transition strength of 19B are investigated in a 17B+n+n model, triggered by a recent experiment showing that 19B exhibits a well-pronounced two-neutron halo structure. Preliminary analysis of the experimental data was performed by employing contact n¿n interactions, which are known to underestimate the s-wave content in other halo nuclei, such as 11Li. In the present Rapid Communication, the three-body hyperspherical formalism with finite-range two-body interactions is used to describe 19B. In particular, two different finite-range n¿n interactions will be used as well as a simple central Gaussian potential whose range is progressively reduced. The purpose is to determine the main properties of the nucleus and investigate how they change when using contactlike n¿n potentials. Special attention is also paid to the dependence on the prescription used to account for three-body effects, i.e., a three-body force or a density-dependent n¿n potential. We have found that the three-body model plus finite-range potentials provide a description of 19B consistent with the experimental data. The results are essentially independent of the short-distance details of the two-body potentials, giving rise to a (s1/2)2 content of about 55%, clearly larger than the initial estimates. Very little dependence has been found as well on the prescription used for the three-body effects. The total computed B(E1) strength is compatible with the experimental result, although we slightly overestimate the data around the low-energy peak of the dB(E1)/d¿ distribution. Finally, we show that a reduction of the n¿n interaction range produces a significant reduction of the s-wave contribution, which then should be expected in calculations using contact interactions. ; This work has been partially supported by SID funds 2019 (Università degli Studi di Padova, Italy) under Project No. CASA_SID19_01, by the Spanish Ministry of Science, Innovation and University MCIU/AEI/FEDER,UE (Spain) under Contract No. PGC2018-093636-B-I00, and by the European Union's Horizon 2020 Research and Innovation Program under Grant Agreement No. 654002 (ENSAR2).

PurposeThe purpose of this paper is to investigate the association between ownership structure and the properties of analysts' forecasts in China's unique corporate setting.Design/methodology/approachMultiple regression models were used to examine the influence of ownership structure mechanisms on analysts' forecast properties for listed Chinese firms during the period 2008-2012.FindingsThe paper finds that analysts' forecast accuracy is higher for listed firms with high levels of foreign ownership and managerial ownership. However, the complex pyramidal ownership structure could make corporate information less transparent and then increase the complexity of forecasting; hence, it results in less precise analysts' forecasts. Interestingly, the relationship between state ownership and analysts' forecast properties appears to be non-linear (an inverted U-shape), and the inflection point at which the relationship becomes negative occurs at state ownership over 45 per cent.Originality/valueTo the best of the author's knowledge, this paper is the first to investigate the influence of ownership structure mechanisms on the properties of analysts' forecasts in an emerging market, and the findings provide some insight on how the properties of analysts' forecast might be shaped by certain ownership and control features in the context of concentrated state ownership and complex pyramidal ownership structure.

The effects of short-range correlation on elastic Coulomb (charge) form factors, charge density distributions as well as root mean square charge radii of various nuclei (for instance, 46, 48, 50Ti, 52, 54Cr, 56, 58Fe, and 72, 74, 76Ge nuclei) are examined. The one- and two body terms of the cluster expansion together with the single-particle harmonic oscillator wave functions are utilized. For the purpose of embedding these effects into the formulae of charge density and form factor we employ the correlation function of Jastrow-type. These formulae depend upon the short-range correlation parameter (which instigates from the Jastrow function) and the oscillator size parameter Both and are found by the fitting to the measured elastic form factors. It is noticed that the embedding of short-range correlation effects into the calculations of and is a requisite for the achievement of a vital change in the computed results and remarkably vital for the characterization of the measured data.

This work was supported by the German Federal Ministry of Education and Research (BMBF projects 05P2015RDFN1 and 05P15WOFNA), through the GSI-TU Darmstadt cooperation agreement, by the State of Hesse through the LOEWE center HIC for FAIR, and the Helmholtz-Gemeinschaft through the graduate school HGS-HIRe. This work was supported by the European Union by means of the European Commission within its Seventh Framework Program (FP7) via ENSAR (Contract No. 262010), and the Spanish CICYT research grants FPA2012-32443, FPA2015-64969-07387, and FPA2015-69640-C2-1-P. This work has supported by the Swedish Research Council under contract number 621-2011-5324. C.A.B. acknowledges support from the U.S. NSF grant No. 1415656 and the U.S. DOE grant No. DE-FG02-08ER41533. ; The quasi-free scattering reactions 11C(p,2p) and 10,11,12C(p,pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton-neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p,2p) and 12C(p,pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single-particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p,2p) are found to be 'significantly smaller than for (p,pn) reactions for all investigated nuclei. ; publishersversion ; published