Suchergebnisse

22 pags., 8 figs., 4 tabs., 1 app. ; A dedicated spectroscopic study of the β decay of Cd127 was conducted at the IGISOL facility at the University of Jyväskylä. Following high-resolution mass separation in a Penning trap, β-γ-γ coincidences were used to considerably extend the decay scheme of In127. The β-decaying 3/2+ and 11/2- states in Cd127 have been identified with the Cd127 ground state and the 283-keV isomer. Their respective half-lives have been measured to 0.45(812)s and 0.36(4) s. The experimentally observed β feeding to excited states of In127 and the decay scheme of In127 are discussed in conjunction with large-scale shell-model calculations. ; The authors thank the accelerator staff at the University of Jyväskylä. This work is supported by the European Union's Horizon 2020 research and innovation programme Grant No. 654002 (ENSAR2), the Swedish Research Council (VR 2013- 4271), the Knut and Alice Wallenberg foundation (KAW 2015.0021), the Academy of Finland under the Finnish Centre of Excellence Program (Nuclear and Accelerator Based Physics Research at JYFL 2012-2017), and the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2017-84756-C4-2-P. The support from the Academy of Finland under Grants No. 275389, No. 284516, No. 312544, and No. 295207 is acknowledged. A.K. and L.C. acknowledge the funding from the European Union's Horizon 2020 research and innovation program under Grant No. 771036 (ERC CoG MAIDEN). U.F. acknowledges support from the Birgit and Hellmuth Hertz Foundation of the Royal Physiographic Society in Lund.

6 pags., 8 figs., 3 tabs. ; CALIFA is the high efficiency and energy resolution calorimeter for the RB experiment at FAIR, intended for detecting high energy light charged particles and gamma rays in scattering experiments, and is being commissioned during the Phase-0 experiments at FAIR, between 2018 and 2020. It surrounds the reaction target in a segmented configuration with 2432 detection units made of long CsI(Tl) finger-shaped scintillator crystals. CALIFA has a 10 year intended operational lifetime as the RB calorimeter, necessitating measures to be taken to ensure enduring performance. In this paper we present a systematic study of two groups of 6 different detection units of the CALIFA detector after more than four years of operation. The energy resolution and light output yield are evaluated under different conditions. Tests cover the aging of the first detector units assembled and investigates recovery procedures for degraded detection units. A possible reason for the observed degradation is given, pointing to the crystal-APD coupling. ; This work has been financially supported by the European Union Horizon 2020 research and innovation programme under grants agree-ments No 262010 (ENSAR) and No 654002 (ENSAR2), the Spanish MICCIN grants FPA47831-C2-1P and FPA2015-69640-C2-1-P, by the Plan Galego de Investigación, Innovación e Crecemento (I2C) of Xunta de Galicia, Spain under projects POS-B/2016/015, GRC2013-011 andED431C 2017/54 and by the German BMBF (No. 05P19RDFN1), TUDarmstadt - GSI cooperation contract, HIC for FAIR.

7 pags., 4 figs., 2 tabs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; The quasi-free scattering reactions C(p,2p) and C(p,pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the RB-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 C(p,2p) and C(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. ; 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. Supported by the Portuguese FCT under the project PTDC/FIS/ 103902/2008.

19 pags., 14 figs., 3 tabs. ; A γ-ray spectroscopic study of Po212 was performed at the Grand Accélérateur National d'Ions Lourds, using the inverse kinematics α-transfer reaction C12(Pb208,Po212)Be8 and the AGATA spectrometer. A careful analysis based on γγ coincidence relations allowed us to establish 14 new excited states in the energy range between 1.9 and 3.3 MeV. None of these states, however, can be considered as candidates for the levels with spins and parities of 1- and 2- and excitation energies below 2.1 MeV, which have been predicted by recent α-cluster model calculations. A systematic comparison of the experimentally established excitation scheme of Po212 with shell-model calculations was performed. This comparison suggests that the six states with excitation energies (spins and parities) of 1744 (4-), 1751 (8-), 1787 (6-), 1946 (4-), 1986 (8-), and 2016 (6-) keV, which previously were interpreted as α-cluster states, may in fact be of positive parity and belong to low-lying shell-model multiplets. This reinterpretation of the structure of Po212 is supported by experimental information with respect to the linear polarization of γ rays, which suggests a magnetic character of the 432-keV γ ray decaying from the state at an excitation energy of 1787 keV to the 61+ yrast state, and exclusive reaction cross sections. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 654002 and FEDER funds. We furthermore acknowledge support from the Spanish Ministerio de Ciencia, Inovación y Universidades under contracts FPA2014-57196-C5, FPA2017-84756-C4, and SEV-2014-0398, the Generalitat Valenciana under Grant No. PROMETEO/2019/005, the Swedish Research Council (Vetenskapsrådet, VR 2016-3969), and the German BMBF under Contracts No. 05P18PKFN9 and No. 05P19PKFNA. ; Peer reviewed