Suchergebnisse

7 pags., 4 figs., 1 tab. ; Exclusive cross sections and momentum distributions have been measured for quasifree one-neutron knockout reactions from a Ca54 beam striking on a liquid hydrogen target at ∼200 MeV/u. A significantly larger cross section to the p3/2 state compared to the f5/2 state observed in the excitation of Ca53 provides direct evidence for the nature of the N=34 shell closure. This finding corroborates the arising of a new shell closure in neutron-rich calcium isotopes. The distorted-wave impulse approximation reaction formalism with shell model calculations using the effective GXPF1Bs interaction and ab initio calculations concur our experimental findings. Obtained transverse and parallel momentum distributions demonstrate the sensitivity of quasifree one-neutron knockout in inverse kinematics on a thick liquid hydrogen target with the reaction vertex reconstructed to final state spin-parity assignments. ; We would like to express our gratitude to the RIKEN Nishina Center accelerator staff for providing the stable and high-intensity beam andtotheBigRIPSteam for operatingthe secondary beams. S. C. acknowledges the support of the IPA program at RIKEN Nishina Center. J. L. acknowledges the support from Research Grants Council (RGC) of Hong Kong with grant of Early Career Scheme (ECS-27303915). K. O., K. Y., and Y. C. acknowledge the support from Grants-in-Aid of the Japan Society for the Promotion of Science under Grants No. JP16K05352. Y. L. S. acknowledges the support of the Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015-705023). V. V. acknowledges support from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2017- 84756-C4-2-P. L. X. C. and B. D. L. would like to thank MOST for its support through the Physics Development Program Grant No. ĐTĐLCN.25/18. D. R. and V. W. acknowledge the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Grant No. SFB1245. V. W. and P. K. acknowledge the German BMBF Grant No. 05P19RDFN1. P. K. was also supported by HGSHIRe. D. S. was supported by Projects No. GINOP-2.3.3- 15-2016-00034 and No. NKFIH-NN114454. I. G. has been supported by HIC for FAIR and Croatian Science Foundation under Projects No. 1257 and No. 7194. K. I. H., D. K., and S. Y. P. acknowledge the support from the NRF grant funded bythe Korea government (No. 2016K1A3A7A09005580 and No. 2018R1A5A1025563). This work was also supported by the United Kingdom Science and Technology Facilities Council (STFC) under Grants No. ST/P005314/1 and No. ST/L005816/1, and by NKFIH (128072), and by JSPS KAKENHI Grant No. 16H02179, and by MEXT KAKENHI Grant No. 18H05404. The development of MINOS were supported by the European Research Council through the ERC Grant No. MINOS-258567. Green's function calculations were performed using HPC resources from the DiRAC Data Intensive service at Leicester, UK (funded by the UK BEIS via STFC capital Grants No. ST/K000373/1 and No. ST/R002363/1 and STFC DiRAC Operations Grant No. ST/R001014/1) and from GENCI-TGCC, France (Project No. A0050507392).

7 pags., 3 figs., 1 tab. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; The first γ-ray spectroscopy of Ar52, with the neutron number N=34, was measured using the K53(p,2p) one-proton removal reaction at ∼210 MeV/u at the RIBF facility. The 21+ excitation energy is found at 1656(18) keV, the highest among the Ar isotopes with N>20. This result is the first experimental signature of the persistence of the N=34 subshell closure beyond Ca54, i.e., below the magic proton number Z=20. Shell-model calculations with phenomenological and chiral-effective-field-theory interactions both reproduce the measured 21+ systematics of neutron-rich Ar isotopes, and support a N=34 subshell closure in Ar52. ; We thank the RIKEN Nishina Center accelerator staff for their work in the primary beam delivery and the Big RIP Steam for preparing the secondary beams. The development of MINOS has been supported by the European Research Council through the ERC Grant No. MINOS 258567. Acknowledges the support from the Enhanced Eurotalents program (PCOFUND-GA-2013-600382) co-funded by CEA and the European Union. H.N.L., A.O. and A.S. acknowledge the support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Project No. 279384907- SFB 1245. C.A.B. acknowledges support from the U.S. NSF Grant No. 1415656 and the U.S. DOE Grant No.DE-FG02-08ER41533.J.D.H.and R.S.acknowledge the support from NSERC and the National Research Council Canada. Y.L.S. acknowledges the support of Marie Skłodowska-Curie Individual Fellowship (H2020-MSCAIF-2015-705023) from the European Union. I.G. has been supported by HIC for FAIR andCroatianScienceFoundation. L.X.C. and B.D.L. have been supported by the Vietnam MOST through the Physics Development Program Grant No. ĐTĐLCN.25/18. K.I.H., D.K. and S.Y.P. have been supported by the NRF grant funded by the Korea government (No. 2017R1A2B2012382 and 2018R1A5A1025563). This work was supported in part by JSPS KAKENHI Grant No. 16H02179, MEXT KAKENHI Grants No. 24105005 and No. 18H05404. This work was also supported by the Office of Nuclear Physics,U.S.Department of Energy,under Grants No.de-sc 0018223 (NUCLEISciDAC-4collaboration) and the Field Work Proposal ERKBP72 at Oak Ridge National Laboratory (ORNL). Computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. Thisresearch used resources of the Oak Ridge Leadership Computing Facility located at ORNL, which is supported by the Office of Science of the Department of Energy under Contract No. DE-AC0500OR22725.

7 pags. 4 figs. ; Fifty-five inclusive single nucleon-removal cross sections from medium mass neutron-rich nuclei impinging on a hydrogen target at ∼250 MeV/nucleon are measured at the RIKEN Radioactive Isotope Beam Factory. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons as compared to odd-proton number projectiles for a given neutron separation energy. Neutron removal cross sections display no even-odd splitting, contrary to nuclear cascade model predictions. Both effects are understood through simple considerations of neutron separation energies and bound state level densities originating in pairing correlations in the daughter nuclei. These conclusions are supported by comparison with semimicroscopic model predictions, highlighting the enhanced role of low-lying level densities in nucleon-removal cross sections from loosely bound nuclei. ; We express our gratitude to the RIKEN Nishina Center accelerator staff for providing the stable and high-intensity uranium beam . A. O. thanks the European Research Council for its support through ERC Grant No. MINOS-258567, the Japanese Society for the Promotion of Science for the long-term fellowship L-13520, the German DFG SFB Grant No. 1245, and the Alexander von Humboldt Foundation. C. S. acknowledges support by the IPA program at the RIKEN Nishina Center. C. A. B. acknowledges support by U.S. Department of Energy Grant No. DE-FG02- 08ER41533 and U.S. National Science Foundation Grant No. 1415656. J. L. R.-S. acknowledges support by the Regional Government of Galicia under the program of postdoctoral fellowships. K. M. acknowledges support from German BMBF Grant No. 05P15PKFNA. M. L. C., M. L., and V. W. acknowledge support from German BMBF Grants No. 05P12RDFN8, No. 05P15RDFN1, and No. 05P12RDFN8, as well as DFG Grant No. SFB 1245. L. X. C. and B. D. L. are supported by the Vietnam MOST through Physics Development Program Grant No. ĐTĐLCN.25/18 and acknowledge the Radioactive Isotope Physics Laboratory of the RIKEN Nishina Center for supporting their stay during the experiment. A. J. and V. V. acknowledge support from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2014-57196-C5-4-P. U.K. participants acknowledge support from the Science and Technology Facilities Council (STFC). Collaborators from I. M. P. were supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences.

9 pags., 3 figs. ; The low-lying level structure of V63 was studied for the first time by the inelastic proton scattering and the proton knock-out reaction in inverse kinematics. The comparison of the newly observed γ-ray transitions at 696(8) keV and 889(16) keV with our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja interaction established two excited states proposed to be the first 11/2- and 9/2- levels. The (p,p′) excitation cross sections were analyzed by the coupled channel formalism assuming pure quadrupole as well as quadrupole+hexadecapole deformations. This resulted in large deformation parameters placing V63 in the island of inversion located below Ni68. ; We are very grateful to the RIKEN Nishina Center accelerator staff for providing the stable beam and to the BigRIPS team for the smooth operation of the secondary beams. The development of the MINOS device has been supported by the European Research Council through the ERC Grant No. MINOS-258567. F.B. was supported by the RIKEN Special Postdoctoral Researcher Program. K.O. acknowledges the support by Grant-in-Aid for Scientific Research JP16K05352. Y.U. acknowledges the support by Grant-in-Aid for Scientific Research No. 20K03981. Y.L.S. acknowledges the support of Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015-705023) from the European Union and the support from the Helmholtz International Center for FAIR. H.N.L. acknowledges the support from the Enhanced Eurotalents program (PCOFUND-GA-2013-600382) co-funded by CEA and the European Union. T.A., C.L., D.R., H.T., V.W., L.Z., H.N.L., V.W., and A.O. acknowledge the support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Project No. 279384907-SFB 1245. R.B.G. acknowledges the support from the DFG under Grant No. BL 1513/1-1. Y.L.S. and A.O. acknowledge the support from the Alexander von Humboldt Foundation. B.D.L. and L.X.C. acknowledge the support from the Vietnam Ministry of Science and Technology under Grant No. ĐTCB.01/21/VKHKTHN. I.G. has been supported by HIC for FAIR and HRZZ under Projects No. 1257 and No. 7194. F.B. acknowledge the support from the RIKEN Special Postdoctoral Researcher Program. D.S. and Z.E. were supported by Projects No. GINOP-2.3.3-15-2016-00034 and K128947. V.V. acknowledges support from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2017-84756-C4-2-P. V.W. and P.K. acknowledge the support from BMBF Grants No. 05P15RDFN1 and No. 05P19RDFN1. P.K. acknowledges support from HGSHIRe. This work was also supported by NKFIH (114454) and by Swedish Research Council under Grants No. 621-2014-5558 and No. 2019-04880. K.I.H., D.K., and S.Y.P. acknowledge the support from the IBS grant funded by the Korea government (No. IBS-R031-D1). T.N. and Y.K. acknowledge the support by JSPS Grant-in-Aid for Scientific Research Grants No. JP16H02179, No. JP18H05404, and No. JP21H04465. ; Peer reviewed

7 pags., 3 figs., 1 tab. ; States in the N = 35 and 37 isotopes 55,57Ca have been populated by direct proton-induced nucleon removal reactions from 56,58Sc and 56Ca beams at the RIBF. In addition, the (p, 2p) quasi-free single- proton removal reaction from 56Ca was studied. Excited states in 55K, 55Ca, and 57Ca were established for the first time via in-beam γ -ray spectroscopy. Results for the proton and neutron removal reactions from 56Ca to states in 55K and 55Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in 57Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at N = 35 to collective excitations at N = 37. ; We would like to thank the RIKEN accelerator and BigRIPS teams for providing the high intensity beams. T.K. acknowledges support by RIKEN Junior Research Associate Program. K.W. acknowledges support from the Spanish Ministerio de Ciencia, Innovación y Universidades RYC-2017-22007. RIUMF receives funding via a contribution through the National Research Council of Canada. J.D.H is further supported by NSERC under grants SAPIN-2018-00027 and RGPAS-2018-522453. VS-IMSRG computations were performed with an allocation of computing resources on Cedar at WestGrid and Compute Canada, and on the Oak Cluster at TRIUMF managed by the University of British Columbia department of Advanced Research Computing (ARC). N.S. and Y.U. acknowledge valuable support by "Priority Issue on post-K computer" and KAKENHI grant 20K03981 and 17K05433. C.B. was supported by the UK Science and Technology Facilities Council (STFC) through grants No. ST/L005816/1 and No. ST/V001108/1. SCGF calculations were per- formed by using HPC resources from GENCI-TGCC, France (Contract No. A009057392) and at the DiRAC DiAL system at the University of Leicester, UK, (funded by the UK BEIS via STFC Capital Grants No. ST/K000373/1 and No. ST/R002363/1 and STFC DiRAC Operations Grant No. ST/R001014/1). I.M. was supported by the RIKEN IPA program, F.B. by the RIKEN Special Postdoctoral Researche Program. D.S. acknowledges support from the European Regional Development Fund contract No. GINOP-2.3.3-15-2016-00034 and the National Research, Development and Innovation Fund of Hungary via Project No. K128947. K. I. H., D. K., and S. Y. P. acknowledge the support from the IBS grant funded by the Korea government (No. IBS-R031-D1). The work was further supported by JSPS KAKENHI Grant Nos. JP16H02179, JP18H05404, JP19H00679, and JP21H01114 and the Deutsche Forschungsgemeinschaft (DFG) under Grant No. BL 1513/1-1 ; Peer reviewed