Cross-shell states in 15^{15}C: a test for p-sd interactions

The low-lying structure of $^{15}$C has been investigated via the neutron-removal $^{16}$C$(d,t)$ reaction. Along with bound neutron sd-shell hole states, unbound p-shell hole states have been firmly confirmed. The excitation energies and the deduced spectroscopic factors of the cross-shell states are an important measure of the $[(p)^{-1}(sd)^{2}]$ neutron configurations in $^{15}$C. Our results show a very good agreement with shell-model calculations using the SFO-tls interaction for $^{15}$C. However, a modification of the $p$-$sd$ and $sd$-$sd$ monopole terms was applied in order to reproduce the $N=9$ isotone $^{17}$O. In addition, the excitation energies and spectroscopic factors have been compared to the first calculations of $^{15}$C with the $ab~ initio$ self-consistent Green's function method employing the NNLO$_{sat}$ interaction. The results show the sensitivity to the size of the $N=8$ shell gap and highlight the need of going beyond the current truncation scheme in the theory

High-Precision Spectroscopy of 20{20}O Benchmarking Ab Initio Calculations in Light Nuclei

International audienceHigh-precision spectroscopy of 20O benchmarking ab-initio calculations in light nucleiI. Zanon,1, 2 E. Cl´ement,3 A. Goasduff,1 J. Men´endez,4 T. Miyagi,5, 6, 7 M. Assi´e,8 M. Ciemala,9F. Flavigny,10 A. Lemasson,3 A. Matta,10 D. Ramos,3 M. Rejmund,3 L. Achouri,10 D. Ackermann,3D. Barrientos,11 D. Beaumel,8 G. Benzoni,12 A.J. Boston,13 H.C. Boston,13 S. Bottoni,14, 12 A. Bracco,12, 14D. Brugnara,1, 15 G. de France,3 N. de Sereville,8 F. Delaunay,10 P. Desesquelles,8 F. Didierjean,16C. Domingo-Prato,17 J. Dudouet,18 J. Eberth,19 D. Fern´andez,20 C. Foug`eres,3 A. Gadea,17 F. Galtarossa,8V. Girard-Alcindor,3 V. Gonzales,21 A. Gottardo,1 F. Hammache,8 L.J. Harkness-Brennan,13 H. Hess,19D.S Judson,13 A. Jungclaus,22 A. Ka¸ska¸s,23 Y.H. Kim,24 A. Ku¸so˘glu,25 M. Labiche,26 S. Leblond,3C. Lenain,10 S.M. Lenzi,27 S. Leoni,12 H. Li,3 J. Ljungvall,8 J. Lois-Fuentes,20 A. Lopez-Martens,8A. Maj,28 R. Menegazzo,27 D. Mengoni,15, 27 C. Michelagnoli,3, 24 B. Million,12 D.R. Napoli,1 J. Nyberg,29G. Pasqualato,15, 27 Zs. Podolyak,30 A. Pullia,12 B. Quintana,31 F.Recchia,15, 27 D. Regueira-Castro,20 P. Reiter,19K. Rezynkina,32 J.S. Rojo,33 M.D. Salsac,34 E. Sanchis,21 M. S¸enyi˘git,23 M. Siciliano,34, 35 D. Sohler,36O. Stezowski,18 Ch. Theisen,34 A. Utepov,3, 10 J.J. Valiente-Dob´on,1 D. Verney,8 and M. Zielinska341INFN Laboratori Nazionali di Legnaro, Legnaro, Italy.2Dipartimento di Fisica e Scienze della Terra, Universit`a di Ferrara, Ferrara, Italy.3Grand Acc´el´erateur National d’Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Caen, France4Department of Quantum Physics and Astrophysics and Institute of Cosmos Sciences, University of Barcelona, Spain5Technische Universit¨at Darmstadt, Department of Physics, Darmstadt, Germany6ExtreMe Matter Institute, GSI Helmholtzzentrum f¨ur Schwerionenforschung GmbH, Darmstadt, Germany7Max-Planck-Institut f¨ur Kernphysik, Heidelberg, Germany8Universit´e Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France9IFJ PAN, Krakow, Poland.10Universit´e de Caen Normandie, ENSICAEN, CNRS/IN2P3, LPC Caen UMR6534, F-14000 Caen, France.11CERN, CH-1211 Geneva 23, Switzerland12INFN Sezione di Milano, I-20133 Milano, Italy13Oliver Lodge Laboratory, The University of Liverpool, Liverpool, UK.14Dipartimento di Fisica, Universit`a di Milano, Milano, Italy15Dipartimento di Fisica, Universit`a di Padova, Padova, Italy.16Universit´e de Strasbourg, IPHC, Strasbourg, France.17Instituto de Fisica Corpuscolar, CSIC-Universidad de Valencia, E-46071 Valencia, Spain.18Universit´e de Lyon, Universit´e Lyon-1, CNRS/IN2P3,UMR5822, IP2I, F-69622 Villeurbanne Cedex, France19Institut f¨ur Kernphysik, Universit¨at zu K¨oln, Z¨ulpicher Str. 77, D-50937 K¨oln, Germany20IGFAE and Dpt. de F´ısica de Part´ıculas, Univ. of Santiago de Compostela, Santiago de Compostela, Spain21Departamento de Ingenier´ıa Electr´onica, Universitat de Valencia, Burjassot, Valencia, Spain22Instituto de Estructura de la Materia, CSIC, Madrid, E-28006 Madrid, Spain23Department of Physics, Faculty of Science, Ankara University, 06100 Besevler - Ankara, Turkey24Institue Laue-Langevin, Grenoble, France.25Department of Physics, Faculty of Science, Istanbul University, Vezneciler/Fatih, Istanbul, Turkey.26STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD, UK27INFN, Sezione di Padova, I-35131 Padova, Italy.28The Henryk Niewodnicza´nski Institute of Nuclear Physics,Polish Academy of Sciences, 31-342 Krak´ow, Poland29Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden30Department of Physics, University of Surrey, Guildford, GU2 7XH, UK31Laboratorio de Radiaciones Ionizantes, Departamento de F´ısica Fundamental,Universidad de Salamanca, E-37008 Salamanca, Spain32Universit´e de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France33Department of Physics, University of York, York, UK.34Irfu, CEA, Universit´e Paris-Saclay, F-91191 Gif-sur-Yvette, France35Physics Division, Argonne National Laboratory, Lemont (IL) 60439, United States.36Institute for Nuclear Research, Atomki, 4001 Debrecen, HungaryThe excited states of unstable 20O were investigated via γ-ray spectroscopy following the19O(d, p)20O reaction at 8 AMeV. By exploiting the Doppler Shift Attenuation Method, the lifetimeof the 2+2 and 3+1 states were firmly established. From the γ-ray branching and E2/M1 mixing ratiosfor transitions deexciting the 2+2 and 3+1 states, the B(E2) and B(M1) were determined. Variouschiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states,along with a standard USDB interaction, were compared with the experimentally obtained data.Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium 2similarity renormalization group ab-initio calculations was performed for the first time in a nucleusfar from stability. It was shown that the ab-initio approaches using chiral EFT forces are challengedby detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilitieswere found to be a very constraining test of the performance of the ab-initio model

High-Precision Spectroscopy of 20{20}O Benchmarking Ab Initio Calculations in Light Nuclei

International audienceHigh-precision spectroscopy of 20O benchmarking ab-initio calculations in light nucleiI. Zanon,1, 2 E. Cl´ement,3 A. Goasduff,1 J. Men´endez,4 T. Miyagi,5, 6, 7 M. Assi´e,8 M. Ciemala,9F. Flavigny,10 A. Lemasson,3 A. Matta,10 D. Ramos,3 M. Rejmund,3 L. Achouri,10 D. Ackermann,3D. Barrientos,11 D. Beaumel,8 G. Benzoni,12 A.J. Boston,13 H.C. Boston,13 S. Bottoni,14, 12 A. Bracco,12, 14D. Brugnara,1, 15 G. de France,3 N. de Sereville,8 F. Delaunay,10 P. Desesquelles,8 F. Didierjean,16C. Domingo-Prato,17 J. Dudouet,18 J. Eberth,19 D. Fern´andez,20 C. Foug`eres,3 A. Gadea,17 F. Galtarossa,8V. Girard-Alcindor,3 V. Gonzales,21 A. Gottardo,1 F. Hammache,8 L.J. Harkness-Brennan,13 H. Hess,19D.S Judson,13 A. Jungclaus,22 A. Ka¸ska¸s,23 Y.H. Kim,24 A. Ku¸so˘glu,25 M. Labiche,26 S. Leblond,3C. Lenain,10 S.M. Lenzi,27 S. Leoni,12 H. Li,3 J. Ljungvall,8 J. Lois-Fuentes,20 A. Lopez-Martens,8A. Maj,28 R. Menegazzo,27 D. Mengoni,15, 27 C. Michelagnoli,3, 24 B. Million,12 D.R. Napoli,1 J. Nyberg,29G. Pasqualato,15, 27 Zs. Podolyak,30 A. Pullia,12 B. Quintana,31 F.Recchia,15, 27 D. Regueira-Castro,20 P. Reiter,19K. Rezynkina,32 J.S. Rojo,33 M.D. Salsac,34 E. Sanchis,21 M. S¸enyi˘git,23 M. Siciliano,34, 35 D. Sohler,36O. Stezowski,18 Ch. Theisen,34 A. Utepov,3, 10 J.J. Valiente-Dob´on,1 D. Verney,8 and M. Zielinska341INFN Laboratori Nazionali di Legnaro, Legnaro, Italy.2Dipartimento di Fisica e Scienze della Terra, Universit`a di Ferrara, Ferrara, Italy.3Grand Acc´el´erateur National d’Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Caen, France4Department of Quantum Physics and Astrophysics and Institute of Cosmos Sciences, University of Barcelona, Spain5Technische Universit¨at Darmstadt, Department of Physics, Darmstadt, Germany6ExtreMe Matter Institute, GSI Helmholtzzentrum f¨ur Schwerionenforschung GmbH, Darmstadt, Germany7Max-Planck-Institut f¨ur Kernphysik, Heidelberg, Germany8Universit´e Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France9IFJ PAN, Krakow, Poland.10Universit´e de Caen Normandie, ENSICAEN, CNRS/IN2P3, LPC Caen UMR6534, F-14000 Caen, France.11CERN, CH-1211 Geneva 23, Switzerland12INFN Sezione di Milano, I-20133 Milano, Italy13Oliver Lodge Laboratory, The University of Liverpool, Liverpool, UK.14Dipartimento di Fisica, Universit`a di Milano, Milano, Italy15Dipartimento di Fisica, Universit`a di Padova, Padova, Italy.16Universit´e de Strasbourg, IPHC, Strasbourg, France.17Instituto de Fisica Corpuscolar, CSIC-Universidad de Valencia, E-46071 Valencia, Spain.18Universit´e de Lyon, Universit´e Lyon-1, CNRS/IN2P3,UMR5822, IP2I, F-69622 Villeurbanne Cedex, France19Institut f¨ur Kernphysik, Universit¨at zu K¨oln, Z¨ulpicher Str. 77, D-50937 K¨oln, Germany20IGFAE and Dpt. de F´ısica de Part´ıculas, Univ. of Santiago de Compostela, Santiago de Compostela, Spain21Departamento de Ingenier´ıa Electr´onica, Universitat de Valencia, Burjassot, Valencia, Spain22Instituto de Estructura de la Materia, CSIC, Madrid, E-28006 Madrid, Spain23Department of Physics, Faculty of Science, Ankara University, 06100 Besevler - Ankara, Turkey24Institue Laue-Langevin, Grenoble, France.25Department of Physics, Faculty of Science, Istanbul University, Vezneciler/Fatih, Istanbul, Turkey.26STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD, UK27INFN, Sezione di Padova, I-35131 Padova, Italy.28The Henryk Niewodnicza´nski Institute of Nuclear Physics,Polish Academy of Sciences, 31-342 Krak´ow, Poland29Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden30Department of Physics, University of Surrey, Guildford, GU2 7XH, UK31Laboratorio de Radiaciones Ionizantes, Departamento de F´ısica Fundamental,Universidad de Salamanca, E-37008 Salamanca, Spain32Universit´e de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France33Department of Physics, University of York, York, UK.34Irfu, CEA, Universit´e Paris-Saclay, F-91191 Gif-sur-Yvette, France35Physics Division, Argonne National Laboratory, Lemont (IL) 60439, United States.36Institute for Nuclear Research, Atomki, 4001 Debrecen, HungaryThe excited states of unstable 20O were investigated via γ-ray spectroscopy following the19O(d, p)20O reaction at 8 AMeV. By exploiting the Doppler Shift Attenuation Method, the lifetimeof the 2+2 and 3+1 states were firmly established. From the γ-ray branching and E2/M1 mixing ratiosfor transitions deexciting the 2+2 and 3+1 states, the B(E2) and B(M1) were determined. Variouschiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states,along with a standard USDB interaction, were compared with the experimentally obtained data.Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium 2similarity renormalization group ab-initio calculations was performed for the first time in a nucleusfar from stability. It was shown that the ab-initio approaches using chiral EFT forces are challengedby detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilitieswere found to be a very constraining test of the performance of the ab-initio model

High-Precision Spectroscopy of O 20 Benchmarking Ab Initio Calculations in Light Nuclei

: The excited states of unstable ^{20}O were investigated via γ-ray spectroscopy following the ^{19}O(d,p)^{20}O reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2_{2}^{+} and 3_{1}^{+} states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+} and 3_{1}^{+} states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models

Low-lying structure of 15^{15}C: Information on the N=8 shell gap

International audienceThe low-lying structure of 15C has been investigated via the neutron-removal d(16C, t) reaction. The experiment was performed at GANIL using a secondary 16C beam produced by fragmentation in the LISE spectrometer at 17.2 MeV/nucleon with an intensity of 5 × 104 pps and 100% purity. The angle and energy of the light ejectile were detected by three MUST2 telescopes. The missing mass technique was used to reconstruct the excitation energy of 15C. In this spectrum, two bound states were observed (gs and the first excited state) and two unbound resonant states above the neutron separation threshold (S n = 1.218 MeV). From the differential cross sections, information on the angular momentum of the transferred nucleon and spectroscopic factors were deduced.The excitation energies and the deduced spectroscopic factors of the negative parity states placed above the neutron separation energy are an important measurement of the 2p-1h configurations in 15C. Our results show good agreement with shell-model calculations with the YSOX interaction and show a sensitivity to the N=8 shell gap

Cross-shell states in 15^{15}C: a test for p-sd interactions

International audienceThe low-lying structure of $^{15}$C has been investigated via the neutron-removal $^{16}$C$(d,t)$ reaction. Along with bound neutron sd-shell hole states, unbound p-shell hole states have been firmly confirmed. The excitation energies and the deduced spectroscopic factors of the cross-shell states are an important measure of the $[(p)^{-1}(sd)^{2}]$ neutron configurations in $^{15}$C. Our results show a very good agreement with shell-model calculations using the SFO-tls interaction for $^{15}$C. However, a modification of the $p$-$sd$ and $sd$-$sd$ monopole terms was applied in order to reproduce the $N=9$ isotone $^{17}$O. In addition, the excitation energies and spectroscopic factors have been compared to the first calculations of $^{15}$C with the $ab~ initio$ self-consistent Green's function method employing the NNLO$_{sat}$ interaction. The results show the sensitivity to the size of the $N=8$ shell gap and highlight the need of going beyond the current truncation scheme in the theory

Cross-shell states in 15^{15}C: a test for p-sd interactions

International audienceThe low-lying structure of $^{15}$C has been investigated via the neutron-removal $^{16}$C$(d,t)$ reaction. Along with bound neutron sd-shell hole states, unbound p-shell hole states have been firmly confirmed. The excitation energies and the deduced spectroscopic factors of the cross-shell states are an important measure of the $[(p)^{-1}(sd)^{2}]$ neutron configurations in $^{15}$C. Our results show a very good agreement with shell-model calculations using the SFO-tls interaction for $^{15}$C. However, a modification of the $p$-$sd$ and $sd$-$sd$ monopole terms was applied in order to reproduce the $N=9$ isotone $^{17}$O. In addition, the excitation energies and spectroscopic factors have been compared to the first calculations of $^{15}$C with the $ab~ initio$ self-consistent Green's function method employing the NNLO$_{sat}$ interaction. The results show the sensitivity to the size of the $N=8$ shell gap and highlight the need of going beyond the current truncation scheme in the theory