18 results on '"B Fernández"'
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2. Neutron Capture on the s -Process Branching Point Tm171 via Time-of-Flight and Activation
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Claudia Lederer-Woods, A Kriesel, L. Piersanti, P. V. Sedyshev, Javier Praena, S. Lo Meo, J. Heyse, G. Vannini, B. Fernández-Domínguez, D. M. Castelluccio, F. Käppeler, D. Macina, Carlos Guerrero, D. Bosnar, M A Millán-Callado, F. Mingrone, J. Andrzejewski, J. Lerendegui-Marco, S. Amaducci, O. Aberle, M. Caamaño, E. Leal-Cidoncha, I. Duran, I. F. Gonçalves, D Berkovits, F. Cerutti, A. Gawlik, A. Goverdovski, G. Tagliente, Thomas Rauscher, V. Bécares, T Rodríguez-González, A Damone, Emilio Andrea Maugeri, G. Cortes, Leonid Weissman, S. Montesano, Michael Paul, K. Rajeev, A. Stamatopoulos, M. Kokkoris, S. Warren, R. Vlastou, E. Jericha, Paolo Finocchiaro, E. Berthoumieux, Francesca Matteucci, T Palchan-Hazan, A. Casanovas, S. Halfon, D. Cano-Ott, M. Diakaki, Ulli Köster, E. González-Romero, P. Kavrigin, D Kijel, V. Variale, Dimitri Rochman, A. Musumarra, Dorothea Schumann, J. A. Ryan, M. Tessler, Ariel Tarifeño-Saldivia, S. J. Lonsdale, A. Manna, P. Vaz, Ralf Nolte, E. Griesmayer, Ignacio Porras, P. J. Woods, L. Cosentino, A. Oprea, Tanja Heftrich, R. Cardella, C. Weiss, T Hirsh, A. R. García, mtext, M. Brugger, A Shor, Alberto Ventura, mrow, E. Dupont, P. C. Rout, Y. Kadi, N. Patronis, A. K. Saxena, V. Khryachkov, P. M. Milazzo, Arnaud Ferrari, C. Beinrucker, A. Pavlik, V. Furman, A. Mengoni, S. Valenta, C. Domingo-Pardo, T. J. Wright, B Kaizer, J. Billowes, Marco Calviani, F. Bečvář, V. Ketlerov, C. Wolf, A. G. Smith, Petar Žugec, E. Mendoza, M. Dietz, Peter Schillebeeckx, H Dafna, S. Heinitz, L. Audouin, Y Eisen, M. Bacak, C. Rubbia, Y Buzaglo, T. Glodariu, Roberto Losito, Rugard Dressler, mtext> Tof, M. Sabaté-Gilarte, A. Tsinganis, Nicola Colonna, M. A. Cortés-Giraldo, Vasilis Vlachoudis, Kathrin Göbel, A. Kimura, D. G. Jenkins, Mario Barbagallo, J. L. Tain, J. Marganiec, Niko Kivel, E. Chiaveri, P. F. Mastinu, M. Krtička, T. Martinez, Y. H. Chen, F. Gunsing, Cristian Massimi, M. Mirea, Rene Reifarth, Stefan Schmidt, F. Calviño, H. Leeb, J. M. Quesada, J. Perkowski, L. Tassan-Got, Sergio Cristallo, Pedro G. Ferreira, Mario Weigand, Tatsuya Katabuchi, A Barak, S. Barros, M. Mastromarco, Anton Wallner, J. Balibrea, and Hideo Harada
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Physics ,General Physics and Astronomy ,7. Clean energy ,01 natural sciences ,Neutron temperature ,Nuclear physics ,Neutron capture ,Stellar nucleosynthesis ,Nucleosynthesis ,0103 physical sciences ,Neutron cross section ,Neutron ,Nuclide ,010306 general physics ,s-process - Abstract
The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable $^{171}$Tm(t$_{1/2}$=1.92 yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of $^{171}$Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the $^{171}$Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.
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- 2020
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3. Evidence for a New Compact Symmetric Fission Mode in Light Thorium Isotopes
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Andreas Martin Heinz, M. Caamaño, Enrique Casarejos, A. Ebran, Yassid Ayyad, A. Chatillon, G. Boutoux, J. Taieb, J. Vargas, J. L. Rodriguez-Sanchez, T. Gorbinet, B. Laurent, F. Farget, A. Prochazka, S. Pietri, D. Cortina-Gil, C. Nociforo, C. Paradela, B. Fernández-Domínguez, E. Pellereau, L. Audouin, N. Kurz, Helmut Weick, Håkan T Johansson, L. Grente, Herbert A. Simon, J. Benlliure, H. Alvarez-Pol, D. M. Rossi, Bernd Voss, G. Belier, J. F. Martin, L. Tassan-Got, A. Kelic-Heil, Beatriz Jurado, Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
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Physics ,Isotope ,Fission ,Nuclear Theory ,General Physics and Astronomy ,Thorium ,chemistry.chemical_element ,Actinide ,[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] ,7. Clean energy ,01 natural sciences ,Effective nuclear charge ,Physics::Geophysics ,Nuclear physics ,chemistry ,0103 physical sciences ,Multiplicity (chemistry) ,010306 general physics ,Nuclear Experiment ,Bond cleavage ,Isotopes of thorium ,Nuclear Physics - Abstract
International audience; Taking benefit of the R3B/SOFIA setup to measure the mass and the nuclear charge of both fission fragments in coincidence with the total prompt-neutron multiplicity, the scission configurations are inferred along the thorium chain, from the asymmetric fission in the heavier isotopes to the symmetric fission in the neutron-deficient thorium. Against all expectations, the symmetric scission in the light thorium isotopes shows a compact configuration, which is in total contrast to what is known in the fission of the heavier thorium isotopes and heavier actinides. This new main symmetric scission mode is characterized by a significant drop in deformation energy of the fission fragments of about 19 MeV, compared to the well-known symmetric scission in the uranium-plutonium region.
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- 2020
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4. First Direct Measurement of Isotopic Fission-Fragment Yields of U 239
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D. Ramos, M. Caamaño, A. Lemasson, M. Rejmund, L. Audouin, H. Álvarez-Pol, J. D. Frankland, B. Fernández-Domínguez, E. Galiana-Baldó, J. Piot, D. Ackermann, S. Biswas, E. Clement, D. Durand, F. Farget, M. O. Fregeau, D. Galaviz, A. Heinz, A. I. Henriques, B. Jacquot, B. Jurado, Y. H. Kim, P. Morfouace, D. Ralet, T. Roger, C. Schmitt, P. Teubig, I. Tsekhanovich
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- 2019
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5. Be7(n,p)Li7 Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN
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Ralf Nolte, E. Griesmayer, L. A. Damone, T. Stora, G. Cortes, J. Lerendegui-Marco, G. Bellia, I. Duran, J. Balibrea-Correa, G. Tagliente, Alexandru Negret, A. Mengoni, I. F. Gonçalves, A. S. Brown, A. Kalamara, Juliana Schell, N. V. Sosnin, Annamaria Mazzone, A. Kimura, Srinivasan Ganesan, A. García-Rios, F. Gunsing, B. Fernández-Domínguez, F. Käppeler, P. J. Woods, Petar Žugec, Rene Reifarth, V. Bécares, S. Heinitz, Cristian Massimi, Ignacio Porras, N. Patronis, A. K. Saxena, Arnaud Ferrari, A. Casanovas, P. M. Milazzo, P. Vaz, Javier Praena, S. Lo Meo, F. Bečvář, Stefan Schmidt, E. Jericha, S. Valenta, M. Bacak, C. Wolf, E. Mendoza, Paolo Finocchiaro, Dorothea Schumann, C. Weiß, Marco Calviani, Cortés-Giraldo, J. M. Quesada, L. Tassan-Got, J. A. Ryan, Peter Schillebeeckx, R. Vlastou, D. Radeck, G. Vannini, A. G. Smith, T.D. Goodacre, M. Mirea, C. Rubbia, A. Stamatopoulos, D. Cano-Ott, A.P. Bernardes, Hideo Harada, M. Brugger, J. Billowes, E. Berthoumieux, M. Mastromarco, M. Diakaki, Sergio Cristallo, C. Seiffert, M. Ayranov, F. Cerutti, D. Bosnar, C. Beinrucker, Massimo Barbagallo, M. Caamaño, E. Leal-Cidoncha, F. Calviño, Simone Gilardoni, T. Glodariu, Roberto Losito, H. Leeb, Maurizio Busso, Anton Wallner, A. Oprea, J. Andrzejewski, A. Gawlik, T. J. Wright, S. Altstadt, R. Cardella, S. Warren, M. Piscopo, Thomas Rauscher, Ariel Tarifeño-Saldivia, S. J. Lonsdale, Y. Kadi, J. Perkowski, Emilio Andrea Maugeri, Rugard Dressler, V. Variale, J. Marganiec, M. Kokkoris, A. Musumarra, A. Dorsival, A. Pavlik, Tatsuya Katabuchi, A. Ventura, Kathrin Göbel, E. González-Romero, A. Masi, A. Tsinganis, Luciano Piersanti, Tanja Heftrich, C. Domingo-Pardo, D. G. Jenkins, A. Riego-Perez, Jan Heyse, Vasilis Vlachoudis, Pedro G. Ferreira, Mario Weigand, M. Sabaté-Gilarte, B. Marsh, L. Audouin, J.G. Martins Correia, P. C. Rout, F. Mingrone, S. Rothe, M. Dietz, L. Cosentino, A. J. M. Plompen, Claudia Lederer-Woods, W.I. Furman, Deniz Kurtulgil, P. V. Sedyshev, E. Dupont, M.J.G. Borge, D. M. Castelluccio, D. Macina, Carlos Guerrero, E. Chiaveri, P. F. Mastinu, K. Rajeev, N. Colonna, Francesca Matteucci, Y. H. Chen, Karl Johnston, M. Krtička, J. Ballof, T. Martinez, O. Aberle, J. L. Tain, U. Kohester, Niko Kivel, R. Catherall, and P. Kavrigin
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Physics ,Range (particle radiation) ,Large Hadron Collider ,010308 nuclear & particles physics ,General Physics and Astronomy ,chemistry.chemical_element ,01 natural sciences ,Cosmology ,Neutron temperature ,Nuclear physics ,chemistry ,Nucleosynthesis ,0103 physical sciences ,Neutron ,Lithium ,Nuclear Experiment ,010306 general physics ,Energy (signal processing) - Abstract
We report on the measurement of the $^{7}$Be($n, p$)$^{7}$Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n\_TOF facility at CERN. This reaction plays a key role in the lithium yield of the Big Bang Nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and showed a large discrepancy between each other. The measurement was performed with a Si-telescope, and a high-purity sample produced by implantation of a $^{7}$Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low-energy, relative to current evaluations, in the region of BBN interest the present results are consistent with the values inferred from the time-reversal $^{7}$Li($p, n$)$^{7}$Be reaction, thus yielding only a relatively minor improvement on the so-called Cosmological Lithium Problem (CLiP). The relevance of these results on the near-threshold neutron production in the p+$^{7}$Li reaction is also discussed.
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- 2018
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6. Be7(n,α)He4Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN
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D. Macina, Carlos Guerrero, M. Sabaté-Gilarte, Rugard Dressler, P. C. Rout, C. Rubbia, W.I. Furman, P. V. Sedyshev, Y. H. Chen, A. Kimura, L. Cosentino, Srinivasan Ganesan, M. Mastromarco, A. Tsinganis, G. Vannini, A. García-Rios, F. Mingrone, C. Lederer, Anton Wallner, Nicola Colonna, J. Andrzejewski, M. Caamaño, A. Casanovas, Mario Barbagallo, Vasilis Vlachoudis, G. Cortes, M. Krtička, P. Kavrigin, N. Patronis, A. K. Saxena, Ralf Nolte, H. Leeb, Arnaud Ferrari, Ignacio Porras, Damir Bosnar, A. Oprea, T. Martinez, Mario Weigand, A. Stamatopoulos, E. Griesmayer, J. Billowes, L. A. Damone, Hideo Harada, M. Mirea, P. Ferreira, M. A. Cortés-Giraldo, S. Montesano, D. Cano-Ott, F. Calviño, R. Cardella, J. Perkowski, J. Vollaire, E. A. Maugeri, F. Gunsing, J. Balibrea-Correa, G. Tagliente, Javier Praena, S. Lo Meo, Cristian Massimi, M. Kokkoris, O. Aberle, E. Jericha, F. Bečvář, Pierfrancesco Mastinu, T. Glodariu, Paolo Finocchiaro, M. Piscopo, M. Bacak, Dorothea Schumann, Ariel Tarifeño-Saldivia, S. J. Lonsdale, J. A. Ryan, E. Mendoza, D. G. Jenkins, E. Leal-Cidoncha, I. Duran, M. Diakaki, P. Vaz, C. Weiß, Roberto Losito, Peter Schillebeeckx, A. Gawlik, Thomas Rauscher, K. Rajeev, P. M. Milazzo, J. Marganiec, F. Cerutti, E. Chiaveri, C. Beinrucker, A. Pavlik, S. Valenta, C. Domingo-Pardo, V. Bécares, E. González-Romero, Marco Calviani, Alfio Pappalardo, A. Mengoni, A. G. Smith, Philip Woods, B. Fernández-Domínguez, F. Käppeler, M. Ayranov, J. L. Tain, M. Brugger, I. F. Gonçalves, Niko Kivel, S. Heinitz, S. Altstadt, S. Warren, V. Variale, S. Barros, Tatsuya Katabuchi, A. Ventura, Rene Reifarth, Stefan Schmidt, J. M. Quesada, L. Tassan-Got, Sergio Cristallo, A. Musumarra, Tanja Heftrich, Annamaria Mazzone, Petar Žugec, A. Riego-Perez, Kathrin Göbel, Jan Heyse, R. Vlastou, E. Berthoumieux, L. Audouin, T. J. Wright, C. Wolf, E. Dupont, J. Lerendegui, A. J. M. Plompen, and D. M. Castelluccio
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Nuclear reaction ,Physics ,010308 nuclear & particles physics ,General Physics and Astronomy ,chemistry.chemical_element ,Alpha particle ,Neutron radiation ,7. Clean energy ,01 natural sciences ,Neutron temperature ,Nuclear physics ,Big Bang nucleosynthesis ,chemistry ,13. Climate action ,Nucleosynthesis ,0103 physical sciences ,Neutron ,Lithium ,Nuclear Experiment ,010306 general physics - Abstract
The energy-dependent cross section of the (7)Bed(n,alpha)He-4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be-7 and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure Be-7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be-7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.
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- 2016
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7. Publisher’s Note: Measurement of the Isoscalar Monopole Rsponse in the Neutron-Rich NucleusNi68[Phys. Rev. Lett. 113, 032504 (2014)]
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J. Pancin, H. Baba, N. L. Achouri, Julien Gibelin, Nasser Kalantar-Nayestanaki, T. Roger, M. Caamaño, Franck Delaunay, Didier Beaumel, U. Garg, L. Caceres, R. Raabe, Daisuke Suzuki, W. Mittig, G. F. Grinyer, Gianluca Colò, Marine Vandebrouck, Y. Blumenfeld, N. Harakeh, O. Sorlin, N. Keeley, E. Khan, P. Roussel-Chomaz, H. Savajols, C. Stodel, J. C. Thomas, and B. Fernández-Domínguez
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Nuclear physics ,Physics ,medicine.anatomical_structure ,Isoscalar ,Magnetic monopole ,medicine ,General Physics and Astronomy ,Neutron ,Nucleus - Published
- 2014
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8. Measurement of the Isoscalar Monopole Response in the Neutron-Rich NucleusNi68
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Marine Vandebrouck, C. Stodel, Gianluca Colò, U. Garg, D. Suzuki, Julien Gibelin, H. Baba, Elias Khan, O. Sorlin, B. Fernández-Domínguez, Y. Blumenfeld, W. Mittig, Franck Delaunay, J. C. Thomas, N. L. Achouri, Riccardo Raabe, N. Keeley, H. Savajols, P. Roussel-Chomaz, T. Roger, D. Beaumel, Nasser Kalantar-Nayestanaki, M. Caamaño, Mohsen Harakeh, G. F. Grinyer, J. Pancin, and L. Caceres
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Physics ,010308 nuclear & particles physics ,Scattering ,Isoscalar ,Nuclear Theory ,Magnetic monopole ,General Physics and Astronomy ,Soft modes ,01 natural sciences ,Resonance (particle physics) ,Nuclear physics ,Cross section (physics) ,medicine.anatomical_structure ,0103 physical sciences ,medicine ,Neutron ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Nucleus - Abstract
The isoscalar monopole response has been measured in the unstable nucleus (68)Ni using inelastic alpha scattering at 50A MeV in inverse kinematics with the active target MAYA at GANIL. The isoscalar giant monopole resonance (ISGMR) centroid was determined to be 21.1 ± 1.9 MeV and indications for a soft monopole mode are provided for the first time at 12.9 ± 1.0 MeV. Analysis of the corresponding angular distributions using distorted-wave-born approximation with random-phase approximation transition densities indicates that the L = 0 multipolarity dominates the cross section for the ISGMR and significantly contributes to the low-energy mode. The L=0 part of this low-energy mode, the soft monopole mode, is dominated by neutron excitations. This demonstrates the relevance of inelastic alpha scattering in inverse kinematics in order to probe both the ISGMR and isoscalar soft modes in neutron-rich nuclei.
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- 2014
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9. Measurement of the Dipole Polarizability of the Unstable Neutron-Rich NucleusNi68
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A. Chatillon, Matthias Heil, Andreas Wagner, Stefanos Paschalis, K. Sümmerer, A. Klimkiewicz, D. Rossi, K. Boretzky, Thomas Nilsson, R. Krücken, A. Kelic-Heil, Yu. A. Litvinov, Ralf Plag, J. Benlliure, U. Datta Pramanik, W. Waluś, N. Kurz, M. Górska, Marielle Chartier, O. Ershova, P. Maierbeck, J. V. Kratz, Enrique Casarejos, H. Emling, O. Kiselev, Arnd R. Junghans, M. Winkler, H. Alvarez-Pol, M. Labiche, Herbert A. Simon, Roy Crawford Lemmon, Thomas Aumann, Heiko Scheit, T. Le Bleis, A. Movsesyan, M. Böhmer, D. Cortina-Gil, Rene Reifarth, Hans Geissel, K. Mahata, Helmut Weick, Håkan T Johansson, F. Aksouh, B. Fernández-Domínguez, Deniz Savran, R. Palit, C. Nociforo, and P. Adrich
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Physics ,Dipole ,Polarizability ,Nuclear Theory ,Transition dipole moment ,General Physics and Astronomy ,Resonance ,Neutron ,Coulomb excitation ,Atomic physics ,Electric dipole transition ,Nuclear Experiment ,Random phase approximation - Abstract
The E1 strength distribution in Ni68 has been investigated using Coulomb excitation in inverse kinematics at the RB3-LAND setup and by measuring the invariant mass in the one- and two-neutron decay channels. The giant dipole resonance and a low-lying peak (pygmy dipole resonance) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic random phase approximation calculations yielding a neutron-skin thickness of 0.17(2) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.
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- 2013
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10. Direct Mass Measurements ofB19,C22,F29,Ne31,Na34and Other Light Exotic Nuclei
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A. Gillibert, Stefanos Paschalis, B. Fernández-Domínguez, G. Frémont, J. F. Libin, B. Pietras, P. Roussel-Chomaz, W. Mittig, Yu. E. Penionzhkevich, N. A. Orr, V. A. Maslov, Antonio Villari, S. Grévy, P. Gangnant, C. Spitaels, L. Gaudefroy, S. Varet, Marielle Chartier, and J. P. Ebran
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Physics ,Valence (chemistry) ,Isotope ,010308 nuclear & particles physics ,Nuclear Theory ,General Physics and Astronomy ,Isotopes of boron ,Mass spectrometry ,Isotopes of sodium ,7. Clean energy ,01 natural sciences ,Isotopes of neon ,0103 physical sciences ,Neutron ,Halo ,Atomic physics ,Nuclear Experiment ,010306 general physics - Abstract
We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei (19)B, (22)C, and (29)F as well as that of (34)Na. In addition, the most precise determinations to date for (23)N and (31)Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in (22)C, with a dominant ν2s(1/2)(2) configuration, and a single-neutron halo in (31)Ne with the valence neutron occupying predominantly the 2p(3/2) orbital. Despite a very low two-neutron separation energy the development of a halo in (19)B is hindered by the 1d(5/2)(2) character of the valence neutrons.
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- 2012
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11. Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei
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L, Gaudefroy, W, Mittig, N A, Orr, S, Varet, M, Chartier, P, Roussel-Chomaz, J P, Ebran, B, Fernández-Domínguez, G, Frémont, P, Gangnant, A, Gillibert, S, Grévy, J F, Libin, V A, Maslov, S, Paschalis, B, Pietras, Yu-E, Penionzhkevich, C, Spitaels, and A C C, Villari
- Abstract
We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei (19)B, (22)C, and (29)F as well as that of (34)Na. In addition, the most precise determinations to date for (23)N and (31)Ne are reported. Coupled with recent interaction cross-section measurements, the present results support the occurrence of a two-neutron halo in (22)C, with a dominant ν2s(1/2)(2) configuration, and a single-neutron halo in (31)Ne with the valence neutron occupying predominantly the 2p(3/2) orbital. Despite a very low two-neutron separation energy the development of a halo in (19)B is hindered by the 1d(5/2)(2) character of the valence neutrons.
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- 2012
12. Migration of Nuclear Shell Gaps Studied in thed(Ne24,pγ)Ne25Reaction
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M. Rejmund, J.M. Casadjian, Luis Caballero, V. P. E. Pucknell, W. N. Catford, S.D. Pain, N. A. Orr, N.L. Achouri, B. Fernández-Domínguez, Ch. Theisen, W. Gelletly, N. Curtis, C. N. Timis, N. Amzal, H. Savajols, Marielle Chartier, N. I. Ashwood, T. D. Baldwin, D. D. Warner, O. Sorlin, Robert Chapman, M. Burns, X. Liang, B. Rubio, K. M. Spohr, Roy Crawford Lemmon, M. Freer, and M. Labiche
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Physics ,Nuclear reaction ,Angular momentum ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Hadron ,General Physics and Astronomy ,Elementary particle ,01 natural sciences ,Nuclear physics ,Baryon ,0103 physical sciences ,Neutron ,Atomic physics ,010306 general physics ,Nucleon ,Radioactive decay - Abstract
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.
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- 2010
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13. Migration of nuclear shell gaps studied in the d(24Ne,pγ)25Ne reaction
- Author
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W N, Catford, C N, Timis, R C, Lemmon, M, Labiche, N A, Orr, B, Fernández-Domínguez, R, Chapman, M, Freer, M, Chartier, H, Savajols, M, Rejmund, N L, Achouri, N, Amzal, N I, Ashwood, T D, Baldwin, M, Burns, L, Caballero, J M, Casadjian, N, Curtis, G, de France, W, Gelletly, X, Liang, S D, Pain, V P E, Pucknell, B, Rubio, O, Sorlin, K, Spohr, Ch, Theisen, and D D, Warner
- Abstract
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.
- Published
- 2009
14. Resonance state in 7H
- Author
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M, Caamaño, D, Cortina-Gil, W, Mittig, H, Savajols, M, Chartier, C E, Demonchy, B, Fernández, M B, Gómez Hornillos, A, Gillibert, B, Jurado, O, Kiselev, R, Lemmon, A, Obertelli, F, Rejmund, M, Rejmund, P, Roussel-Chomaz, and R, Wolski
- Abstract
The existence of the 7H nuclear system was investigated via a one-proton transfer reaction with a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The existence of the 7H was confirmed with the identification of seven events where the system was formed with a resonance energy of 0.57(-0.21)(+0.42) MeV above the 3H+4n threshold and a resonance width of 0.09(-0.06)(+0.94) MeV. This study represents an unambiguous proof of the existence of the most neutron-proton unbalanced system presently found.
- Published
- 2007
15. Shedding Light on the Origin of ^{204}Pb, the Heaviest s-Process-Only Isotope in the Solar System.
- Author
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Casanovas-Hoste A, Domingo-Pardo C, Lerendegui-Marco J, Guerrero C, Tarifeño-Saldivia A, Krtička M, Pignatari M, Calviño F, Schumann D, Heinitz S, Dressler R, Köster U, Aberle O, Andrzejewski J, Audouin L, Bécares V, Bacak M, Balibrea-Correa J, Barbagallo M, Barros S, Bečvář F, Beinrucker C, Berthoumieux E, Billowes J, Bosnar D, Brugger M, Caamaño M, Calviani M, Cano-Ott D, Cardella R, Castelluccio DM, Cerutti F, Chen YH, Chiaveri E, Colonna N, Cortés G, Cortés-Giraldo MA, Cosentino L, Damone LA, Diakaki M, Dupont E, Durán I, Fernández-Domínguez B, Ferrari A, Ferreira P, Finocchiaro P, Furman V, Göbel K, García AR, Gawlik-Ramięga A, Glodariu T, Gonçalves IF, González-Romero E, Goverdovski A, Griesmayer E, Gunsing F, Harada H, Heftrich T, Heyse J, Jenkins DG, Jericha E, Käppeler F, Kadi Y, Katabuchi T, Kavrigin P, Ketlerov V, Khryachkov V, Kimura A, Kivel N, Kokkoris M, Leal-Cidoncha E, Lederer-Woods C, Leeb H, Lo Meo S, Lonsdale SJ, Losito R, Macina D, Marganiec J, Martínez T, Massimi C, Mastinu P, Mastromarco M, Matteucci F, Maugeri EA, Mendoza E, Mengoni A, Milazzo PM, Mingrone F, Mirea M, Montesano S, Musumarra A, Nolte R, Oprea A, Patronis N, Pavlik A, Perkowski J, Porras I, Praena J, Quesada JM, Rajeev K, Rauscher T, Reifarth R, Riego-Perez A, Romanets Y, Rout PC, Rubbia C, Ryan JA, Sabaté-Gilarte M, Saxena A, Schillebeeckx P, Schmidt S, Sedyshev P, Smith AG, Stamatopoulos A, Tagliente G, Tain JL, Tassan-Got L, Tsinganis A, Valenta S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Wallner A, Warren S, Weigand M, Weiss C, Wolf C, Woods PJ, Wright T, and Žugec P
- Abstract
Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of ^{204}Pb, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow, ^{204}Tl (t_{1/2}=3.78 yr), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on ^{204}Tl, conducted at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of ^{204}Tl produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the s-process temperatures of kT≈8 keV and kT≈30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new ^{204}Tl MACS, the uncertainty arising from the ^{204}Tl(n,γ) cross section on the s-process abundance of ^{204}Pb has been reduced from ∼30% down to +8%/-6%, and the s-process calculations are in agreement with the latest solar system abundance of ^{204}Pb reported by K. Lodders in 2021.
- Published
- 2024
- Full Text
- View/download PDF
16. Measurement of the ^{140}Ce(n,γ) Cross Section at n_TOF and Its Astrophysical Implications for the Chemical Evolution of the Universe.
- Author
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Amaducci S, Colonna N, Cosentino L, Cristallo S, Finocchiaro P, Krtička M, Massimi C, Mastromarco M, Mazzone A, Maugeri EA, Mengoni A, Roederer IU, Straniero O, Valenta S, Vescovi D, Aberle O, Alcayne V, Andrzejewski J, Audouin L, Babiano-Suarez V, Bacak M, Barbagallo M, Bennett S, Berthoumieux E, Billowes J, Bosnar D, Brown A, Busso M, Caamaño M, Caballero-Ontanaya L, Calviño F, Calviani M, Cano-Ott D, Casanovas A, Cerutti F, Chiaveri E, Cortés G, Cortés-Giraldo MA, Damone LA, Davies PJ, Diakaki M, Dietz M, Domingo-Pardo C, Dressler R, Ducasse Q, Dupont E, Durán I, Eleme Z, Fernández-Domínguez B, Ferrari A, Furman V, Göbel K, Garg R, Gawlik-Ramięga A, Gilardoni S, Gonçalves IF, González-Romero E, Guerrero C, Gunsing F, Harada H, Heinitz S, Heyse J, Jenkins DG, Junghans A, Käppeler F, Kadi Y, Kimura A, Knapová I, Kokkoris M, Kopatch Y, Kurtulgil D, Ladarescu I, Lederer-Woods C, Leeb H, Lerendegui-Marco J, Lonsdale SJ, Macina D, Manna A, Martínez T, Masi A, Mastinu P, Mendoza E, Michalopoulou V, Milazzo PM, Mingrone F, Moreno-Soto J, Musumarra A, Negret A, Nolte R, Ogállar F, Oprea A, Patronis N, Pavlik A, Perkowski J, Petrone C, Piersanti L, Pirovano E, Porras I, Praena J, Quesada JM, Ramos-Doval D, Rauscher T, Reifarth R, Rochman D, Rubbia C, Sabaté-Gilarte M, Saxena A, Schillebeeckx P, Schumann D, Sekhar A, Smith AG, Sosnin NV, Sprung P, Stamatopoulos A, Tagliente G, Tain JL, Tarifeño-Saldivia A, Tassan-Got L, Thomas T, Torres-Sánchez P, Tsinganis A, Ulrich J, Urlass S, Vannini G, Variale V, Vaz P, Ventura A, Vlachoudis V, Vlastou R, Wallner A, Woods PJ, Wright T, and Žugec P
- Abstract
^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.
- Published
- 2024
- Full Text
- View/download PDF
17. Evidence for a New Compact Symmetric Fission Mode in Light Thorium Isotopes.
- Author
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Chatillon A, Taïeb J, Alvarez-Pol H, Audouin L, Ayyad Y, Bélier G, Benlliure J, Boutoux G, Caamaño M, Casarejos E, Cortina-Gil D, Ebran A, Farget F, Fernández-Domínguez B, Gorbinet T, Grente L, Heinz A, Johansson HT, Jurado B, Kelić-Heil A, Kurz N, Laurent B, Martin JF, Nociforo C, Paradela C, Pellereau E, Pietri S, Prochazka A, Rodríguez-Sánchez JL, Rossi D, Simon H, Tassan-Got L, Vargas J, Voss B, and Weick H
- Abstract
Taking benefit of the R3B/SOFIA setup to measure the mass and the nuclear charge of both fission fragments in coincidence with the total prompt-neutron multiplicity, the scission configurations are inferred along the thorium chain, from the asymmetric fission in the heavier isotopes to the symmetric fission in the neutron-deficient thorium. Against all expectations, the symmetric scission in the light thorium isotopes shows a compact configuration, which is in total contrast to what is known in the fission of the heavier thorium isotopes and heavier actinides. This new main symmetric scission mode is characterized by a significant drop in deformation energy of the fission fragments of about 19 MeV, compared to the well-known symmetric scission in the uranium-plutonium region.
- Published
- 2020
- Full Text
- View/download PDF
18. Resonance state in 7H.
- Author
-
Caamaño M, Cortina-Gil D, Mittig W, Savajols H, Chartier M, Demonchy CE, Fernández B, Gómez Hornillos MB, Gillibert A, Jurado B, Kiselev O, Lemmon R, Obertelli A, Rejmund F, Rejmund M, Roussel-Chomaz P, and Wolski R
- Abstract
The existence of the 7H nuclear system was investigated via a one-proton transfer reaction with a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The existence of the 7H was confirmed with the identification of seven events where the system was formed with a resonance energy of 0.57(-0.21)(+0.42) MeV above the 3H+4n threshold and a resonance width of 0.09(-0.06)(+0.94) MeV. This study represents an unambiguous proof of the existence of the most neutron-proton unbalanced system presently found.
- Published
- 2007
- Full Text
- View/download PDF
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