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1. Probing exotic cross-shell interactions at N=28 with single-neutron transfer on 47K

Author

Paxman, C. J., Matta, A., Catford, W. N., Lotay, G., Assié, M., Clément, E., Lemasson, A., Ramos, D., Orr, N. A., Galtarossa, F., Girard-Alcindor, V., Dudouet, J., Achouri, N. L., Ackermann, D., Barrientos, D., Beaumel, D., Bednarczyk, P., Benzoni, G., Bracco, A., Canete, L., Cederwall, B., Ciemala, M., Delahaye, P., Doherty, D. T., Domingo-Pardo, C., Fernández-Domínguez, B., Fernández, D., Flavigny, F., Fougères, C., de France, G., Franchoo, S., Gadea, A., Gibelin, J., González, V., Gottardo, A., Goyal, N., Hammache, F., Harkness-Brennan, L. J., Harrouz, D. S., Jacquot, B., Judson, D. S., Jungclaus, A., Kaşkaş, A., Korten, W., Labiche, M., Lalanne, L., Lenain, C., Leoni, S., Ljungvall, J., Lois-Fuentes, J., Lokotko, T., Lopez-Martens, A., Maj, A., Marqués, F. M., Martel, I., Menegazzo, R., Mengoni, D., Million, B., Nyberg, J., Pérez-Vidal, R. M., Plagnol, L., Podolyák, Zs., Pullia, A., Quintana, B., Regueira-Castro, D., Reiter, P., Rejmund, M., Rezynkina, K., Sanchis, E., Şenyiğit, M., de Séréville, N., Siciliano, M., Sohler, D., Stezowski, O., Thomas, J. -C., Utepov, A., Valiente-Dobón, J. J., Verney, D., and Zielińska, M.

Subjects
Nuclear Experiment
Abstract

We present the first measurement of the $^{47}$K($d,p\gamma$)$^{48}$K transfer reaction, performed in inverse kinematics using a reaccelerated beam of $^{47}$K. The level scheme of $^{48}$K has been greatly extended with nine new bound excited states identified and spectroscopic factors deduced. Detailed comparisons with SDPF-U and SDPF-MU shell-model calculations reveal a number of discrepancies with these results, and a preference for SDPF-MU is found. Intriguingly, an apparent systematic overestimation of spectroscopic factors and a poor reproduction of the energies for 1$^-$ states suggests that the mixing between the $\pi s^{\,\,\,1}_{1/2} d^{\,\,\,4}_{3/2}$ and $\pi s^{\,\,\,2}_{1/2} d^{\,\,\,3}_{3/2}$ proton configurations in $^{48}$K is not correctly described using current interactions, challenging our descriptions of light $N=28$ nuclei., Comment: 7 pages, 3 figures, 1 table

Published
2024

2. Search for a neutron dark decay in $^6$He

Author

Joubioux, M. Le, Savajols, H., Mittig, W., Fléchard, X., Hayen, L., Penionzhkevich, Yu. E., Ackermann, D., Borcea, C., Caceres, L., Delahaye, P., Didierjean, F., Franchoo, S., Grillet, A., Jacquot, B., Lebois, M., Ledoux, X., Lecesne, N., Liénard, E., Lukyanov, S., Naviliat-Cuncic, O., Piot, J., Singh, A., Smirnov, V., Stodel, C., Testov, D., Thomas, J. C., and Verney, D.

Subjects
Nuclear Experiment
Abstract

Neutron dark decays have been suggested as a solution to the discrepancy between bottle and beam experiments, providing a dark matter candidate that can be searched for in halo nuclei. The free neutron in the final state following the decay of $^6$He into $^4$He $+$ $n$ + $\chi$ provides an exceptionally clean detection signature when combined with a high efficiency neutron detector. Using a high-intensity $^6$He$^+$ beam at GANIL, a search for a coincident neutron signal resulted in an upper limit on a dark decay branching ratio of Br$_\chi \leq 4.0\times10^{-10}$ (95\% C.L.). Using the dark neutron decay model proposed originally by Fornal and Grinstein, we translate this into an upper bound on a dark neutron branching ratio of $\mathcal{O}(10^{-5})$, improving over global constraints by one to several orders of magnitude depending on $m_\chi$.

Published
2023
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3. Experimental evidence of the effect of nuclear shells on fission dissipation and time

Author

Ramos, D., Caamano, M., Farget, F., Rodriguez-Tajes, C., Lemasson, A., Schmitt, C., Audouin, L., Benlliure, J., Casarejos, E., Clement, E., Cortina, D., Delaune, O., Derkx, X., Dijon, A., Dore, D., Fernandez-Dominguez, B., de France, G., Heinz, A., Jacquot, B., Paradela, C., Rejmund, M., Roger, T., and Salsac, M. -D.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

Nuclear fission is still one of the most complex physical processes we can observe in nature due to the interplay of macroscopic and microscopic nuclear properties that decide the result. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations, and scarce experimental data make it poorly understood. In this letter, we present the first experimental determination of the dissipation energy in fission as a function of the fragment split, for three different fissioning systems. The amount of dissipation was obtained through the measurement of the relative production of fragments with even and odd atomic numbers with respect to different initial fission energies. The results reveal a clear effect of particular nuclear shells on the dissipation and fission dynamics. In addition, the relative production of fragments with even and odd atomic numbers appears as a potential contributor to the long-standing problem of the time scale in fission.

Published
2023
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4. $^{178}$Hg and asymmetric fission of neutron-deficient pre-actinides

Author

Jhingan, A., Schmitt, C., Lemasson, A., Biswas, S., Kim, Y. H., Ramos, D., Andreyev, A. N., Curien, D., Ciemala, M., Clément, E., Dorvaux, O., De Canditiis, B., Didierjean, F., Duchêne, G., Dudouet, J., Frankland, J., Frémont, G., Goupil, J., Jacquot, B., Raison, C., Ralet, D., Retailleau, B. -M., Stuttgé, L., Tsekhanovich, I., Andreev, A. V., Goriely, S., Hilaire, S., Lemaître, J-F., Möller, P., and Schmidt, K. -H.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

Fission at low excitation energy is an ideal playground to probe the impact of nuclear structure on nuclear dynamics. While the importance of structural effects in the nascent fragments is well-established in the (trans-)actinide region, the observation of asymmetric fission in several neutron-deficient pre-actinides can be explained by various mechanisms. To deepen our insight into that puzzle, an innovative approach based on inverse kinematics and an enhanced version of the VAMOS++ heavy-ion spectrometer was implemented at the GANIL facility, Caen. Fission of $^{178}$Hg was induced by fusion of $^{124}$Xe and $^{54}$Fe. The two fragments were detected in coincidence using VAMOS++ supplemented with a new SEcond Detection arm. For the first time in the pre-actinide region, access to the pre-neutron mass and total kinetic energy distributions, and the simultaneous isotopic identification of one the fission fragment, was achieved. The present work describes the experimental approach, and discusses the pre-neutron observables in the context of an extended asymmetric-fission island located south-west of $^{208}Pb. A comparison with different models is performed, demonstrating the importance of this "new" asymmetric-fission island for elaborating on driving effects in fission.

Published
2022
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5. Structure of $^{83}$As, $^{85}$As and $^{87}$As: from semi-magicity to $\gamma$-softness

Author

Rezynkina, K., Dao, D. D., Duchene, G., Dudouet, J., Nowacki, F., Clement, E., Lemasson, A., Andreoiu, C., Astier, A., de Angelis, G., de France, G., Delafosse, C., Deloncle, I., Didierjean, F., Dombradi, Z., Ducoin, C., Gadea, A., Gottardo, A., Guinet, D., Jacquot, B., Jones, P., Konstantinopoulos, T., Kuti, I., Korichi, A., Lenzi, S. M., Li, G., Blanc, F. Le, Lizarazo, C., Lozeva, R., Maquart, G., Million, B., Michelagnoli, C., Napoli, D. R., Navin, A., Perez-Vidal, R. M., Petrache, C. M., Pietralla, N., Ralet, D., Ramdhane, M., Rejmund, M., Stezowski, O., Schmitt, C., Sohler, D., and Verney, D.

Subjects
Nuclear Experiment
Abstract

The structure of $^{83}$As, $^{85}$As and $^{87}$As have been studied in fusion-fission reaction $^{238}$U+$^9$Be. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident $\gamma$-rays were detected in the $\gamma$-ray tracking array AGATA. New transitions in $^{83}$As and $^{85}$As are reported and placed in the level schemes. A level scheme of the excited states in $^{87}$As is proposed for the first time. The data are interpreted in frame of Large-Scale Shell-Model calculations, SU3 symmetries and Beyond Mean-Field frameworks. A spherical regime at magic number $N$=50 is predicted and the location of the proton $g_{9/2}$ orbital is proposed for the first time. Development of collectivity in a prolate deformed, $\gamma$-soft regime in the open shell cases $^{85}$As and $^{87}$As, most neutron-rich isotopes beyond $N$=50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the $9/2^+$ state in $^{79}$Cu, one proton above $^{78}$Ni.

Published
2022
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6. Experimental investigation of ground-state properties of $^7$H with transfer reactions

Author

Caamaño, M., Roger, T., Moro, A. M., Grinyer, G. F., Pancin, J., Bagchi, S., Sambi, S., Gibelin, J., Fernandez-Dominguez, B., Itagaki, N., Benlliure, J., Cortina-Gil, D., Farget, F., Jacquot, B., Perez-Loureiro, D., Pietras, B., Raabe, R., Ramos, D., Tajes, C. Rodriguez, Savajols, H., and Vandebrouck, M.

Subjects
Nuclear Experiment
Abstract

The properties of nuclei with extreme neutron-to-proton ratios, far from those naturally occurring on Earth, are key to understand nuclear forces and how nucleons hold together to form nuclei. $^7$H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron-to-proton ratio known so far. However, its sheer existence and properties are still a challenge for experimental efforts and theoretical models. Here we report experimental evidences on the formation of $^7$H as a resonance, detected with independent observables, and the first measurement of the structure of its ground state. The resonance is found at $\sim$0.7 MeV above the $^3$H+4n mass, with a narrow width of $\sim$0.2 MeV and a $1/2^+$ spin and parity. These data are consistent with a $^7$H as a $^3$H core surrounded by an extended four-neutron halo, with a unique four-neutron decay and a relatively long half-life thanks to neutron pairing; a prime example of new phenomena occurring in what would be the most pure-neutron nuclear matter we can access in the laboratory.

Published
2021
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7. First beams at Neutrons For Science

Author

Ledoux, X., Foy, J. C., Ducret, J. E., Frelin, A. M., Ramos, D., Mrazek, J., Simeckova, E., Behal, R., Caceres, L., Glagolev, V., Jacquot, B., Lemasson, A., Pancin, J., Piot, 1 J., Stodel, C., and Vandebrouck, M.

Subjects
Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

The neutrons for science facility (NFS), the first operational experimental area of the new GANIL/SPIRAL-2 facility, received its first beams in December 2019. Proton-induced reaction cross-sections as well as neutron beam characteristics were measured during the first commissioning phases. The first results, showing the features of the facility, are presented here and compared with previously published data. The physics cases and the first accepted experiments are presented as well.

Published
2021
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8. Complete set of bound negative-parity states in the neutron-rich 18N nucleus

Author

Ziliani, S., Ciemała, M., Crespi, F. C. L., Leoni, S., Fornal, B., Suzuki, T., Otsuka, T., Maj, A., Bednarczyk, P., Benzoni, G., Bracco, A., Boiano, C., Bottoni, S., Brambilla, S., Bast, M., Beckers, M., Braunroth, T., Camera, F., Cieplicka-Orynczak, N., Clément, E., Coelli, S., Dorvaux, O., Erturk, S., De France, G., Fransen, C., Goldkuhle, A., Grebosz, J., Harakeh, M. N., Iskra, Ł. W., Jacquot, B., Karpov, A., Kicinska-Habior, M., Kimi, Y. -H., Kmiecik, M., Lemasson, A., Lewitowicz, M., Lenzi, S., Li, H., Matea, I., Mazurek, K., Michelagnoli, C., Matejska-Minda, M., Million, B., Müller-Gatermann, C., Nanal, V., Napiorkowski, P., Napoli, D. R., Palit, R., Rejmund, M., Schmitt, Ch., Stanoiu, M., Stefan, I., Vardaci, E., Wasilewska, B., Wieland, O., Zieblinski, M., and Zielinska, M.

Subjects
Nuclear Experiment
Abstract

High-resolution gamma-ray spectroscopy of 18N is performed with the Advanced GAmma Tracking Array AGATA, following deep-inelastic processes induced by an 18O beam on a 181Ta target. Six states are newly identified, which together with the three known excitations exhaust all negative-parity excited states expected in 18N below the neutron threshold. Spin and parities are proposed for all located states on the basis of decay branchings and comparison with large-scale shell-model calculations performed in the p-sd space, with the YSOX interaction. Of particular interest is the location of the 0^-_1 and 1^-_2 excitations, which provide strong constrains for cross-shell p-sd matrix elements based on realistic interactions, and help to simultaneously reproduce the ground and first-excited states in 16N and 18N, for the first time. Understanding the 18N structure may also have significant impact on neutron-capture cross-section calculations in r-process modeling including light neutron-rich nuclei.

Published
2021
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9. Pseudo spin doublet bands and Gallagher Moszkowski doublet bands in $^{100}$Y

Author

Wang, E. H., Hamilton, J. H., Ramayya, A. V., Zachary, C. J., Lemasson, A., Navin, A., Rejmund, M., Bhattacharyya, S., Chen, Q. B., Zhang, S. Q., Eldridge, J. M., Hwang, J. K., Brewer, N. T., Luo, Y. X., Rasmussen, J. O., Zhu, S. J., Ter-Akopian, G. M., Oganessian, Yu. Ts., Caamaño, M., Clément, E., Delaune, O., Farget, F., de France, G., and Jacquot, B.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

New transitions in neutron rich $^{100}$Y have been identified in a $^9$Be+$^{238}$U experiment with mass- and Z- gates to provide full fragment identification. These transitions and high spin levels of $^{100}$Y have been investigated by analyzing the high statistics $\gamma$-$\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$-$\gamma$ coincidence data from the spontaneous fission of $^{252}$Cf at the Gammasphere detector array. Two new bands, 14 new levels and 23 new transitions have been identified. The $K^{\pi}=4^+$ new band decaying to an 1s isomeric state is assigned to be the high-$K$ Gallagher-Moszkowski (GM) partner of the known $K^{\pi}=1^+$ band, with the $\pi 5/2[522] \otimes \nu 3/2[411]$ configuration. This 4$^+$ band is also proposed to be the pseudo spin partner of the new $K^{\pi}=5^+$ band with a 5$^{+}$ $\pi 5/2[422] \otimes \nu 5/2[413]$ configuration, to form a $\pi 5/2[422] \otimes \nu [312$ $5/2,3/2]$ neutron pseudospin doublet. Constrained triaxial covariant density functional theory and quantal particle rotor model calculations have been applied to interpret the band structure and available electromagnetic transition probabilities and are found in good agreement with experimental values.

Published
2021
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10. Accessing tens-to-hundreds femtoseconds nuclear state lifetimes with low-energy binary heavy-ion reactions

Author

Ciemala, M., Ziliani, S., Crespi, F. C. L., Leoni, S., Fornal, B., Maj, A., Bednarczyk, P., Benzoni, G., Bracco, A., Boiano, C., Bottoni, S., Brambilla, S., Bast, M., Beckers, M., Braunroth, T., Camera, F., Cieplicka-Orynczak, N., Clement, E., Coelli, S., Dorvaux, O., Erturk, S., De France, G., Fransen, C., Goldkuhle, A., Grebosz, J., Harakeh, M. N., Iskra, L. W., Jacquot, B., Karpov, A., Kicinska-Habior, M., Kim, Y. -H., Kmiecik, M., Lemasson, A., Lenzi, S. M., Lewitowicz, M., Li, H., Matea, I., Mazurek, K., Michelagnoli, C., Matejska-Minda, M., Million, B., Muller-Gatermann, C., Nanal, V., Napiorkowski, P., Napoli, D. R., Palit, R., Rejmund, M., Schmitt, Ch., Stanoiu, M., Stefan, I., Vardaci, E., Wasilewska, B., Wieland, O., Zieblinski, M., and Zielinska, M.

Subjects
Nuclear Experiment
Abstract

A novel Monte Carlo technique has been developed to determine lifetimes of excited states in the tens-to-hundreds femtoseconds range. The method is applied to low-energy heavy-ion binary reactions populating nuclei with complex velocity distributions. Its relevance is demonstrated in connection with the $^{18}$O(7.0 MeV/u) + $^{181}$Ta experiment, performed at GANIL with the AGATA+VAMOS+PARIS setup, to study neutron-rich O, C, N, ... nuclei. Excited states in $^{17}$O and $^{19}$O, with known lifetimes, are used to validate the method over the $\sim$20-400 fs lifetime-sensitivity range. Emphasis is given to the unprecedented position resolution provided by $\gamma$-tracking arrays, which turns out to be essential for reaching the required accuracy in Doppler-shift correction, at the basis of the detailed analysis of $\gamma$-ray lineshape and resulting state lifetime determination. The technique is anticipated to be an important tool for lifetime investigations in exotic neutron-rich nuclei, produced with intense ISOL-type beams.

Published
2020
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11. Prompt-delayed $\gamma$-ray spectroscopy of neutron-rich $^{119,121}$In isotopes

Author

Biswas, S., Lemasson, A., Rejmund, M., Navin, A., Kim, Y. H., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, Soumik, Bhattacharyya, S., Clément, E., Crawford, H. L., de France, G., Fallon, P., Frémont, G., Goupil, J., Jacquot, B., Li, H. J., Ljungvall, J., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R. M., and Ropert, J.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The fusion and transfer induced fission reaction $^{9}$Be($^{238}$U,~f) with 6.2 MeV/u beam energy, using a unique setup consisting of AGATA, VAMOS++ and EXOGAM detectors, was used to populate through the fission process and study the neutron-rich $^{119,121}$In isotopes. This setup enabled the prompt-delayed $\gamma$-ray spectroscopy of isotopes in the time range of $100~\rm{ns} - 200~\mu\rm{s}$. In the odd-$A$ $^{119,121}$In isotopes, indications of a short half-life $19/2^{-}$ isomeric state, in addition to the previously known $25/2^{+}$ isomeric state, were observed from the present data. Further, new prompt transitions above the $25/2^{+}$ isomer in $^{121}$In were identified along with reevaluation of its half-life. The experimental data were compared with the theoretical results obtained in the framework of large-scale shell-model calculations in a restricted model space. The $\langle \pi g_{9/2} \nu h_{11/2};I \arrowvert \hat{\mathcal{H}}\arrowvert \pi g_{9/2} \nu h_{11/2};I\rangle$ two-body matrix elements of residual interaction were modified to explain the excitation energies and the $B(E2)$ transition probabilities in the neutron-rich In isotopes. The (i) decreasing trend of $E(29/2^{+}) - E(25/2^{+})$ in odd-In (with dominant configuration $\pi g_{9/2}^{-1}\nu h_{11/2}^{-2}$ and maximum aligned spin of $29/2^{+}$) and (ii) increasing trend of $E(27/2^{+}) - E(23/2^{+})$ in odd-Sb (with dominant configuration $\pi g_{7/2}^{+1}\nu h_{11/2}^{-2}$ and maximum aligned spin of $27/2^{+}$) with increasing neutron number could be understood as a consequence of hole-hole and particle-hole interactions, respectively., Comment: Accepted for publication in Phys. Rev. C

Published
2020
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12. Scission configuration of $^{239}$U from yields and kinetic information of fission fragments

Author

Ramos, D., Caamano, M., Lemasson, A., Rejmund, M., Audouin, L., Alvarez-Pol, H., Frankland, J. D., Fernandez-Dominguez, B., Galiana-Baldo, E., Piot, J., Ackermann, D., Biswas, S., Clement, E., Durand, D., Farget, F., Fregeau, M. O., Galaviz, D., Heinz, A., Henriques, A. I., Jacquot, B., Jurado, B., Kim, Y. H., Morfouace, P., Ralet, D., Roger, T., Schmitt, C., Teubig, P., and Tsekhanovich, I.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The simultaneous measurement of the isotopic fission-fragment yields and fission-fragment velocities of $^{239}$U has been performed for the first time. The $^{239}$U fissioning system was produced in one-neutron transfer reactions between a $^{238}$U beam at 5.88 MeV/nucleon and a $^{9}$Be target. The combination of inverse kinematics at low energy and the use of the VAMOS++ spectrometer at the GANIL facility allows the isotopic identification of the full fission-fragment distribution and their velocity in the reference frame of the fissioning system. The proton and neutron content of the fragments at scission, their total kinetic and total excitation energy, as well as the neutron multiplicity were determined. Information from the scission point configuration is obtained from these observables and the correlation between them. The role of the octupole-deformed proton and neutron shells in the fission-fragment production is discussed., Comment: 8 pages, 7 figures

Published
2020
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13. Testing ab initio nuclear structure in neutron-rich nuclei: lifetime measurements of second 2+ states in 16C and 20O

Author

Ciemala, M., Ziliani, S., Crespi, F. C. L., Leoni, S., Fornal, B., Maj, A., Bednarczyk, P., Benzoni, G., Bracco, A., Boiano, C., Bottoni, S., Brambilla, S., Bast, M., Beckers, M., Braunroth, T., Camera, F., Cieplicka-Orynczak, N., Clement, E., Coelli, S., Dorvaux, O., Erturk, S., de France, G., Fransen, C., Goldkuhle, A., Grebosz, J., Harakeh, M. N., Iskra, L. W., Jacquot, B., Karpov, A., Kicinska-Habior, M., Kim, Y., Kmiecik, M., Lemasson, A., Lenzi, S. M., Lewitowicz, M., Li, H., Matea, I., Mazurek, K., Michelagnoli, C., Matejska-Minda, M., Million, B., Muller-Gatermann, C., Nanal, V., Napiorkowski, P., Napoli, D. R., Palit, R., Rejmund, M., Schmitt, Ch., Stanoiu, M., Stefan, I., Vardaci, E., Wasilewska, B., Wieland, O., Zieblinski, M., Zielinska, M., Atac, A., Barrientos, D., Birkenbach, B., Boston, A. J., Cederwall, B., Charles, L., Collado, J., Cullen, D. M., Desesquelles, P., Domingo-Pardo, C., Dudouet, J., Eberth, J., Gonzalez, V., Goupil, J., Harkness-Brennan, L. J., Hess, H., Judson, D. S., Jungclaus, A., Korten, W., Labiche, M., Lefevre, A., Menegazzo, R., Mengoni, D., Nyberg, J., Perez-Vidal, R. M., Podolyak, Zs., Pullia, A., Recchia, F., Reiter, P., Saillant, F., Salsac, M. D., Sanchis, E., Stezowski, O., Theisen, Ch., Valiente-Dobon, J. J., Holt, J. D., Menendez, J., Schwenk, A., and Simonis, J.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense ISOL-type beams become available.

Published
2020
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14. First direct measurement of isotopic fission-fragment yields of $^{239}$U

Author

Ramos, D., Caamano, M., Lemasson, A., Rejmund, M., Audouin, L., Alvarez-Pol, H., Frankland, J. D., Fernandez-Dominguez, B., Galiana-Baldo, E., Piot, J., Ackermann, D., Biswas, S., Clement, E., Durand, D., Farget, F., Fregeau, M. O., Galaviz, D., Heinz, A., Henriques, A. I., Jacquot, B., Jurado, B., Kim, Y. H., Morfouace, P., Ralet, D., Roger, T., Schmitt, C., Teubig, P., and Tsekhanovich, I.

Subjects
Nuclear Experiment
Abstract

A direct and complete measurement of isotopic fission-fragment yields of $^{239}$U has been performed for the first time. The $^{239}$U fissioning system was produced with an average excitation energy of 8.3 MeV in one-neutron transfer reactions between a $^{238}$U beam and a $^{9}$Be target at Coulomb barrier energies. The fission fragments were detected and isotopically identified using the VAMOS++ spectrometer at the GANIL facility. This measurement allows to directly evaluate the fission models at excitation energies of fast neutrons, relevant for next-generation nuclear reactors. The present data, in agreement with model calculations, do not support the recently reported anomaly in the fission-fragment yields of $^{239}$U and confirm the persistence of spherical shell effects in the Sn region at excitation energies exceeding the fission barrier by few MeV.

Published
2019
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15. Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich $^{122-131}$Sb$_{51}$ isotopes

Author

Biswas, S., Lemasson, A., Rejmund, M., Navin, A., Kim, Y. H., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, S., Bhattacharyya, S., Clément, E., Crawford, H. L., de France, G., Fallon, P., Frémont, G., Goupil, J., Jacquot, B., Li, H. J., Ljungvall, J., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R. M., Ropert, J., Barrientos, D., Benzoni, G., Birkenbach, B., Boston, A. J., Boston, H. C., Cederwall, B., Collado, J., Cullen, D. M., Désesquelles, P., Domingo-Pardo, C., Dudouet, J., Eberth, J., Gonzalez, V., Harkness-Brennan, L. J., Hess, H., Jungclaus, A., Korten, W., Labiche, M., Lefevre, A., Menegazzo, R., Mengoni, D., Million, B., Napoli, D. R., Pullia, A., Quintana, B., Ralet, D., Recchia, F., Reiter, P., Saillant, F., Salsac, M. D., Sanchis, E., Stezowski, O., Theisen, Ch., Valiente-Dobon, J. J., and Zielinska, M.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The neutron-rich $^{122-131}$Sb isotopes were produced as fission fragments in the reaction $^{9}$Be($^{238}$U,~f) with 6.2 MeV/u beam energy. An unique setup, consisting of AGATA, VAMOS++ and EXOGAM detectors, was used which enabled the prompt-delayed gamma-ray ($\gamma$) spectroscopy of fission fragments in the time range of 100 ns - 200 $\mu$s. New isomers, prompt and delayed transitions were established in the even-A $^{122-130}$Sb isotopes. In the odd-A $^{123-131}$Sb isotopes, new prompt and delayed $\gamma$-ray transitions were identified, in addition to the confirmation of the previously known isomers. The half-lives of the isomeric states and the $B(E2)$ transition probabilities of the observed transitions depopulating these isomers were extracted. The experimental data was compared with the theoretical results obtained in the framework of Large-Scale Shell-Model (LSSM) calculations in a restricted model space. Modifications of several components of the shell model interaction were introduced to obtain a consistent agreement with the excitation energies and the $B(E2)$ transition probabilities in neutron-rich Sn and Sb isotopes. The isomeric configurations in Sn and Sb were found to be relatively pure. Further, the calculations revealed that the presence of a single valence proton, mainly in the $g_{7/2}$ orbital in Sb isotopes, leads to significant mixing (due to the $\nu\pi$ interaction) of: (i) the neutron seniorities ($\upsilon_{\nu}$) and (ii) the neutron angular momentum ($I_{\nu}$). The above features have a weak impact on the excitation energies, but have an important impact on the $B(E2)$ transition probabilities. In addition, a constancy of the relative excitation energies irrespective of neutron seniority and neutron number in Sn and Sb was observed., Comment: 23 pages, 18 figures, 10 tables

Published
2019
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16. New exotic beams from the SPIRAL 1 upgrade

Author

Delahaye, P., Dubois, M., Maunoury, L., Angot, J., Bajeat, O., Blank, B., Cam, J. C., Chauveau, P., Frigot, R., Jacquot, B., Jardin, P., Lecomte, P., Hormigos, S., Kamalou, O., Kuchi, V., Osmond, B., Retailleau, B. M., Savalle, A., Stora, T., Toivanen, V., Thomas, J. C., Traykov, E., Ujic, P., and Vondrasek, R.

Subjects
Physics - Accelerator Physics, Nuclear Experiment
Abstract

Since 2001, the SPIRAL 1 facility has been one of the pioneering facilities in ISOL techniques for reaccelerating radioactive ion beams: the fragmentation of the heavy ion beams of GANIL on graphite targets and subsequent ionization in the Nanogan ECR ion source has permitted to deliver beams of gaseous elements (He, N, O, F, Ne, Ar, Kr) to numerous experiments. Thanks to the CIME cyclotron, energies up to 20 AMeV could be obtained. In 2014, the facility was stopped to undertake a major upgrade, with the aim to extend the production capabilities of SPIRAL 1 to a number of new elements. This upgrade, which is presently under commissioning, consists in the integration of an ECR booster in the SPIRAL 1 beam line to charge breed the beam of different 1+ sources. A FEBIAD source (the so-called VADIS from ISOLDE) was chosen to be the future workhorse for producing many metallic ion beams. The charge breeder is an upgraded version of the Phoenix booster which was previously tested in ISOLDE. The performances of the aforementioned ingredients of the upgrade (targets, 1+ source and charge breeder) have been and are still being optimized in the frame of different European projects (EMILIE, ENSAR and ENSAR2). The upgraded SPIRAL 1 facility will provide soon its first new beams for physics and further beam development are undertaken to prepare for the next AGATA campaign. The results obtained during the on-line commissioning period permit to evaluate intensities for new beams from the upgraded facility., Comment: 9 pages, 12 figures, conference proceedings of EMIS 2018, CERN, Geneva, to appear in Nuclear Instruments and Methods B

Published
2019
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17. Evidence for coexisting shapes in $^{98}$Zr through lifetime measurements

Author

Singh, Purnima, Korten, W., Hagen, T. W., Görgen, A., Grente, L., Salsac, M. -D., Farget, F., Clément, E., de France, G., Braunroth, T., Bruyneel, B., Celikovic, I., Delaune, O., Dewald, A., Dijon, A., Delaroche, J. -P., Girod, M., Hackstein, M., Jacquot, B., Libert, J., Litzinger, J., Ljungvall, J., Louchart, C., Gottardo, A., Michelagnoli, C., Müller-Gatermann, C., Napoli, D. R., Otsuka, T., Pillet, N., Recchia, F., Rother, W., Sahin, E., Siem, S., Sulignano, B., Togashi, T., Tsunoda, Y., Theisen, Ch., and Valiente-Dobon, J. J.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The lifetimes of first excited 2$^+$, 4$^+$ and 6$^+$ states in $^{98}$Zr were measured with the Recoil-Distance Doppler Shift method in an experiment performed at GANIL. Excited states in $^{98}$Zr were populated using the fission reaction between a 6.2 MeV/u $^{238}$U beam and a $^{9}$Be target. The $\gamma$ rays were detected with the EXOGAM array in correlation with the fission fragments identified in mass and atomic number in the VAMOS++ spectrometer. Our result shows very small B(E2;2$_1^+$ $\rightarrow$ 0$_1^+$) value in $^{98}$Zr thereby confirming the very sudden onset of collectivity at $N=60$. The experimental results are compared to large-scale Monte Carlo Shell model and beyond mean field calculations. The present results indicate coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.

Published
2019
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18. Deformed band structures in neutron-rich $^{152-158}$Pm isotopes

Author

Bhattacharyya, S., Wang, E. H., Navin, A., Rejmund, M., Hamilton, J. H., Ramayya, A. V., Hwang, J. K., Lemasson, A., Afanasjev, A. V., Bhattacharya, Soumik, Ranger, J., Caamaño, M., Clément, E., Delaune, O., Farget, F., de France, G., Jacquot, B., Luo, Y. X., Oganessian, Yu. Ts., Rasmussen, J. O., Ter-Akopian, G. M., and Zhu, S. J.

Subjects
Nuclear Experiment
Abstract

High spin band structures of neutron-rich $^{152-158}$Pm isotopes have been obtained from the measurement of prompt $\gamma$-rays of isotopically identified fragments produced in fission of $^{238}$U+$^{9}$Be and detected using the VAMOS++ magnetic spectrometer and EXOGAM segmented Clover array at GANIL and also from the high statistics $\gamma$-$\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$-$\gamma$ data from the spontaneous fission of $^{252}$Cf using Gammasphere. The excited states in $^{157}$Pm and those above the isomers in even-A Pm isotopes $^{152,154,156,158}$Pm have been identified for the first time. The spectroscopic information on the rotational band structures in odd-A Pm isotopes has been extended considerably to higher spins and the possibility of the presence of reflection asymmetric shapes is explored. The configuration assignments are based on the results of Cranked Relativistic Hartree-Bogoliubov calculations. From the systematics of bands in odd-A Pm isotopes and weak population of opposite parity bands, octupole deformed shapes in neutron rich Pm isotopes beyond $N=90$ seem unlikely to be present.

Published
2019
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19. Identification of new transitions and mass assignments of levels in $^{143-153}$Pr

Author

Wang, E. H., Lemasson, A., Hamilton, J. H., Ramayya, A. V., Hwang, J. K., Eldridge, J. M., Navin, A., Rejmund, M., Bhattacharyya, S., Liu, S. H., Brewer, N. T., Luo, Y. X., Rasmussen, J. O., Liu, H. L., Zhou, H., Liu, Y. X., Li, H. J., Sun, Y., Xu, F. R., Zhu, S. J., Ter-Akopian, G. M., Oganessian, Yu. Ts., Caamaño, M., Clément, E., Delaune, O., Farget, F., de France, G., and Jacquot, B.

Subjects
Nuclear Experiment
Abstract

The previously reported levels assigned to 151,152,153Pr have recently been called into question regarding their mass assignment. The above questioned level assignments are clarified by measuring g-transitions tagged with A and Z in an in-beam experiment in addition to the measurements from 252Cf spontaneous fission (SF) and establish new spectroscopic information from $N=84$ to $N=94$ in the Pr isotopic chain. The isotopic chain 143-153Pr has been studied from the spontaneous fission of 252Cf by using Gammasphere and also from the measurement of the prompt g-rays in coincidence with isotopically-identified fission fragments using VAMOS++ and EXOGAM at GANIL. The latter were produced using 238U beams on a 9Be target at energies around the Coulomb barrier. The g-g-g-g data from 252Cf (SF) and those from the GANIL in-beam A- and Z-gated spectra were combined to unambiguously assign the various transitions and levels in 151,152,153Pr and other isotopes. New transitions and bands in 145,147,148,149,150Pr were identified by using g-g-g and g-g-g-g coincidences and A and Z gated g-g spectra. The transitions and levels previously assigned to 151,153Pr have been confirmed by the (A,Z) gated spectra. The transitions previously assigned to 152Pr are now assigned to 151Pr on the basis of the (A,Z) gated spectra. Two new bands with 20 new transitions in 152Pr and one new band with 7 new transitions in 153Pr are identified from the g-g-g-g coincidence spectra and the (A,Z) gated spectrum. In addition, new g-rays are also reported in 143-146Pr. New levels of 145,147-153Pr have been established, reliable mass assignments of the levels in 151,152,153Pr have been reported and new transitions have been identified in 143-146Pr showing the new avenues that are opened by combining the two experimental approaches., Comment: Accepted in Phys. Rev. C

Published
2015
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20. Transfer reactions in inverse kinematics, an experimental approach for fission investigations

Author

Rodríguez-Tajes, C., Farget, F., Derkx, X., Caamaño, M., Delaune, O., Schmidt, K. -H., Clément, E., Dijon, A., Heinz, A., Roger, T., Audouin, L., Benlliure, J., Casarejos, E., Cortina, D., Doré, D., Fernández-Domínguez, B., Jacquot, B., Jurado, 1 B., Navin, A., Paradela, C., Ramos, D., Romain, P., Salsac, M. D., and Schmitt, C.

Subjects
Nuclear Experiment
Abstract

Inelastic and multi-nucleon transfer reactions between a $^{238}$U beam, accelerated at 6.14 MeV/u, and a $^{12}$C target were used for the production of neutron-rich, fissioning systems from U to Cm. A Si telescope, devoted to the detection of the target-like nuclei, provided a characterization of the fissioning systems in atomic and mass numbers, as well as in excitation energy. Cross-sections, angular and excitation-energy distributions were measured for the inelastic and transfer channels. Possible excitations of the target-like nuclei were experimentally investigated for the first time, by means of g -ray measurements. The decays from the first excited states of $^{12}$C, $^{11}$B and $^{10}$Be were observed with probabilities of 0.12 - 0.14, while no evidence for the population of higher-lying states was found. Moreover, the fission probabilities of $^{238}$U, $^{239}$Np and $^{240,241,242}$Pu and $^{244}$Cm were determined as a function of the excitation energy., Comment: 16 pages, 12 figures

Published
2013
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21. Discovery of a new isomeric state in $^{68}$Ni: Evidence for a highly-deformed proton intruder state

Author

Dijon, A., Clément, E., De France, G., De Angelis, G., Duchêne, G., Dudouet, J., Franchoo, S., Gadea, A., Gottardo, A., Hüyük, T., Jacquot, B., Kusoglu, A., Lebhertz, D., Lehaut, G., Martini, M., Napoli, D. R., Nowacki, F., Péru, S., Poves, A., Recchia, F., Redon, N., Sahin, E., Schmitt, C., Sferrazza, M., Sieja, K., Stezowski, O., Valiente-Dobon, J. J., Vancraeyenest, A., and Zheng, Y.

Subjects
Nuclear Experiment
Abstract

We report on the observation of a new isomeric state in $^{68}$Ni. We suggest that the newly observed state at 168(1) keV above the first 2$^+$ state is a $\pi(2p-2h)$ 0$^{+}$ state across the major Z=28 shell gap. Comparison with theoretical calculations indicates a pure proton intruder configuration and the deduced low-lying structure of this key nucleus suggests a possible shape coexistence scenario involving a highly deformed state., Comment: 5 pages, 3 figures, accepted for publication in Physical Review C

Published
2012
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22. GANIL Status report

Author

Jacquot, B., Chautard, F., Savalle, A., and Collaboration, the SPIRAL

Subjects
Nuclear Experiment, Physics - Accelerator Physics
Abstract

The GANIL-Spiral facility (Caen, France) is dedicated to the acceleration of heavy ion beams for nuclear physics, atomic physics, radiobiology and material irradiation. The production of radioactive ion beams for nuclear physics studies represents the main part of the activity. The facility possesses a versatile combination of equipments, which permits to produce accelerated radioactive ion beams with two complementary methods: Isotope Separation In Line (ISOL) and In-Flight Separation techniques (IFS). Considering the future of GANIL, SPIRAL II projects aims to produce high intensity secondary beams, by fission induced with a 5 mA deuteron beam on an uranium target., Comment: 5 pages, 5 figures, to be appear in the proceedings of the 17th International Conference on Cyclotrons and their Applications

Published
2005

23. Structure of <math><mmultiscripts><mi>As</mi><mprescripts/><none/><mn>83</mn></mmultiscripts><mo>,</mo></math> <math><mmultiscripts><mi>As</mi><mprescripts/><none/><mn>85</mn></mmultiscripts><mo>,</mo></math> and <math><mmultiscripts><mi>As</mi><mprescripts/><none/><mn>87</mn></mmultiscripts></math>: From semimagicity to <math><mi>γ</mi></math> softness

Author

Rezynkina, K., Dao, D.D., Duchene, G., Dudouet, J., Nowacki, F., Clément, E., Lemasson, A., Andreoiu, C., Astier, A., de Angelis, G., de France, G., Delafosse, C., Deloncle, I., Didierjean, F., Dombradi, Z., Ducoin, C., Gadea, A., Gottardo, A., Guinet, D., Jacquot, B., Jones, P., Konstantinopoulos, T., Kuti, I., Korichi, A., Lenzi, S.M., Li, G., Le Blanc, F., Lizarazo, C., Lozeva, R., Maquart, G., Million, B., Michelagnoli, C., Napoli, D.R., Navin, A., Perez-Vidal, R.M., Petrache, C.M., Pietralla, N., Ralet, D., Ramdhane, M., Rejmund, M., Stezowski, O., Schmitt, C., Sohler, D., Verney, D., Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Grand Accélérateur National d'Ions Lourds (GANIL), 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), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; The structure of As83, As85, and As87 have been studied in fusion-fission reaction U238+Be9. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident γ rays were detected in the γ-ray tracking array AGATA. New transitions in As83 and As85 are reported and placed in the level schemes. A level scheme of the excited states in As87 is proposed for the first time. The data are interpreted in frame of large-scale shell-model calculations, SU3 symmetries, and beyond mean-field frameworks. A spherical regime at magic number N=50 is predicted and the location of the proton g9/2 orbital is proposed for the first time. Development of collectivity in a prolate deformed, γ-soft regime in the open shell cases As85 and As87, most neutron-rich isotopes beyond N=50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the 9/2+ state in Cu79, one proton above Ni78.

Published
2022

24. Complete set of bound negative-parity states in the neutron-rich $^{18}$N nucleus

Author

Ziliani, S., Ciema��a, M., Crespi, F. C. L., Leoni, S., Fornal, B., Suzuki, T., Otsuka, T., Maj, A., Bednarczyk, P., Benzoni, G., Bracco, A., Boiano, C., Bottoni, S., Brambilla, S., Bast, M., Beckers, M., Braunroth, T., Camera, F., Cieplicka-Orynczak, N., Cl��ment, E., Coelli, S., Dorvaux, O., Erturk, S., De France, G., Fransen, C., Goldkuhle, A., Grebosz, J., Harakeh, M. N., Iskra, ��. W., Jacquot, B., Karpov, A., Kicinska-Habior, M., Kimi, Y. -H., Kmiecik, M., Lemasson, A., Lewitowicz, M., Lenzi, S., Li, H., Matea, I., Mazurek, K., Michelagnoli, C., Matejska-Minda, M., Million, B., M��ller-Gatermann, C., Nanal, V., Napiorkowski, P., Napoli, D. R., Palit, R., Rejmund, M., Schmitt, Ch., Stanoiu, M., Stefan, I., Vardaci, E., Wasilewska, B., Wieland, O., Zieblinski, M., Zielinska, M., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; High-resolution γ-ray spectroscopy of N18 is performed with the Advanced GAmma Tracking Array, following deep-inelastic processes induced by an O18 beam on a Ta181 target. Six states are newly identified, which together with the three known excitations exhaust all negative-parity excited states expected in N18 below the neutron threshold. Spin and parities are proposed for all located states on the basis of decay branchings and comparison with large-scale shell-model calculations performed in the p-sd space, with the YSOX interaction. Of particular interest is the location of the 01− and 12− excitations, which provide strong constrains for cross-shell p-sd matrix elements based on realistic interactions and help to simultaneously reproduce the ground and first-excited states in N16 and N18, for the first time. Understanding the N18 structure may also have significant impact on neutron-capture cross-section calculations in r-process modeling including light neutron-rich nuclei.

Published
2021

25. Lifetime measurements of excited states in neutron-rich $^{53}$Ti : Benchmarking effective shell-model interactions

Author

Goldkuhle, A., Blazhev, A., Fransen, C., Dewald, A., Beckers, M., Birkenbach, B., Braunroth, T., Clément, E., Dudouet, J., Eberth, J., Hess, H., Jacquot, B., Jolie, J., Kim, Y.-H., Lemasson, A., Lenzi, S., Li, H., Litzinger, J., Michelagnoli, C., Müller-Gatermann, C., Nara Singh, B., Pérez-Vidal, R., Ralet, D., Reiter, P., Vogt, A., Warr, N., Zell, K., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; Level lifetimes of the yrast (5/2 −) to 13/2 − states in the neutron-rich nucleus 53 Ti, produced in a multinucleon-transfer reaction, have been measured for the first time. The recoil distance Doppler-shift method was employed and lifetimes of the excited states were extracted by a lineshape analysis aided by Geant4-based Monte-Carlo simulations. The experiment was performed at the Grand Accélérateur National d'Ions Lourds facility in Caen, France, by using the Advanced Gamma Tracking Array for the γ-ray detection coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification and the Cologne plunger for deep-inelastic reactions. Reduced transition probabilities, deduced from the lifetimes, give new information on the nuclear structure of 53 Ti, and are used to benchmark different shell-model calculations using established interactions in the fp shell.

Published
2020

26. Prompt-delayed γ -ray spectroscopy of neutron-rich in 119,121 isotopes

Author

Biswas, S, Lemasson, A, Rejmund, M, Navin, A, Kim, YH, Michelagnoli, C, Stefan, I, Banik, R, Bednarczyk, P, Bhattacharya, S, Bhattacharyya, S, Clément, E, Crawford, HL, De France, G, Fallon, P, Frémont, G, Goupil, J, Jacquot, B, Li, HJ, Ljungvall, J, Maj, A, Ménager, L, Morel, V, Palit, R, Pérez-Vidal, RM, and Ropert, J

Subjects
Nuclear Experiment
Abstract

Background: The Z=50 shell closure, near N=82, is unique in the sense that it is the only shell closure with the spin-orbit partner orbitals, πg9/2 and πg7/2, enclosing the magic gap. The interaction of the proton hole/particle in the above-mentioned orbitals with neutrons in the νh11/2 orbital is an important prerequisite to the understanding of the nuclear structure near N=82 and the νπ interaction. Purpose: To explore the structural similarity between the high-spin isomeric states in In (Z=49), Sn (Z=50), and Sb (Z=51) isotopes from a microscopic point of view. In addition, to understand the role of a proton hole or particle in the spin-orbit partner orbitals, πg9/2 and πg7/2, respectively, with neutron holes in the νh11/2 orbital on these aforementioned isomers. Methods: The fusion and transfer induced fission reaction Be9(U238, f) with 6.2 MeV/u beam energy, using a unique setup consisting of AGATA, VAMOS++, and EXOGAM detectors, was used to populate through the fission process and study the neutron-rich In119,121 isotopes. This setup enabled the prompt-delayed γ-ray spectroscopy of isotopes in the time range of 100ns-200μs. Results: In the odd-AIn119,121 isotopes, indications of a short half-life 19/2- isomeric state, in addition to the previously known 25/2+ isomeric state, were observed from the present data. Further, new prompt transitions above the 25/2+ isomer in In121 were identified along with reevaluation of its half-life. Conclusions: The experimental data were compared with the theoretical results obtained in the framework of large-scale shell-model calculations in a restricted model space. The (πg9/2νh11/2;I|Ĥ|πg9/2νh11/2;I) two-body matrix elements of residual interaction were modified to explain the excitation energies and the B(E2) transition probabilities in the neutron-rich In isotopes. The (i) decreasing trend of E(29/2+)-E(25/2+) in odd-In (with dominant configuration πg9/2-1νh11/2-2 and maximum aligned spin of 29/2+) and (ii) increasing trend of E(27/2+)-E(23/2+) in odd-Sb (with dominant configuration πg7/2+1νh11/2-2 and maximum aligned spin of 27/2+) with increasing neutron number could be understood as a consequence of hole-hole and particle-hole interactions, respectively.

Published
2020

27. Prompt-delayed γ -ray spectroscopy of neutron-rich $^{119,121}$In isotopes

Author

Biswas, S., Lemasson, A., Rejmund, M., Navin, A., Kim, Y. H., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, Soumik, Bhattacharyya, S., Clément, E., Crawford, H. L., de France, G., Fallon, P., Frémont, G., Goupil, J., Jacquot, B., Li, H. J., Ljungvall, J., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R. M., Ropert, J., 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), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and 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)

Subjects
Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nuclear Structure
Abstract

The fusion and transfer induced fission reaction $^{9}$Be($^{238}$U,~f) with 6.2 MeV/u beam energy, using a unique setup consisting of AGATA, VAMOS++ and EXOGAM detectors, was used to populate through the fission process and study the neutron-rich $^{119,121}$In isotopes. This setup enabled the prompt-delayed $\gamma$-ray spectroscopy of isotopes in the time range of $100~\rm{ns} - 200~\mu\rm{s}$. In the odd-$A$ $^{119,121}$In isotopes, indications of a short half-life $19/2^{-}$ isomeric state, in addition to the previously known $25/2^{+}$ isomeric state, were observed from the present data. Further, new prompt transitions above the $25/2^{+}$ isomer in $^{121}$In were identified along with reevaluation of its half-life. The experimental data were compared with the theoretical results obtained in the framework of large-scale shell-model calculations in a restricted model space. The $\langle \pi g_{9/2} \nu h_{11/2};I \arrowvert \hat{\mathcal{H}}\arrowvert \pi g_{9/2} \nu h_{11/2};I\rangle$ two-body matrix elements of residual interaction were modified to explain the excitation energies and the $B(E2)$ transition probabilities in the neutron-rich In isotopes. The (i) decreasing trend of $E(29/2^{+}) - E(25/2^{+})$ in odd-In (with dominant configuration $\pi g_{9/2}^{-1}\nu h_{11/2}^{-2}$ and maximum aligned spin of $29/2^{+}$) and (ii) increasing trend of $E(27/2^{+}) - E(23/2^{+})$ in odd-Sb (with dominant configuration $\pi g_{7/2}^{+1}\nu h_{11/2}^{-2}$ and maximum aligned spin of $27/2^{+}$) with increasing neutron number could be understood as a consequence of hole-hole and particle-hole interactions, respectively., Comment: Accepted for publication in Phys. Rev. C

Published
2020

28. Testing $ab initio$ nuclear structure in neutron-rich nuclei: lifetime measurements of second 2$^+$ states in $^{16}$C and $^{20}$O

Author

Ciemala, M., Ziliani, S., Crespi, F.C.L., Leoni, S., Fornal, B., Maj, A., Bednarczyk, P., Benzoni, G., Bracco, A., Boiano, C., Bottoni, S., Brambilla, S., Bast, M., Beckers, M., Braunroth, T., Camera, F., Cieplicka-Orynczak, N., Clément, E., Coelli, S., Dorvaux, O., Erturk, S., de France, G., Fransen, C., Goldkuhle, A., Grebosz, J., Harakeh, M.N., Iskra, L.W., Jacquot, B., Karpov, A., Kicinska-Habior, M., Kim, Y., Kmiecik, M., Lemasson, A., Lenzi, S.M., Lewitowicz, M., Li, H., Matea, I., Mazurek, K., Michelagnoli, C., Matejska-Minda, M., Million, B., Muller-Gatermann, C., Nanal, V., Napiorkowski, P., Napoli, D.R., Palit, R., Rejmund, M., Schmitt, Ch., Stanoiu, M., Stefan, I., Vardaci, E., Wasilewska, B., Wieland, O., Zieblinski, M., Zielinska, M., Atac, A., Barrientos, D., Birkenbach, B., Boston, A.J., Cederwall, B., Charles, L., Collado, J., Cullen, D.M., Desesquelles, P., Domingo-Pardo, C., Dudouet, J., Eberth, J., Gonzalez, V., Goupil, J., Harkness-Brennan, L.J., Hess, H., Judson, D.S., Jungclaus, A., Korten, W., Labiche, M., Lefevre, A., Menegazzo, R., Mengoni, D., Nyberg, J., Perez-Vidal, R.M., Podolyak, Zs., Pullia, A., Recchia, F., Reiter, P., Saillant, F., Salsac, M.D., Sanchis, E., Stezowski, O., Theisen, Ch., Valiente-Dobon, J.J., Holt, J.D., Menendez, J., Schwenk, A., Simonis, J., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), 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), Institut Laue-Langevin (ILL), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), ILL, 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), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear Theory (nucl-th), nucl-th, Nuclear Theory, Nuclear Physics - Theory, Starke Wechselwirkung und exotische Kerne – Abteilung Blaum, FOS: Physical sciences, Nuclear Physics - Experiment, ddc:530, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nucl-ex, Nuclear Structure, Nuclear Experiment
Abstract

To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2+ state in neutron-rich O20,τ(22+)=150−30+80fs, and an estimate for the lifetime of the second 2+ state in C16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted γ-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O18(7.0MeV/u)+Ta181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced γ-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O20 and with the no-core shell model for C16. The present measurement shows the power of electromagnetic observables, determined with high-precision γ spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available. To test the predictive power of ab initio nuclear structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles nuclear structure calculations, complementing common benchmarks based on nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the nuclear chart, including r-process nuclei, when intense ISOL-type beams become available.

Published
2020

29. Lifetime measurements in Ti 52,54 to study shell evolution toward N=32

Author

Goldkuhle, A., Fransen, C., Blazhev, A., Beckers, M., Birkenbach, B., Braunroth, T., Clément, E., Dewald, A., Dudouet, J., Eberth, J., Hess, H., Jacquot, B., Jolie, J., Kim, Y.H., Lemasson, A., Lenzi, Silvia M., Li, H.J., Litzinger, J., Michelagnoli, C., Müller-Gatermann, C., Nara Singh, B.S., Pérez-Vidal, R.M., Ralet, D., Reiter, P., Vogt, A., Warr, N., Zell, K.O., Ataç, A., Barrientos, D., Barthe-Dejean, C., Benzoni, G., Boston, A.J., Boston, H.C., Bourgault, P., Burrows, I., Cacitti, J., Cederwall, B., Ciemala, M., Cullen, D.M., De France, G., Domingo Pardo, César, Foucher, J.L., Fremont, G., Gadea, Andrés, Gangnant, P., González, V., Goupil, J., Henrich, C., Houarner, C., Sanchis, E., Ministerio de Economía y Competitividad (España), and Ministerio de Ciencia, Innovación y Universidades (España)

Subjects
Nuclear Experiment
Abstract

AGATA Collaboration, Lifetimes of the excited states in the neutron-rich Ti52,54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accélérateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the γ-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 21+ to 81+ yrast states in Ti52,54 and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N=32 subshell closure. The B(E2) values for Ti52 determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes.

Published
2019

30. Excitations of the magic N=50 neutron-core revealed in Ga 81

Author

Dudouet, J., Lemasson, A., Maquart, G., Nowacki, F., Verney, D., Rejmund, M., Duchêne, G., Stezowski, O., Clément, E., Michelagnoli, C., Korichi, A., Andreoiu, C., Astier, A., De Angelis, G., De France, G., Delafosse, C., Deloncle, I., Didierjean, F., Dombrádi, Zs., Ducoin, C., Gadea, Andrés, Gottardo, A., Guinet, D., Jacquot, B., Jones, P., Konstantinopoulos, T., Kuti, I., Le Blanc, F., Lenzi, Silvia M., Li, G., Lozeva, R., Million, B., Napoli, D.R., Navin, A., Pérez-Vidal, R. M., Petrache, C.M., Ralet, D., Ramdhane, M., Redon, N., Schmitt, C., Sohler, D., Ministerio de Economía y Competitividad (España), and Ministerio de Ciencia, Innovación y Universidades (España)

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Physics::Atomic and Molecular Clusters, Nuclear Experiment
Abstract

The high-spin states of the neutron-rich Ga81, with three valence protons outside a Ni78 core, were measured. The measurement involved prompt γ-ray spectroscopy of fission fragments isotopically identified using the combination of the variable mode spectrometer (VAMOS++) and the advanced gamma tracking array (AGATA). The new γ-ray transitions, observed in coincidence with Ga81 ions, and the corresponding level scheme do not confirm the high-spin levels reported earlier. The newly observed high-spin states in Ga81 are interpreted using the results of state-of-the-art large-scale shell model (LSSM) calculations. The lower excitation energy levels are understood as resulting from the recoupling of three valence protons to the closed doubly magic core, while the highest excitation energy levels correspond to excitations of the magic N=50 neutron core. These results support the doubly magic character of Ni78 and the persistence of the N=50 shell closure but also highlight the presence of strong proton-neutron correlations associated with the promotion of neutrons across the magic N=50 shell gap, only few nucleons away from Ni78.

Published
2019

31. Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich Sb 51122-131 isotopes

Author

Biswas, S., Lemasson, A., Rejmund, M., Navin, A., Kim, Y. H., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, S., Bhattacharyya, S., Clément, E., Crawford, H. L., De France, G., Fallon, P., Frémont, G., Goupil, J., Jacquot, B., Li, H. J., Ljungvall, J., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R. M., Ropert, J., Barrientos, D., Benzoni, G., Birkenbach, B., Boston, A. J., Boston, H. C., Cederwall, B., Collado, J., Cullen, D. M., Désesquelles, P., Domingo-Pardo, C., Dudouet, J., Eberth, J., González, V., Harkness-Brennan, L. J., Hess, H., Jungclaus, A., Korten, W., Labiche, M., Lefevre, A., Menegazzo, R., Mengoni, D., Million, B., Napoli, D. R., Pullia, A., Quintana, B., Ralet, D., Recchia, F., Reiter, P., Saillant, F., Salsac, M. D., Sanchis, E., Stezowski, O., Theisen, Ch, Valiente-Dobón, J. J., and Zielińska, M.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Background: Levels fulfilling the seniority scheme and relevant isomers are commonly observed features in semimagic nuclei; for example, in Sn isotopes (Z=50). Seniority isomers in Sn, with dominantly pure neutron configurations, directly probe the underlying neutron-neutron (νν) interaction. Furthermore, an addition of a valence proton particle or hole, through neutron-proton (νπ) interaction, affects the neutron seniority as well as the angular momentum. Purpose: Benchmark the reproducibility of the experimental observables, like the excitation energies (EX) and the reduced electric-quadrupole transition probabilities [B(E2)], with the results obtained from shell-model interactions for neutron-rich Sn and Sb isotopes with N

Published
2019

32. Excitations of the magic $N=50$ neutron-core revealed in $^{81}$Ga

Author

Dudouet, J., Lemasson, A., Maquart, G., Nowacki, F., Verney, D., Rejmund, M., Duchêne, G., Stezowski, O., Clément, E., Michelagnoli, C., Korichi, A., Andreoiu, C., Astier, A., De Angelis, G., De France, G., Delafosse, C., Deloncle, I., Didierjean, F., Dombradi, Z., Ducoin, C., Gadea, A., Gottardo, A., Guinet, D., Jacquot, B., Jones, P., Konstantinopoulos, T., Kuti, I., Le Blanc, F., Lenzi, S.M., Li, G., Lozeva, R., Million, B., Napoli, D.R., Navin, A., Pérez-Vidal, R.M., Petrache, C.M., Ralet, D., Ramdhane, M., Redon, N., Schmitt, C., Sohler, D., Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), 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), Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-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), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Physics::Atomic and Molecular Clusters, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nuclear Structure
Abstract

International audience; The high-spin states of the neutron-rich Ga81, with three valence protons outside a Ni78 core, were measured. The measurement involved prompt γ-ray spectroscopy of fission fragments isotopically identified using the combination of the variable mode spectrometer (VAMOS++) and the advanced gamma tracking array (AGATA). The new γ-ray transitions, observed in coincidence with Ga81 ions, and the corresponding level scheme do not confirm the high-spin levels reported earlier. The newly observed high-spin states in Ga81 are interpreted using the results of state-of-the-art large-scale shell model (LSSM) calculations. The lower excitation energy levels are understood as resulting from the recoupling of three valence protons to the closed doubly magic core, while the highest excitation energy levels correspond to excitations of the magic N=50 neutron core. These results support the doubly magic character of Ni78 and the persistence of the N=50 shell closure but also highlight the presence of strong proton-neutron correlations associated with the promotion of neutrons across the magic N=50 shell gap, only few nucleons away from Ni78.

Published
2019

33. Lifetime measurements in Ti-52,Ti-54 to study shell evolution toward N=32

Author

Goldkuhle, A., Fransen, C., Blazhev, A., Beckers, M., Birkenbach, B., Braunroth, T., Clement, E., Dewald, A., Dudouet, J., Eberth, J., Hess, H., Jacquot, B., Jolie, J., Kim, Y-H, Lemasson, A., Lenzi, S. M., Li, H. J., Litzinger, J., Michelagnoli, C., Mueller-Gatermann, C., Singh, B. S. Nara, Perez-Vidal, R. M., Ralet, D., Reiter, P., Vogt, A., Warr, N., Zell, K. O., Atac, A., Barrientos, D., Barthe-Dejean, C., Benzoni, G., Boston, A. J., Boston, H. C., Bourgault, P., Burrows, I, Cacitti, J., Cederwall, B., Ciemala, M., Cullen, D. M., De France, G., Domingo-Pardo, C., Foucher, J-L, Fremont, G., Gadea, A., Gangnant, P., Gonzalez, V, Goupil, J., Henrich, C., Houarner, C., Jean, M., Judson, D. S., Korichi, A., Korten, W., Labiche, M., Lefevre, A., Legeard, L., Legruel, F., Leoni, S., Ljungvall, J., Maj, A., Maugeais, C., Menager, L., Menard, N., Menegazzo, R., Mengoni, D., Million, B., Munoz, H., Napoli, D. R., Navin, A., Nyberg, Johan, Ozille, M., Podolyak, Zs, Pullia, A., Raine, B., Recchia, F., Ropert, J., Saillant, F., Salsac, M. D., Sanchis, E., Schmitt, C., Simpson, J., Spitaels, C., Stezowski, O., Theisen, Ch, Toulemonde, M., Tripon, M., Dobon, J-J Valiente, Voltolini, G., and Zielinska, M.

Subjects
Subatomär fysik, Subatomic Physics, Nuclear Experiment
Abstract

Lifetimes of the excited states in the neutron-rich Ti-52,Ti-54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accelerateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the gamma-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 2(1)(+) to 8(1)(+) yrast states in Ti-52,Ti-54 and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N = 32 subshell closure. The B(E2) values for Ti-52 determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes.

Published
2019

34. Evidence for Coexisting Shapes through Lifetime Measurements in $^{98}$Zr

Author

Singh, Purnima, Korten, W., Hagen, T.W., Görgen, A., Grente, L., Salsac, M.-D., Farget, F., Clément, E., De France, G., Braunroth, T., Bruyneel, B., Celikovic, I., Delaune, O., Dewald, A., Dijon, A., Delaroche, J.-P., Girod, M., Hackstein, M., Jacquot, B., Libert, J., Litzinger, J., Ljungvall, J., Louchart, C., Gottardo, A., Michelagnoli, C., Müller-Gatermann, C., Napoli, D.R., Otsuka, T., Pillet, N., Recchia, F., Rother, W., Sahin, E., Siem, S., Sulignano, B., Togashi, T., Tsunoda, Y., Theisen, Ch., Valiente-Dobon, J.J., Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Grand Accélérateur National d'Ions Lourds (GANIL), 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), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), and 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)

Subjects
Physics and Astronomy (all), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nuclear Physics
Abstract

The lifetimes of the first excited 2^{+}, 4^{+}, and 6^{+} states in ^{98}Zr were measured with the recoil-distance Doppler shift method in an experiment performed at GANIL. Excited states in ^{98}Zr were populated using the fission reaction between a 6.2 MeV/u ^{238}U beam and a ^{9}Be target. The γ rays were detected with the EXOGAM array in correlation with the fission fragments identified by mass and atomic number in the VAMOS++ spectrometer. Our result shows a very small B(E2;2_{1}^{+}→0_{1}^{+}) value in ^{98}Zr, thereby confirming the very sudden onset of collectivity at N=60. The experimental results are compared to large-scale Monte Carlo shell model and beyond-mean-field calculations. The present results indicate the coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.

Published
2018

35. Isotopic fission-fragment distributions of $^{238}$U, $^{239}$Np, $^{240}$Pu, $^{244}$Cm , and $^{250}$Cf produced through inelastic scattering, transfer, and fusion reactions in inverse kinematics

Author

Ramos, D., Caamaño, M., Farget, F., Rodriguez-Tajes, C., Audouin, L., Benlliure, J., Casarejos, E., Clement, E., Cortina, D., Delaune, O., Derkx, X., Dijon, A., Doré, D., Fernández-Domínguez, B., De France, G., Heinz, A., Jacquot, B., Navin, A., Paradela, C., Rejmund, M., Roger, T., Salsac, M.D., Schmitt, C., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut de Physique Nucléaire d'Orsay (IPNO), 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), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, 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)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; Transfer- and fusion-induced fission in inverse kinematics has proved to be a powerful tool to investigate nuclear fission, widening information on the fission fragments and access to unstable fissioning systems with respect to other experimental approaches. An experimental campaign is being carried out at GANIL with this technique since 2008. In these experiments, a beam of U238, accelerated to 6.1 MeV/u, impinges on a C12 target. Fissioning systems from U to Cf are populated through inelastic scattering, transfer, and fusion reactions, with excitation energies that range from a few MeV up to 46 MeV. The use of inverse kinematics, the SPIDER telescope, and the VAMOS spectrometer allow the characterization of the fissioning system in terms of mass, nuclear charge, and excitation energy, and the isotopic identification of the full fragment distribution. This work reports on new data from the second experiment of the campaign on fission-fragment yields of the heavy actinides U238, Np239, Pu240, Cm244, and Cf250, which are of interest from both fundamental and application points of view.

Published
2018

36. Deformed band structures in neutron-rich $^{152-158}$Pm isotopes

Author

Bhattacharyya, S., Wang, E. H., Navin, A., Rejmund, M., Hamilton, J. H., Ramayya, A. V., Hwang, J. K., Lemasson, A., Afanasjev, A. V., Bhattacharya, Soumik, Ranger, J., Caama��o, M., Cl��ment, E., Delaune, O., Farget, F., de France, G., Jacquot, B., Luo, Y. X., Oganessian, Yu. Ts., Rasmussen, J. O., Ter-Akopian, G. M., Zhu, S. J., Grand Accélérateur National d'Ions Lourds (GANIL), 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 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)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, Nuclear Structure
Abstract

High spin band structures of neutron-rich $^{152-158}$Pm isotopes have been obtained from the measurement of prompt $\gamma$-rays of isotopically identified fragments produced in fission of $^{238}$U+$^{9}$Be and detected using the VAMOS++ magnetic spectrometer and EXOGAM segmented Clover array at GANIL and also from the high statistics $\gamma$-$\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$-$\gamma$ data from the spontaneous fission of $^{252}$Cf using Gammasphere. The excited states in $^{157}$Pm and those above the isomers in even-A Pm isotopes $^{152,154,156,158}$Pm have been identified for the first time. The spectroscopic information on the rotational band structures in odd-A Pm isotopes has been extended considerably to higher spins and the possibility of the presence of reflection asymmetric shapes is explored. The configuration assignments are based on the results of Cranked Relativistic Hartree-Bogoliubov calculations. From the systematics of bands in odd-A Pm isotopes and weak population of opposite parity bands, octupole deformed shapes in neutron rich Pm isotopes beyond $N=90$ seem unlikely to be present.

Published
2018

37. Prompt-delayed γ -ray spectroscopy with AGATA, EXOGAM and VAMOS++

Author

Kim, YH, Lemasson, A, Rejmund, M, Navin, A, Biswas, S, Michelagnoli, C, Stefan, I, Banik, R, Bednarczyk, P, Bhattacharya, S, Bhattacharyya, S, Clément, E, Crawford, HL, De France, G, Fallon, P, Goupil, J, Jacquot, B, Li, HJ, Ljungvall, J, Macchiavelli, AO, Maj, A, Ménager, L, Morel, V, Palit, R, Pérez-Vidal, RM, Ropert, J, and Schmitt, C

Subjects
Particle and Plasma Physics, Astrophysics::High Energy Astrophysical Phenomena, Molecular, Nuclear, Nuclear Experiment, Nuclear & Particles Physics, Atomic
Abstract

© 2017, SIF, Springer-Verlag GmbH Germany. A new experimental setup to measure prompt-delayed γ-ray coincidences from isotopically identified fission fragments, over a wide time range of 100ns-200μ s, is presented. The fission fragments were isotopically identified, on an event-by-event basis, using the VAMOS++ large acceptance spectrometer. The prompt γ rays emitted at the target position and corresponding delayed γ rays emitted at the focal plane of the spectrometer were detected using, respectively, thirty two crystals of the AGATA γ-ray tracking array and seven EXOGAM HPGe Clover detectors. Fission fragments produced in fusion and transfer-induced fission reactions, using a 238U beam at an energy of 6.2 MeV/u impinging on a 9Be target, were used to characterize and qualify the performance of the detection system.

Published
2017

38. Kr 3696 60 -Low- Z Boundary of the Island of Deformation at N=60

Author

Dudouet, J., Lemasson, A., Duchêne, G., Rejmund, M., {Clément}, E, {Michelagnoli}, C, Didierjean, F., {Korichi}, A, Maquart, G., {Stezowski}, O, Lizarazo, C., Pérez-Vidal, R. M., Andreoiu, C, {de Angelis}, G, {Astier}, A, Delafosse, C., Deloncle, I., Dombradi, Z., {de France}, G, Gadea, A, {Gottardo}, A, {Jacquot}, B, Jones, P., {Konstantinopoulos}, T, Kuti, I., Le Blanc, F., {Lenzi}, S M, Li, G., Lozeva, R, Million, B., {Napoli}, D R, Navin, A., {Petrache}, C M, Pietralla, N., Ralet, D., Ramdhane, M., Redon, N., Schmitt, C., {Sohler}, D, Verney, D., Barrientos, D., Birkenbach, B., Burrows, I., Charles, L., Collado-Vides, Julio, Cullen, D. M., Désesquelles, P., Domingo-Pardo, C, González, V., Harkness-Brennan, L., Hess, H., Judson, D. S., Karolak, M., {Korten}, W, Labiche, M, Ljungvall, J., {Menegazzo}, R, Mengoni, D., {Pullia}, A, {Recchia}, F, Reiter, P., {Salsac}, M -D, Sanchis, E., Theisen, Ch, {Valiente-Dobón}, J J, and Zielińska, M.

Subjects
Nuclear Experiment
Abstract

Prompt γ-ray spectroscopy of the neutron-rich Kr96, produced in transfer- and fusion-induced fission reactions, has been performed using the combination of the Advanced Gamma Tracking Array and the VAMOS++ spectrometer. A second excited state, assigned to Jπ=4+, is observed for the first time, and a previously reported level energy of the first 2+ excited state is confirmed. The measured energy ratio R4/2=E(4+)/E(2+)=2.12(1) indicates that this nucleus does not show a well-developed collectivity contrary to that seen in heavier N=60 isotones. This new measurement highlights an abrupt transition of the degree of collectivity as a function of the proton number at Z=36, of similar amplitude to that observed at N=60 at higher Z values. A possible reason for this abrupt transition could be related to the insufficient proton excitations in the g9/2, d5/2, and s1/2 orbitals to generate strong quadrupole correlations or to the coexistence of competing different shapes. An unexpected continuous decrease of R4/2 as a function of the neutron number up to N=60 is also evidenced. This measurement establishes the Kr isotopic chain as the low-Z boundary of the island of deformation for N=60 isotones. A comparison with available theoretical predictions using different beyond mean-field approaches shows that these models fail to reproduce the abrupt transitions at N=60 and Z=36.

Published
2017

39. γ-ray spectroscopy of neutron rich Ag isotopes: πg9/2n × νh11/2m structure and triaxiality

Author

Kim, Y. H., Biswas, S., Rejmund, M., Navin, A., Lemasson, A., Caamano, M., Clément, E., Delaune, O., Fanny Farget, France, G., Jacquot, B., 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), 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 Lion, Michel

Subjects
[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; The fission process produces neutron-rich nuclides far from stability withcomparable excitation energy and relatively high angular momentum. Therefore it isused as an important tool to study the variety of different nuclear structures . Thecollective band around neutron-rich Ag isotopes have configuration of two intruderorbitals πg9/2n ×νh11/2m which presents triaxiality . The interpretations of thesenuclei towards the mid-shell were usually carried out by the deformed basis collectiveshell models as- suming deformation in the core and few quasi particles. The viewfrom large-scale shell model with spherical basis could bring new perspective in thisregion, such as unexpected breaking of natural seniority in In arising from protonneutron interaction.The 113-121Ag isotopes which lie at the borderline of spherical and deformedbasis shell model calculations were studied by exploiting the prompt γ-rayspectroscopy of the isotopically identified fission fragments using the VAMOS++spectrometer and the EXOGAM Ge-array at GANIL [5]. Low-lying high-spin states ofneutron-rich 113,118-121Ag have been established for the first time [6]. The excitedstates of both odd-A and even-A isotopes followed the smooth systematics of thosein Cd core. A large signature splitting in odd-A isotopes and a signature inversion ineven-A isotopes, which is often used as a finger print of triaxial deformation, throughout long chain of isotopes in 50 < N < 82 region, is striking. The large-scale shellmodelcalculations reproduce the experimental spectra and the signature splitting,revealing their microscopic nature. The natural seniority ordering was broken moreseverely than In isotopes [4] inducing strong mixed wave functions.The main features of signature splitting are reproduced by crude shell modelincluding only πg9/2 and νh11/2, indicating the yrast band in the Ag isotopes can beessentially understood based on πg9/2n×νh11/2m multiplet, without any particularassumption about the deformation. This simplicity behind the complex structures inthe wave function could be owing to the strong contribution from both proton andneutron intruder orbitals with unique parity, which makes the configuration of theband fairly pure. Perspectives of the recent experiment with VAMOS++ and AGATAγ-ray tracking detectors will be discussed.

Published
2017

40. Measurement of lifetimes in $^{62,64}$Fe, $^{61,63}$Co, and $^{59}$Mn

Author

Klintefjord, M., Ljungvall, J., Görgen, A., Lenzi, M., Bello Garrote, F., Blazhev, A., Clément, E., De France, G., Delaroche, P., Dewald, A., Doherty, D., Fransen, C., Gengelbach, A., Georgiev, G., Girod, M., Goasduff, A., Gottardo, A., Hadyńska-Klȩk, K., Jacquot, B., Désesquelles, P., Konstantinopoulos, T., Korichi, A., Lemasson, A., Libert, J., Lopez-Martens, A., Michelagnoli, C., Navin, A., Nyberg, J., Pérez-Vidal, R., Roccia, S., Sahin, E., Stefan, I., Stuchbery, E., Zielińska, M., Barrientos, D., Birkenbach, B., Boston, A., Charles, L., Ciemala, M., Dudouet, J., Eberth, J., Gadea, A., González, V., Harkness-Brennan, L., Hess, H., Jungclaus, A., Korten, W., Menegazzo, R., Mengoni, D., Million, B., Pullia, A., Ralet, D., Recchia, F., Reiter, P., Salsac, M. D., Sanchis, E., Stezowski, O., Theisen, Ch., Valiente Dobon, J. J., 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), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), AGATA, 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), 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), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Physics - Experiment, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Expérience GANIL/AGATA/VAMOS++; International audience; Lifetimes of the 41+ states in 62,64Fe and the 11/21− states in 61,63Co and 59Mn were measured at the Grand Accélérateur National d'Ions Lourds (GANIL) facility by using the Advanced Gamma Tracking Array (AGATA) and the large-acceptance variable mode spectrometer (VAMOS++). The states were populated through multinucleon transfer reactions with a U238 beam impinging on a Ni64 target, and lifetimes in the picosecond range were measured by using the recoil distance Doppler shift method. The data show an increase of collectivity in the iron isotopes approaching N=40. The reduction of the subshell gap between the ν2p1/2 and ν1g9/2 orbitals leads to an increased population of the quasi-SU(3) pair (ν1g9/2,ν2d5/2), which causes an increase in quadrupole collectivity. This is not observed for the cobalt isotopes with N

Published
2017

41. Kr-96(36)60-Low-Z Boundary of the Island of Deformation at N=60

Author

Dudouet, J., Lemasson, A., Duchêne, G., Rejmund, M., Clément, E., Michelagnoli, C., Didierjean, F., Korichi, A., Sanchis Peris, Enrique, González Millán, Vicente, Domingo Pardo, César, Pérez-Vidal, R. M., Collado, J., De Angelis, G., Astier, A., Delafosse, C., Deloncle, I., Dombradi, Z., de France, G., Gadea Raga, Andrés, Gottardo, A., Jacquot, B., Menegazzo, R., Konstantinopoulos, T., Valiente Dobón, J. J., Recchia, F., Lenzi, S. M., Barrientos, D., Lozeva, R., Million, B., Napoli, D. R., Navin, A., Petrache, C. M., Pietralla, N., Ralet, D., Ramdhane, M., Redon, N., Schmitt, C., Sohler, D., and Verney, D.

Subjects
Física nuclear, Nuclear Experiment, Espectroscòpia de ressonància magnètica nuclear
Abstract

Prompt.-ray spectroscopy of the neutron-rich Kr-96, produced in transfer-and fusion-induced fission reactions, has been performed using the combination of the Advanced Gamma Tracking Array and the VAMOS + +spectrometer. A second excited state, assigned to J pi = 4(+), is observed for the first time, and a previously reported level energy of the first 2+ excited state is confirmed. The measured energy ratio R-4/2 = E(4(+))/E(2(+)) = 2.12(1) indicates that this nucleus does not show a well-developed collectivity contrary to that seen in heavier N = 60 isotones. This new measurement highlights an abrupt transition of the degree of collectivity as a function of the proton number at Z = 36, of similar amplitude to that observed at N = 60 at higher Z values. A possible reason for this abrupt transition could be related to the insufficient proton excitations in the g(9/2), d(5/2), and s(1/2) orbitals to generate strong quadrupole correlations or to the coexistence of competing different shapes. An unexpected continuous decrease of R-4/2 as a function of the neutron number up to N = 60 is also evidenced. This measurement establishes the Kr isotopic chain as the low-Z boundary of the island of deformation for N = 60 isotones. A comparison with available theoretical predictions using different beyond mean-field approaches shows that these models fail to reproduce the abrupt transitions at N = 60 and Z = 36.

Published
2017

42. Prompt-delayed $\gamma$ -ray spectroscopy with AGATA, EXOGAM and VAMOS++

Author

Kim, Y.H., Lemasson, A., Rejmund, M., Navin, A., Biswas, S., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, S., Bhattacharyya, S., Clément, E., Crawford, H.L., de France, G., Fallon, P., Goupil, J., Jacquot, B., Li, H.J., Ljungvall, J., Macchiavelli, A.O., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R.M., Ropert, J., Schmitt, C., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut de Physique Nucléaire d'Orsay (IPNO), 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), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), and 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)

Subjects
Astrophysics::High Energy Astrophysical Phenomena, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; A new experimental setup to measure prompt-delayed $\gamma$ -ray coincidences from isotopically identified fission fragments, over a wide time range of 100ns-200μ s, is presented. The fission fragments were isotopically identified, on an event-by-event basis, using the VAMOS++ large acceptance spectrometer. The prompt $\gamma$ rays emitted at the target position and corresponding delayed $ \gamma$ rays emitted at the focal plane of the spectrometer were detected using, respectively, thirty two crystals of the AGATA $\gamma$ -ray tracking array and seven EXOGAM HPGe Clover detectors. Fission fragments produced in fusion and transfer-induced fission reactions, using a$^{238}$U beam at an energy of 6.2 MeV/u impinging on a$^{9}$Be target, were used to characterize and qualify the performance of the detection system.

Published
2017

43. Effects of one valence proton on seniority and angular momentum of neutrons in neutron-rich 51 122-131Sb isotopes

Author

Biswas, S., Lemasson, A., Rejmund, M., Navin, A., Kim, Y.H., Michelagnoli, C., Stefan, I., Banik, R., Bednarczyk, P., Bhattacharya, S., Bhattacharyya, S., Clément, E., Crawford, H.L., de France, G., Fallon, P., Frémont, G., Goupil, J., Jacquot, B., Li, H.J., Ljungvall, J., Maj, A., Ménager, L., Morel, V., Palit, R., Pérez-Vidal, R.M., Ropert, J., Barrientos, D., Benzoni, G., Birkenbach, B., Boston, A.J., Boston, H.C., Cederwall, B., Collado, J., Cullen, D.M., Désesquelles, P., Domingo-Pardo, C., Dudouet, J., Eberth, J., Gonzalez, V., Harkness-Brennan, L.J., Hess, H., Jungclaus, A., Korten, W., Labiche, M., Lefevre, A., Menegazzo, R., Mengoni, D., Million, B., Napoli, D.R., Pullia, A., Quintana, B., Ralet, D., Recchia, F., Reiter, P., Saillant, F., Salsac, M.D., Sanchis, E., Stezowski, O., Theisen, C., Valiente-Dobón, J.J., and Zielińska, M.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Background: Levels fulfilling the seniority scheme and relevant isomers are commonly observed features in semimagic nuclei; for example, in Sn isotopes (Z=50). Seniority isomers in Sn, with dominantly pure neutron configurations, directly probe the underlying neutron-neutron (νν) interaction. Furthermore, an addition of a valence proton particle or hole, through neutron-proton (νπ) interaction, affects the neutron seniority as well as the angular momentum. Purpose: Benchmark the reproducibility of the experimental observables, like the excitation energies (EX) and the reduced electric-quadrupole transition probabilities [B(E2)], with the results obtained from shell-model interactions for neutron-rich Sn and Sb isotopes with N

Published
2019

44. Lifetime measurements in 52,54Ti to study shell evolution toward N=32

Author

Goldkuhle, A., Fransen, C., Blazhev, A., Beckers, M., Birkenbach, B., Braunroth, T., Clément, E., Dewald, A., Dudouet, J., Eberth, J., Hess, H., Jacquot, B., Jolie, J., Kim, Y.H., Lemasson, A., Lenzi, S.M., Li, H.J., Litzinger, J., Michelagnoli, C., Müller-Gatermann, C., Nara Singh, B.S., Pérez-Vidal, R.M., Ralet, D., Reiter, P., Vogt, A., Warr, N., Zell, K.O., Ataç, A., Barrientos, D., Barthe-Dejean, C., Benzoni, G., Boston, A.J., Boston, H.C., Bourgault, P., Burrows, I., Cacitti, J., Cederwall, B., Ciemala, M., Cullen, D.M., De France, G., Domingo-Pardo, C., Foucher, J.L., Fremont, G., Gadea, A., Gangnant, P., González, V., Goupil, J., Henrich, C., Houarner, C., Jean, M., Judson, D.S., Korichi, A., Korten, W., Labiche, M., Lefevre, A., Legeard, L., Legruel, F., Leoni, S., Ljungvall, J., Maj, A., Maugeais, C., Ménager, L., Ménard, N., Menegazzo, R., Mengoni, D., Million, B., Munoz, H., Napoli, D.R., Navin, A., Nyberg, J., Ozille, M., Podolyak, Zs., Pullia, A., Raine, B., Recchia, F., Ropert, J., Saillant, F., Salsac, M.D., Sanchis, E., Schmitt, C., Simpson, J., Spitaels, C., Stezowski, O., Theisen, Ch., Toulemonde, M., Tripon, M., Valiente Dobón, J.J., Voltolini, G., Zielińska, M., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Laue-Langevin (ILL), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), AGATA, ILL, Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), 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)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear Physics - Experiment, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nuclear Structure
Abstract

International audience; Lifetimes of the excited states in the neutron-rich Ti52,54 nuclei, produced in a multinucleon-transfer reaction, were measured by employing the Cologne plunger device and the recoil-distance Doppler-shift method. The experiment was performed at the Grand Accélérateur National d'Ions Lourds facility by using the Advanced Gamma Tracking Array for the γ-ray detection, coupled to the large-acceptance variable mode spectrometer for an event-by-event particle identification. A comparison between the transition probabilities obtained from the measured lifetimes of the 21+ to 81+ yrast states in Ti52,54 and that from the shell-model calculations based on the well-established GXPF1A, GXPF1B, and KB3G fp shell interactions support the N=32 subshell closure. The B(E2) values for Ti52 determined in this work are in disagreement with the known data, but are consistent with the predictions of the shell-model calculations and reduce the previously observed pronounced staggering across the even-even titanium isotopes.

Published
2019

45. Structural changes at large angular momentum in neutron-rich $^{121,123}$Cd

Author

Rejmund, M., Navin, A., Bhattacharyya, S., Caamano, M., Clément, E., Delaune, O., Farget, F., de France, G., Jacquot, B., Lemasson, A., 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), Variable Energy Cyclotron Centre, Universidade de Santiago de Compostela [Spain] (USC ), and 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)

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Expérience GANIL/EXOGAM/VAMOS; International audience; Prompt γ rays of isotopically identified neutron-rich isotopes of Cd, produced in transfer- and fusion-fissioninduced by the 238U beam at 6.2 MeV/u on a 9Be target, were measured using the EXOGAM γ -ray detectorarray and the magnetic spectrometer VAMOS++. New results for the level scheme of 121,123Cd, extending torelatively large angular momentum are reported. The energy levels above 2-MeV excitation energy, are found todiffer from those observed in lighter isotopes of Cd indicating a change in structure in these more neutron-richnuclei. These states are not explained by large-scale shell model calculations, that explain well the structure ofthe underlying Sn isotopes and the neighboring even-A Cd isotopes. The present data, especially for the odd-Anuclei, point to a deficiency in the matrix elements related to the p-n residual interaction and provide a newdomain for testing widely used shell model interactions employed for understanding the evolution of structure inneutron-rich nuclei.

Published
2016

46. Lifetime measurements on fission fragments in the A similar to 100 region

Author

Grente, L., Salsac, M. D., Wolfram KORTEN, Goergen, A., Hagen, T. W., Braunroth, T., Bruyneel, B., Celikovic, I., Clement, E., Delaune, O., Dijon, A., Drouart, A., Ertuerk, S., Farget, F., France, G., Gottardo, A., Hackstein, M., Jacquot, B., Libert, J., Litzinger, J., Ljungvall, J., Louchart, C., Michelagnoli, C., Napoli, D. R., Navin, A., Pillet, N., Pipidis, A., Recchia, F., Rejmund, M., Rother, W., Sahin, E., Schmitt, C., Siem, S., Sulignano, B., Valiente-Dobon, J. J., Zell, K. O., Chatillon, A, Farget, F, Faust, H, Fioni, G, Goutte, D, Goutte, H, Napoli, Daniel Ricardo -- 0000-0002-8154-6958, KORTEN, Wolfram -- 0000-0002-3940-0816, Delaune, Olivier -- 0000-0002-1087-2342, Celikovic, Igor -- 0000-0002-5642-4393, Gorgen, Andreas -- 0000-0003-1916-9941, Recchia, Francesco -- 0000-0002-8428-0112, de France, Gilles -- 0000-0002-7439-1759, Clement, Emmanuel -- 0000-0003-1887-717X, Sahin, Eda -- 0000-0003-0683-5140, GOTTARDO, Andrea -- 0000-0002-0390-5767, and [Grente, L. -- Salsac, M. -D. -- Korten, W. -- Bruyneel, B. -- Drouart, A. -- Louchart, C. -- Sulignano, B.] CEA Saclay, IRFU Serv Phys Nucl, F-91191 Gif Sur Yvette, France -- [Goergen, A. -- Hagen, T. W. -- Siem, S.] Univ Oslo, Dept Phys, N-0316 Oslo, Norway -- [Braunroth, T. -- Hackstein, M. -- Litzinger, J. -- Rother, W. -- Zell, K. O.] Univ Cologne, Inst Kernphys, D-50937 Cologne, Germany -- [Celikovic, I. -- Clement, E. -- Delaune, O. -- Dijon, A. -- Farget, F. -- de France, G. -- Jacquot, B. -- Navin, A. -- Rejmund, M. -- Schmitt, C.] GANIL, CEA DSM, CNRS IN2P3, F-14706 Caen, France -- [Celikovic, I.] Univ Belgrade, Inst Nucl Sci VINCA, YU-11000 Belgrade, Serbia -- [Ertuerk, S.] Nigde Univ, Fac Sci, Nigde, Turkey -- [Gottardo, A. -- Michelagnoli, C. -- Napoli, D. R. -- Pipidis, A. -- Recchia, F. -- Sahin, E. -- Valiente-Dobon, J. J.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, I-35020 Legnaro, Italy -- [Libert, J. -- Pillet, N.] CEA, DAM, DIF, F-91297 Arpajon, France -- [Ljungvall, J.] Univ Paris 11, F-91405 Orsay, France -- [Ljungvall, J.] CNRS, CSNSM, IN2P3, F-91405 Orsay, France

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

5th International Workshop on Nuclear Fission and Fission Product Spectroscopy (FISSION) -- MAY 28-31, 2013 -- Caen, FRANCE, WOS: 000342384500002, Lifetimes of first 4(+) and 6(+) states have been measured in neutron-rich isotopes of Zr, Mo, Ru and Pd using the recoil distance Doppler shift method at GANIL. The nuclei were produced through a fusion-fission reaction in inverse kinematics. The fission fragments were fully identified in the large-acceptance VAMOS spectrometer and gamma -rays were detected in coincidence with the EXOGAM germanium array. Lifetimes of excited states in the range of 1-100 ps were measured with the Cologne plunger. Preliminary lifetime results are presented as well as a discussion on the evolution of the collectivity in this region., ILL, CEA DSM & DAM, CNRS IN2P3, ENSICAEN, GANIL, Scientific and Technological Council of Turkey [210T043], S. Erturk acknowledges the Scientific and Technological Council of Turkey for their support with project number 210T043.

Published
2013

47. The Super Separator Spectrometer image and the associated detection systems: SIRIUS & LEB-REGLIS3

Author

Déchery, F., Savajols, H., Authier, M., Drouart, A., Nolen, J., Ackermann, D., Amthor, A.M., Bastin, B., Berryhill, A., Boutin, D., Caceres, L., Coffey, M., Delferrière, O., Dorvaux, O., Gall, B., Hauschild, K., Hue, A., Jacquot, B., Karkour, N., Laune, B., Blanc, F. Le, Lecesne, N., Lopez-Martens, A., Lutton, F., Manikonda, S., Meinke, R., Olivier, G., Payet, J., Piot, J., Pochon, O., Prince, V., Souli, M., Stelzer, G., Stodel, C., Stodel, M.H., Sulignano, B., Traykov, E., Uriot, D., Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM SNO), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Univ. Paris-Sud, 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), CSNSM ELEC, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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)-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), Georg Bollen, Wolfgang Mittig, Dave Morrissey, Stefan Schwarz, Antonio Villari, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-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 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)

Subjects
[PHYS]Physics [physics], Separator, Detector, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, SPIRAL2, Spectrometer, Spectroscopy
Abstract

International audience; The Super Separator Spectrometer (S3S3) facility is developed in the framework of the SPIRAL2 project [1]. S3S3 has been designed to extend the capability of the facility to perform experiments with extremely low cross sections, taking advantage of the very high intensity stable beams of the superconducting linear accelerator of SPIRAL2. It will mainly use fusion-evaporation reactions to reach extreme regions of the nuclear chart: new opportunities will be opened for super-heavy element studies and spectroscopy at and beyond the driplines. In addition to our previous article (Déchery et al. [2]) introducing the optical layout of the spectrometer and the expected performances, this article will present the current status of the main elements of the facility: the target station, the superconducting multipole, and the magnetic and electric dipoles, with a special emphasis on the status of the detection system SIRIUS and on the low-energy branch which includes the REGLIS3 system. S3S3 will also be a source of low energy radioactive isotopes for delivery to the DESIR facility.

Published
2015

48. Near- and sub-barrier fusion of 20O incident ions with 12C target nuclei

Author

Rudolph, M.J., Gosser, Z.Q., Brown, K., Hudan, S., De Souza, R.T., Chbihi, A., Jacquot, B., Famiano, M., Liang, J.F., Shapira, D., Mercier, D., Grand Accélérateur National d'Ions Lourds (GANIL), 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), Centre de Calcul de l'IN2P3 (CC-IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and 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)

Subjects
26.60.Gj, 25.60.Pj, 25.70.Jj, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Expérience GANIL/SPIRAL; Evaporation residues resulting from fusion of 20O incident ions with 12C target nuclei have been measured for the first time. The cross-section associated with compound nuclei that de-excite via emission of charged particles is extracted. The resulting excitation function is compared with the predictions of a standard fusion model followed by statistical decay code. A significant underprediction of the measured cross-section by the fusion-evaporation model raises the question of whether the fusion cross-section is larger for the neutron-rich projectile or the statistical de-excitation is incorrectly predicted.

Published
2012

49. Beam diagnostic overview of the SPIRAL2 RNB section

Author

Jamet, C., André, T., Gueroult, E., Jacquot, B., Renoux, N., Savalle, A., Signoret, T., Varenne, F., Fontbonne, J.M., 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), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Lion, Michel

Subjects
[PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], Physics::Accelerator Physics, [PHYS.PHYS.PHYS-ACC-PH] Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], Nuclear Experiment
Abstract

International audience; An extension to the existing GANIL facility in Caen, France is under construction. The new SPIRAL 2 construction will be realized in two phases, for the first phase the construction started in January 2011 and will consists of the accelerator buildings with two experimental facilities S3 and Neutrons for science (NFS). The second phase is the so called production building where radioactive ions are produced through the ISOL (Isotope Separation On Line) method. The produced radioactive ion beams (RIBs) will be extracted and accelerated up to 60keV from the ion sources, after beam purification the beam will be driven in the secondary beam lines either to a new experimental facility DESIR (Decay, excitation and storage of radioactive ions) constructed during the second phase of the new installation or the RIBs will be charge breed to form multi-charged ions that will be driven to the existing GANIL facility and post accelerated in the CIME cyclotron. This overview article gives a description of the secondary beam lines, the foreseen beam diagnostics which will allow tuning and controlling the radioactive ion beams in the secondary beam lines constructed in the SPIRAL2 Phase 2.

Published
2011

50. A neutron beam facility at SPIRAL-2

Author

Ledoux, X., Aïche, M., Ban, G., Barreau, G., Baumann, P., Bem, P., Blideanu, V., Blomgren, J., Czajkowski, S., Dessagne, P., Dupont, E., Doré, D., Ethvignot, T., Fischer, U., Gunsing, F., Jacquot, B., Jurado, B., Kerveno, M., Lecolley, F.R., Lecouey, J.L., Negoita, F., Oberstedt, S., Petrascu, M., Plompen, A.J.M., Rejmund, F., Ridikas, D., Rudolf, G., Shcherbakov, O., Simakov, S.P., Taïeb, J., Avrigeanu, M., Avrigeanu, V., Audouin, L., Fallot, Muriel, Giot, Lydie, Perrot, L., Tassan-Got, L., Tsekhanovich, I., Département de Physique Théorique et Appliquée (DPTA), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE), IFIN-HH, 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), Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), SPIRAL2, 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), Normandie Université (NU)-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), 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), and Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Ion beam, [PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph], Nuclear Theory, Nuclear data, Neutron scattering, Neutron radiation, 7. Clean energy, Neutron time-of-flight scattering, Neutron temperature, Nuclear physics, Neutron source, Physics::Accelerator Physics, Neutron, Nuclear Experiment
Abstract

International audience; The future SPIRAL-2 facility is mainly composed of a high-power superconducting driver LINAC, delivering a high-intensity deuteron, proton and heavy ions beams. The first two beams are particularly well suited to the construction of a neutron beam and irradiation facility called Neutrons for Science (NFS). Thick C and Be target-converters with incident deuteron beam will produce an intense white neutron spectrum, while thin 7Li target and incident proton beam allows generating quasi-monoenergetic neutrons. The 1–40MeV neutron energy range will be covered and characterized by very intense fluxes available. The primary ion beam characteristics (energy, time resolution, intensity, etc.) are adequate to create a neutron time-of-flight facility. Irradiation stations for neutron, proton and deuteron induced reactions could also be built in order to perform cross-sections measurements by activation techniques. In this paper we will discuss the potential of this new installation to investigate numerous topics, both in fundamental and applied physics. In particular, cross section measurements could be performed for different purposes like nuclear data evaluation, fission and fusion technology, Accelerator Driven Systems, nuclear medicine, astrophysics, etc.

Published
2007

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