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27 results on '"Rigollet, C"'

1. Coulomb and nuclear excitations of $^{70}$Zn and $^{68}$Ni at intermediate energy

Author

Calinescu, S., Sorlin, O., Matea, I., Carstoiu, F., Dao, D., Nowacki, F., de Angelis, G., Astabatyan, R., Bagchi, S., Borcea, C., Borcea, R., Cáceres, L., Ciemála, M., Clément, E., Dombrádi, Z., Franchoo, S., Gottardo, A., Grévy, S., Guerin, H., Harakeh, M. N., Harca, I. M., Kamalou, O., Kmiecik, M., Krasznahorkay, A., Krzysiek, M., Kuti, I., Lepailleur, A., Lukyanov, S., Maj, A., Maslov, V., Mazurek, K., Morfouace, P., Mrazek, J., Negoita, F., Niikura, M., Olivier, L., Penionzhkevich, Y., Perrot, L., Petrone, C., Podolyák, Z., Rigollet, C, Roger, T., Rotaru, F., Sohler, D., Stanoiu, M., Stefan, I., Stuhl, L., Thomas, J. C., Vajta, Z., Vandebrouck, M., and Wieland, O.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The reduced transition probabilities $B(E2; 0^+_{g.s.}\rightarrow2_1^+,2^+_2)$ in $^{70}$Zn and the full $B(E2; 0^+_{g.s.}\rightarrow2^+)$ strength up to S$_n$=7.79 MeV in $^{68}$Ni have been determined at the LISE/GANIL facility using the Coulomb-excitation technique at intermediate beam energy on a $^{208}$Pb target. The $\gamma$ rays emitted in-flight were detected with an array of 46 BaF$_2$ crystals. The angles of the deflected nuclei were determined in order to disentangle and extract the Coulomb and nuclear contributions to the excitation of the 2$^+$ states. The measured $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of 1432(124) e$^2$fm$^4$ for $^{70}$Zn falls in the lower part of the published values which clustered either around 1600 or above 2000 e$^2$fm$^4$, while the $B(E2; 0^+_{g.s.}\rightarrow2^+_2)$ of 53(7) e$^2$fm$^4$ agrees very well with the two published values. The relatively low $B(E2; 0^+_{g.s.}\rightarrow2_1^+)$ of 301(38) e$^2$fm$^4$ for $^{68}$Ni agrees with previous studies and confirms a local magicity at $Z=28, N=40$. Combining the results of the low-energy spectra of $^{68}$Ni and $^{70}$Zn and their shell-model interpretations, it is interesting to notice that four different shapes (spherical, oblate, prolate and triaxial) are present. Finally, a summed $E2$ strength of only about 150 e$^2$fm$^4$ has been found experimentally at high excitation energy, likely due to proton excitations across the $Z=28$ gap. The experimental distribution of this high-energy $E2$ excitation agrees with SM calculations, but its strength is about two times weaker.

Published
2021

2. Signature of a possible $\alpha$-cluster state in $N=Z$ doubly-magic $^{56}$Ni

Author

Bagchi, S., Akimune, H., Gibelin, J., Harakeh, M. N., Kalantar-Nayestanaki, N., Achouri, N. L., Bastin, B., Boretzky, K., Bouzomita, H., Caamaño, M., Càceres, L., Damoy, S., Delaunay, F., Fernández-Domínguez, B., Fujiwara, M., Garg, U., Grinyer, G. F., Kamalou, O., Khan, E., Krasznahorkay, A., Lhoutellier, G., Libin, J. F., Lukyanov, S., Mazurek, K., Najafi, M. A., Pancin, J., Penionzkhevich, Y., Perrot, L., Raabe, R., Rigollet, C., Roger, T., Sambi, S., Savajols, H., Senoville, M., Stodel, C., Suen, L., Thomas, J. C., Vandebrouck, M., and Van de Walle, J.

Subjects
Nuclear Experiment
Abstract

An inelastic $\alpha$-scattering experiment on the unstable $N=Z$, doubly-magic $^{56}$Ni nucleus was performed in inverse kinematics at an incident energy of 50 A.MeV at GANIL. High multiplicity for $\alpha$-particle emission was observed within the limited phase-space of the experimental setup. This observation cannot be explained by means of the statistical-decay model. The ideal classical gas model at $kT$ = 0.4 MeV reproduces fairly well the experimental momentum distribution and the observed multiplicity of $\alpha$ particles corresponds to an excitation energy around 96 MeV. The method of distributed $m\alpha$-decay ensembles is in agreement with the experimental results if we assume that the $\alpha$-gas state in $^{56}$Ni exists at around $113^{+15}_{-17}$ MeV. These results suggest that there may exist an exotic state consisting of many $\alpha$ particles at the excitation energy of $113^{+15}_{-17}$ MeV., Comment: Accepted for publication in the European Physical Journal A

Published
2020
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3. Probing the Z = 6 spin-orbit shell gap with (p,2p) quasi-free scattering reactions

Author

Syndikus, I., Petri, M., Macchiavelli, A. O., Paschalis, S., Bertulani, C. A., Aumann, T., Alvarez-Pol, H., Atar, L., Beceiro-Novo, S., Benlliure, J., Boillos, J. M., Boretzky, K., Borge, M. J. G., Brown, B. A., Caamaño, M., Caesar, C., Casarejos, E., Catford, W., Cederkall, J., Chulkov, L. V., Cortina-Gil, D., Cravo, E., Crespo, R., Dillmann, I., Fernández, P. Díaz, Elekes, Z., Enders, J., Farinon, F., Fraile, L. M., Redondo, D. Galaviz, Geissel, H., Gernhäuser, R., Golubev, P., Göbel, K., Heil, M., Heine, M., Heinz, A., Henriques, A., Holl, M., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Kröll, T., Kurz, N., Langer, C., Bleis, T. Le, Machado, J. F. D. C., Marganiec-Gałazka, J., Nacher, E., Nilsson, T., Nociforo, C., Panin, V., Perea, A., Pietri, S. B., Plag, R., Reifarth, R., Revel, A., Ribeiro, G., Rigollet, C., Rossi, D. M., Savran, D., Scheit, H., Simon, H., Sorlin, O., Tengblad, O., Togano, Y., Vandebrouck, M., Volkov, V., Wheldon, F. Wamers C., Wilson, G. L., Winfield, J. S., Weick, H., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., and Zuber, K.

Subjects
Nuclear Experiment
Abstract

The evolution of the traditional nuclear magic numbers away from the valley of stability is an active field of research. Experimental efforts focus on providing key spectroscopic information that will shed light into the structure of exotic nuclei and understanding the driving mechanism behind the shell evolution. In this work, we investigate the Z = 6 spin-orbit shell gap towards the neutron dripline. To do so, we employed $^{A}$N(p,2p)$^{A-1}$C quasi-free scattering reactions to measure the proton component of the 2$^+_1$ state of $^{16,18,20}$C. The experimental findings support the notion of a moderate reduction of the proton 1p$_{1/2}$-1p$_{3/2}$ spin-orbit splitting, at variance to recent claims for a prevalent Z = 6 magic number towards the neutron dripline., Comment: 27 pages, 5 figures, 2 tables. Submitted to Physics Letter B

Published
2020
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4. Strong neutron pairing in core+4n nuclei

Author

Revel, A., Marques, F. M., Sorlin, O., Aumann, T., Caesar, C., Holl, M., Panin, V., Vandebrouck, M., Wamers, F., Alvarez-Pol, H., Atar, L., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boillos, J. M., Boretzky, K., Borge, M. J. G., Caamano, M., Casarejos, E., Catford, W. N., Cederkäll, J., Chartier, M., Chulkov, L., Cortina-Gil, D., Cravo, E., Crespo, R., Pramanik, U. Datta, Fernandez, P. Diaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Galaviz, D., Geissel, H., Gernhauser, R., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Hufnagel, A., Ignatov, A., Johansson, H. T., Jonson, B., Kahlbow, J., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knyazev, A., Kroll, T., Kurz, N., Labiche, M., Langer, C., Bleis, T. Le, Lemmon, R., Lindberg, S., Machado, J., Marganiec, J., Movsesyan, A., Nacher, E., Najafi, M., Nikolskii, E., Nilsson, T., Nociforo, C., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Reifarth, R., Ribeiro, G., Rigollet, C., Roder, M., Rossi, D., Savran, D., Scheit, H., Simon, H., Syndikus, I., Taylor, J. T., Tengblad, O., Thies, R., Togano, Y., Velho, P., Volkov, V., Wagner, A., Weick, H., Wheldon, C., Wilson, G., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., and Zuber, K.

Subjects
Nuclear Experiment
Abstract

The emission of neutron pairs from the neutron-rich $N\!=\!12$ isotones $^{18}$C and $^{20}$O has been studied by high-energy nucleon knockout from $^{19}$N and $^{21}$O secondary beams, populating unbound states of the two isotones up to 15~MeV above their two-neutron emission thresholds. The analysis of triple fragment-$n$-$n$ correlations shows that the decay $^{19}$N$(-1p)^{18}$C$^*\!\rightarrow^{16}$C+$n$+$n$ is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a $^{14}$C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay $^{21}$O$(-1n)^{20}$O$^*\!\rightarrow^{18}$O+$n$+$n$, attributed to its formation through the knockout of a deeply-bound neutron that breaks the $^{16}$O core and reduces the number of pairs., Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev. Lett

Published
2018
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5. Effective proton-neutron interaction near the drip line from unbound states in $^{25,26}$F

Author

Vandebrouck, M., Lepailleur, A., Sorlin, O., Aumann, T., Caesar, C., Holl, M., Panin, V., Wamers, F., Stroberg, S. R., Holt, J. D., Santos, F. De Oliveira, Alvarez-Pol, H., Atar, L., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Bogner, S. K., Boillos, J. M., Boretzky, K., Borge, M. J. G., Caamano, M., Casarejos, E., Catford, W., Cederkäll, J., Chartier, M., Chulkov, L., Cortina-Gil, D., Cravo, E., Crespo, R., Pramanik, U. Datta, Fernandez, P. Diaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Galaviz, D., Geissel, H., Gernhauser, R., Gibelin, J., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Hergert, H., Hufnagel, A., Ignatov, A., Johansson, H. T., Jonson, B., Kahlbow, J., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knyazev, A., Kröll, T., Kurz, N., Labiche, M., Langer, C., Bleis, T. Le, Lemmon, R., Lindberg, S., Machado, J., Marganiec, J., Marques, F. M., Movsesyan, A., Nacher, E., Najafi, M., Nikolskii, E., Nilsson, T., Nociforo, C., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Reifarth, R., Ribeiro, G., Rigollet, C., Röder, M., Rossi, D., Savran, D., Scheit, H., Schwenk, A., Simon, H., Syndikus, I., Taylor, J., Tengblad, O., Thies, R., Togano, Y., Velho, P., Volkov, V., Wagner, A., Weick, H., Wheldon, C., Wilson, G., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., and Zuber, K.

Subjects
Nuclear Experiment
Abstract

Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The $^{26}$F nucleus, composed of a deeply bound $\pi0d\_{5/2}$ proton and an unbound $\nu0d\_{3/2}$ neutron on top of an $^{24}$O core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a $J^{\pi} = 1^{+}\_1 - 4^{+}\_1$ multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The $J^{\pi} = 1^{+}\_1, 2^{+}\_1,4^{+}\_1$ bound states have been determined, and only a clear identification of the $J^{\pi} =3^{+}\_1$ is missing.Purpose: We wish to complete the study of the $J^{\pi} = 1^{+}\_1 - 4^{+}\_1$ multiplet in $^{26}$F, by studying the energy and width of the $J^{\pi} =3^{+}\_1$ unbound state. The method was firstly validated by the study of unbound states in $^{25}$F, for which resonances were already observed in a previous experiment.Method: Radioactive beams of $^{26}$Ne and $^{27}$Ne, produced at about $440A$\,MeV by the FRagment Separator at the GSI facility, were used to populate unbound states in $^{25}$F and $^{26}$F via one-proton knockout reactions on a CH$\_2$ target, located at the object focal point of the R$^3$B/LAND setup. The detection of emitted $\gamma$-rays and neutrons, added to the reconstruction of the momentum vector of the $A-1$ nuclei, allowed the determination of the energy of three unbound states in $^{25}$F and two in $^{26}$F. Results: Based on its width and decay properties, the first unbound state in $^{25}$F is proposed to be a $J^{\pi} = 1/2^-$ arising from a $p\_{1/2}$ proton-hole state. In $^{26}$F, the first resonance at 323(33)~keV is proposed to be the $J^{\pi} =3^{+}\_1$ member of the $J^{\pi} = 1^{+}\_1 - 4^{+}\_1$ multiplet. Energies of observed states in $^{25,26}$F have been compared to calculations using the independent-particle shell model, a phenomenological shell-model, and the ab initio valence-space in-medium similarity renormalization group method.Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40\% in comparison to the models, pointing to the need of implementing the role of the continuum in theoretical descriptions, or to a wrong determination of the atomic mass of $^{26}$F., Comment: 14 pages, 7 figures, 3 tables, submitted to PRC

Published
2017
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6. Determination of the Neutron-Capture Rate of 17C for the R-process Nucleosynthesis

Author

Heine, M., Typel, S., Wu, M. -R., Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Aumann, T., Avdeichikov, V., Barr, M., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Crespo, R., Pramanik, U. Datta, Fernandez, P. Diaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Göbel, K., Golubev, P., Diaz, D. Gonzalez, Hagdahl, J., Heftrich, T., Heil, M., Heinz, A., Henriques, A., Holl, M., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Kurz, N., Labiche, M., Langer, C., Bleis, T. Le, Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Martínez-Pinedo, G., Maroussov, V., Mostazo, M., Movsesyan, A., Najafi, A., Neff, T., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D., del Rio, J. Sanchez, Savran, D., Scheit, H., Simon, H., Sorlin, O., Stoica, V., Streicher, B., Taylor, J. T., Tengblad, O., Terashima, S., Thies, R., Togano, Y., Uberseder, E., Van de Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., and Zuber, K.

Subjects
Nuclear Experiment, Astrophysics - Solar and Stellar Astrophysics
Abstract

With the R$^{3}$B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of $^{18}$C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of $^{17}$C into the ground state of $^{18}$C. Those data have been used to constrain theoretical calculations for transitions populating excited states in $^{18}$C. This allowed to derive the astrophysical cross section $\sigma^{*}_{\mathrm{n}\gamma}$ accounting for the thermal population of $^{17}$C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures $T_{9}\leq{}1$~GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of $^{17}$C on the production of second- and third-peak elements in contrast to earlier sensitivity studies.

Published
2016
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7. Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

Author

Thies, R., Heinz, A., Adachi, T., Aksyutina, Y., Alcantara-Núñes, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Aumann, T., Avdeichikov, V., Barr, M., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Crespo, R., Datta, U., Fernández, P. Díaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estradé, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Göbel, K., Golubev, P., Diaz, D. Gonzalez, Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Henriques, A., Holl, M., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Kurz, N., Labiche, M., Langer, C., Bleis, T. Le, Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Maroussov, V., Mostazo, M., Movsesyan, A., Najafi, A., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D., del Rio, J. Sanchez, Savran, D., Scheit, H., Simon, H., Sorlin, O., Stoica, V., Streicher, B., Taylor, J. T., Tengblad, O., Terashima, S., Togano, Y., Uberseder, E., Van de Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., and Zuber, K.

Subjects
Nuclear Experiment
Abstract

Background: Models describing nuclear fragmentation and fragmentation-fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool to reach the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from 10,12-18C and 10-15B isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent dataset. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1pxn) for relativistic 10,12-18C and 10-15B isotopes impinging on a carbon target. Comparing model calculations to the data, we find that EPAX is not able to describe the data satisfactorily. Using ABRABLA07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease ABRABLA07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data have allowed for a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study.

Published
2016
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8. Coulomb breakup of neutron-rich $^{29,30}$Na isotopes near the island of inversion

Author

Rahaman, A ., Datta, Ushasi, Aumann, T., Beceiro-Novo, S., Boretzky, K., Caesar, C., Carlson, B. V., Catford, W. N., Chakraborty, S., Chartier, M., Cortina-Gil, D., Angelis, G. De., Gonzalez-Diaz, D., Emling, H., Fernandez, P. Diaz, Fraile, L. M., Ershova, O., Geissel, H., Jonson, B., Johansson, H., Kalantar-Nayestanaki, N., Krücken, R., Kröll, T., Kurcewicz, J., Langer, C., Bleis, T. Le, Leifels, Y., Münzenberg, G., Marganiec, J., Nilsson, T., Nociforo, C., Najafi, A., Panin, V., Paschalis, S., Plag, R., Reifarth, R., Rigollet, C., Ricciardi, V., Rossi, D., Scheit, H., Simon, H., Scheidenberger, C., Typel, S., Taylor, J., Togano, Y., Volkov, V., Weick, H., Wagner, A., Wamers, F., Weigand, M., Winfield, J. S., Yakorev, D., and Zoric, M.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

First results are reported on the ground state configurations of the neutron-rich $^{29,30}$Na isotopes, obtained via Coulomb dissociation (CD) measurements as a method of the direct probe. The invariant mass spectra of those nuclei have been obtained through measurement of the four-momentum of all decay products after Coulomb excitation on a $^{208}Pb$ target at energies of 400-430 MeV/nucleon using FRS-ALADIN-LAND setup at GSI, Darmstadt. Integrated Coulomb-dissociation cross-sections (CD) of 89 $(7)$ mb and 167 $(13)$ mb up to excitation energy of 10 MeV for one neutron removal from $^{29}$Na and $^{30}$Na respectively, have been extracted. The major part of one neutron removal, CD cross-sections of those nuclei populate core, in its' ground state. A comparison with the direct breakup model, suggests the predominant occupation of the valence neutron in the ground state of $^{29}$Na${(3/2^+)}$ and $^{30}$Na${(2^+)}$ is the $d$ orbital with small contribution in the $s$-orbital which are coupled with ground state of the core. The ground state configurations of these nuclei are as $^{28}$Na$_{gs (1^+)\otimes\nu_{s,d}$ and $^{29}$Na$_{gs}(3/2^+)\otimes\nu_{ s,d}$, respectively. The ground state spin and parity of these nuclei, obtained from this experiment are in agreement with earlier reported values. The spectroscopic factors for the valence neutron occupying the $s$ and $d$ orbitals for these nuclei in the ground state have been extracted and reported for the first time. A comparison of the experimental findings with the shell model calculation using MCSM suggests a lower limit of around 4.3 MeV of the sd-pf shell gap in $^{30}$Na., Comment: Modified version of the manuscript is accepted for publication in Journal of Physics G, Jan., 2017

Published
2016
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9. A neutron spectrometer for studying giant resonances with (p, n) reactions in inverse kinematics

Author

Stuhl, L., Krasznahorkay, A., Csatlós, M., Algora, A., Gulyás, J., Kalinka, G., Timár, J., Kalantar-Nayestanaki, N., Rigollet, C., Bagchi, S., and Najafi, M. A.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

A neutron spectrometer, the European Low-Energy Neutron Spectrometer (ELENS), has been constructed to study exotic nuclei in inverse-kinematics experiments. The spectrometer, which consists of plastic scintillator bars, can be operated in the neutron energy range of 100 keV to 10 MeV. The neutron energy is determined using the time-of-flight technique, while the position of the neutron detection is deduced from the time-difference information from photomultipliers attached to both ends of each bar. A novel wrapping method has been developed for the plastic scintillators. The array has a larger than 25% detection efficiency for neutrons of approximately 500 keV in kinetic energy and an angular resolution of less than 1 degree. Details of the design, construction and experimental tests of the spectrometer will be presented., Comment: 10 pages, 13 figures

Published
2013
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10. Nuclear astrophysics with radioactive ions at FAIR

Author

Reifarth, R., Altstadt, S., Göbel, K., Heftrich, T., Heil, M., Koloczek, A., Langer, C., Plag, R., Pohl, M., Sonnabend, K., Weigand, M., Adachi, T., Aksouh, F., Al-Khalili, J., AlGarawi, M., AlGhamdi, S., Alkhazov, G., Alkhomashi, N., Alvarez-Pol, H., Alvarez-Rodriguez, R., Andreev, V., Andrei, B., Atar, L., Aumann, T., Avdeichikov, V., Bacri, C., Bagchi, S., Barbieri, C., Beceiro, S., Beck, C., Beinrucker, C., Belier, G., Bemmerer, D., Bendel, M., Benlliure, J., Benzoni, G., Berjillos, R., Bertini, D., Bertulani, C., Bishop, S., Blasi, N., Bloch, T., Blumenfeld, Y., Bonaccorso, A., Boretzky, K., Botvina, A., Boudard, A., Boutachkov, P., Boztosun, I., Bracco, A., Brambilla, S., Monago, J. Briz, Caamano, M., Caesar, C., Camera, F., Casarejos, E., Catford, W., Cederkall, J., Cederwall, B., Chartier, M., Chatillon, A., Cherciu, M., Chulkov, L., Coleman-Smith, P., Cortina-Gil, D., Crespi, F., Crespo, R., Cresswell, J., Csatlós, M., Déchery, F., Davids, B., Davinson, T., Derya, V., Detistov, P., Fernandez, P. Diaz, DiJulio, D., Dmitry, S., Doré, D., Duenas, J., Dupont, E., Egelhof, P., Egorova, I., Elekes, Z., Enders, J., Endres, J., Ershov, S., Ershova, O., Fernandez-Dominguez, B., Fetisov, A., Fiori, E., Fomichev, A., Fonseca, M., Fraile, L., Freer, M., Friese, J., Borge, M. G., Redondo, D. Galaviz, Gannon, S., Garg, U., Gasparic, I., Gasques, L., Gastineau, B., Geissel, H., Gernhäuser, R., Ghosh, T., Gilbert, M., Glorius, J., Golubev, P., Gorshkov, A., Gourishetty, A., Grigorenko, L., Gulyas, J., Haiduc, M., Hammache, F., Harakeh, M., Hass, M., Heine, M., Hennig, A., Henriques, A., Herzberg, R., Holl, M., Ignatov, A., Ignatyuk, A., Ilieva, S., Ivanov, M., Iwasa, N., Jakobsson, B., Johansson, H., Jonson, B., Joshi, P., Junghans, A., Jurado, B., Körner, G., Kalantar, N., Kanungo, R., Kelic-Heil, A., Kezzar, K., Khan, E., Khanzadeev, A., Kiselev, O., Kogimtzis, M., Körper, D., Kräckmann, S., Kröll, T., Krücken, R., Krasznahorkay, A., Kratz, J., Kresan, D., Krings, T., Krumbholz, A., Krupko, S., Kulessa, R., Kumar, S., Kurz, N., Kuzmin, E., Labiche, M., Langanke, K., Lazarus, I., Bleis, T. Le, Lederer, C., Lemasson, A., Lemmon, R., Liberati, V., Litvinov, Y., Löher, B., Herraiz, J. Lopez, Münzenberg, G., Machado, J., Maev, E., Mahata, K., Mancusi, D., Marganiec, J., Perez, M. Martinez, Marusov, V., Mengoni, D., Million, B., Morcelle, V., Moreno, O., Movsesyan, A., Nacher, E., Najafi, M., Nakamura, T., Naqvi, F., Nikolski, E., Nilsson, T., Nociforo, C., Nolan, P., Novatsky, B., Nyman, G., Ornelas, A., Palit, R., Pandit, S., Panin, V., Paradela, C., Parkar, V., Paschalis, S., Pawłowski, P., Perea, A., Pereira, J., Petrache, C., Petri, M., Pickstone, S., Pietralla, N., Pietri, S., Pivovarov, Y., Potlog, P., Prokofiev, A., Rastrepina, G., Rauscher, T., Ribeiro, G., Ricciardi, M., Richter, A., Rigollet, C., Riisager, K., Rios, A., Ritter, C., Frutos, T. Rodríguez, Vignote, J. Rodriguez, Röder, M., Romig, C., Rossi, D., Roussel-Chomaz, P., Rout, P., Roy, S., Söderström, P., Sarkar, M. Saha, Sakuta, S., Salsac, M., Sampson, J., Saez, J. Sanchez del Rio, Rosado, J. Sanchez, Sanjari, S., Sarriguren, P., Sauerwein, A., Savran, D., Scheidenberger, C., Scheit, H., Schmidt, S., Schmitt, C., Schnorrenberger, L., Schrock, P., Schwengner, R., Seddon, D., Sherrill, B., Shrivastava, A., Sidorchuk, S., Silva, J., Simon, H., Simpson, E., Singh, P., Slobodan, D., Sohler, D., Spieker, M., Stach, D., Stan, E., Stanoiu, M., Stepantsov, S., Stevenson, P., Strieder, F., Stuhl, L., Suda, T., Sümmerer, K., Streicher, B., Taieb, J., Takechi, M., Tanihata, I., Taylor, J., Tengblad, O., Ter-Akopian, G., Terashima, S., Teubig, P., Thies, R., Thoennessen, M., Thomas, T., Thornhill, J., Thungstrom, G., Timar, J., Togano, Y., Tomohiro, U., Tornyi, T., Tostevin, J., Townsley, C., Trautmann, W., Trivedi, T., Typel, S., Uberseder, E., Udias, J., Uesaka, T., Uvarov, L., Vajta, Z., Velho, P., Vikhrov, V., Volknandt, M., Volkov, V., von Neumann-Cosel, P., von Schmid, M., Wagner, A., Wamers, F., Weick, H., Wells, D., Westerberg, L., Wieland, O., Wiescher, M., Wimmer, C., Wimmer, K., Winfield, J. S., Winkel, M., Woods, P., Wyss, R., Yakorev, D., Yavor, M., Cardona, J. Zamora, Zartova, I., Zerguerras, T., Zgura, I., Zhdanov, A., Zhukov, M., Zieblinski, M., Zilges, A., and Zuber, K.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Nuclear Experiment
Abstract

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes., Comment: Invited Talk given at the Conference Nuclear Physice in Astrophysics VI (NPA6), Lisbon, Portugal, May 19-24 2013. To appear in the NPA6 Proceedings in Journal of Physics: Conference Series (JPCS)

Published
2013
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11. Beyond the Neutron Drip-Line: The Unbound Oxygen Isotopes 25O and 26O

Author

Caesar, C., Simonis, J., Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Aumann, T., Avdeichikov, V., Barr, M., Beceiro, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L., Cortina-Gil, D., Pramanik, U. Datta, Fernandez, P. Diaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Golubev, P., Diaz, D. Gonzalez, Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Holl, M., Holt, J. D., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Labiche, M., Langer, C., Bleis, T. Le, Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Maroussov, V., Menéndez, J., Mostazo, M., Movsesyan, A., Najafi, A., Nilsson, T., Nociforo, C., Panin, V., Perea, A., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D. M., del Rio, J. Sanchez, Savran, D., Scheit, H., Schwenk, A., Simon, H., Sorlin, O., Stoica, V., Streicher, B., Taylor, J., Tengblad, O., Terashima, S., Thies, R., Togano, Y., Uberseder, E., Van de Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., Zoric, M., Zuber, K., and collaboration, R3B

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The very neutron-rich oxygen isotopes 25O and 26O are investigated experimentally and theoret- ically. In this first R3B-LAND experiment, the unbound states are populated at GSI via proton- knockout reactions from 26F and 27F at relativistic energies around 450 MeV/nucleon. From the kinematically complete measurement of the decay into 24O plus one or two neutrons, the 25O ground- state energy and lifetime are determined, and upper limits for the 26O ground state are extracted. In addition, the results provide evidence for an excited state in 26O at around 4 MeV. The ex- perimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.

Published
2012
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12. Neutron-skin thickness from the study of the anti-analog giant dipole resonance

Author

Krasznahorkay, A., Stuhl, L., Csatlós, M., Algora, A., Gulyás, J., Timár, J., Paar, N., Vretenar, D., Boretzky, K., Heil, M., Litvinov, Yu. A., Rossi, D., Scheidenberger, C., Simon, H., Weick, H., Bracco, A., Brambilla, S., Blasi, N., Camera, F., Giaz, A., Million, B., Pellegri, L., Riboldi, S., Wieland, O., Altstadt, S., Fonseca, M., Glorius, J., Göbel, K., Heftrich, T., Koloczek, A., Kräckmann, S., Langer, C., Plag, R., Pohl, M., Rastrepina, G., Reifarth, R., Schmidt, S., Sonnabend, K., Weigand, M., Harakeh, M. N., Kalantar-Nayestanaki, N., Rigollet, C., Bagchi, S., Najafi, M. A., Aumann, T., Atar, L., Heine, M., Holl, M., Movsesyan, A., Schrock, P., Volkov, V., Wamers, F., Fiori, E., Löher, B., Marganiec, J., Savran, D., Johansson, H. T., Fernández, P. Diaz, Garg, U., and Balabanski, D. L.

Subjects
Nuclear Experiment
Abstract

The gamma-decay of the anti-analog of the giant dipole resonance (AGDR) has been measured to the isobaric analog state excited in the p(124Sn,n) reaction at a beam energy of 600 MeV/nucleon. The energy of the transition was also calculated with state-of-the-art self-consistent random-phase approximation (RPA) and turned out to be very sensitive to the neutron-skin thickness (\DeltaR_(pn)). By comparing the theoretical results with the measured one, the \DeltaR_(pn) value for 124Sn was deduced to be 0.175 \pm 0.048 fm, which agrees well with the previous results. The energy of the AGDR measured previously for ^(208)Pb was also used to determine the \DeltaR_(pn) for ^(208)Pb. In this way a very precise \DeltaR_(pn) = 0.181 \pm 0.031 neutron-skin thickness has been obtained for 208Pb. The present method offers new possibilities for measuring the neutron-skin thicknesses of very exotic isotopes., Comment: 5 pages, 3 figures

Published
2012
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13. NeuLAND: The High-Resolution Neutron Time-of-Flight Spectrometer for R³B at FAIR

Author

Boretzky, K., Gašparic, I., Heil, M., Mayer, J., Heinz, A., Caesar, C., Kresan, D., Simon, H., Törnqvist, H. T., Körper, D., Alkhazov, G., Atar, L., Aumann, T., Bemmerer, D., Bondarev, S. V., Bott, L. T., Chakraborty, S., Cherciu, M. I., Chulkov, L. V., Ciobanu, M., Datta, U., Filippo, E., Douma, C. A., Dreyer, J., Elekes, Z., Enders, J., Galaviz, D., Geraci, E., Gnoffo, B., Göbel, K., Golovtsov, V. L., Gonzalez Diaz, D., Gruzinsky, N., Haiduc, M., Heftrich, T., Heggen, H., Hehner, J., Hensel, T., Hoemann, E., Holl, M., Horvat, A., Horváth, Á., Ickert, G., Ignatov, A., Jelavi Malencia, D., Johansson, H. T., Jonson, B., Kahlbow, J., Kalantar-Nayestanaki, N., Kelic-Heil, A., Kempe, M., Koch, K., Kozlenko, N. G., Krivshich, A. G., Kurz, N., Kuznetsov, V., Langer, C., Leifels, Y., Lihtar, I., Löher, B., Machado, J., Martorana, N. S., Miki, K., Nilsson, T., Nyman, G. H., Orischin, E. M., Pagano, E. V., Pirrone, S., Politi, G., Potlog, P.-M., Rahaman, A., Reifarth, R., Rigollet, C., Röder, M., Rossi, D. M., Russotto, P., Savran, D., Scheit, H., Schindler, F., Stach, D., Stan, E., Stomvall Gill, J., Teubig, P., Trimarchi, M., Uvarov, L., Volknandt, M., Wagner, A., Wagner, V., Wranne, S., Yakorev, D., Zanetti, L., Zilges, A., and Zuber, K.

Subjects
reactions with relativistic radioactive beams, multi-neutron detection, plastic scintillator scintillator array, Nuclear Experiment, high-energy neutron detection
Abstract

NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5x5x250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250x250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.

Published
2021

14. Quasifree (p, pN) scattering of light neutron-rich nuclei near N=14

Author

Diaz Fernandez, P., Alvarez-Pol, H., Crespo, R., Cravo, E., Atar, L., Deltuva, A., Aumann, T., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boillos, J. M., Boretzky, K., Borge, M. J. G., Caamano, M., Cabanelas, P., Caesar, C., Casarejos, E., Catford, W., Cederkall, J., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Pramanik, U. Datta, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fernandez-Dominguez, B., Fraile, L. M., Freer, M., Galaviz, D., Geissel, H., Gernhaeuser, R., Golubev, P., Goebel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Kalantar-Nayestanaki, N., Najafi, A., Rigollet, C., Taylor, J. T., Wagner, A., and Research unit Nuclear & Hadron Physics

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The (RB)-B-3 collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable C-12 beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p, pn) and (p, 2p) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N = 14 to N = 15. Method: The structure of the projectiles O-23, O-22, and N-21 has been studied simultaneously via (p, pn) and (p, 2p) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the (RB)-B-3-LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p, pn) and (p, 2p) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p, pn) channels, indications of a change in the structure of these nuclei moving from N = 14 to N = 15 have been observed, i.e., from the 0d(5/2) shell to the 1s(1/2). This supports previous observations of a subshell closure at N = 14 for neutron-rich oxygen isotopes and its weakening for the nitrogen isotopes.

Published
2018

15. Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength

Author

Atar, L, Paschalis, S, Barbieri, C, Bertulani, CA, Diaz Fernandez, P, Holl, M, Najafi, MA, Panin, V, Alvarez-Pol, H, Aumann, T, Avdeichikov, V, Beceiro-Novo, S, Bemmerer, D, Benlliure, J, Boillos, JM, Boretzky, K, Borge, MJG, Caamano, M, Caesar, C, Casarejos, E, Catford, W, Cederkall, J, Chartier, M, Chulkov, L, Cortina-Gil, D, Cravo, E, Crespo, R, Dillmann, I, Elekes, Z, Enders, J, Ershova, O, Estrade, A, Farinon, F, Fraile, LM, Freer, M, Galaviz Redondo, D, Geissel, H, Gernhaeuser, R, Golubev, P, Goebel, K, Hagdahl, J, Heftrich, T, Heil, M, Heine, M, Heinz, A, Henriques, A, Hufnagel, A, Ignatov, A, Johansson, HT, Jonson, B, Kahlbow, J, Kalantar-Nayestanaki, N, Kanungo, R, Kelic-Heil, A, Knyazev, A, Kroell, T, Kurz, N, Labiche, M, Langer, C, Le Bleis, T, Lemmon, R, Lindberg, S, Machado, J, Marganiec-Galazka, J, Movsesyan, A, Nacher, E, Nikolskii, EY, Nilsson, T, Nociforo, C, Perea, A, Petri, M, Pietri, S, Plag, R, Reifarth, R, Ribeiro, G, Rigollet, C, Rossi, DM, Roeder, M, Savran, D, Scheit, H, Simon, H, Sorlin, O, Syndikus, I, Taylor, JT, Tengblad, O, Thies, R, Togano, Y, Vandebrouck, M, Velho, P, Volkov, V, Wagner, A, Wamers, F, Weick, H, Wheldon, C, Wilson, GL, Winfield, JS, Woods, P, Yakorev, D, Zhukov, M, Zilges, A, Zuber, K, and Collaboration, R3B

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R3B/LAND setup with incident beam energies in the range of 300–450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type AO(p,2p)A−1N have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry.

Published
2018

16. Quasifree ($p,pN$) scattering of light neutron-rich nuclei near $N=14$

Author

Díaz Fernández, P., Alvarez-Pol, H., Crespo, R., Cravo, E., Atar, L., Deltuva, A., Aumann, T., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C.A., Boillos, J.M., Boretzky, K., Borge, M.J.G., Caamaño, M., Cabanelas, P., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chartier, M., Chulkov, L.V., Cortina-Gil, D., Datta Pramanik, U., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estradé, A., Farinon, F., Fernández-Domínguez, B., Fraile, L.M., Freer, M., Galaviz, D., Geissel, H., Gernhäuser, R., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Holl, M., Hufnagel, A., Ignatov, A., Johansson, H.T., Jonson, B., Jurčiukonis, D., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knyazev, A., Kröll, T., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lindberg, S., Machado, J., Marganiec, J., Moro, A.M., Movsesyan, A., Nacher, E., Najafi, A., Nikolskii, E., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietras, B., Pietri, S., Plag, R., Reifarth, R., Ribeiro, G., Rigollet, C., Rossi, D., Röder, M., Savran, D., Scheit, H., Simon, H., Sorlin, O., Syndikus, I., Taylor, J.T., Tengblad, O., Thies, R., Togano, Y., Vandebrouck, M., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Wheldon, C., Wilson, G., Winfield, J.S., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., Zuber, 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), 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
Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The RB3 collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable C12 beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p,pn) and (p,2p) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N=14 to N=15. Method: The structure of the projectiles O23, O22, and N21 has been studied simultaneously via (p,pn) and (p,2p) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B-LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p,pn) and (p,2p) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p,pn) channels, indications of a change in the structure of these nuclei moving from N=14 to N=15 have been observed, i.e., from the 0d5/2 shell to the 1s1/2. This supports previous observations of a subshell closure at N=14 for neutron-rich oxygen isotopes and its weakening for the nitrogen isotopes.

Published
2018
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17. Structure of $^{13}$Be studied in proton knockout from $^{14}$B

Author

Ribeiro, G., Nácher, E., Tengblad, O., Díaz Fernández, P., Aksyutina, Y., Alvarez-Pol, H., Atar, L., Aumann, T., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boillos, J. M., Boretzky, K., Borge, M. J. G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chartier, M., Chulkov, L., Cortina-Gil, D., Cravo, E., Crespo, R., Datta Pramanik, U., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Holl, M., Hufnagel, A., Ignatov, A., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Kurz, N., Kröll, T., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lindberg, S., Machado, J., Marganiec, J., Movsesyan, A., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Reifarth, R., Rigollet, C., Riisager, K., Rossi, D., Röder, M., Savran, D., Scheit, H., Simon, H., Sorlin, O., Syndikus, I., Taylor, J. T., Thies, R., Velho, P., Wagner, A., Wamers, F., Vandebrouck, M., Weick, H., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Zhukov, M. V., Zilges, A., Zuber, K., 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), R$^3$B, 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
radioactive beams, nuclear structure, Nuclear Theory, Aucun, 13Be, Nuclear Reactions, unbound nuclei, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

Physical review / C 98(2), 024603 (2018). doi:10.1103/PhysRevC.98.024603, Published by Inst., Woodbury, NY

Published
2018
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18. Quasi-free (p,pN) scattering of light neutron-rich nuclei around N = 14

Author

Diaz Fernandez, P., Alvarez-Pol, H., Crespo, R., Cravo, E., Atar, L., Deltuva, A., Aumann, T., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boillos, J. M., Boretzky, K., Borge, M. J. G., Caamano, M., Cabanelas, P., Caesar, C., Casarejos, E., Catford, W., Cederkall, J., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Datta Pramanik, U., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fernandez-Dominguez, B., Fraile, L. M., Freer, M., Galaviz, D., Geissel, H., Gernhäuser, R., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Holl, M., Hufnagel, A., Ignatov, A., Johansson, H. T., Jonson, B., Jurciukonis, D., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knyazev, A., Kröll, T., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lindberg, S., Machado, J., Marganiec, J., Moro, A. M., Movsesyan, A., Nacher, E., Najafi, A., Nikolskii, E., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietras, B., Pietri, S., Plag, R., Reifarth, R., Ribeiro, G., Rigollet, C., Rossi, D., Röder, M., Savran, D., Scheit, H., Simon, H., Sorlin, O., Syndikus, I., Taylor, J. T., Tengblad, O., Thies, R., Togano, Y., Vandebrouck, M., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Wheldon, C., Wilson, G., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., and Zuber, K.

Subjects
quasi-free scattering reactions radioactive beams single-particle, Nuclear Experiment
Abstract

In this work we investigate for the first time the quasi-free scattering reactions (p,pn) and (p,2p) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N = 14 to N = 15.

Published
2018

19. Quasifree ($p$, $2p$) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength

Author

Atar, Leyla, Paschalis, Stefanos, Barbieri, C., Bertulani, C. A., Fernández, P. Díaz, Holl, M., Najafi, M.A, Panin, V., Alvarez-Pol, H., Aumann, T., Avdeichikov, V., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Boillos, J.M., Boretzky, K., Borge, M. J. G., Caamaño, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chartier, M., Chulkov, L., Cortina-Gil, D., Cravo, E., Crespo, R., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L.M, Freer, M., Redondo, D. Galaviz, Geissel, H., Gernhäuser, R., Golubev, P., Göbel, K., Hagdahl, J., Heftrich, T., Heil, M., Heine, M., Heinz, A., Henriques, A., Hufnagel, A., Ignatov, A., Johansson, H.T, Jonson, B, Kahlbow, J., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knyazev, A., Kröll, T., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lindberg, S., Machado, J., Marganiec-Gałązka, J., Movsesyan, A., Nacher, E., Nikolskii, E.Y., Nilsson, T., Nociforo, C., Perea, A., Petri, Marina, Pietri, S., Plag, R., Reifarth, R., Ribeiro, G., Rigollet, C., Rossi, D.M., Röder, M., Savran, D., Scheit, H., Simon, H., Sorlin, O., Syndikus, I., Taylor, J. T., Tengblad, O, Thies, R., Togano, Y., Vandebrouck, M., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Wheldon, C., Wilson, G.L., Winfield, J.S., Woods, P., Yakorev, D., Zhukov, M., Zilges, A., Zuber, K, 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), 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), 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), Helmholtz Centre for Heavy Ion Research, Department of Energy (US), National Science Foundation (US), Ministerio de Economía y Competitividad (España), Science and Technology Facilities Council (UK), Federal Ministry of Education and Research (Germany), University of Leicester, and Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nuclear Theory, ddc:550, Aucun, Nuclear Experiment
Abstract

7 pags., 4 figs., tab., Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the (RB)-B-3/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type O-A(p,2p)NA-1 have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry., This work was supported by the German Federal Ministry for Education and Research (BMBF project 05P15RDFN1), and through the GSI-TU Darmstadt cooperation agreement. The work of C. B., W. C., and G.W. was supported by the United Kingdom Science and Technology Facilities Council (STFC) under Grants No. ST/L005743/1 and No. ST/P005314/1. SCGF calculations were performed at the DiRAC Complexity system of the University of Leicester (BIS National E-1023 infrastructure capital Grant No. ST/K000373/1 and STFC 1024 Grant No. ST/K0003259/1). C. A. B. acknowledges support by the U.S. DOE Grant No. DE-FG02- 08ER41533 and the U.S. NSF Grant No. 1415656. L. M. F. acknowledges funding from MINECO FPA2015-65035-P project.

Published
2018
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20. Effective proton-neutron interaction near the drip line from unbound states in F-25,F-26

Author

Kalantar-Nayestanaki, N., Najafi, M., Rigollet, C., and Research unit Nuclear & Hadron Physics

Subjects
RICH NUCLEI, Nuclear Experiment, DETECTOR
Abstract

Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F-26 nucleus, composed of a deeply bound pi 0d(5/2) proton and an unbound v0d(3/2) neutron on top of an O-24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a J(pi) = 1(1)(+) - 4(1)(+) multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The J(pi) = 1(1)(+), 2(1)(+), 4(1)(+) bound states have been determined, and only a clear identification of the J(pi) = 3(1)(+) is missing. Purpose: We wish to complete the study of the J(pi) = 1(1)(+) - 4(1)(+) multiplet in F-26, by studying the energy and width of the J(pi) = 3(1)(+) unbound state. The method was first validated by the study of unbound states in F-25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne-26 and Ne-27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F-25 and F-26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the (RB)-B-3/LAND setup. The detection of emitted. rays and neutrons, added to the reconstruction of the momentum vector of the A - 1 nuclei, allowed the determination of the energy of three unbound states in F-25 and two in F-26. Results: Based on its width and decay properties, the first unbound state in F-25, at the relative energy of 49(9) keV, is proposed to be a J(pi) = 1/ 2(-) arising from a p1/2 proton- hole state. In F-26, the first resonance at 323(33) keV is proposed to be the J(pi) = 3(1)(+) member of the J(pi) = 1(1)(+) - 4(1)(+) multiplet. Energies of observed states in F-25,F-26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton- neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F-26.

Published
2017

21. Determination of the Neutron-Capture Rate of 17C for the R-process Nucleosynthesis

Author

Heine, M., Typel, S., Wu, M.-R., Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Avdeichikov, T. A. V., Barr, M., Beceiro-Novo, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Crespo, R., Datta Pramanik, U., Diaz Fernandez, P., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Göbel, K., Golubev, P., Gonzalez Diaz, D., Hagdahl, J., Heftrich, T., Heil, M., Heinz, A., Henriques, A., Holl, M., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Martínez-Pinedo, G., Maroussov, V., Mostazo, M., Movsesyan, A., Najafi, A., Neff, T., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D., Sanchez Del Rio, J., Savran, D., Scheit, H., Simon, H., Sorlin (Ganil), O., Stoica, V., Streicher, B., Taylor, J. T., Tengblad, O., Terashima, S., Thies, R., Togano, Y., Uberseder, E., Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., and Zuber, K.

Subjects
r-process, nucleosynthesis, Coulomb dissociation, Nuclear Experiment, radiative neutron capture
Abstract

With the R3B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of 18C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of 17C into the ground state of 18C. Those data have been used to constrain theoretical calculations for transitions populating excited states in 18C. This allowed to derive the astrophysical cross section σ∗nγ accounting for the thermal population of 17C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures T9≤1~GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of 17C on the production of second- and third-peak elements in contrast to earlier sensitivity studies.

Published
2017

22. Determination of the Neutron-Capture Rate of $^{17}$C for the R-process Nucleosynthesis

Author

Heine, M., Typel, S., Wu, M. -R, Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Aumann, T., Avdeichikov, V., Barr, M., Beceiro-Novo, S., Daniel Bemmerer, Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Caesar, C., Casarejos, E., Catford, W., Cederkäll, J., Chakraborty, S., Chartier, M., Chulkov, L. V., Cortina-Gil, D., Crespo, R., Datta Pramanik, U., Diaz Fernandez, P., Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhäuser, R., Göbel, K., Golubev, P., Gonzalez Diaz, D., Hagdahl, J., Heftrich, T., Heil, M., Heinz, A., Henriques, A., Holl, M., Ickert, G., Ignatov, A., Jakobsson, B., Johansson, H. T., Jonson, B., Kalantar-Nayestanaki, N., Kanungo, R., Kelic-Heil, A., Knöbel, R., Kröll, T., Krücken, R., Kurcewicz, J., Kurz, N., Labiche, M., Langer, C., Le Bleis, T., Lemmon, R., Lepyoshkina, O., Lindberg, S., Machado, J., Marganiec, J., Martínez-Pinedo, G., Maroussov, V., Mostazo, M., Movsesyan, A., Najafi, A., Neff, T., Nilsson, T., Nociforo, C., Panin, V., Paschalis, S., Perea, A., Petri, M., Pietri, S., Plag, R., Prochazka, A., Rahaman, A., Rastrepina, G., Reifarth, R., Ribeiro, G., Ricciardi, M. V., Rigollet, C., Riisager, K., Röder, M., Rossi, D., Sanchez Del Rio, J., Savran, D., Scheit, H., Simon, H., Sorlin, O., Stoica, V., Streicher, B., Taylor, J. T., Tengblad, O., Terashima, S., Thies, R., Togano, Y., Uberseder, E., Walle, J., Velho, P., Volkov, V., Wagner, A., Wamers, F., Weick, H., Weigand, M., Wheldon, C., Wilson, G., Wimmer, C., Winfield, J. S., Woods, P., Yakorev, D., Zhukov, M. V., Zilges, A., Zuber, K., Helmholtz zentrum für Schwerionenforschung GmbH (GSI), KVI-CART, University of Groningen, University of Groningen [Groningen], 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), R3B Collaboration, Research unit Nuclear & Hadron Physics, 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
astro-ph.SR, Astrophysics - Solar and Stellar Astrophysics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nucl-ex, Nuclear Experiment, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

International audience; With the R$^{3}$B-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of $^{18}$C at a projectile energy around 425~AMeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of $^{17}$C into the ground state of $^{18}$C. Those data have been used to constrain theoretical calculations for transitions populating excited states in $^{18}$C. This allowed to derive the astrophysical cross section $\sigma^{*}_{\mathrm{n}\gamma}$ accounting for the thermal population of $^{17}$C target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures $T_{9}\leq{}1$~GK. Network simulations with updated neutron-capture rates and hydrodynamics according to the neutrino-driven wind model as well as the neutron-star merger scenario reveal no pronounced influence of neutron capture of $^{17}$C on the production of second- and third-peak elements in contrast to earlier sensitivity studies.

Published
2017
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23. Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes

Author

Thies, R, Heinz, A, Adachi, T, Aksyutina, Y, Alcantara-Nunes, J, Altstadt, S, Alvarez-Pol, H, Ashwood, N, Aumann, T, Avdeichikov, V, Barr, M, Beceiro-Novo, S, Bemmerer, D, Benlliure, J, Bertulani, CA, Boretzky, K, Borge, MJG, Burgunder, G, Camano, M, Caesar, C, Casarejos, E, Catford, W, Cederkall, J, Chakraborty, S, Chartier, M, Chulkov, LV, Cortina-Gil, D, Crespo, R, Datta, U, Diaz Fernandez, P, Dillmann, I, Elekes, Z, Enders, J, Ershova, O, Estrade, A, Farinon, F, Fraile, LM, Freer, M, Freudenberger, M, Fynbo, HOU, Galaviz, D, Geissel, H, Gernhauser, R, Gobel, K, Golubev, P, Diaz, DG, Hagdahl, J, Heftrich, T, Heil, M, Heine, M, Henriques, A, Holl, M, Ickert, G, Ignatov, A, Jakobsson, B, Johansson, HT, Jonson, B, Kalantar-Nayestanaki, N, Kanungo, R, Knobel, R, Kroll, T, Krucken, R, Kurcewicz, J, Kurz, N, Labiche, M, Langer, C, Le Bleis, T, Lemmon, R, Lepyoshkina, O, Lindberg, S, Machado, J, Marganiec, J, Maroussov, V, Mostazo, M, Movsesyan, A, Najafi, A, Nilsson, T, Nociforo, C, Panin, V, Paschalis, S, Perea, A, Petri, M, Pietri, S, Plag, R, Prochazka, A, Rahaman, A, Rastrepina, G, Reifarth, R, Ribeiro, G, Ricciardi, MV, Rigollet, C, Riisager, K, Roder, M, Rossi, D, Sanchez del Rio, J, Savran, D, Scheit, H, Simon, H, Sorlin, O, Stoica, V, Streicher, B, Taylor, JT, Tengblad, O, Terashima, S, Togano, Y, Uberseder, E, Van de Walle, J, Velho, P, Volkov, V, Wagner, A, Wamers, F, Weick, H, Weigand, M, Wheldon, C, Wilson, G, Wimmer, C, Winfield, JS, Woods, P, Yakorev, D, Zhukov, MV, Zilges, A, Zuber, K, Collaboration, R, Helmholtz zentrum für Schwerionenforschung GmbH (GSI), 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), R3B Collaboration, KVI - Center for Advanced Radiation Technology, Research unit Nuclear & Hadron Physics, Federal Ministry of Education and Research (Germany), Nuclear Astrophysics Virtual Institute (Germany), Helmholtz Association, Science and Technology Facilities Council (UK), Department of Energy (US), Ministerio de Economía y Competitividad (España), Swedish Research Council, Helmholtz Centre for Heavy Ion Research, National Science Foundation (US), 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, Ion beam, 010308 nuclear & particles physics, Fission, Projectile, Nuclear Theory, Fragmentation (computing), Aucun, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear physics, nuclear fragmentation fission radioactive ion beam facilities C10 C12−18 B10−15 isotope, 0103 physical sciences, Neutron, Física nuclear, Nuclear Experiment (nucl-ex), 010306 general physics, Nucleon, Nuclear Experiment, Excitation, Beam (structure)
Abstract

R. Thies et al.; 9 pags., 7 figs., 1 tab., Background: Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from C10,12-18 and B10-15 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1pxn) for relativistic C10,12-18 and B10-15 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study. ©2016 American Physical Society, We thank the FRS and the GSI accelerator staff for their efforts. This work was supported by the Swedish Research Council. O.T. was supported by the Spanish Research Council under project FPA2012-32443, C.A.B. acknowledges support from the U.S. DOE Grant No. DE-FG02-08ER41533 and the U.S. NSF Grant No. 1415656. L.M.F. acknowledges support by the Spanish Research Council under project FPA2013-41267-P and M.R. was supported by GSI (F&E, DR-ZUBE), German BMBF (06DR134I and 05P09CRFN5), the Nuclear Astrophysics Virtual Institute (NAVI, HGF VHVI- 417) and the Helmholtz Association Detector Technology and Systems Platform. T.K. acknowledges support by the German BMBF No. 06DA9040I, No. 05P12RDFN8, and No. 05P15RDFN1. C.W. acknowledges funding by the UK STFC No. ST/E500651/1, while N.A. and M.F. acknowledge funding by the UK STFC No. ST/F011989/1.

Published
2016
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24. Beyond the neutron drip line: The unbound oxygen isotopes O-25 and O-26

Author

Caesar, C., Simonis, J., Adachi, T., Aksyutina, Y., Alcantara, J., Altstadt, S., Alvarez-Pol, H., Ashwood, N., Aumann, T., Avdeichikov, V., Barr, M., Beceiro, S., Bemmerer, D., Benlliure, J., Bertulani, C. A., Boretzky, K., Borge, M. J. G., Burgunder, G., Caamano, M., Casarejos, E., Catford, W., Cederkaell, J., Chakraborty, S., Chartier, M., Chulkov, L., Cortina-Gil, D., Pramanik, U. Datta, Fernandez, P. Diaz, Dillmann, I., Elekes, Z., Enders, J., Ershova, O., Estrade, A., Farinon, F., Fraile, L. M., Freer, M., Freudenberger, M., Fynbo, H. O. U., Galaviz, D., Geissel, H., Gernhaeuser, R., Golubev, P., Diaz, D. Gonzalez, Hagdahl, J., Heftrich, T., Heil, M., Kalantar-Nayestanaki, N., Rigollet, C., Streicher, B., Van de Walle, J., and KVI - Center for Advanced Radiation Technology

Subjects
Nuclear Theory, RICH NUCLEI, PARTICLE STABILITY, Nuclear Experiment, DETECTOR, RELATIVISTIC HEAVY-IONS
Abstract

The very neutron-rich oxygen isotopes O-25 and O-26 are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from F-26 and F-27 at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into O-24 plus one or two neutrons, the O-25 ground-state energy and width are determined, and upper limits for the O-26 ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in O-26 at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.

Published
2013

25. Superallowed Gamow-Teller decay of the doubly magic nucleus Sn-100

Author

Hinke, C. B., Boehmer, M., Boutachkov, P., Faestermann, T., Geissel, H., Gerl, J., Gernhaeuser, R., Gorska, M., Gottardo, A., Grawe, H., Grebosz, J. L., Kruecken, R., Kurz, N., Liu, Z., Maier, L., Nowacki, F., Pietri, S., Podolyak, Zs, Sieja, K., Steiger, K., Straub, K., Weick, H., Wollersheim, H. -J., Woods, P. J., Al-Dahan, N., Alkhomashi, N., Atac, A., Blazhev, A., Braun, N. F., Celikovic, I. T., Davinson, T., Dillmann, I., Domingo-Pardo, C., Doornenbal, P. C., de France, G., Farrelly, G. F., Farinon, F., Goel, N., Habermann, T. C., Hoischen, R., Janik, R., Karny, M., Kaskas, A., Kojouharov, I. M., Kroell, Th, Litvinov, Y., Myalski, S., Nebel, F., Nishimura, S., Nociforo, C., Nyberg, J., Parikh, A. R., Prochazka, A., Regan, P. H., Rigollet, C., Schaffner, H., Scheidenberger, C., Schwertel, S., Soederstroem, P. -A., Steer, S. J., Stolz, A., Strmen, P., and KVI - Center for Advanced Radiation Technology

Subjects
IDENTIFICATION, Nuclear Theory, SHELL-MODEL, BETA-DECAY, Nuclear Experiment
Abstract

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During beta(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of Sn-100, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the beta-decay of Sn-100, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear beta-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, In-100, are well reproduced by modern, large-scale shell model calculations.

Published
2012

26. Quadrupole moment of superdeformed bands in Tb-151

Author

Finck, C, Stezowski, O, Beck, FA, Appelbe, DE, Byrski, T, Courtin, S, Cullen, DM, Curien, D, de France, G, Duchene, G, Erturk, S, Gall, BJP, Garg, U, Haas, B, Khadiri, N, Kharraja, B, Kintz, N, Nourreddine, A, Prevost, D, Rigollet, C, Savajols, H, Twin, PJ, Vivien, JP, Zuber, K, and Research unit Nuclear & Hadron Physics

Subjects
NUCLEI, Nuclear Theory, ROTATIONAL BANDS, IDENTICAL BANDS, Nuclear Experiment, DECAY, MASS REGION
Abstract

The quadrupole moments of the first two superdeformed (SD) bands in the nucleus Tb-151 have been measured with the Doppler Shift Attenuation Method (DSAM) using the EUROGAM gamma-ray spectrometer, The first excited band (B2) is identical to the yrast SD band of Dy-152 in terms of dynamical moments of inertia and gamma-ray energies. The measured relative quadrupole moments of the yrast band (B1) with respect to the band B2 are nicely reproduced by self-consitent Hartree-Fock calculations. The variation of the Q(0) value at the bottom of the yrast band suggests a large admixture between wave functions in the normal and the SD wells. This could explain the rather high deexcitation spin for the yrast band.

Published
1998

27. Superdeformed bands in Ho-153

Author

Appelbe, DE, Beausang, CW, Cullen, DM, Duchene, G, Finck, C, Rigollet, C, Smith, MB, Stezowski, O, Twin, PJ, and Research unit Nuclear & Hadron Physics

Subjects
DY-152, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Nuclear Experiment
Abstract

In a recent experiment carried out with the EUROGAM PHASE II gamma-ray spectrometer three new superdeformed (SD) bands have been established in Ho-153. The properties of these SD bands are discussed in terms of proton particle-hole excitations and are compared to the SD bands in the adjacent nuclei. This is the first observation of SD structures in a Z = 67 nucleus.

Published
1997

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