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L. Caceres,
D. Sohler,
S. Grévy,
O. Sorlin,
Zs. Dombradi,
B. Bastin,
N. L. Achouri,
J. C. Angélique,
F. Azaiez, D. Baiborodin, [......],
F. Nowacki,
N. A. Orr,
Y. Penionzhkevich,
Zs. Podolyak,
F. Pougheon,
A. Poves,
P. Roussel-Chomaz,
M. G. Saint-Laurent,
M. Stanoiu,
I. Stefan
[show abstract]
[hide abstract]
ABSTRACT: The structure of the $^{44}$S nucleus has been studied at GANIL through the
one proton knock-out reaction from a $^{45}$Cl secondary beam at 42
A$\cdot$MeV. The $\gamma$ rays following the de-excitation of $^{44}$S were
detected in flight using the 70 BaF${_2}$ detectors of the Ch\^{a}teau de
Cristal array. An exhaustive $\gamma\gamma$-coincidence analysis allowed an
unambiguous construction of the level scheme up to an excitation energy of 3301
keV. The existence of the spherical 2$^+_2$ state is confirmed and three new
$\gamma$-ray transitions connecting the prolate deformed 2$^+_1$ level were
observed. Comparison of the experimental results to shell model calculations
further supports a prolate and spherical shape coexistence with a large mixing
of states built on the ground state band in $^{44}$S.
01/2012;
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B Bastin,
S Grévy,
D Sohler,
O Sorlin,
Zs Dombrádi,
N L Achouri,
J C Angélique,
F Azaiez, D Baiborodin,
R Borcea, [......],
N A Orr,
Y Penionzhkevich,
Zs Podolyák,
F Pougheon,
P Roussel-Chomaz,
M G Saint-Laurent,
M Stanoiu,
I Stefan,
F Nowacki,
A Poves
[show abstract]
[hide abstract]
ABSTRACT: The energies of the excited states in very neutron-rich (42)Si and (41,43)P have been measured using in-beam gamma-ray spectroscopy from the fragmentation of secondary beams of (42,44)S at 39A MeV. The low 2(+) energy of (42)Si, 770(19) keV, together with the level schemes of (41,43)P, provides evidence for the disappearance of the Z=14 and N=28 spherical shell closures, which is ascribed mainly to the action of proton-neutron tensor forces. New shell model calculations indicate that (42)Si is best described as a well-deformed oblate rotor.
Physical Review Letters 08/2007; 99(2):022503. · 7.37 Impact Factor
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J. M. Daugas,
M. Sawicka,
M. Pfützner,
I. Matea,
H. Grawe,
R. Grzywacz,
N. L. Achouri,
J. C. Angélique, D. Baiborodin,
F. Becker, [......],
M. G. Saint‐Laurent,
J. E. Sauvestre,
G. Sletten,
O. Sorlin,
M. Stanoiu,
I. Stefan,
C. Stodel,
C. Theisen,
D. Verney,
J. Zylicz
[show abstract]
[hide abstract]
ABSTRACT: An island of isomers have recently been observed on both sides of the N=40 shell below the Ni isotopes. Isomeric states in the 65Fe and 67Fe allow the knowledge of the single particle structure around the νg9/2 shell. Moreover, the excitation energy of the first 2+ and 4+ states in the 68Fe have been established by β‐γ correlation. The evolution of the structure of the Fe isotopes going far away from the valley of stability is, for the first time, given for N>40. © 2006 American Institute of Physics
AIP Conference Proceedings. 04/2006; 831(1):427-429.
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C Timis,
J C Angélique,
A Buta,
N L Achouri, D Baiborodin,
P Baumann,
C Borcea,
S Courtin,
P Dessagne,
Z Dlouhy, [......],
F Negoita,
F Nowacki,
F de Oliveira,
N A Orr,
J Péter,
S Pietri,
Yu E Penionzhkevich,
E Poirier,
M Stanoiu,
G Walter
[show abstract]
[hide abstract]
ABSTRACT: An experimental spectroscopic investigation of 35Al has been performed. The delayed neutron and γ spectra, following the β decay of 35Al, have been measured using the delayed neutron detector array TONNERRE coupled with high efficiency γ detectors. A detailed analysis of such spectra allows one to extract the level schemes of its daughters. These levels are compared with the few previously existing data and shell-model calculations. Based on triple β–γ–n coincidences eight new levels above the neutron separation energy in 34Si were for the first time observed.
Journal of Physics G Nuclear and Particle Physics 09/2005; 31(10):S1965. · 4.18 Impact Factor
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F. de Oliveira Santos,
P. Himpe,
M. Lewitowicz,
I. Stefan,
N. Smirnova,
N. L. Achouri,
J. C. Angélique,
C. Angulo,
L. Axelsson, D. Baiborodin, [......],
M. G. Saint Laurent,
F. Sarazin,
H. Savajols,
M. Sawicka,
O. Sorlin,
M. Stanoiu,
C. Stodel,
G. Thiamova,
D. Verney,
A. C. C. Villari
[show abstract]
[hide abstract]
ABSTRACT: The excitation function for the elastic-scattering reaction p( 18Ne, p) 18Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus 19Na. In addition, two-proton emission events have been identified and are discussed.
European Physical Journal A 04/2005; 24(2):237-247. · 2.19 Impact Factor
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H. Savajols,
B. Jurado,
W. Mittig, D. Baiborodin,
W. Catford,
M. Chartier,
C.E. Demonchy,
Z. Dlouhy,
A. Gillibert,
L. Giot,
A. Khouaja,
A. Lépine-Szily,
S. Lukyanov,
J. Mrazek,
N. Orr,
Y. Penionzhkevich,
S. Pita,
M. Rousseau,
P. Roussel-Chomaz,
A.C.C. Villari
[show abstract]
[hide abstract]
ABSTRACT: A new SPEG mass measurement experiment has been performed to determine masses closer to the neutron drip-line in the mass
region A ∼ 10–50. The precision of 37 masses has been improved and 8 masses were measured for the first time. The region covered
was motivated by the study of shell structure and of shape coexistence in the region of closed shells N = 20 and N = 28. The evolution of the two neutron separation energies and the shell correction energy have been studied as a function
of the neutron number. The results thus obtained provide a means of identifying, in exotic nuclei, new nuclear structure effects
that are well illustrated by the changes of the conventional magic structure.
12/2004: pages 23-26;
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O. Sorlin,
Zs. Dombrádi,
D. Sohler,
F. Azaiez,
J. Timár,
Yu. -E. Penionzhkevich,
F. Amorini, D. Baiborodin,
A. Bauchet,
F. Becker, [......],
F. Nowacki,
F. Pougheon,
M. G. Saint-Laurent,
F. Sarazin,
J. A. Scarpaci,
G. Sletten,
M. Stanoiu,
C. Stodel,
M. Taylor,
Ch. Theisen
[show abstract]
[hide abstract]
ABSTRACT: The structure of the neutron-rich odd-even nuclei 37, 39 15P 22,24 and 43, 45 17Cl 26,28 nuclei has been investigated through in-beam -ray spectroscopy using the fragmentation of a 60.3 A . MeV 48Ca beam on a thin Be target. Level schemes as well as spin assignments are proposed for the nuclei studied in the present work. The experimental data are compared to shell model calculations and related to the onset of collectivity within the sd orbitals around N = 28.
European Physical Journal A 10/2004; 22(2):173-178. · 2.19 Impact Factor
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S. M. Lukyanov,
Yu. E. Penionzhkevich,
D. Guillemaud-Mueller,
M. Lewitowicz,
R. Anne,
R. Astabatyan, D. Baiborodin,
C. Borcea,
A. Buta,
F. de Oliveira Santos, [......],
S. Lobastov,
I. Matea,
J. Mrazek,
A. C. Mueller,
F. Negoita,
F. Pougheon,
O. Perru,
Yu. G. Sobolev,
I. Stefan,
D. Verney
[show abstract]
[hide abstract]
ABSTRACT: The neutron drip line in the neon-magnesium region has been explored by the projectile fragmentation of a 48Ca(59.8 A MeV) beam using the new fragment separator LISE-2000 at GANIL. New neutron-rich isotopes, 34Ne and 37Na, have been observed together with some evidence for the particle instability of 33Ne and 36Na.
Physics of Atomic Nuclei 08/2003; 66(9):1639-1642. · 0.57 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: A survey of experimental results obtained at GANIL (Caen, France) on the study of the properties of very neutron-rich nuclei
(Z=6–20, A=20–60) near the neutron drip line and resulting in an appearance of further evidence for the new magic number N=16 is presented. Very recent data on mass measurements of neutron-rich nuclei at GANIL and some characteristics of binding
energies in this region are discussed. Nuclear binding energies are very sensitive to the existence of nuclear shells, and
together with the measurements of instability of doubly magic nuclei 10He and 28O, they provide information on changes in neutron shell closures of very neutron-rich isotopes. The behavior of the two-neutron
separation energies S
2n
derived from mass measurements gives very clear evidence for the existence of the new shell closure N=16 for Z=9 and 10 appearing between the 2s
1/2 and 1d
3/2 orbitals. This fact, strongly supported by the instability of C, N, and O isotopes with N>16, confirms the magic character of N=16 for the region from carbon up to neon, while the shell closure at N=20 tends to disappear for Z≤13. Decay studies of these hardly accessible short-lived neutron-rich nuclei from oxygen to silicon using in-beam γ-ray spectroscopy are also reported.
Physics of Atomic Nuclei 07/2003; 66(8):1536-1543. · 0.57 Impact Factor
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D. Sohler,
Zs. Dombrádi,
J. Timár,
O. Sorlin, F. Azaiez, F. Amorini,
M. Stanoiu,
M. J. Lopez,
M. G. Saint-Laurent,
F. Becker,
F. Sarazin,
C. Stodel, [......],
G. Sletten,
R. Lucas,
C. Theisen, D. Baiborodin,
Z. Dlouhy,
J. Mrazek,
C. Borcea,
A. Bauchet,
C. J. Moore,
M. J. Taylor
[show abstract]
[hide abstract]
ABSTRACT: The structure of neutron-rich 40,42,44S nuclei has been investigated through in-beam γ-ray spectroscopy using the fragmentation reaction of a 60 MeV A 48Ca beam on a thin Be target. Eγ, Iγ, γγ-coincidence, and γ-ray angular distributions were measured for each produced fragment. The level schemes previously containing only a single γ transition were extended, and spin values were proposed for the new states. The experimental results were interpreted by use of microscopic collective-model and large-scale shell-model calculations. The results of the model calculations are consistent with each other, and give a reasonable description of the experimental results. Both models predict an erosion of the N=28 shell closure at Z=16 and suggest a deformed ground state for 40,42S and a spherical-deformed mixed configuration for 44S.
Phys. Rev. C. 11/2002; 66(5).
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F. Azaiez,
M. Belleguic,
D. Sohler,
M. Stanoiu,
Zs. Dombrádi,
O. Sorlin,
J. Timár,
F. Amorini, D. Baiborodin,
A. Bauchet, [......],
B.M. Nyakó,
Yu.-E. Penionzhkevich,
M.G. Saint-Laurent,
F. Sarazin,
J.A. Scarpaci,
G. Sletten,
C. Stodel,
M. Taylor,
C. Theisen,
G. Voltolini
[show abstract]
[hide abstract]
ABSTRACT: The structure of neutron-rich light nuclei around N = 20 and 28 has been investigated at GANIL by means of in-beam gamma-spectroscopy using fragmentation reactions of 36S and 48Ca beams on a Be target. Gamma-decay of relatively high-lying excited states have been measured for the first time in nuclei
around 32Mg and 44S. Level schemes are proposed and discussed for a large number of these neutron-rich nuclei around N = 20 and N = 28.
European Physical Journal A 08/2002; 15(1):93-97. · 2.19 Impact Factor
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S M Lukyanov,
Yu E Penionzhkevich,
R Astabatyan,
S Lobastov,
Yu Sobolev,
D Guillemaud-Mueller,
G Faivre,
F Ibrahim,
A C Mueller,
F Pougheon, [......],
F de Oliveira Santos,
D Verney,
Z Dlouhý,
J Mrázek, D Baiborodin,
F Negoita,
C Borcea,
A Buta,
I Stefan,
S Grevy
[show abstract]
[hide abstract]
ABSTRACT: The neutron drip line in a neon–magnesium region has been explored by the projectile fragmentation of a 59.8 A MeV 48Ca beam using the new fragment separator LISE 2000 at GANIL. New neutron-rich isotopes, 34Ne and 37Na, have been observed together with some evidence for the particle instability of 33Ne and 36Na. The neutron drip line in a neon–magnesium region has been explored by the projectile fragmentation of a 59.8 A MeV 48Ca beam using the new fragment separator LISE 2000 at GANIL. New neutron-rich isotopes, 34Ne and 37Na, have been observed together with some evidence for the particle instability of 33Ne and 36Na.
Journal of Physics G Nuclear and Particle Physics 08/2002; 28(9):L41. · 4.18 Impact Factor
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O Sorlin,
S Leenhardt,
C Donzaud,
J Duprat,
F Azaiez,
F Nowacki,
H Grawe,
Zs Dombrádi,
F Amorini,
A Astier, [......],
Yu-E Penionzhkevich,
F Pougheon,
A Poves,
N Redon,
M G Saint-Laurent,
J A Scarpaci,
G Sletten,
M Stanoiu,
O Tarasov,
Ch Theisen
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich (66,68)Ni have been produced at GANIL via interactions of a 65.9A MeV 70Zn beam with a 58Ni target. Their reduced transition probability B(E2;0(+)(1)-->2+) has been measured for the first time by Coulomb excitation in a (208)Pb target at intermediate energy. The B(E2) value for (68)Ni(40) is unexpectedly small. An analysis in terms of large scale shell model calculations stresses the importance of proton core excitations to reproduce the B(E2) values and indicates the erosion of the N = 40 harmonic-oscillator subshell by neutron-pair scattering.
Physical Review Letters 03/2002; 88(9):092501. · 7.37 Impact Factor
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W Mittig,
H Savajols, D Baiborodin,
J M Casandjian,
C E Demonchy,
P Roussel-Chomaz,
F Sarazin,
Z Dlouh,
J Mrazek,
A V Belozyorov,
S M Lukyanov,
Y E Penionzhkevich,
N Alamanos,
A Drouart,
A Gillibert,
C Jouanne,
V Lapoux,
E Pollacco,
A Korichi,
J A Scarpaci
[show abstract]
[hide abstract]
ABSTRACT: Following mass measurements in the region N = 20 and N = 28, we have studied inelastic nuclear scattering for the nuclei 34 Si, 33 Al and 32 Mg. No evidence for a low-lying shape isomeric 0 + state was found in 34 Si, and an upper limit for the population cross-section could be established, rendering its existence very unlikely. A new transition was found in 33 Al, that is a good candidate for a 2p-2h state and therefore a determination of the 2p-2h gap at N = 20. Inelastic nuclear scattering strongly excites 3 − states, as seen in 34 Si. A strong transition was found in 32 Mg that should correspond to the first 3 − in this nucleus, lying very low as compared to theory and systematics in this region.
European Physical Journal A 01/2002; 15:157-160. · 2.19 Impact Factor
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F. Sarazin,
H. Savajols,
W. Mittig,
F. Nowacki,
N. A. Orr,
Z. Ren,
P. Roussel-Chomaz,
G. Auger, D. Baiborodin,
A. V. Belozyorov, [......],
A. Gillibert,
A. S. Lalleman,
M. Lewitowicz,
S. M. Lukyanov,
F. de Oliveira,
Y. E. Penionzhkevich,
D. Ridikas,
O. Tarasov,
H. Sakuraï,
A. de Vismes
[show abstract]
[hide abstract]
ABSTRACT: A mass measurement experiment by a time of flight method with the SPEG spectrometer at GANIL has been performed to investigate
the N=20 and N=28 shell closures far from stability. The masses of 31 neutron-rich nuclei in the range A=29–47 have been measured. The precision of 19 masses has been significantly improved and 12 masses were measured for the
first time. The neutron-rich Cl, S and P isotopes are seen to exhibit a change in shell structure around N=28. Comparison with shell model and relativistic mean field calculations demonstrate that the observed effects arise from
deformed prolate ground state configurations associated with shape coexistence. The evidence of an isomeric state in the 43S and its interpretation by a shell model calculation confirm the analysis of the masses and constitutes the first evidence
of the predicted shape coexistence around N=28.
Hyperfine Interactions 12/2000; 132(1):147-152. · 0.21 Impact Factor
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Z. Dlouhý,
J. C. Angéligue,
R. Anne,
G. Auger,
F. Azaiez, D. Baiborodin,
C. Borcea,
E. Caurier,
A. Gillibert,
S. Grevy, [......],
P. Roussel-Chomaz,
M. G. Saint-Laurent,
H. Sakurai,
F. Sarazin,
H. Savajols,
O. Sorlin,
O. Tarasov,
G. Thiamová,
A. de Vismes,
J. Winfield
[show abstract]
[hide abstract]
ABSTRACT: We present a review of experimental studies on the properties of extremely neutronrich nuclei (Z=6–20, A=20–60) near the neutron drip line. Recent data on mass measurements of neutron-rich nuclei at GANIL (Caen, France) and some
characteristics of binding energies in this region are discussed. Being sensitive to the existence of nuclear shells separation
energies S2n
together with the evidence of particle instability of doubly magic nuclei 10He and 28O could provide information on changes in shell closures. Particularly opening of an N=16 shell and vanishing of the N=20 shell for very neutron-rich isotopes is under discussion. Decay studies of these hardly accessible short-lived neutronrich
nuclei from oxygen to silicon using the in-beam γ-ray spectroscopy are also reported.
Czechoslovak Journal of Physics 12/2000; 51:A245-A253. · 0.42 Impact Factor
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D. Sohler,
J. Timár,
Zs. Dombrádi,
B.M. Nyakó,
F. Azaiez,
O. Sorlin,
F. Amorini,
M. Belleguic,
C. Bourgeois,
C. Donzaud, [......],
F. Becker,
C. Theisen,
C. Borcea,
Z. Dlouhy,
J. Mrazek,
R. Lucas,
C. Moore,
M. Taylor,
G. Sletten,
F. Nowacki
[show abstract]
[hide abstract]
ABSTRACT: Excited states of neutron-rich Ar,Cl,S nd P isotopes h ve been produced vi fragment tion of 48 Ca beam t the GANIL,nd studied by using segmented clover Ge nd BaF 2 -r y detectors in ddition to the SPEG.In the present contribution the in-beam -spectroscopic results obtained on 40,42,44 S and 46 Ar are discussed nd compared with the results of recent large-scale shell model calculation.Evidence has been deduced on coexistence of spherical and deformed sh pes in the 44 S nucleus.
Acta Physica Hungarica 12/2000; 12(2-4):281-285.
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Z Dlouhý,
Yu Penionzhkevich,
R Anne, D Baiborodin,
C Borcea,
A Fomichev,
D Guillemaud-Mueller,
R Kalpakchieva,
M Lewitowicz,
S Lukyanov, [......],
Yu Oganessian,
R D Page,
A Reed,
M G Saint-Laurent,
E Sokol,
N Skobelev,
O Sorlin,
O Tarasov,
V Toneev,
W Trinder
[show abstract]
[hide abstract]
ABSTRACT: Some regularities in the production of isotopes with are investigated in reactions induced by beams at on targets , and . A search for using a beam of the neutron-rich has been performed. Evidence for particle instability of was obtained. In the same experiment, the half lives of the very neutron-rich isotopes and were measured for the first time.
Journal of Physics G Nuclear and Particle Physics 12/1998; 25(4):859. · 4.18 Impact Factor
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J.M. Daugas,
R. Grzywacz,
M. Lewitowicz,
L. Achouri,
J.C. Angélique, D. Baiborodin,
K. Bennaceur,
R. Bentida,
R. Béraud,
C. Borcea, [......],
M.J. Lopez Jimenez,
F. Nowacki,
F. de Oliveira Santos,
M. Pfützner,
P.H. Regan,
K. Rykaczewski,
J.E. Sauvestre,
M. Sawicka,
G. Sletten,
M. Stanoiu
[show abstract]
[hide abstract]
ABSTRACT: A new isomeric state in 78Zn has been identified and studied in the fragmentation of a 60.5 AMeV 86Kr beam on a natNi target. The measured energies of the transitions and the half-life, T1/2=319(9) ns, of the isomeric decay suggest a spin and parity assignment Iπ=8+. The deduced B(E2,8+→ 6+) value equals 1.21(5) W.u. is well reproduced in large scale shell model calculations using realistic interactions in the proton-neutron 2p3/2, 1f5/2, 2p1/2, 1g9/2 model space. Standard E2 polarisation charges of 0.5e for both protons and neutrons were used. This result consists the first experimental evidence of the persistance of the N=50 shell gap in the vicinity of 7828Ni50.
Physics Letters B. 476:213-218.
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B. Jurado,
H. Savajols,
W. Mittig,
N.A. Orr,
P. Roussel-Chomaz, D. Baiborodin,
W.N. Catford,
M. Chartier,
C.E. Demonchy,
Z. Dlouhý,
A. Gillibert,
L. Giot,
A. Khouaja,
A. Lépine-Szily,
S. Lukyanov,
J. Mrazek,
Y.E. Penionzhkevich,
S. Pita,
M. Rousseau,
A.C. Villari
[show abstract]
[hide abstract]
ABSTRACT: Mass measurements of very neutron-rich nuclei near the N=20 and 28 shell closures are presented. Seven masses have been determined for the first time and the precision of 36 masses has been significantly improved. These results are used to investigate the evolution of the odd–even staggering of binding energies with neutron number. Special attention is paid to the evolution of the N=28 shell closure as the neutron dripline is approached. Changes in shell structure are observed around N=28 for the P and S isotopes but not for Si. This may be interpreted as a persistence of the shell closure at N=28 or as the result of a very sudden onset in deformation at 42Si.
Physics Letters B.
