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C Rodriguez-Tajes,
H Alvarez-Pol,
T Aumann,
E Benjamim,
J Benlliure,
MJG Borge, M Caamano,
E Casarejos,
A Chatillon,
D Cortina-Gil, [......],
A Perea,
D Perez-Loureiro,
A Prochazka,
S Schwertel,
H Simon,
K Summerer,
O Tengblad,
H Weick,
M Winkler,
M Zhukov
Physical Review C 11/2012; 82. · 3.31 Impact Factor
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F. Farget, M. Caamano,
O. Delaune,
O. B. Tarasov,
X. Derkx,
K. -H. Schmidt,
A. M. Amthor,
L. Audouin,
C. -O. Bacri,
G. Barreau, [......],
M. Rejmund,
T. Roger,
M. -G. Saint-Laurent,
H. Savajols,
C. Schmitt,
B. M. Sherill,
C. Stodel,
J. Taieb,
J. -C. Thomas,
A. C. Villari
[show abstract]
[hide abstract]
ABSTRACT: During the fission process, the nucleus deforms and elongates up to the two
fragments inception and their final separation at scission deformation. The
evolution of the nucleus energy with deformation is determined by the
macroscopic properties of the nucleus, and is also strongly influenced by the
single-particle structure of the nucleus. The fission fragment distribution is
a direct consequence of the deformation path the nucleus has encountered, and
therefore is the most genuine experimental observation of the potential energy
landscape of the deforming nucleus. Very asymmetric fusion-fission reactions at
energy close to the Coulomb barrier, produce well-defined conditions of the
compound nucleus formation, where processes such as quasi-fission,
pre-equilibrium emission and incomplete fusion are negligible. In the same
time, the excitation energy is sufficient to reduce significantly structural
effects, and mostly the macroscopic part of the potential is responsible for
the formation of the fission fragments. We use inverse kinematics combined with
spectrometers to select and identify the fission fragments produced in
$^{238}$U+$^{12}$C at a bombarding energy close to and well-above the Coulomb
barrier. For the first time, the isotopic yields are measured over the complete
atomic-number distribution, between Z=30 and Z=63. The experimental set-up also
allows to identify transfer-induced reactions, which lead to low-energy fission
where the nuclear shell structure shows a strong influence on the
fission-fragment distributions. The resulting set of data gives the possibility
to observe the fission fragment properties over a wide range of excitation
energy, and they reveal the vanishing of the shell effects in the potential
energy of the fissioning nucleus, as well as the influence of fission dynamics.
09/2012;
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C Rodriguez-Tajes,
D Cortina-Gil,
H Alvarez-Pol,
T Aumann,
E Benjamim,
J Benlliure,
M J G Borge, M Caamano,
E Casarejos,
A Chatillon, [......],
A Perea,
D Perez-Loureiro,
A Prochazka,
S Schwertel,
H Simon,
K Summerer,
O Tengblad,
H Weick,
M Winkler,
M V Zhukov
Eur.Phys.J. A. 01/2012; 48:95.
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F. Hammache,
M. Heil,
S. Typel,
D. Galaviz,
K. Sümmerer,
A. Coc,
F. Uhlig,
F. Attallah, M. Caamano,
D. Cortina, [......],
E. Schwab,
K Schwarz,
F. Schümann,
P. Senger,
O. Sorlin,
V. Tatischeff,
J. -P. Thibaud,
E. Vangioni,
A Wagner,
W. Walus
[show abstract]
[hide abstract]
ABSTRACT: The recently claimed observations of non-negligible amounts of 6Li in old
halo stars have renewed interest in the Big-Bang Nucleosynthesis (BBN) of 6Li.
One important ingredient in the predicted BBN abundance of 6Li is the
low-energy 2H(alpha,gamma)6Li cross section. Up to now, the only available
experimental result for this cross section showed an almost constant
astrophysical S-factor below 400 keV, contrary to theoretical expectations. We
report on a new measurement of the 2H(alpha,gamma)6Li reaction using the
break-up of 6Li at 150 A MeV. Even though we cannot separate experimentally the
Coulomb contribution from the nuclear one, we find clear evidence for
Coulomb-nuclear interference by analyzing the scattering-angular distributions.
This is in-line with our theoretical description which indicates a drop of the
S_24-factor at low energies as predicted also by most other models.
Consequently, we find even lower upper limits for the calculated primordial 6Li
abundance than before.
11/2010;
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[show abstract]
[hide abstract]
ABSTRACT: Based on a wide systematics of fission-fragment distributions measured in low-energy fission, the even-odd staggering in the fission-fragment element yields is investigated. The well-established evolution of the global even-odd effect with the fissioning system is found to be only a partial aspect of the even-odd structure. Indeed, it is shown that the global even-odd effect is varying systematically with the mean asymmetry of the fission-fragment distribution, and that the general increase of the even-odd staggering with asymmetry is depending on the fissioning system. Thus, the dependency of the even-odd effect with the fissioning system is accredited in part to the asymmetry evolution of the charge distribution, and not solely related to the dissipated energy as it has been done earlier. This interpretation is strongly supported by data measured in inverse kinematics, which cover the complete charge distribution and include precise yields at symmetry. The relevance of the order parameter to describe the even-odd effect in fission-fragment yields as a general property is explored.
09/2009;
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P Maierbeck,
R Gernhäuser,
R Krücken,
T Kröll,
H Alvarez-Pol,
F Aksouh,
T Aumann,
K Behr,
E A Benjamim,
J Benlliure, [......],
B Sitar,
M Stanoiu,
K Summerer,
O Tengblad,
H Weick,
S Winkler,
B A Brown,
T Otsuka,
J Tostevin,
W D M Rae
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV ν p 3 / 2 − 1 -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1 / 2 − state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N = 34 gap in 54Ca.
Physics Letters B 01/2009; 675(1):22-27. · 3.95 Impact Factor
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P Maierbeck,
R Gernhauser,
R Krucken,
Th. Kroll,
H Alvarez-Pol,
F Aksouh,
T Aumann,
K Behr,
E A Benjamim,
J Benlliure, [......],
B Sitar,
M Stanoiu,
K Summerer,
O Tengblad,
H Weick,
S Winkler,
B A Brown,
T Otsuka,
J A Tostevin,
W D M Rae
01/2009;
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I Tanihata,
M Alcorta,
D Bandyopadhyay,
R Bieri,
L Buchmann,
B Davids,
N Galinski,
D Howell,
W Mills,
S Mythili, [......],
H Savajols,
T Roger, M Caamano,
W Mittig,
P Roussel-Chomaz,
R Kanungo,
A Gallant,
M Notani,
G Savard,
I J Thompson
[show abstract]
[hide abstract]
ABSTRACT: The p((11)Li, (9)Li)t reaction has been studied for the first time at an incident energy of 3A MeV at the new ISAC-2 facility at TRIUMF. An active target detector MAYA, built at GANIL, was used for the measurement. The differential cross sections have been determined for transitions to the (9)Li ground and first excited states in a wide range of scattering angles. Multistep transfer calculations using different (11)Li model wave functions show that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.
Physical Review Letters 05/2008; 100(19):192502. · 7.37 Impact Factor
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I. Tanihata,
M. Alcorta,
D. Bandyopadhyay,
R. Bieri,
L. Buchmann,
B. Davids,
N. Galinski,
D. Howell,
W. Mills,
R. Openshaw, [......],
H. Savajols,
T. Roger, M. Caamano,
W. Mittig,
P. Roussel-Chomaz,
R. Kanungo,
A. Gallant,
M. Notani,
G. Savard,
I. J. Thompson
[show abstract]
[hide abstract]
ABSTRACT: The p(\nuc{11}{Li},\nuc{9}{Li})t reaction has been studied for the first time at an incident energy of 3$A$ MeV delivered by the new ISAC-2 facility at TRIUMF. An active target detector MAYA, build at GANIL, was used for the measurement. The differential cross sectionshave been determined for transitions to the \nuc{9}{Li} ground andthe first excited states in a wide range of scattering angles. Multistep transfer calculations using different \nuc{11}{Li} model wave functions, shows that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.
03/2008;
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R Gernhauser,
H Alvarez-Pol,
F Aksouh,
T Aumann,
K Behr,
E A Benjamim,
J Benlliure,
V Bildstein,
M Bohmer,
K Boretzky, [......],
H Schaffner,
G Schrieder,
S Schwertel,
H Simon,
B Sitar,
M Stanoiu,
K Summerer,
O Tengblad,
H Weick,
S Winkler
Book of Abstracts; 01/2008
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P Maierbeck,
R Gernhauser,
R Krucken,
T Kroll,
H Alvarez-Pol,
F Aksouh,
T Aumann,
K Behr,
E A Benjamim,
J Benlliure, [......],
H Schaffner,
G Schrieder,
S Schwertel,
H Simon,
B Sitar,
M Stanoiu,
K Summerer,
O Tengblad,
H Weick,
S Winkler
01/2008;
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M. Caamano,
D. Cortina-Gil,
W. Mittig,
H. Savajols,
M. Chartier,
C. E. Demonchy,
B. Fernandez,
M. B. Gomez Hornillos,
A. Gillibert,
B. Jurado,
O. Kiselev,
R. Lemmon,
A. Obertelli,
F. Rejmund,
M. Rejmund,
P. Roussel-Chomaz,
R. Wolski
[show abstract]
[hide abstract]
ABSTRACT: The 7H resonance was produced via one-proton transfer reaction with a 8He beam at 15.4A MeV and a 12C gas target. The experimental setup was based on the active-target MAYA which allowed a complete reconstruction of the reaction kinematics. The characterization of the identified 7H events resulted in a resonance energy of 0.57(+0.42-0.21) MeV above the 3H+4n threshold and a resonance width of 0.09(+0.94-0.06) MeV.
03/2007;
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C. Dossat,
A. Bey,
B. Blank,
G. Canchel,
A. Fleury,
J. Giovinazzo,
I. Matea,
F. de Oliveira Santos,
G. Georgiev,
S. Grévy,
I. Stefan,
J. C. Thomas,
N. Adimi,
C. Borcea,
D. Cortina Gil, M. Caamano,
M. Stanoiu,
F. Aksouh,
B. A. Brown,
L. V. Grigorenko
[show abstract]
[hide abstract]
ABSTRACT: In an experiment at the SISSI/LISE3 facility of GANIL, we have studied the decay of the two proton-rich nuclei 45Fe and 48Ni. We identified 30 implantations of 45Fe and observed for the second time four implantation events of 48Ni. In 17 cases, 45Fe decays by two-proton emission with a decay energy of 1.154(16) MeV and a half-life of T1/2=1.6-0.3+0.5 ms. The observation of 48Ni and of its decay allows us to deduce a half-life of T1/2=2.1-0.7+2.1 ms. One out of four decay events is completely compatible with two-proton radioactivity and may therefore indicate that 48Ni has a two-proton radioactivity branch. We discuss all information now available on two-proton radioactivity for 45Fe and 48Ni and compare it to theoretical models.
Phys. Rev. C. 11/2005; 72(5).
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C. Dossat,
A. Bey,
B. Blank,
G. Canchel,
A. Fleury,
J. Giovinazzo,
I. Matea,
F. de Oliveira Santos,
G. Georgiev,
S. Grevy, [......],
J. C. Thomas,
Instituut voor Kern- en Stralingsfysica, Celetijnenlaan Leuven,
N. Adimi,
C. Borcea,
D. Cortina Gil, M. Caamano,
M. Stanoiu,
F. Aksouh,
B.A. Brown,
L.V. Grigorenko
[show abstract]
[hide abstract]
ABSTRACT: In an experiment at the SISSI/LISE3 facility of GANIL, we have studied the decay of the two proton-rich nuclei {sup 45}Fe and {sup 48}Ni. We identified 30 implantations of {sup 45}Fe and observed for the second time four implantation events of {sup 48}Ni. In 17 cases, {sup 45}Fe decays by two-proton emission with a decay energy of 1.154(16) MeV and a half-life of T{sub 1/2}=1.6{sub -0.3}{sup +0.5} ms. The observation of {sup 48}Ni and of its decay allows us to deduce a half-life of T{sub 1/2}=2.1{sub -0.7}{sup +2.1} ms. One out of four decay events is completely compatible with two-proton radioactivity and may therefore indicate that {sup 48}Ni has a two-proton radioactivity branch. We discuss all information now available on two-proton radioactivity for {sup 45}Fe and {sup 48}Ni and compare it to theoretical models.
Physical Review. C, Nuclear Physics. 10/2005; 72(5).
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B Blank,
A Bey,
G Canchel,
C Dossat,
A Fleury,
J Giovinazzo,
I Matea,
N Adimi,
F De Oliveira,
I Stefan, [......],
S Grévy,
J C Thomas,
C Borcea,
D Cortina, M Caamano,
M Stanoiu,
F Aksouh,
B A Brown,
F C Barker,
W A Richter
[show abstract]
[hide abstract]
ABSTRACT: The nucleus 54Zn has been observed for the first time in an experiment at the SISSI/LISE3 facility of GANIL in the quasifragmentation of a 58Ni beam at 74.5 MeV/nucleon in a (nat)Ni target. The fragments were analyzed by means of the ALPHA-LISE3 separator and implanted in a silicon-strip detector where correlations in space and time between implantation and subsequent decay events allowed us to generate almost background free decay spectra for about 25 different nuclei at the same time. Eight 54Zn implantation events were observed. From the correlated decay events, the half-life of 54Zn is determined to be 3.2(+1.8)(-0.8) ms. Seven of the eight implantations are followed by two-proton emission with a decay energy of 1.48(2) MeV. The decay energy and the partial half-life are compared to model predictions and allow for a test of these two-proton decay models.
Physical Review Letters 07/2005; 94(23):232501. · 7.37 Impact Factor
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M Caamano,
P M Walker,
P H Regan,
M Pfutzner,
Z Podolyak,
J Gerl,
M Hellstrom,
P Mayet,
M N Mineva,
A Aprahamian, [......],
K H Schmidt,
P D Stevenson,
C Theisen,
F Vives,
D D Warner,
C Wheldon,
H J Wollersheim,
S Wooding,
F Xu,
O Yordanov
[show abstract]
[hide abstract]
ABSTRACT: Relativistic projectile fragmentation of Pb-208 has been used to produce isomers in neutron-rich, A approximate to 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of gamma-rays emitted by stopped ions has led to the assignment of isomers in Ta-188, W-190, Re-192, Re-193, Os-195, Ir-197, Ir-198, Pt-200, Pt-201, Pt-202 and Au-203, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for Er-174, Er-175, Hf-185, Re-191, Re-194 and Ir-199. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In Pt-200 and Pt-201. the assignments are supported by gamma-gamma coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics.
European Physical Journal A. 01/2005; 23(2):201-215.
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[show abstract]
[hide abstract]
ABSTRACT: We have measured production cross sections and longitudinal momentum distributions of fragments from neutron-deficient 36Ar at 1.05 A.GeV. The production cross-sections show excellent agreement with the predictions of the semiempirical formula EPAX. We have compared these results, involving extremly neutron deficient nuclei, with model calculations to extract informa tion about the response of these models close to the driplines. The longitudinal momentum distributions have also been extracted and are compared with the Goldhaber and Morrissey systematics. Comment: 16 pages, 6 figures
10/2003;
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JN Orce,
AM Bruce,
A Emmanouilidis,
C Wheldon,
FR Xu,
PM Walker, M Caamano,
Z Podolyak,
H El-Masri,
PD Stevenson,
AP Byrne,
GD Dracoulis,
JC Hazel,
T Kibedi,
DM Cullen
[show abstract]
[hide abstract]
ABSTRACT: A partial decay scheme for Xe-128 is presented. The K-pi = 8(-) state is isomeric with a half-life of 73(5) ns. Theoretical calculations have been performed using the configuration constrained blocking method based on a non-axial Woods-Saxon potential. Large gamma-deformation and gamma-softness have been predicted for the ground state. The strong shape-driving effect of the K-pi = 8- state results in a much smaller value of gamma for this configuration. This may partly explain the isomerism, despite the gamma-softness. Measured hindrance factors are discussed in the context of the gamma-softness of this nucleus.
Acta Physica Polonica Series B 04/2003; 34(4):2253-2256. · 0.90 Impact Factor
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HM El-Masri,
PM Walker,
Z Podolyak, M Caamano,
GD Dracoulis,
AP Byrne,
T Kibedi,
AM Baxter,
J Hazel,
AM Bruce,
JN Orce,
A Emmanoulidis,
DM Cullen,
C Wheldon
[show abstract]
[hide abstract]
ABSTRACT: The Re-180 nucleus has been studied at high angular momentum using the Yb-174(B-11,5n) reaction at the Australian National University, with the CAESAR array for gamma-ray detection and the Super-E solenoid for electron-conversion measurements. A tau = 13 +/- 1 mus, 6-quasiparticle isomer and two intrinsic states and their associated bands have been established. The validity of the K quantum number is discussed.
Acta Physica Polonica Series B 04/2003; 34(4):2301-2304. · 0.90 Impact Factor
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N Orce,
AM Bruce,
A Emmanouilidis,
AP Byrne,
GD Dracoulis,
JC Hazel,
T Kibedi,
PM Walker,
Z Podolyak, M Caamano,
H El-Masri,
C Wheldon,
DM Cullen
[show abstract]
[hide abstract]
ABSTRACT: For prolate deformations around is an element of(2) approximate to 0.22 at neutron number N = 74 the neutron orbits 7/2(+)[404] and 9/2(-)[514] are close to the Fermi surface and may combine to give a K-pi= 8(-) isomeric state. This K-pi = 8(-) isomeric state decays to the 8(+) member of the yrast band in Dy-140, Gd-138, (SM)-S-136, Nd-134, Ce-132 and Ba-130. There is no evidence for such a transition in Xe-128 and this will be explained in terms of the nuclear structure of the region.
Progress of Theoretical Physics Supplement 01/2002; · 1.06 Impact Factor
