-
J. P. Vivien,
A. Nourreddine, F. A. Beck,
T. Byrski,
C. Gehringer,
B. Haas,
J. C. Merdinger,
D. C. Radford,
Y. Schutz,
J. Dudek,
W. Nazarewicz
[show abstract]
[hide abstract]
ABSTRACT: Quasicontinuum γ-decay studies of 144Gd have been performed using the 120Sn(28Si, 4n)reaction at 125, 135, 145, and 155 MeV bombarding energies. Angular distribution and multiplicity measurements have been done at the above energies. At 145 MeV bombarding energy, a lifetime measurement has also been performed. Although a collective behavior has been observed, the present data do not give evidence for population of superdeformed rotational bands. Theoretical interpretation using the cranking model with the Woods-Saxon field is given. The effects of temperature and pairing on the superdeformed configuration are discussed; superdeformation effects are predicted to disappear below I∼60–70 ħ when temperature exceeds ∼500 keV.
Phys. Rev. C. 05/2013; 33(6).
-
J. Robin,
Th. Byrski,
G. Duchêne, F.A. Beck,
D. Curien,
N. Dubray,
J. Dudek,
A. Góźdź,
A. Odahara,
N. Schunck, [......],
E. S. Paul,
C. Petrache,
I. Piqueras,
N Redon,
A. Saltarelli,
J Simpson,
O. Stezowski,
R. Venturelli,
J.P. Vivien,
K Zuber
[show abstract]
[hide abstract]
ABSTRACT: A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV gamma-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new gamma-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the 152Tb and the two others to the 151Tb nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations.
Papers from the Department of Physics. 05/2013;
-
S. Akkoyun,
A. Algora,
B. Alikhani,
F. Ameil,
G. de Angelis,
L. Arnold,
A. Astier,
A. Ataç,
Y. Aubert,
C. Aufranc, [......],
D. Weisshaar,
D. Wells,
O. Wieland,
A. Wiens,
G. Wittwer,
H. J. Wollersheim,
F. Zocca,
N. V. Zamfir,
M. Ziȩbliński,
A. Zucchiatti
[show abstract]
[hide abstract]
ABSTRACT: The Advanced GAmma Tracking Array (AGATA) is a European project to develop
and operate the next generation gamma-ray spectrometer. AGATA is based on the
technique of gamma-ray energy tracking in electrically segmented high-purity
germanium crystals. This technique requires the accurate determination of the
energy, time and position of every interaction as a gamma ray deposits its
energy within the detector volume. Reconstruction of the full interaction path
results in a detector with very high efficiency and excellent spectral
response. The realization of gamma-ray tracking and AGATA is a result of many
technical advances. These include the development of encapsulated
highly-segmented germanium detectors assembled in a triple cluster detector
cryostat, an electronics system with fast digital sampling and a data
acquisition system to process the data at a high rate. The full
characterization of the crystals was measured and compared with
detector-response simulations. This enabled pulse-shape analysis algorithms, to
extract energy, time and position, to be employed. In addition, tracking
algorithms for event reconstruction were developed. The first phase of AGATA is
now complete and operational in its first physics campaign. In the future AGATA
will be moved between laboratories in Europe and operated in a series of
campaigns to take advantage of the different beams and facilities available to
maximize its science output. The paper reviews all the achievements made in the
AGATA project including all the necessary infrastructure to operate and support
the spectrometer.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/2011; 668:26. · 1.21 Impact Factor
-
J. Robin,
A. Odahara,
G. Duchêne, F. A. Beck,
P. Twin,
Th. Byrski,
D. Curien,
N. Adimi,
D. E. Appelbe,
P. Bednarczyk, [......],
E. S. Paul,
C. Petrache,
I. Piqueras,
N. Redon,
A. Saltarelli,
J. Simpson,
O. Stezowski,
R. Venturelli,
J. P. Vivien,
K. Zuber
[show abstract]
[hide abstract]
ABSTRACT: The Euroball array has been used to search for linking transitions between the superdeformed (SD) and the normal deformed (ND) wells in 151Tb. Many γ rays in the energy range 2–4 MeV have been observed in coincidence with the yrast SD band. It is proposed that the highest energy transition of 3748 keV and the strongest line (2818 keV) of the previously observed transitions both decay from the same SD level as their links with the ND states have been identified. The current spectra have insufficient statistics to completely identify the decay point in the SD band. Theoretical calculations covering SD bands in the A≈150 region enable the two possible spin assignments to be compared with experimental data on proposed links in 149Gd and 152Dy. It is concluded that the energy of the lowest SD band member in 151Tb has an excitation energy of 12861 keV and a spin of 65/2+.
Phys. Rev. C. 09/2008; 78(3).
-
J. Robin,
Th. Byrski,
G. Duchêne, F. A. Beck,
D. Curien,
N. Dubray,
J. Dudek,
A. Góźdź,
A. Odahara,
N. Schunck, [......],
E. S. Paul,
C. Petrache,
I. Piqueras,
N. Redon,
A. Saltarelli,
J. Simpson,
O. Stezowski,
R. Venturelli,
J. P. Vivien,
K. Zuber
[show abstract]
[hide abstract]
ABSTRACT: A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV γ-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new γ-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the 152Tb and the two others to the 151Tb nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations.
Phys. Rev. C. 01/2008; 77(1).
-
Physical Review C 01/2008; 77. · 3.31 Impact Factor
-
J Robin,
T Byrski,
G Duchene, F A Beck,
D Curien,
N Dubray,
J Dudek,
A Gozdz,
A Odahara,
N Schunck, [......],
E S Paul,
C Petrache,
I Piqueras,
N Redon,
A Saltarelli,
J Simpson,
O Stezowski,
R Venturelli,
J P Vivien,
K Zuber
[show abstract]
[hide abstract]
ABSTRACT: A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV gamma-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new gamma-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the Tb-152 and the two others to the Tb-151 nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations.
Physical Review C. 01/2008; 77(1):10.
-
G. Benzoni,
J. Robin,
A. Bracco,
F. C. L. Crespi,
A. De Conto,
S. Leoni,
B. Million,
D. Montanari,
G. Duchêne,
D. Curien, [......], F. A. Beck,
P. Bednarczyk,
S. Courtin,
O. Dorvaux,
B. J. P. Gall,
P. Joshi,
A. Nourreddine,
I. Piqueras,
J. P. Vivien,
P. J. Twin
[show abstract]
[hide abstract]
ABSTRACT: The experimental study of the unresolved rotational bands, forming ridge structures in γ-γ spectra, has been performed on the superdeformed nucleus 151Tb. γ transitions from the reaction 27Al, at 155 MeV, on 130Te were measured with EUROBALL IV in high fold coincidence. The analysis of the intensities and count fluctuations of the ridge structures shows the existence of ≈30 discrete rotational bands of superdeformed nature, half of which is in direct coincidence with the superdeformed yrast band. A comparison with band mixing model predictions and with a previous work on the superdeformed nucleus 143Eu is presented.
Phys. Rev. C. 04/2007; 75(4).
-
11/2003; 44:561-607.
-
N. Redon,
N. Buforn,
R. Duffait,
P. Lautesse,
M. Meyer,
A. Prévost,
O. Stézowski,
A. Astier,
A. Bauchet,
I. Deloncle, [......],
R. Lucas, F.A. Beck,
P. Bednardcyk,
D. Curien,
G. Duchêne,
O. Dorvaux,
B.J.P. Gall,
N. Kintz,
J.P. Vivien,
D.M. Cullen
[show abstract]
[hide abstract]
ABSTRACT: We report the results of an experiment, realized with the EUROBALL IV spectrometer, in which superdeformed (SD) states have been populated in 197,198Pb nuclei. Crosstalk transitions between two signature partner SD bands in 197Pb have been observed with an established M1 character, giving access to the magnetic properties of the
n\nu
[752]5/2 intruder orbital. Six new SD bands have been identified in 197,198Pb. The results are interpreted in the framework of cranked Hartree-Fock calculations. A mixing between quasi-particle excitations and an octupole vibration is suggested in the two SD isotopes.
European Physical Journal A 03/2003; 20(1):31-32. · 2.19 Impact Factor
-
Th. Byrski, F. A. Beck,
P. Bednarczyk,
N. Kintz,
K. Zuber,
J. P. Vivien,
S. Courtin,
D. Curien,
G. Duchêne,
C. Finck,
B. Gall,
A. Nourreddine,
A. Odahara,
O. Stezowski,
C. Theisen
[show abstract]
[hide abstract]
ABSTRACT: An enhanced population of the 149Gd yrast superdeformed band has been observed in the reaction 124Sn(31P,p5n) using the EUROBALL IV multidetector associated with an inner ball. This effect is explained as the consequence of a higher probability of trapping residual nuclei into the superdeformed well whose depth has been increased due to favorable temperature and of total energy and angular momentum selection with the inner ball.
Phys. Rev. C. 03/2002; 65(3).
-
N. Nica,
G. Duchêne,
V. E. Iacob,
J. Dudek, F. A. Beck,
Th. Byrski,
D. Curien,
G. de France,
B. Haas,
B. Kharraja, [......],
M. Aïche,
M. M. Aléonard,
J. F. Chemin,
C. W. Beausang,
S. Clarke,
P. J. Dagnall,
M. Smith,
P. J. Twin,
J. Simpson,
M. A. Bentley
[show abstract]
[hide abstract]
ABSTRACT: The high-spin decay scheme of 155Er, known previously, has been considerably extended by using the EUROGAM II γ-ray array. The so-called quasi-isotropic gating data-analysis method, capable of providing spin and parity assignments with triple or quadruple coincidence data has been used. With such coincidence information, we have determined γ-ray angular distributions, DCO ratios, and linear polarizations for many of the observed transitions. The level scheme is interpreted by using the particle-hole analysis based on the deformed Woods-Saxon potential and the monopole pairing interaction. The results indicate that at ∼12.3 MeV excitation energy, all nine valence particles around the 64146Gd82 core exhaust the maximum spin of I=79/2ħ. At higher spin, relatively high-energy transitions, of the order of ∼1.5 MeV, related to the breaking of the proton or neutron cores are observed. According to the calculations, this corresponds to an oblate-shape polarization of the nucleus with quadrupole deformation β2∼-0.12.
Phys. Rev. C. 08/2001; 64(3).
-
01/2001;
-
A. Prévost,
N. Buforn,
A. Astier,
R. Duffait,
M. Meyer,
S. Perriès,
N. Redon,
O. Stézowski,
A. Bauchet,
I. Deloncle, [......],
A. Goergen,
H. Huebel,
E. Mergel,
S. Neumann,
D. Robach,
N. Nenoff,
G. Schoenwaber,
A.N. Wilson,
R. Lucas, F.A. Beck
International Winter Meeting of Nuclear Physics 39 - Ricerca Scientifica ed Educazione Permanente Supplemento, Bormio, Italy; 01/2001
-
A. Prévost,
N. Buforn,
A. Astier,
R. Duffait,
M. Meyer,
S. Perriès,
N. Redon,
O. Stézowski,
A. Bauchet,
I. Deloncle, [......],
G. Schönwaßer,
A. N. Wilson,
R. Lucas, F. A. Beck,
D. Curien,
G. Duchêne,
B. J. P. Gall,
N. Kintz,
J. P. Vivien,
D. M. Cullen
[show abstract]
[hide abstract]
ABSTRACT: We report the identification of six new superdeformed (SD) bands in 197,198Pb observed with the EUROBALL IV spectrometer. The results are interpreted in the framework of cranked Hartree-Fock calculations
with approximate projection on the particle number by means of the Lipkin-Nogami method. A mixing between quasi-particle excitations
and an octupole vibration is suggested in the two SD isotopes. We have estimated the ordering of the neutron valence orbitals
and confirm indirectly a N = 118 SD gap.
European Physical Journal A 01/2001; 10:13-19. · 2.19 Impact Factor
-
N. Buforn,
A. Astier,
R. Duffait,
M. Meyer,
S. Perriès,
A. Prévost,
N. Redon,
O. Stézowski,
A. Goergen,
H. Hübel, [......],
M.G. Porquet,
A.N. Wilson,
R. Lucas, F.A. Beck,
D. Curien,
G. Duchêne,
B.J.P. Gall,
N. Kintz,
J.P. Vivien,
D.M. Cullen
[show abstract]
[hide abstract]
ABSTRACT: This work has established eight cross-talk transitions between the two signature partner superdeformed (SD) bands in 197Pb with the EUROBALL IV spectrometer. Directional correlations from oriented states measurements confirm the ΔI = 1 character of these transitions. The flat behaviour of the dynamical moment of inertia and the agreement between the experimental
and microscopic HF+BCS values of (g
K - g
R)K/Q
0 suggest that the configuration of the SD bands is based upon the υ[752]5/2- neutron intruder orbital. The derived effective spin gyromagnetic factor g
s
eff is found to be not quenched, and is close to the theoretical g
s
free value.
European Physical Journal A 01/2000; 9(1):29-34. · 2.19 Impact Factor
-
N. Buforn,
A. Astier,
R. Duffait,
M. Meyer,
S. Perriès,
A. Prévost,
N. Redon,
O. Stézowski,
A. Goergen,
H. Hübel, [......],
M. G. Porquet,
A. N. Wilson,
R. Lucas, F. A. Beck,
D. Curien,
G. Duchêne,
B. J. P. Gall,
N. Kintz,
J. P. Vivien,
D. M. Cullen
The European Physical Journal A - Hadrons and Nuclei. 01/2000; 9:29-34.
-
N Buforn,
A Astier,
R Duffait,
M Meyer,
S Perrì Es,
A Prévost,
N Redon,
O Stézowski,
A Goergen,
H Hübel, [......],
M G Porquet,
A N Wilson,
R Lucas, F A Beck,
D Curien,
G Duchêne,
B J P Gall,
N Kintz,
J P Vivien,
D M Cullen
[show abstract]
[hide abstract]
ABSTRACT: This work has established eight cross-talk transitions between the two signature partner su-perdeformed (SD) bands in 197 Pb with the EUROBALL IV spectrometer. Directional correlations from oriented states measurements confirm the ∆I = 1 character of these transitions. The flat behaviour of the dynamical moment of inertia and the agreement between the experimental and microscopic HF+BCS values of (g K − gR) K/Q0 suggest that the configuration of the SD bands is based upon the ν[752]5/2 − neutron intruder orbital. The derived effective spin gyromagnetic factor g eff s is found to be not quenched, and is close to the theoretical g free s value.
Eur. Phys. J. A. 01/2000; 910202080(21):29-34.
-
M. Aïche,
M.M. Aléonard,
G. Barreau,
D. Boivin,
F. Bourgine,
J.F. Chemin,
J.N. Scheurer,
T.P. Doan,
A. Brondi,
G. La Rana,
R. Moro,
A. Principe,
E. Vardaci,
D. Curien,
G. Duchêne,
G. de France, F.A. Beck,
B. Haas,
J.P. Vivien,
F. Hannachi
[show abstract]
[hide abstract]
ABSTRACT: The study of the !-particle energy distributions associated with ND and SD states in 151,152Dy has been carried out. The Dy isotopes were produced in the reaction 37Cl + 123Sb at 191 MeV via the (ŏn) and (Ŏn) channels, respectively. In 151Dy the !-particle energy distributions associated to ND and SD are very different from each other, both at the low and high energy sides inducing a difference of 3 MeV in the !-particle mean energy. In 152Dy the situation is different; the !-particle spectral shapes are similar and a difference in the !-particle mean energy of only 0.7 MeV is deduced. A description in terms of energy localization of entry states is given.
European Physical Journal A 09/1999; 6(2):121-129. · 2.19 Impact Factor
-
N. Kintz,
Ch. Finck,
O. Stezowski,
J. P. Vivien,
A. Nourreddine,
K. Zuber,
D. E. Appelbe,
C. W. Beausang, F. A. Beck,
T. Byrski, [......],
S. Ertuerk,
G. de France,
B. J. P. Gall,
B. Haas,
N. Khadiri,
A. Lopez-Martens,
E. Pachoud,
C. Rigollet,
M. Smith,
P. J. Twin
[show abstract]
[hide abstract]
ABSTRACT: A long run performed with EUROGAM II allowed remeasuring the
149Gd superdeformed (SD) band 1. The Δ I = 4
bifurcation in band 1 is confirmed and two resolved γ -ray
transitions linking the SD band 1 and the normal deformed states have
been observed.
Acta Physica Polonica Series B 02/1999; 30:793. · 0.90 Impact Factor
