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[show abstract]
[hide abstract]
ABSTRACT: Recent improvements in the intensities and optical qualities of radioactive beams have made possible the study of elastic
and inelastic proton scattering on unstable nuclei. The design and performances of an innovative silicon strip detector array
devoted to such experiments are described. The quality of the data obtained are illustrated with recent results obtained at
the GANIL facility for unstable oxygen, sulfur and argon isotopes. Methods to analyse the data using phenomenological and
microscopic optical model potentials are discussed.
Pramana 04/2012; 57(2):493-504. · 0.57 Impact Factor
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A. Lépine-Szily,
G. F. Lima,
A. C. C. Villari,
W. Mittig,
R. Lichtenthäler,
M. Chartier,
N. A. Orr,
J. C. Angélique,
G. Audi,
J. M. Casandjian, [......],
S. Lukyanov,
M. MacCormick,
D. J. Morrissey,
A. N. Ostrowski,
B. M. Sherrill,
C. Stephan, T. Suomijärvi,
L. Tassan-Got,
D. J. Vieira,
J. M. Wouters
[show abstract]
[hide abstract]
ABSTRACT: Proton-rich isotopes of Ga, Ge, As, Se and Br had their total reaction cross-sections (σR) measured. Root-mean-squared matter radii were determined from Glauber model calculations, which reproduced the experimental σR values. For all isotopic series a decrease of the rrms with increasing neutron number and a correlation with deformation was observed.
European Physical Journal A 01/2005; 25:227-230. · 2.19 Impact Factor
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T. Zerguerras,
B. Blank,
Y. Blumenfeld, T. Suomijärvi,
D. Beaumel,
B. A. Brown,
M. Chartier,
M. Fallot,
J. Giovinazzo,
C. Jouanne,
V. Lapoux,
I. Lhenry-Yvon,
W. Mittig,
P. Roussel-Chomaz,
H. Savajols,
J. A. Scarpaci,
A. Shrivastava,
M. Thoennessen
[show abstract]
[hide abstract]
ABSTRACT: Light proton-rich bound and unbound nuclei were produced by means of stripping reactions of secondary beams of 20Mg and 18Ne. The decays of the unbound nuclei 18,19Na have been measured by detecting their decay products 17,18Ne and one proton and by performing an invariant-mass reconstruction. For 18Na, the present work is the first measurement of its decay. As the decay scheme of this nucleus could not be determined, two possible scenarios are proposed and discussed. In addition, the decay of excited states in 17Ne via two-proton emission was observed. The proton-proton angular distribution is isotropic for the first two-proton-emitting states, whereas higher-lying states seem to decay by a correlated two-proton emission, consistent with a 2He emission pattern for part of the decay strength.
European Physical Journal A 05/2004; 20(3):389-396. · 2.19 Impact Factor
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M. Chartier,
G. F. Lima,
A. Lépine‐Szily,
G. Audi,
W. Mittig,
N. Orr,
R. Lichtenthaler,
J.‐C. Angélique,
J.‐M. Casandjian,
A. Cunsolo, [......],
M. Mac Cormick,
D. J. Morrissey,
A. N. Ostrowski,
B. M. Sherrill,
C. Stephan, T. Suomijärvi,
L. Tassan‐Got,
D. J. Vieira,
A. C. C. Villari,
J. M. Wouters
[show abstract]
[hide abstract]
ABSTRACT: The masses of very neutron‐deficient 66As, 68,70,71Se and 71Br were measured for the first time and those of 64,65Ge and 67As remeasured, with total uncertainties ranging from 200 to 1000 keV, including systematic, extrapolation and statistical errors, using the SPEG direct time‐of‐flight method at GANIL. These new results are discussed and compared to other recent experimental data and mass predictions. © 2003 American Institute of Physics
AIP Conference Proceedings. 03/2003; 656(1):275-282.
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D. Santonocito,
P. Piattelli,
Y. Blumenfeld, T. Suomijärvi,
C. Agodi,
N. Alamanos,
R. Alba,
F. Auger,
G. Bellia,
Ph. Chomaz, [......],
P. Finocchiaro,
N. Frascaria,
A. Gillibert,
J. H. Le Faou,
K. Loukachine,
C. Maiolino,
E. Migneco,
J. C. Roynette,
P. Sapienza,
J. A. Scarpaci
[show abstract]
[hide abstract]
ABSTRACT: Central and mid-central collisions which lead to the formation of a heavy residue in the 37A MeV 36Ar+98Mo reaction have been studied with the MEDEA multidetector array coupled to a Parallel Plate Avalanche Counter. The dependence of the high energy gamma ray and light charged particle production as a function of the linear momentum transferred to the fused system has been studied. The unique potentialities of the MEDEA detector have made it possible to follow the evolution of the reaction dynamics from the pre-equilibrium stage to the formation of a heavy compound nucleus. The analysis of the correlation between the most energetic photons and protons shows how both of them are mainly produced in the most energetic primary nucleon-nucleon collisions. The multiplicity of high energy (Eγ>30MeV) γ rays has been found to increase with the linear momentum transfer, showing the dominance of two-body dissipation in the transfer mechanism and giving a tool to correlate the momentum transfer with the centrality of the collision. Light charged particle kinetic energy spectra show how in these collisions, compound systems with excitation energies of more than 3AMeV and temperature up to 7 MeV are formed. The experimental findings are compared with Boltzmann-Nordheim-Vlasov calculations. A scenario is found where the nucleus-nucleus interaction starts with two-body nucleon-nucleon collisions in the overlap region of nuclear densities. These collisions give rise to the production of high energy nucleons and γ rays, and play a fundamental role in the energy transfer from the relative motion to internal excitation of the quasiprojectile and the target.
Phys. Rev. C. 10/2002; 66(4).
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H. Scheit,
F. Maréchal,
T. Glasmacher,
E. Bauge,
Y. Blumenfeld,
J. P. Delaroche,
M. Girod,
R. W. Ibbotson,
K. W. Kemper,
J. Libert,
B. Pritychenko, T. Suomijärvi
[show abstract]
[hide abstract]
ABSTRACT: Elastic and inelastic proton scattering to the 21+ states of the neutron-rich argon isotopes 42Ar and 44Ar have been measured in inverse kinematics with a beam energy of 33 MeV/nucleon. Phenomenological distorted wave Born approximation calculations are compared with the data and quadrupole deformation parameters of |β2|=0.32±0.05 and |β2|=0.31±0.05 are extracted for the 21+ states in 42Ar and 44Ar, respectively. A consistent microscopic proton scattering analysis has been applied to all even-even argon isotopes from A=36 to A=44. This analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux nucleon-nucleon effective interaction. The predicted cross sections agree very well with the experimental data, suggesting this microscopic analysis as a tool to test the structure of nuclei far from stability.
Phys. Rev. C. 12/2000; 63(1).
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E. Khan,
Y. Blumenfeld,
Nguyen Van Giai, T. Suomijärvi,
N. Alamanos,
F. Auger,
G. Colò,
N. Frascaria,
A. Gillibert,
T. Glasmacher,
M. Godwin,
K.W. Kemper,
V. Lapoux,
I. Lhenry,
F. Maréchal,
D.J. Morrissey,
A. Musumarra,
N.A. Orr,
S. Ottini-Hustache,
J.E. Sauvestre
[show abstract]
[hide abstract]
ABSTRACT: Proton elastic and inelastic scattering angular distributions to the 2+1 and the 3−1 states for the neutron-rich nucleus 20O were measured with a secondary beam using the MUST silicon strip detector array. Data for 18O were also obtained for comparison. A phenomenological analysis has been used to deduce the deformation parameters βp,p′ for the collective excitations. Matter and transition densities were generated from self-consistent QRPA calculations. DWBA calculations using microscopic optical potentials obtained with these densities and the JLM interaction are compared to the data. The isovector character of the 2+1 state in 20O is confirmed and predictions are discussed for the properties of the heavier neutron-rich oxygen isotopes.
Physics Letters B 09/2000; 490(1-2):45-52. · 3.95 Impact Factor
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A Lagoyannis,
F Auger,
A Musumarra,
N Alamanos,
E.C Pollacco,
A Pakou,
Y Blumenfeld,
F Braga,
M La Commara,
A Drouart, [......],
D Pierroutsakou,
M Romoli,
P Roussel-Chomaz,
M Sandoli,
D Santonocito,
J.A Scarpaci,
J.L Sida, T Suomijärvi,
S Karataglidis,
K Amos
[show abstract]
[hide abstract]
ABSTRACT: Proton elastic and inelastic scattering to the first excited state of 6He have been measured over a wide angular range using a 40.9A MeV 6He beam. The data have been analyzed with a fully microscopic model of proton–nucleus scattering using 6He wave functions generated from large space shell model calculations. The inelastic scattering data show a remarkable sensitivity to the halo structure of 6He.
Physics Letters B. 04/2000;
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F. Maréchal, T. Suomijärvi,
Y. Blumenfeld,
A. Azhari,
D. Bazin,
J. A. Brown,
P. D. Cottle,
M. Fauerbach,
T. Glasmacher,
S. E. Hirzebruch,
J. K. Jewell,
J. H. Kelley,
K. W. Kemper,
P. F. Mantica,
D. J. Morrissey,
L. A. Riley,
J. A. Scarpaci,
H. Scheit,
M. Steiner
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich argon isotope 43Ar has been studied by quasielastic and inelastic proton scattering performed in inverse kinematics. The measured inelastic angular distribution for the second excited state is in good agreement with an L=2 transition. Assuming this transition to be E2, yields a β2 value for this state of 0.25±0.03 when compared with distorted-wave Born approximation calculations. This value is comparable to the one reported for the stable isotope 40Ar. Moreover it is similar to those measured by Coulomb excitation for the neighboring even-even isotopes 42Ar and 44Ar indicating that the structure of the argon isotopes is stable as a function of neutron number.
Phys. Rev. C. 11/1999; 60(6).
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F. Maréchal, T. Suomijärvi,
Y. Blumenfeld,
A. Azhari,
E. Bauge,
D. Bazin,
J. A. Brown,
P. D. Cottle,
J. P. Delaroche,
M. Fauerbach, [......],
S. E. Hirzebruch,
J. K. Jewell,
J. H. Kelley,
K. W. Kemper,
P. F. Mantica,
D. J. Morrissey,
L. A. Riley,
J. A. Scarpaci,
H. Scheit,
M. Steiner
[show abstract]
[hide abstract]
ABSTRACT: Elastic and inelastic proton scattering has been measured in inverse kinematics on the unstable nucleus 40S. A phenomenological distorted wave Born approximation analysis yields a quadrupole deformation parameter β2=0.35±0.05 for the 21+ state. Consistent phenomenological and microscopic proton scattering analyses have been applied to all even-even sulfur isotopes from A=32 to A=40. The second analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux nucleon-nucleon effective interaction. This microscopic analysis suggests the presence of a neutron skin in the heavy sulfur isotopes. The analysis is consistent with normalization values for λv and λw of 0.95 for both the real and imaginary parts of the Jeukenne-Lejeune-Mahaux potential.
Phys. Rev. C. 08/1999; 60(3).
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M. C. Mermaz,
B. Berthier,
J. Barrette,
J. Gastebois,
A. Gillibert,
R. Lucas,
J. Matuszek,
A. Miczaika,
E. Van Renterghem, T. Suomijärvi, [......],
L. Kraus,
I. Linck,
B. Lott,
V. Rauch,
R. Rebmeister,
F. Scheibling,
N. Schulz,
J. C. Sens,
C. Grunberg,
W. Mittig
[show abstract]
[hide abstract]
ABSTRACT: One-proton and one-neutron stripping reactions induced by a 793 MeV16O beam bombarding a208Pb target have been studied at the GANIL facility using a high resolution energy loss magnetic spectrometer. The reactions are governed by two semi classical selection rules which are naturally contained in the one-step EFR-DWBA formalism. Relative intensities of the populated states are well reproduced by this formalism which, on the other hand, fails to predict correctly absolute cross section values.
Zeitschrift für Physik A Hadrons and Nuclei 11/1987; 326(4):353-359.
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V. Lapoux,
N. Alamanos,
F. Auger,
Y. Blumenfeld,
J.M. Casandjian,
M. Chartier,
M.D. Cortina-Gil,
V. Fékou-Youmbi,
A. Gillibert,
M. Mac Cormic, [......],
W. Mittig,
F. De Oliveira Santos,
N. A. Orr,
A. N. Ostrowski,
S. Ottini-Hustache,
P. Roussel-Chomaz,
J.A. Scarpaci,
J.-L. Sida, T. Suomijärvi,
J.S. Winfield
[show abstract]
[hide abstract]
ABSTRACT: The 10;11Be(p,p) and (12C, 12C) reactions were analyzed to determine the in uence of the weak binding energies of exotic nuclei on their interaction potential. The elastic cross sections were measured at GANIL in inverse kinematics using radioactive 10;11Be beams produced at energies of 39:1 A and 38:4A MeV. The elastic proton scattering data were analyzed within the framework of the microscopic Jeukenne-Lejeune-Mahaux (JLM) nucleon-nucleus potential. The angular distributions are found to be best reproduced by reducing the real part of the microscopic optical potential, as a consequence of the coupling to the continuum. These effects modify deeply the elastic potential. Including the Virtual Coupling Potential (VCP), we show the ability of the general optical potentials to reproduce the data for scattering of unstable nuclei, using realistic densities. Finally, the concepts needed to develop a more general and microscopic approach of the VCP are discussed.
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R. Liguori Neto,
P. Roussel-Chomaz,
L. Rochais,
N. Alamanos,
F. Auger,
B. Fernandez,
J. Gastebois,
A. Gillibert,
R. Lacey,
A. Miczaika, [......],
S.K. Mark,
R. Turcotte,
Y. Blumenfeld,
N. Frascaria,
J.P. Garron,
J.C. Roynette,
J.A. Scarpaci, T. Suomijärvi,
A. Van der Woude,
A.M. Van den Berg
[show abstract]
[hide abstract]
ABSTRACT: Elastic and inelastic scattering of 1435 MeV 17O ions on 208Pb, 120Sn, 90Zr and 60Ni have been measured. Hindrance in the excitation of the first 3− states is observed. Parameters of the isoscalar giant monopole and quadrupole resonances are obtained. The quadrupole resonance exhausts ∼ 55% of the energy-weighted sum rule while the observed monopole resonance corresponds to more than 100% of the sum rule. Strength is also observed at high excitation energy in all targets.
Nuclear Physics A.
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T. Suomijärvi,
D. Beaumel,
Y. Blumenfeld,
Ph. Chomaz,
N. Frascaria,
J.P. Garron,
J.C. Roynette,
J.A. Scarpaci,
J. Barrette,
B. Fernandez,
J. Gastebois,
W. Mittig
[show abstract]
[hide abstract]
ABSTRACT: Giant resonances in 90Zr and 208Pb have been studied by inelastic scattering of 40Ar at 41 MeV/u. Strength distributions and exhausted sum-rule values of different multipolarities are presented. The peak-to-background ratios and differential cross sections from inelastic scattering of heavy ions are compared to those obtained with light projectiles. The influence of Coulomb interaction on the excitation of giant resonances and the possibility to study high multipole resonances by intermediate-energy heavy ions are discussed.
Nuclear Physics A.
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T. Suomijärvi,
J.H. Kelley,
S.E. Hirzebruch,
A. Azhari,
D. Bazin,
Y. Blumenfeld,
J.A. Brown,
P.D. Cottle,
S. Danczyk,
M. Fauerbach,
T. Glasmacher,
J.K. Jewell,
K.W. Kemper,
F. Maréchal,
D.J. Morrissey,
S. Ottini,
J.A. Scarpaci,
P. Thirolf
[show abstract]
[hide abstract]
ABSTRACT: Elastic and inelastic scattering of protons on unstable 38S nuclei has been measured in inverse kinematics by using a 38S secondary beam at 39 MeV/nucleon. The excitation energy spectrum is measured up to 5 MeV. The first 2+ state is seen at 1.2 MeV excitation energy, and strength at around 3–5 MeV is also observed. Angular distributions for inelastic and elastic scattering are shown and compared to optical potential and folding model calculations. The preliminary β2 value extracted for the first 2+ state is 0.38±0.05.
Nuclear Physics A.
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T. Suomijärvi,
J.H. Le Faou,
Y. Blumenfeld,
P. Piattelli,
C. Agodi,
N. Alamanos,
R. Alba,
F. Auger,
G. Bellia,
Ph. Chomaz, [......],
M. Lamehi-Rachti,
R. Liguori-Neto,
C. Maiolino,
E. Migneco,
G. Russo,
J.C. Roynette,
D. Santonocito,
P. Sapienza,
J.A. Scarpaci,
A. Smerzi
[show abstract]
[hide abstract]
ABSTRACT: Gamma-rays, light charged particles and evaporation residues emitted from hot nuclei formed in the 36Ar + 90Zr reaction at 27 MeV/u have been measured with a nearly 4π barium fluoride multidetector. It is shown that hot Sn-like nuclei with a range of excitation energies between 300 and 600 MeV are produced. The γ-ray yield from the decay of the Giant Dipole Resonance in these nuclei is shown to remain constant over this excitation energy range. The measured γ-ray spectra are compared with statistical calculations encompassing several recent theoretical models for the quenching of gamma-ray emission from the dipole resonance at very high temperatures.
Nuclear Physics A.
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C. Jouanne,
V. Lapoux,
F. Auger,
N. Alamanos,
A. Drouart,
A. Gillibert,
G. Lobo,
A. Musumarra,
L. Nalpas,
E. Pollacco,
J.-L. Sida,
M. Trotta,
Y. Blumenfeld,
E. Khan, T. Suomijärvi,
T. Zerguerras,
P. Roussel-Chomaz,
H. Savajols,
A. Lagoyannis,
A. Pakou
[show abstract]
[hide abstract]
ABSTRACT: To probe the ground state and transition densities, elastic and inelastic scattering on a proton target were measured in inverse kinematics for the unstable $^{10}$C and $^{11}$C nuclei at 45.3 and 40.6 MeV/nucleon, respectively. The detection of the recoil proton was performed by the MUST telescope array, in coincidence with a wall of scintillators for the quasiprojectile. The differential cross sections for elastic and inelastic scattering to the first excited states are compared to the optical model calculations performed within the framework of the microscopic nucleon-nucleus Jeukenne-Lejeune-Mahaux potential. Elastic scattering is sensitive to the matter-root-mean square radius found to be 2.42$\pm$0.1 and 2.33$\pm$0.1 fm, for $^{10,11}$C, respectively. The transition densities from cluster and mean-field models are tested, and the cluster model predicts the correct order of magnitude of cross sections for the transitions of both isotopes. Using the Bohr-Mottelson prescription, a profile for the $^{10}$C transition density from the $0^+$ ground to the $2_1^+$ state is deduced from the data. The corresponding neutron transition matrix element is extracted: Mn=5.51$\pm$1.09 fm$^2$.
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E. Khan,
Y. Blumenfeld,
Nguyen Van Giai, T. Suomijärvi,
N. Alamanos,
F. Auger,
G. Colò,
N. Frascaria,
A. Gillibert,
T. Glasmacher, [......],
N.A. Orr,
S. Ottini-Hustache,
P. Piattelli,
E.C. Pollacco,
P. Roussel-Chomaz,
J.C. Roynette,
D. Santonocito,
J.E. Sauvestre,
J.A. Scarpaci,
C. Volpe
[show abstract]
[hide abstract]
ABSTRACT: Proton elastic and inelastic scattering angular distributions to the 2+1 and the 3−1 states for the neutron-rich nucleus 20O were measured with a secondary beam using the MUST silicon strip detector array. Data for 18O were also obtained for comparison. A phenomenological analysis has been used to deduce the deformation parameters βp,p′ for the collective excitations. Matter and transition densities were generated from self-consistent QRPA calculations. DWBA calculations using microscopic optical potentials obtained with these densities and the JLM interaction are compared to the data. The isovector character of the 2+1 state in 20O is confirmed and predictions are discussed for the properties of the heavier neutron-rich oxygen isotopes.
Physics Letters B.
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P. Piattelli,
Y. Blumenfeld,
J.H. Le Faou, T. Suomijärvi,
C. Agodi,
N. Alamanos,
R. Alba,
F. Auger,
G. Bellia,
Ph. Chomaz, [......],
A. Gillibert,
M. Lamehi-Rachti,
R. Liguori-Neto,
K. Loukachine,
C. Maiolino,
E. Migneco,
J.C. Roynette,
D. Santonocito,
P. Sapienza,
J.A. Scarpaci
[show abstract]
[hide abstract]
ABSTRACT: The study of the Giant Dipole Resonance (GDR) excited in hot nuclei allows to follow the evolution of collective motion with increasing nuclear temperature. A brief review of the characteristics of the GDR excited in nuclei with excitation energies up to ∼ 500 MeV is given. The results of recent experiments in which very hot nuclei have been studied with a nearly 4π detector are presented. Gamma-rays, light charged particles and evaporation residues emitted from hot nuclei of mass around 115 and excitation energies above 300 MeV, formed in the at 27 MeV/u and at 37 MeV/u reactions, have been measured with the MEDEA multidetector. The γ-ray yield from the decay of the Giant Dipole Resonance in these nuclei has been found to be independent of excitation energy and bombarding energy. The measured γ-ray spectra are compared with statistical calculations encompassing several recent theoretical models for the quenching of gamma-ray emission from the dipole resonance at very high temperatures. The best agreement with the data is obtained by assuming a cut-off of the resonance γ-emission above an excitation energy of 250 MeV.
Nuclear Physics A.
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P. Piattelli,
D. Santonocito,
Y. Blumenfeld, T. Suomijärvi,
C. Agodi,
N. Alamanos,
R. Alba,
F. Auger,
G. Bellia,
Ph. Chomaz, [......],
P. Finocchiaro,
N. Frascaria,
A. Gillibert,
J.H. Le Faou,
K. Loukachine,
C. Maiolino,
E. Migneco,
J.C. Roynette,
P. Sapienza,
J.A. Scarpaci
[show abstract]
[hide abstract]
ABSTRACT: High energy γ-rays (Eγ>35 MeV) have been measured in coincidence with heavy residues emitted in reactions induced by a 37 MeV/u 36Ar beam on a 98Mo target. The γ-ray yield increases strongly with increasing linear momentum transfer indicating the importance of two-body collisions in the transfer mechanism. The high energy γ-ray multiplicity has been used to correlate the linear momentum transfer to the impact parameter. This correlation is compared to dynamical BNV simulations to show the essential role of two body nucleon-nucleon collisions at these bombarding energies.
Physics Letters B.
