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E Sahin,
G De Angelis,
G Duchene,
T Faul,
A Gadea,
A F Lisetskiy,
D Ackermann,
A Algora,
S Aydin,
F Azaiez, [......],
D A Torres,
M Trotta,
P Ujic,
C Ur,
J J Valiente-Dobón,
D Verney,
M Yalcinkaya,
P T Wady,
K T Wiedemann,
K Zuber
[show abstract]
[hide abstract]
ABSTRACT: The level structures of the N = 50 83 As, 82 Ge, and 81 Ga isotones have been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA–PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the γ -ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N = 50 shell closure in the region of 78 Ni (Z = 28). The comparison of the experimen-tal level schemes with the shell-model calculations yields an N = 50 energy gap value of 4.7(3) MeV at Z = 28. This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell model calculations, does not support a weakening of the N = 50 shell gap down to Z = 28.: NUCLEAR REACTIONS 238 U(82 Se, 81 Ga), (82 Se, 82 Ge), (82 Se, 83 As), E = 515 MeV; measured E γ , I γ (θ), γ γ -coin, reaction fragments, (fragment)γ -coin using PRISMA magnetic spectrometer, γ after deexcitation using Ge Compton-suppressed detectors of CLARA array, thin and thick target; deduced σ (θ), levels, J , π ; calculated levels, J , π using shell model
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[show abstract]
[hide abstract]
ABSTRACT: The assumption of an exact isospin symmetry would imply equal strengths for
mirror E1 transitions (at least, in the long-wavelength limit). Actually, large
violations of this symmetry rule have been indicated by a number of
experimental results, the last of which is the 67As - 67Se doublet investigated
at GAMMASPHERE. Here, we examine in detail various possible origins of the
observed asymmetry. The coherent effect of Coulomb-induced mixing with the
high-lying Giant Isovector Monopole Resonance is proposed as the most probable
process to produce a large asymmetry in the E1 transitions, with comparatively
small effect on the other properties of the parent and daughter levels.
09/2012;
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S. Bottoni,
G. Benzoni,
S. Leoni,
D. Montanari,
A. Bracco,
F. Azaiez,
S. Franchoo,
I. Stefan,
N. Blasi,
F. Camera, [......],
C. Ur,
F. Scarlassara,
A. Gadea,
A. Maj,
J. Wrzesinski,
K. Zuber,
Zs. Dombradi,
S. Szilner,
A. Saltarelli,
G. Pollarolo
[show abstract]
[hide abstract]
ABSTRACT: The heavy-ion reaction 22Ne+208Pb at 128 MeV beam energy has been studied using the PRISMA-CLARA experimental setup at Legnaro National Laboratories. Elastic, inelastic, and one-nucleon transfer differential cross sections are measured and global agreement is obtained with semiclassical and distorted-wave Born approximation (DWBA) calculations. In particular, the angular distribution of the 2+ state of 22Ne is analyzed by DWBA and a similar calculation is performed for the unstable 24Ne nucleus, using existing data from the reaction 24Ne+208Pb at 182 MeV (measured at SPIRAL with the VAMOS-EXOGAM setup). In both cases the DWBA model gives a good reproduction of the experiment, pointing to a strong reduction of the β2C charge deformation parameter in 24Ne. This follows the trend predicted for the evolution of the quadrupole deformation along the Ne isotopic chain.
Phys. Rev. C. 06/2012; 85(6).
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F. Recchia,
S. M. Lenzi,
S. Lunardi,
E. Farnea,
A. Gadea,
N. Mărginean,
D. R. Napoli,
F. Nowacki,
A. Poves,
J. J. Valiente-Dobón, [......],
G. Montagnoli, R. Orlandi,
G. Pollarolo,
E. Sahin,
F. Scarlassara,
R. P. Singh,
A. M. Stefanini,
S. Szilner,
C. A. Ur,
O. Wieland
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich cobalt isotopes up to A=67 have been studied through multinucleon transfer reactions by bombarding a 238U target with a 460-MeV 70Zn beam. Unambiguous identification of prompt γ rays belonging to each nucleus has been achieved using coincidence relationships with the ions detected in a high-acceptance magnetic spectrometer. The new data are discussed in terms of the systematics of the cobalt isotopes and interpreted with large-scale shell-model calculations in the fpgd model space. In particular, very different shapes can be described in 67Co, at the edge of the island of inversion at N=40, where a low-lying highly deformed band coexists with a spherical structure.
Phys. Rev. C. 06/2012; 85(6).
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W Urban,
K Sieja,
G S Simpson,
T Soldner,
T Rzaca-Urban,
A Zlomaniec,
I Tsekhanovich,
J A Dare,
A G Smith,
J L Durell,
J F Smith, R Orlandi,
A Scherillo,
I Ahmad,
J P Greene,
J Jolie,
A Linneman
Phys.Rev. C. 01/2012; 85:014329.
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W. Królas,
R. Broda,
B. Fornal,
R. V. F. Janssens,
A. Gadea,
S. Lunardi,
J. J. Valiente-Dobon,
D. Mengoni,
N. Mărginean,
L. Corradi, [......],
I. Pokrovskiy,
G. Pollarolo,
E. Sahin,
F. Scarlassara,
D. Seweryniak,
S. Szilner,
B. Szpak,
C. A. Ur,
J. Wrzesiński,
S. Zhu
[show abstract]
[hide abstract]
ABSTRACT: Excited states in the Z=19, N=29 neutron-rich 48K isotope have been studied using deep-inelastic transfer reactions with a thick target at Gammasphere and with a thin target at the PRISMA-CLARA spectrometer. The lowest excited states were located; they involve a proton hole in the s1/2 or d3/2 orbital coupled to a p3/2 neutron. A new 7.1(5)-ns, 5+ isomer, the analog of the 7/2− isomer in 47K, was identified. Based on the observed γ-decay pattern of the isomer a revised spin-parity assignment of 1− is proposed for the ground state of 48K.
Phys. Rev. C. 11/2011; 84(6).
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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
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D. Montanari,
S. Leoni,
L. Corradi,
G. Pollarolo,
G. Benzoni,
N. Blasi,
S. Bottoni,
A. Bracco,
F. Camera,
A. Corsi, [......],
S. Lunardi,
G. Montagnoli,
F. Scarlassara,
C. Ur,
G. Lo Bianco,
A. Zucchiatti,
S. Szilner,
M. Kmiecik,
A. Maj,
W. Meczynski
[show abstract]
[hide abstract]
ABSTRACT: Elastic, inelastic, and one-nucleon transfer channels in the 48Ca + 64Ni reaction have been measured at ≈6 MeV/nucleon with the PRISMA-CLARA setup, at Legnaro National Laboratory, consisting of the coupling of a large solid angle magnetic spectrometer with a germanium array. By trajectory reconstruction the reaction products have been fully identified in mass, nuclear charge, and kinetic energy, while coincident γ spectra of binary partners have been constructed after Doppler correction. Absolute differential cross sections have been extracted for the inelastic excitation and one-nucleon transfer, also for specific excited states. The data are in good agreement with semiclassical calculations and distorted wave Born approximation predictions. The work outlines an experimental method which can become valuable to extract structural information from heavy-ion reaction studies.
Phys. Rev. C. 11/2011; 84(5).
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S Leoni,
D Montanari,
G Benzoni,
N Blasi,
G Bocchi,
A Bracco,
F Camera,
A Corsi,
F C L Crespi,
B Million, [......],
D Mengoni,
G Montagnoli,
F Scarlassara,
C Ur,
G Lo Bianco,
A Zucchiatti,
M Kmiecik,
A Maj,
W Meczynski,
G Pollarolo
[show abstract]
[hide abstract]
ABSTRACT: The population and gamma decay of neutron rich nuclei around 48Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions (DIC) on 64Ni, at an energy approximately twice the Coulomb barrier. The reaction properties of the main products are investigated, focusing on total cross sections and angular distributions both integrated in energy and associated to the population of specific excited states. Gamma spectroscopy studies are also performed, giving evidence, for the first time in transfer reactions with heavy ions, of a large spin alignment (~70%), perpendicular to the reaction plane. This makes possible the use of angular distributions and polarization measurements to firmly establish the spin and parity of excited states populated in nucleon transfer channels, as in the case of 49Ca, where candidates for particle-core coupling are investigated. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for a detailed investigation of moderately neutron rich systems.
Journal of Physics Conference Series 09/2011; 312(9):092037.
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D.D. DiJulio,
J. Cederkall,
C. Fahlander,
A. Ekstr¨om,
P. Golubev,
K. Mattsson,
D. Rudolph,
G. de Angelis,
S. Aydin,
A. Y. Deo, [......],
P. Reiter,
E. Sahin,
J. Smith,
P.A. S¨oderstr¨om,
D.A. Torres,
G.M. Tveten,
C.A. Ur,
J.J. Valiente-Dob´on,
A. Wendt,
M. Zieli´nska
[show abstract]
[hide abstract]
ABSTRACT: Excited states of the nucleus 170Er have been studied by Coulomb excitation using the GASP γ -ray detector system at the Laboratori Nazionali di Legnaro. The ground-state band along with a low-lying \ensuremathKπ=0+ band and γ -vibrational band were populated during the experiment. Based on the measured γ -ray yields, a set of interband and intraband matrix elements has been extracted using the Coulomb excitation code GOSIA. The resulting E2 matrix elements are compared to collective model predictions.
European Physical Journal A 02/2011; 47(1):25. · 2.19 Impact Factor
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D Tonev,
G de Angelis,
P Petkov,
S Iliev, R Orlandi,
C Ur,
N Goutev,
M S Yavahchova,
R Menegazzo,
D Bazzacco, [......],
D Mengoni,
D R Napoli,
H Penttilä,
F Recchia,
E Sahin,
R P Singh,
A Saltarelli,
J J Valiente-Dobón,
H -F Wirth,
Q Zhong
[show abstract]
[hide abstract]
ABSTRACT: Using the 20Ne + 12C fusion-evaporation reaction at E20Ne = 33 MeV and the multidetector array GASP in conjuction with the EUCLIDES charged particle detector, angular correlations of coincident pairs of γ transitions and lifetimes in mirror nuclei 31S and 31P have been measured at the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. A comparison of the determined B(E1) strengths of the analog mirror 7/2− → 5/2+ transitions indicates the presence of a violation of isospin symmetry.
Journal of Physics Conference Series 02/2011; 267(1):012048.
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P -A Söderström,
F Recchia,
J Nyberg,
A Al-Adili,
A Ataç,
S Aydin,
D Bazzacco,
P Bednarczyk,
B Birkenbach,
D Bortolato, [......],
P Reiter,
E Sahin,
J F Smith,
J Strachan,
D Tonev,
C Unsworth,
C A Ur,
J J Valiente-Dobón,
C Veyssiere,
A Wiens
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2011; 638(1):96 - 109. · 1.21 Impact Factor
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K Wimmer,
T Kröll,
R Krücken,
V Bildstein,
R Gernhäuser,
B Bastin,
N Bree,
J Diriken,
P Van Duppen,
M Huyse, [......],
H B Jeppesen,
E Fiori,
G Georgiev,
G Schrieder,
S Das Gupta,
G Lo Bianco,
S Nardelli,
J Butterworth,
J Johansen,
K Riisager
[show abstract]
[hide abstract]
ABSTRACT: The "island of inversion" nucleus 32 Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32 Mg has been identified by the characteristic angular distribution of the protons of the Δ L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.
Physical Review Letters 12/2010; 105(25):252501. · 7.37 Impact Factor
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K. Wimmer,
T. Kröll,
R. Krücken,
V. Bildstein,
R. Gernhäuser,
B. Bastin,
N. Bree,
J. Diriken,
P. Van Duppen,
M. Huyse, [......],
H. B. Jeppesen,
E. Fiori,
G. Georgiev,
G. Schrieder,
S. Das Gupta,
G. Lo Bianco,
S. Nardelli,
J. Butterworth,
J. Johansen,
K. Riisager
[show abstract]
[hide abstract]
ABSTRACT: The Island of Inversion nucleus 32Mg has been studied by a (t,p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32Mg has been identified by the characteristic angular distribution of the protons of the DeltaL = 0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low gamma-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell model calculations. Comment: Phys. Rev. Lett. accepted for publication http://prl.aps.org
10/2010;
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R. Broda,
J. Wrzesiński,
A. Gadea,
N. Mărginean,
B. Fornal,
L. Corradi,
A. M. Stefanini,
W. Królas,
T. Pawłat,
B. Szpak, [......], R. Orlandi,
I. Pokrovskiy,
G. Pollarolo,
E. Sahin,
F. Scarlassara,
R. Silvestri,
S. Szilner,
C. A. Ur,
M. Trotta,
S. Zhu
[show abstract]
[hide abstract]
ABSTRACT: Excited states in the N=30 neutron-rich isotope 49K have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target γ-coincidence data from Gammasphere. The d3/2 proton-hole state is located 92 keV above the s1/2 ground state, and the proton-particle f7/2 state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2+ of two neutrons above the N=28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations.
Phys. Rev. C. 09/2010; 82(3).
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Proc.4th.Intern.Workshop Nuclear Fission and Fission-Product Spectroscopy; 01/2010
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D A Torres,
R Chapman,
K -M Spohr,
J F Smith,
V Kumar,
A Hodsdon,
X Liang, R Orlandi,
P Wady,
Z Wang, [......],
J J Valiente-Dobon,
F D Vedova,
M Axiotis,
T Martinez,
S J Freeman,
A G Smith,
G Jones,
N Thompson,
F Haas,
F Tatjana
Proc.4th.Intern.Workshop Nuclear Fission and Fission-Product Spectroscopy; 01/2010
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R Orlandi,
G de Angelis,
P G Bizzeti,
S Lunardi,
A Gadea,
A M Bizzeti-Sona,
A Bracco,
F Brandolini,
M P Carpenter,
C J Chiara, [......],
W Reviol,
E Sahin,
D G Sarantites,
D Seweryniak,
D Tonev,
C A Ur,
J J Valiente-Dobón,
R Wadsworth,
K T Wiedemann,
S Zhu
[show abstract]
[hide abstract]
ABSTRACT: Isospin symmetry breaking has been investigated in mass A=67 mirror nuclei through the experimental determination of the E1 strengths of analog electromagnetic transitions. Lifetimes of excited states have been measured in (67)Se and (67)As with the centroid shift method. Through the comparison of the B(E1) strengths of the mirror 9/2(+)-->7/2(-) transitions, the isovector and the isoscalar components of the electromagnetic transition amplitude were extracted. The presence of a large isoscalar component provides evidence for coherent contributions to isospin mixing, probably involving the isovector giant monopole resonance.
Physical Review Letters 07/2009; 103(5):052501. · 7.37 Impact Factor
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Phys.Rev. C. 01/2009; 80:024304.
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W Urban,
H Faust,
M Jentschel,
U Koster,
J Krempel,
Th. Materna,
P Mutti,
T Soldner,
J Genevey,
J A Pinston, [......],
J L Durell,
A G Smith,
B J Varley,
I Tsekhanovich,
J Jolie,
A Linnemann,
A Scherillo, R Orlandi,
J F Smith,
I Ahmad
Proc.13th Intern.Symposium on Capture Gamma-Ray Spectroscopy and Related Topics; 01/2009
