| 1. |
- Lieder, R M, et al.
(författare)
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Gamma-ray tracking arrays
- 2001
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Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS, VOL 46. ; , s. 399-407
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Konferensbidrag (refereegranskat)abstract
- The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve "gamma -ray tracking front-end on digital signal processing techniques, which allows to extract energy, timing and spatial information on the interactions of a gamma -ray in the Ge detector by pulse shape analysis of its signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.
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| 2. |
- Lieder, R. M., et al.
(författare)
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Development of magnetic rotation in light Gd nuclei; study of Gd-142
- 2002
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 13:3, s. 297-305
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in Gd-142 have been populated by means of the Ru-99(Ti-48, 2p3n) reaction at 2-10 MeV and investigated with the gamma-spectrometer EUROBALL III and the charged-particle detector array ISIS. The features of four dipole bands have been determined and compared with tilted-axis cranking model calculations indicating that they are magnetic rotational bands. A transition from regular to irregular bands has been found approaching N = 82 demonstrating that this is a general phenomenon in nuclei near a double-shell closure.
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| 3. |
- Lieder, R. M., et al.
(författare)
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From highly to superdeformed shapes : study of Gd-143
- 2000
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 671:04-jan, s. 52-70
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Tidskriftsartikel (refereegranskat)abstract
- A superdeformed band has been discovered in Gd-143 consisting Of 15 transitions. It does not show the band crossing observed in the neighbouring heavier Gd isotopes and it is degenerate with the superdeformed band in Eu-143. In contrast to other degenerate bands at superdeformed shape, the configurations of the bands are quite different here. They result from the exchange of a nu 6(4) with a pi[404]9/2 configuration. In addition, a collective band has been observed which adopts a well-deformed triaxial shape at high spins according to calculations. The transition from highly to superdeformed shapes proceeds via triaxial shapes.
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| 4. |
- Lieder, R. M., et al.
(författare)
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Investigations of the level scheme of Gd-144 and lifetimes in the quadrupole bands
- 2004
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 21:1, s. 37-55
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Tidskriftsartikel (refereegranskat)abstract
- For a level scheme investigation of Gd-144 an experiment with the gamma-spectrometer EUROBALL III has been carried out and lifetimes have been measured with the gamma-spectrometer GASP using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the Mo-100(Ti-48,4n) reaction at 215 MeV and the Cd-114(S-36,6n) reaction at E = 182 MeV, respectively. The known quadrupole band has been modified and a new one has been established. Reduced E2 transition probabilities B(E2) were determined for seven members of these quadrupole bands. They show values between approximate to60 and 130 W.u. and this considerable enhancement gives evidence for a significant nuclear deformation. A (pih(11/2))(2) circle times (vh(11/2))(-2) configuration may be assigned to one of the quadrupole bands according to total Routhian surface calculations. The spin dependence of the B(E2) values has been explained by IBM calculations involving high-spin quasiparticle excitations.
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| 5. |
- Algora, A., et al.
(författare)
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Pronounced Shape Change Induced by Quasiparticle Alignment
- 2000
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 61:3
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Tidskriftsartikel (refereegranskat)abstract
- Mean lifetimes of high-spin states of Kr-74 have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the Ca-40(Ca-40, alpha 2p) reaction at a beam energy of 160 MeV with the GASP gamma-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.
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| 6. |
- Simancas, J.F., et al.
(författare)
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The seismic crustal structure of the Ossa-Morena Zone and its geological interpretation
- 2004
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Ingår i: Journal of Iberian Geology. - 1698-6180 .- 1886-7995. ; 30, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- The IBERSEIS deep reflection seismic experiment has provided a crustal image of the Variscan orogen of southwest Iberia. A brief presentation of the entire seismic profile is given, and then the Ossa-Morena Zone (OMZ) and its boundaries are considered. The crust of the OMZ is shown to be divided into an upper crust, characterized by dominantly NE-dipping reflectivity, and a poorly reflective lower crust. The reflectivity of the upper crust has good correlation with the geological cross-section constructed from surface mapping. In the seismic image, the upper crustal geological structures are seen to merge in the middle crust. Nevertheless, the OMZ middle crust is not a mere detachment level, as it shows very unusual features: it appears as a band of strong reflectivity and irregular thickness (the Iberian Reflective Body, IRB) that we interpret as a great sill-like intrusion of basic rocks. The boundaries of the OMZ are considered sutures of the orogen, and their geometrical features, as deduced from geological mapping and the seismic image, are in accordance with the transpressional character of the Variscan collision recorded in SW Iberia. The present Moho is flat, obliterating the root of the orogen.
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| 7. |
- Spolaore, P., et al.
(författare)
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Identification and study of the very neutron deficient nuclide I-111 : search for octupole correlations in the region of N approximate to Z approximate to 56
- 2001
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 682, s. 387C-393C
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the neutron-deficient nuclide I-111 have been populated with the fusion reaction Ni-58 + Ni-58 at a beam energy of 210 MeV, in an experiment performed at the Tandem Accelerator of the Laboratori Nazionali di Legnaro. The gamma spectrometer GASP was used in time coincidence with the ISIS Si-ball and the CAMEL recoil mass spectrometer for the positive identification of the nuclide. Gamma transitions and structure details previously attributed to I-111 by Other authors are only partially confirmed. The obtained level scheme includes new rotational bands and a new low lying structure which suggests the presence of octupole correlations at predicted rotational frequency values.
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| 8. |
- Weiszflog, M., et al.
(författare)
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High-spin Spectroscopy of 63Ga and 65Ga
- 2001
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 11, s. 25-38
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the nuclei Ga-63 and Ga-65 were studied following the reaction S-32 + Ca-40 at a reaction energy of 125 MeV and using the GASP gamma -ray spectrometer in combination with the ISIS charged-particle detector system. In addition to low-lying negative-parity states with single-particle character, rotational-like cascades built on the 9/2(+) and 19/2(-) states have been observed in both nuclei. Sidebands with negative parity in Ga-63 and positive parity in Ga-65 could be established. The experimental results are compared with Total Routhian Surface calculations which describe the nuclei as moderately deformed (beta (2) approximate to 0.25) and gamma soft at low rotational frequencies. The highest experimentally observed positive-parity state in Ga-65 (41/2(+)) is in good agreement with the calculated crossing of the collective band with a non-collective one terminating at this spin.
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| 9. |
- Formicola, A, et al.
(författare)
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Astrophysical S-factor of 14N(p,γ)15O
- 2004
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 591:1-2, s. 61-68
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Tidskriftsartikel (refereegranskat)abstract
- We report on a new measurement of the 14N(p,γ) 15O capture cross section at Ep=140 to 400 keV using the 400 kV LUNA accelerator facility at the Laboratori Nazionali del Gran Sasso (LNGS). The uncertainties have been reduced with respect to previous measurements and their analysis. We have analyzed the data using the R-matrix method and we find that the ground state transition accounts for about 15% of the total S-factor. The main contribution to the S-factor is given by the transition to the 6.79 MeV state. We find a total S(0)=1.7±0.2 keVb, in agreement with recent extrapolations. The result has important consequences for the solar neutrino spectrum as well as for the age of globular clusters. © 2004 Elsevier B.V. All rights reserved.
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| 10. |
- Imbriani, G., et al.
(författare)
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The bottleneck of CNO burning and the age of Globular Clusters
- 2004
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 420:2, s. 625-629
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Tidskriftsartikel (refereegranskat)abstract
- The transition between the Main Sequence and the Red Giant Branch in low mass stars is powered by the onset of CNO burning, whose bottleneck is 14N(p, γ) 15O. The LUNA collaboration has recently improved the low energy measurements of the cross section of this key reaction. We analyse the impact of the revised reaction rate on the estimate of the Globular Cluster ages, as derived from the turnoff luminosity. We found that the age of the oldest Globular Clusters should be increased by about 0.7-1 Gyr with respect to the current estimates.
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