AGATA Collaboration(Krzysiek, M. et al), & Gadea, A. (2016). Pygmy dipole resonance in Ce-140 via inelastic scattering of O-17. Phys. Rev. C, 93(4), 044330–8pp.
Abstract: The gamma decay from the high-lying states of Ce-140 excited via inelastic scattering of O-17 at a bombarding energy of 340 MeV was measured using the high-resolution AGATA-demonstrator array in coincidence with scattered ions detected in two segmented Delta E-E silicon detectors. Angular distributions of scattered ions and emitted gamma rays were measured, as well as their differential cross sections. The excitation of 1(-) states below the neutron separation energy is similar to the one obtained in reactions with the alpha isoscalar probe. The comparison between the experimental differential cross sections and the corresponding predictions using the distorted-wave Born approximation allowed us to extract the isoscalar component of identified 1(-) pygmy states. For this analysis the form factor obtained by folding microscopically calculated transition densities and optical potentials was used.
|
Testov, D. et al, & Gadea, A. (2019). The 4pi highly-efficient light-charged-particle detector EUCLIDES, installed at the GALILEO array for in-beam gamma-ray spectroscopy. Eur. Phys. J. A, 55(4), 47–8pp.
Abstract: .In a fusion-evaporation reaction, nuclei are produced by evaporating light-charged particles and neutrons from the compound nucleus. Typically, a nucleus of interest is produced as a result of a part of the total cross-section and, in order to guarantee a good channel discrimination, a particle detector, like the EUCLIDES 4 Si-ball array, is necessary. EUCLIDES has been quoted in more than a hundred publications resulting from many experiments performed in combination with the EUROBALL and GASP -ray spectrometers. The present paper reports on the upgraded version of EUCLIDES, that is presently coupled to the new GALILEO -ray spectrometer, installed at the Laboratori Nazionali di Legnaro, INFN. The design, characteristics and performance of the EUCLIDES array are presented and discussed.
|
Gosta G. et al., & Gadea, A. (2021). Probing isospin mixing with the giant dipole resonance in the Zn-60 compound nucleus. Phys. Rev. C, 103(4), L041302–6pp.
Abstract: An experimental study of the isospin mixing in the mass region A = 60 was made by measuring the gamma decay from the giant dipole resonance in the compound nuclei Zn-60 and Zn-62. These compound nuclei were populated at two different excitation energies, E* = 47 MeV and E* = 58 MeV using the fusion evaporation reactions S-32 + Si-28 at the bombarding energy of 86 and 110 MeV and S-32 + Si-30 at 75 and 98 MeV. In the experiment, performed at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare (INFN), the gamma rays were measured with the GALILEO detection system in which large-volume LaBr3(Ce) detectors were added to the HPGe detectors. The Coulomb spreading width was obtained from the comparison of the two reactions and then the isospin mixing parameter at zero temperature and the isospin-symmetry-breaking correction for beta decay were deduced. The present results were compared with data of the same type in other mass regions and with data from mass and beta-decay measurements and with theory. The present data allow us to deduce for the first time a consistent picture for mass dependence of isospin mixing and for the corresponding correction for the beta decay, supporting a reliable extension to the very interesting region of Sn-100.
|
AGATA Collaboration, Doncel, M., Recchia, F., Quintana, B., Gadea, A., & Farnea, E. (2010). Experimental test of the background rejection, through imaging capability, of a highly segmented AGATA germanium detector. Nucl. Instrum. Methods Phys. Res. A, 622(3), 614–618.
Abstract: The development of highly segmented germanium detectors as well as the algorithms to identify the position of the interaction within the crystal opens the possibility to locate the gamma-ray source using Compton imaging algorithms. While the Compton-suppression shield, coupled to the germanium detector in conventional arrays, works also as an active filter against the gamma rays originated outside the target, the new generation of position sensitive gamma-ray detector arrays has to fully rely on tracking capabilities for this purpose. In specific experimental conditions, as the ones foreseen at radioactive beam facilities, the ability to discriminate background radiation improves the sensitivity of the gamma spectrometer. In this work we present the results of a measurement performed at the Laboratori Nazionali di Legnaro (LNL) aiming the evaluation of the AGATA detector capabilities to discriminate the origin of the gamma rays on an event-by-event basis. It will be shown that, exploiting the Compton scattering formula, it is possible to track back gamma rays coming from different positions, assigning them to specific emitting locations. These imaging capabilities are quantified for a single crystal AGATA detector.
|
Broda, R. et al, & Gadea, A. (2010). Proton-hole states in the N=30 neutron-rich isotope K-49. Phys. Rev. C, 82(3), 034319–7pp.
Abstract: Excited states in the N = 30 neutron-rich isotope K-49 have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target gamma-coincidence data from Gammasphere. The d(3/2) proton-hole state is located 92 keV above the s(1/2) ground state, and the proton-particle f(7/2) 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.
|
