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Szilner, S. et al, & Gadea, A. (2013). Transfer Reaction Studies with Spectrometers. Acta Phys. Pol. B, 44(3), 417–426.
Abstract: The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers, coupled to large gamma arrays. The recent results of gamma-particle coincident measurements in Ca-40+Zr-96 and Ar-40+Pb-208 reactions demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynamics. The development of collectivity has been followed in odd Ar isotopes populated in the Ar-40+Pb-208 reaction through the excitation of the 11/2(-) states, understood as the coupling of single particle degrees of freedom to nuclear vibration quanta. Pair transfer modes is another important degree of freedom which is presently being studied with Prisma in inverse kinematics at energies far below the Coulomb barrier. First results from the Zr-96+Ca-40 reaction elucidate the role played by nucleon-nucleon correlation.
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Bottoni, S., Benzoni, G., Leoni, S., Montanari, D., Bracco, A., Vigezzi, E., et al. (2013). Reaction dynamics and gamma spectroscopy of Ne isotoopes by the heavy ion reaction Ne-22+Pb-208. Acta Phys. Pol. B, 44(3), 457–461.
Abstract: The heavy ion reaction Ne-22+Pb-208 at 128 MeV beam energy has been studied using the PRISMA-CLARA experimental setup at Legnaro National Laboratories. Aim of the experiment is the measurement of elastic, inelastic and one nucleon transfer cross sections. The data are presented in parallel with similar results for the unstable Ne-24 nucleus, using existing data from the reaction Ne-24+Pb-208 at 182 MeV (measured at SPIRAL with the VAMOS-EXOGAM setup). A comparison with angular distributions obtained by semiclassical and DWBA predictions for the quadrupole deformation parameter is also discussed. In particular, the DWBA analysis allowed to determine the beta(C)(2) charge deformation parameter both in Ne-22 and Ne-24.
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Doncel, M. et al, Gadea, A., & Huyuk, T. (2013). Lifetime measurements in neutron-rich Cu isotopes. Acta Phys. Pol. B, 44(3), 505–510.
Abstract: The nuclear structure of neutron-rich nuclei close to the double-magic nucleus Ni-78 has been investigated by measuring the lifetime of excited states. In this contribution, it will be presented the lifetime of the J(pi) = 7/2(-) excited state at 981 keV of the Cu-71 isotope, measured using the AGATA Demonstrator coupled to the PRISMA spectrometer and the Koln plunger setup. This is the first time this combined setup has been used for a lifetime measurement.
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Hadynska-Klek, K. et al, & Gadea, A. (2013). Towards the determination of superdeformation in Ca-42. Acta Phys. Pol. B, 44(3), 617–625.
Abstract: The Coulomb excitation experiment to study electromagnetic structure of low-lying states in Ca-42 with a focus on a possible superdeformation in this nucleus was performed at the Laboratori Nazionali di Legnaro in Italy. Preliminary values of the determined quadrupole deformation parameters for both the ground state band and the presumed superdeformed band are presented.
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Mijatovic, T., Szilner, S., Corradi, L., Montanari, D., Courtin, S., Fioretto, E., et al. (2015). Pairing Correlation Study in the 40Ar + 208Pb Multinucleon Transfer Reaction. Acta Phys. Pol. B, 46(3), 439–442.
Abstract: The Ar-40 + Pb-208 multinucleon transfer reaction has been studied at E-lab = 255 MeV with the large solid angle magnetic spectrometer PRISMA. Mass and charge yields, differential and total cross sections, total kinetic energy loss distributions of different channels were simultaneously measured. Angular distributions were measured in a wide angular range by matching different spectrometer angular settings. Absolute cross sections were obtained by careful evaluation of the spectrometer response function. These cross sections for different transfer channels allow the discussion of the role played by nucleon-nucleon correlations.
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AGATA Collaboration(Alexander, T. et al), & Gadea, A. (2015). Isomeric ratios in Hg-206. Acta Phys. Pol. B, 46(3), 601–605.
Abstract: Hg-206 was populated in the fragmentation of an E/A = 1 GeV Pb-208 beam at GSI. It was part of a campaign to study nuclei around Pb-208 via relativistic Coulomb excitation. The observation of the known isomeric states confirmed the identification of the fragmentation products. The isomeric decays were also used to prove that the correlations between beam identification detectors and the AGATA gamma-ray tracking array worked properly and that the tracking efficiency was independent of the time relative to the prompt flash.
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AGATA Collaboration(Krzysiek, M. et al), & Gadea, A. (2016). Gamma decay of the possible 1(-) two-phonon state in Ce-140 excited via inelastic scattering of O-17. Acta Phys. Pol. B, 47(3), 859–866.
Abstract: The gamma decay from the low-lying dipole states of Ce-140 excited via inelastic scattering of O-17 at 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 of the TRACE array. Particular attention is here given to the decay of the first 1(-) state at 3643 keV which is considered to be of two-phonon character. The gamma-gamma coincidence method was applied to select desired decay branch. No direct decay from this state was observed to 2(+) and 3(-) phonon states which would be the proof of the pure harmonic coupling. The comparison between experimentally obtained differential cross sections and analysis with distorted wave Born approximation (DWBA) allowed to conclude that the first 1(-) state has a different nature than higher-lying pygmy dipole states. This was possible using the form factor obtained by folding a microscopically calculated transition density.
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Montanari, D., Farnea, E., Leoni, S., Pollarolo, G., Corradi, L., Benzoni, G., et al. (2011). Response function of the magnetic spectrometer PRISMA. Eur. Phys. J. A, 47(1), 4–7pp.
Abstract: The response function of the magnetic spectrometer PRISMA is studied via a Monte Carlo simulation that employs a ray tracing code to determine the trajectories of individual rays through the electromagnetic fields. The calculated response is tested on angular and energy distributions provided by theoretical calculations for the Ca-48 + Ni-64 multinucleon transfer reaction and applied to the corresponding experimental data.
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Bizzeti, P. G., Sona, P., Michelagnoli, C., Melon, B., Bazzacco, D., Farnea, E., et al. (2015). Analyzing power of AGATA triple clusters for gamma-ray linear polarization. Eur. Phys. J. A, 51(4), 49–11pp.
Abstract: We have investigated the ability of AGATA triple clusters to measure the linear polarization of gamma rays, exploiting the azimuthal-angle dependence of the Compton scattering differential cross section. To this aim, partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of Pd-104 and Pd-108, which decay to the ground state by emission of gamma rays of 555.8 keV and 433.9 keV, respectively. Pulse-shape analysis and gamma-ray tracking techniques have been used to determine the position and time sequence of the interaction points inside the germanium crystals. Anisotropies in the detection efficiency have been taken into account using 661.6 keV gammas from a Cs-137 radioactive source. We obtain an average analyzing power of 0.451(34) at 433.9 keV and 0.484(24) at 555.8 keV.
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Huyuk, T. et al, Gadea, A., Aliaga-Varea, R. J., & Domingo-Pardo, C. (2016). Conceptual design of the early implementation of the NEutron Detector Array (NEDA) with AGATA. Eur. Phys. J. A, 52(3), 55–8pp.
Abstract: The NEutron Detector Array (NEDA) project aims at the construction of a new high-efficiency compact neutron detector array to be coupled with large gamma-ray arrays such as AGATA. The application of NEDA ranges from its use as selective neutron multiplicity filter for fusion-evaporation reaction to a large solid angle neutron tagging device. In the present work, possible configurations for the NEDA coupled with the Neutron Wall for the early implementation with AGATA has been simulated, using Monte Carlo techniques, in order to evaluate their performance figures. The goal of this early NEDA implementation is to improve, with respect to previous instruments, efficiency and capability to select multiplicity for fusion-evaporation reaction channels in which 1, 2 or 3 neutrons are emitted. Each NEDA detector unit has the shape of a regular hexagonal prism with a volume of about 3.23 l and it is filled with the EJ301 liquid scintillator, that presents good neutron-gamma discrimination properties. The simulations have been performed using a fusion-evaporation event generator that has been validated with a set of experimental data obtained in the Ni-58 + Fe-56 reaction measured with the Neutron Wall detector array.
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