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AGATA Collaboration(Soderstrom, P. A. et al), & Gadea, A. (2012). High-spin structure in K-40. Phys. Rev. C, 86(5), 054320–9pp.
Abstract: High-spin states of K-40 have been populated in the fusion-evaporation reaction C-12(Si-30,np)K-40 and studied by means of gamma-ray spectroscopy techniques using one triple-cluster detector of the Advanced Gamma Tracking Array at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. Several states with excitation energy up to 8 MeV and spin up to 10(-) have been discovered. These states are discussed in terms of J = 3 and T = 0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum.
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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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Capra, S. et al, & Gadea, A. (2022). GALTRACE: A highly segmented silicon detector array for charged particle spectroscopy and discrimination. Nuovo Cim. C, 45(5), 98–4pp.
Abstract: GALTRACE is an array of segmented silicon detectors specifically built to work as an ancillary of the GALILEO gamma-ray spectrometer at Legnaro National Laboratory of INFN. GALTRACE consists of four telescopic Delta E-Edetectors which allow discriminating light charged particles also via pulse-shape analysis techniques. The good angular and energy resolutions, together with particle discrimination capabilities, make GALTRACE suitable for experiments where coincidences with specific emitted particles allow for the selection of reaction channels with very low cross section. The first in-beam experiment is reported here, aiming at identifying a narrow resonance, near-proton-threshold state in B-11, currently under discussion.
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Goasduff, A. et al, & Gadea, A. (2021). The GALILEO gamma-ray array at the Legnaro National Laboratories. Nucl. Instrum. Methods Phys. Res. A, 1015, 165753–15pp.
Abstract: GALILEO, a new 4 pi high-resolution gamma-detection array, based on HPGe detectors, has been developed and installed at the Legnaro National Laboratories. The GALILEO array greatly benefits from a fully-digital readout chain, customized DAQ, and a variety of complementary detectors to improve the resolving power by the detection of particles, ions or high-energy gamma-ray transitions. In this work, a full description of the array, including electronics and DAQ, is presented together with its complementary instrumentation.
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Jungclaus, A. et al, Gadea, A., & Montaner-Piza, A. (2016). First observation of gamma rays emitted from excited states south-east of Sn-132: The pi g(9/2)(-1) circle times nu f(7/2) multiplet of In-132(83). Phys. Rev. C, 93(4), 041301–6pp.
Abstract: For the first time, the gamma decay of excited states has been observed in a nucleus situated in the quadrant south-east of doubly magic Sn-132, a region in which experimental information so far is limited to ground-state properties. Six gamma rays with energies of 50, 86, 103, 227, 357, and 602 keV were observed following the beta-delayed neutron emission from Cd-133(85), populated in the projectile fission of a U-238 beam at the Radioactive Isotope Beam Factory at RIKEN within the EURICA project. The new experimental information is compared to the results of a modern realistic shell-model calculation, the first one in this region very far from stability, focusing in particular on the pi 0g(9/2)(-1) circle times nu 1f(7/2) particle-hole multiplet in In-132(83). In addition, theoretical estimates based on a scaling of the two-body matrix elements for the pi h(11/2)(-1) circle times nu g(9/2) analog multiplet in Tl-208(127), one major proton and one major neutron shell above, are presented.
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Aydin, S. et al, Gadea, A., & Huyuk, T. (2012). High-spin structure and intruder excitations in Cl-36. Phys. Rev. C, 86(2), 024320–13pp.
Abstract: Excited states up to J(pi) = 11(-) at 10 296 keV and J(pi) = 10(+) at 10 707 keV have been populated in the odd-odd Cl-36 nucleus using the Mg-24(N-14,2p) fusion-evaporation reaction at E-lab = 31 MeV. Twenty new states and 62 new gamma transitions have been identified by employing gamma-gamma and gamma-gamma-gamma coincidences. Lifetimes have been investigated by the Doppler shift attenuation method. The experimental data have been compared with the results of large-scale shell-model calculations performed using different effective interactions and model spaces allowing particle-hole excitations across the N = Z = 20 shell gap.
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de Angelis, G. et al, & Gadea, A. (2012). Shape isomerism and shape coexistence effects on the Coulomb energy differences in the N = Z nucleus As-66 and neighboring T=1 multiplets. Phys. Rev. C, 85(3), 034320–7pp.
Abstract: Excited states of the N = Z = 33 nucleus As-66 have been populated in a fusion-evaporation reaction and studied using gamma-ray spectroscopic techniques. Special emphasis was put into the search for candidates for the T = 1 states. A new 3(+) isomer has been observed with a lifetime of 1.1(3) ns. This is believed to be the predicted oblate shape isomer. The excited levels are discussed in terms of the shell model and of the complex excited Vampir approaches. Coulomb energy differences are determined from the comparison of the T = 1 states with their analog partners. The unusual behavior of the Coulomb energy differences in the A = 70 mass region is explained through different shape components (oblate and prolate) within the members of the same isospin multiplets. This breaking of the isospin symmetry is attributed to the correlations induced by the Coulomb interaction.
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Krolas, W. et al, & Gadea, A. (2011). Coupling of the proton-hole and neutron-particle states in the neutron-rich (48)K isotope. Phys. Rev. C, 84(6), 064301–8pp.
Abstract: Excited states in the Z = 19, N = 29 neutron-rich (48)K 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 s(1/2) or d(3/2) orbital coupled to a p(3/2) neutron. A new 7.1(5)-ns, 5(+) isomer, the analog of the 7/2 isomer in (47)K, was identified. Based on the observed gamma-decay pattern of the isomer a revised spin-parity assignment of 1(-) is proposed for the ground state of (48)K.
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AGATA Collaboration(Liu, X. et al), Gadea, A., Jurado, M., Domingo-Pardo, C., Huyuk, T., & Perez-Vidal, R. M. (2022). Evidence for spherical-oblate shape coexistence in Tc-87. Phys. Rev. C, 106(3), 034304–6pp.
Abstract: Excited states in the neutron-deficient nucleus Tc-87 have been studied via the fusion-evaporation reaction 54Fe(36Ar, 2n1p) Tc-87 at 115 MeV beam energy. The AGATA gamma-ray spectrometer coupled to the DIAMANT, NEDA, and Neutron Wall detector arrays for light-particle detection was used to measure the prompt coincidence of gamma rays and light particles. Six transitions from the deexcitation of excited states belonging to a new band in Tc-87 were identified by comparing gamma-ray intensities in the spectra gated under different reaction channel selection conditions. The constructed level structure was compared with the shell model and total Routhian surface calculations. The results indicate that the new band structure in 87Tc is built on a spherical configuration, which is different from that assigned to the previously identified oblate yrast rotational band.
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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.
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