Person: Benito García, Jaime
Universidad Complutense de Madrid
Faculty / Institute
Estructura de la Materia, Física Térmica y Electrónica
Now showing 1 - 10 of 18
PublicationDecay studies in the A similar to 225 Po-Fr region from the DESPEC campaign at GSI in 2021(Soc. Italiana Fisica, 2022-09) Benito García, Jaime; Fraile Prieto, Luis Mario; Llanos Expósito, Marcos; Murias, J. R.; otros, ...The HISPEC-DESPEC collaboration aims at investigating the struc-ture of exotic nuclei formed in fragmentation reactions with decay spectroscopymeasurements, as part of the FAIR Phase-0 campaign at GSI. This paper reportson first results of an experiment performed in spring 2021, with a focus on beta-decaystudies in the Po-Fr nuclei in the 220 < A <230 island of octupole deformationexploiting the DESPEC setup. Ion-beta correlations and fast-timing techniques arebeing employed, giving an insight into this difficult-to-reach region. PublicationReaction Channel selection techniques and gamma - gamma fast-timing spectroscopy using the v-Ball Spectrometer(Iop Publishing Ltd, 2020) Benito García, Jaime; Fraile Prieto, Luis Mario; Vedia Fernández, María Victoria; otros, ...The reaction of a pulsed O-18 beam on a self-supporting and gold-backed isotopically-enriched Dy-164 target of thickness 6.3 mg/cm(2) at separate primary beam energies of 71, 76 and 80 MeV was studied at the accelerator at the ALTO facility of the IPN Orsay. The gamma rays produced were detected using the newly-constructed v-Ball spectrometer which comprised of HPGe and LaBr3(Ce) detectors. This conference paper describes the methodology and effectiveness of multiplicity/sum-energy gating, for channel selection between fusion evaporation events and lower multiplicity/energy events from inelastic nuclear scattering and Coulomb excitation of the target, and from two-neutron transfer reactions to Dy-166. PublicationFirst lifetime investigations of N > 82 iodine isotopes: The quest for collectivity(Amer Physical Soc, 2021-07-19) Benito García, Jaime; Fraile Prieto, Luis Mario; Sánchez Tembleque, Víctor; Vedia Fernández, María Victoria; otros, ...We report on spectroscopic information and lifetime measurements in the neutron-rich I-135,I-137,I-139 isotopes. This is the first lifetime data on iodine isotopes beyond N = 82. Excited states were populated in fast neutron-induced fission of U-238 at the ALTO facility of IJCLab with the LICORNE neutron source and detected using the hybrid nu-ball spectrometer. The level schemes of the I-135,I-137,I-139 isotopes are revised in terms of excited states with up to maximum spin-parity of (33/2(+)), populated for the first time in fast neutron-induced fission. We provide first results on the lifetimes of the (9/2(1)(+)) and (13/2(1)(+)) states in I-137 and I-139, and the (17/2(1)(+)) state in 137I. In addition, we give upper lifetime limits for the (11/2(1)(+)) states in I135-139, the (15/2(1)(+)) state in I-137, the (17/2(1)(+)) state in I-139, and reexamine the (29/2(1)(+)) state in I-137. The isomeric data in I-13(5) are reinvestigated, such as the previously known (15/2(1)(+)) and (23/21) isomers with T-1/2 of 1.64(14) and 4.6(7) ns, respectively, as obtained in this work. The new spectroscopic information is compared to that from spontaneous or thermal-neutron induced fission and discussed in the context of large scale shell-model (LSSM) calculations for the region beyond Sn-132, indicating the behavior of collectivity for the three valence-proton iodine chain with N = 82, 84, 86. PublicationInvestigation of Low-lying States in 133Sn Populated in the β Decay of 133In Using Isomer-selective Laser Ionization(Jagiellonian Univ Press, 2018-03) Fraile Prieto, Luis Mario; Benito García, Jaime; Carmona Gallardo, Mariano; Martínez Pérez, Cristina; Sánchez-Tembleque Verbo, Victor; Udías Moinelo, José Manuel; Vedia Fernández, María Victoria; Villa Abaunza, Amaia; otros, ...Excited states in the neutron-rich isotope Sn-133 were studied via the beta decay of In-133. Isomer selective ionization using the ISOLDE RILIS enabled the beta decays of In-133(gs) (I-pi = 9/2(+)) and In-133m (I-pi = 1/2(-)) to be studied independently for the first time. A description of the experimental setup at the ISOLDE Decay Station is presented together with preliminary results from the experiment. Publicationbeta decay of In-133: gamma emission from neutron-unbound states in Sn-133(American Physical Society, 2019-02-05) Fraile Prieto, Luis Mario; Benito García, Jaime; Carmona, M.; Martínez Pérez, María Cristina; Sánchez-Tembleque Verbo, Victor; Udías Moinelo, José Manuel; Vedia Fernández, María Victoria; Villa Abaunza, Amaia; otros, ...Excited states in Sn-133 were investigated through the beta decay of In-133 at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for In-133, allowing us to study separately, and in detail, the beta-decay branch of In-133 J(pi)= (9/2(+)) ground state and its J(pi) = (1/2(-)) isomer.Thanks to the large spin difference of the two beta-decaying states of In-133, it is possible to investigate separately the lower and higher spin states in the daughter, Sn-133, and thus to probe independently different single-particle and single-hole levels. We report here new gamma transitions observed in the decay of In-133, including those assigned to the deexcitation of the neutron-unbound states. PublicationNew β-decaying state in Bi-214(Amer Physical Soc, 2021-11-02) Benito García, Jaime; Fraile Prieto, Luis Mario; Rodríguez Murias, Javier; Sánchez Tembleque, Víctor; Vedia Fernández, María VictoriaA new beta-decaying state in Bi-214 has been identified at the ISOLDE Decay Station at the CERN-ISOLDE facility. A preferred I-pi = (8(-)) assignment was suggested for this state based on the beta-decay feeding pattern to levels in Po-214 and shell-model calculations. The half-life of the I-pi = (8) state was deduced to be T-1/2 = 9.39(10) min. The deexcitation of the levels populated in Po-214 by the beta decay of this state was investigated via gamma-gamma coincidences and a number of new levels and transitions was identified. Shell-model calculations for excited states in Bi-214 and Po-214 were performed using two different effective interactions: the H208 and the modified Kuo-Herling particle interaction. Both calculations agree on the interpretation of the new beta-decaying state as an I-pi = 8 - isomer and allow for tentative assignment of shell-model states to several high-spin states in Po-214. PublicationThe experiments to determine the electron capture and beta-decay of B-8 into the highly excited states of Be-8(Iop Publishing Ltd, 2020) Benito García, Jaime; Fraile Prieto, Luis Mario; otros, ...The main goal of this work is to study the structure of the highest energy states in Be-8 populated following the beta(+)-decay and the electron capture (EC) of B-8. With this aim, two experiments were performed at ISOLDE-CERN in 2017 and 2018. The first experiment had the aim to resolve the 2(+) doublet at 16.6 and 16.9 MeV, in order to study their isospin mixing. The second experiment aimed to determine a value or give an experimental upper limit to the branching ratio of the exotic EC-p decay. In this paper, we present the experimental setups and we discuss the analysis and present the preliminary results obtained so far. Publicationγ-ray Spectroscopy of Se-85 produced in Th-232 fission(Jagellonian University, 2020) Benito García, Jaime; Fraile Prieto, Luis Mario; Sánchez Tembleque, Víctor; Vedia Fernández, María Victoria; otros, ...Excited states in the neutron-rich Se-85 nucleus have been studied using for the first time a fast neutron-induced fission of Th-232. The experiment was performed at the ALTO facility of the IPN Orsay. Coupling of the LICORNE directional neutron source with the nu-ball high-resolution gamma-ray spectrometer provided unique access to high-spin states in neutron-rich fission fragments from the Th-232(n,f) reaction. A preliminary level scheme of Se-85 was established by the analysis of prompt gamma-gamma-gamma coincidences. Identification of the all known yrast states in Se-85 is the first step towards studies of more neutron-rich Se isotopes. PublicationNature of seniority symmetry breaking in the semimagic nucleus Ru-94(Amer Physical Soc, 2022-03-25) Benito García, Jaime; Fraile Prieto, Luis Mario; Sánchez Tembleque, Víctor; otros, ...Direct lifetime measurements via gamma -gamma coincidences using a fast timing detector array consisting of LaBr3(Ce) scintillators has been applied to determine the lifetime of low-lying states in the semimagic (N = 50) nucleus Ru-94. The experiment was carried out as the first in a series of "FAIR-0" experiments with the DESPEC experimental setup at the Facility for Antiproton and Ion Research (FAIR). Excited states in Ru-94 were populated primarily via the beta-delayed proton emission of Pd-95 nuclei, produced in the projectile fragmentation of an 850 MeV/nucleon Xe-124 beam impinging on a 4 g/cm(2) Be-9 target. While the deduced E2 strength for the 2(+) -> 0(+) transition in the yrast cascade follows the expected behavior for conserved seniority symmetry, the intermediate 4(+) -> 2(+) transition exhibits a drastic enhancement of transition strength in comparison with pure-seniority model predictions as well as standard shell model predictions in the f pg proton hole space with respect to doubly magic Sn-100. The anomalous behavior is ascribed to a subtle interference between the wave function of the lowest seniority v = 2, I-pi = 4(+) state and that of a close-lying v = 4 state that exhibits partial dynamic symmetry. In addition, the observed strongly prohibitive 6(+) -> 4(+) transition can be attributed to the same mechanism but with a destructive interference. It is noted that such effects may provide stringent tests of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations. PublicationMulti-quasiparticle sub-nanosecond isomers in W-178(Elsevier Science BV, 2020-02-10) Benito García, Jaime; Fraile Prieto, Luis Mario; Sánchez-Tembleque Verbo, Victor; Vedia Fernández, María VictoriaWe report on the first measurement of the half-lives of K-pi = 11(-) and 12(+) four-quasiparticle states in the even-even nucleus W-178. The sub-nanosecond half-lives were measured by applying the centroid shift method to data taken with LaBr3(Ce) scintillator detectors of the NuBall array at the ALTO facility in Orsay, France. The half-lives of these states only became experimentally accessible by the combination of several experimental techniques - scintillator fast timing, isomer spectroscopy with a pulsed beam, and the event-by-event calorimetry information provided by the NuBall array. The measured half-lives are 476(44)ps and 275(65)ps for the I-pi = 11(-) and 12(+) states, respectively. The decay transitions include weakly hindered E1 and E2 branches directly to the ground-state band, bypassing the two-quasiparticle states. This is the first such observation for an E1 transition. The interpretation of the small hindrance hinges on mixing between the ground-state band and the t-band. (C) 2019 The Author(s). Published by Elsevier B.V.