Study of the evaporative decay of excited 88Mo nuclei produced in almost mass-symmetric reactions at 6–12 MeV/amu

Medium-mass nuclei (A ≈ 100) are predicted to be candidates for shape phase transitions at high spin. Experimental studies on their decay are however rather scarce in the literature. In this work some results on the characteristics of charged species emitted by excited 88Mo compound nuclei produced in the reaction 48Ti +40 Ca are presented. Three bombarding energies were measured, 300, 450, 600 MeV, in order to better follow the evolution of the fusion-evaporation and fusion-fission channels. The experiment was carried out with a setup featuring an efficient detector for charged products coupled to a BaF2 scintillator array for hard photons. In this paper we only deal with charged products, neglecting the coincident gamma ray events elsewhere described. Experimental data have been compared with the prediction of the statistical model in its implementation in the Gemini++ code, well suited even for high spin systems

First results on the 32S+40,48Ca reactions at 17.7 AMeV studied with GARFIELD setup at LNL

The 32S+40,48Ca systems at 17 A MeV have been characterized both for fusion and for peripheral events thanks to the GARFIELD setup, which covers a wide angular range and has high granularity; moreover, isotopic identification for forward emitted ions up to Z around 15 is obtained. The main evidences reported here concern pre-equilibrium emission, which was put into evidence in fusion-evaporation events, and isospin diffusion observed studying the average N/Z of the Quasi-Projectile as a function of the target isospin

Time of flight identification with FAZIA

This contribution reports on the time of flight implementation in the FAZIA Si-Si-CsI(Tl) telescopes, focusing on the basic ideas of the method and on some preliminary results from recent experiments at LNS

Time of flight identification with FAZIA

FAZIA (Forward A and Z identification Array) is an array of threestage Si-Si-CsI(Tl) telescopes. It was designed to operate with beams in the 20– 100MeV/u energy range and it provides charge and mass discrimination over a wide range of nuclei and energies. In the perspective of FAZIA experiments at lower energies (e.g. to be realized at the new ISOL facilities SPES and/or Spiral2), and in general to lower the identification thresholds, the time of flight (ToF) information could be used. Usually, the time of flight can be obtained in two ways: either two detectors (start and stop) are used at a certain well-measured distance, or the start time mark is given by the accelerator RF signal. In order to work also in the absence of pulsed beam, we are studying and implementing a new approach that works for those events where at least one ejectile is properly discriminated in mass. The identified fragments can be used to extract the event start time mark from their energy and mass. This algorithm needs a perfect synchronisation among all the ADC clock signals and a precise tuning of all the possible clock skews. This contribution reports on such recent FAZIA activity, focusing on the basic ideas of the method and on some first results from recent experiments at LNS

Charged particle decay of hot and rotating 88^{88}Mo nuclei in fusion-evaporation reactions

A study of fusion-evaporation and (partly) fusion-fission channels for the $^{88}$Mo compound nucleus, produced at different excitation energies in the reaction $^{48}$Ti + $^{40}$Ca at 300, 450 and 600 MeV beam energies, is presented. Fusion-evaporation and fusion-fission cross sections have been extracted and compared with the existing systematics. Experimental data concerning light charged particles have been compared with the prediction of the statistical model in its implementation in the Gemini++ code, well suited even for high spin systems, in order to tune the main model parameters in a mass region not abundantly covered by exclusive experimental data. Multiplicities for light charged particles emitted in fusion evaporation events are also presented. Some discrepancies with respect to the prediction of the statistical model have been found for forward emitted $\alpha$-particles; they may be due both to pre-equilibrium emission and to reaction channels (such as Deep Inelastic Collisions, QuasiFission/QuasiFusion) different from the compound nucleus formation.Comment: 14 pages, 14 figure

Non-statistical decay and α\alpha-correlations in the 12^{12}C+12^{12}C fusion-evaporation reaction at 95 MeV

Multiple alpha coincidence and correlations are studied in the reaction $^{12}$C+$^{12}$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $\alpha$-particles are addressed, which are associated with anomalously high branching ratios with respect the predictions by Hauser-Feshbach calculations. Triple alpha emission appears kinematically compatible with a sequential emission from a highly excited Mg. The phase space distribution of $\alpha$-$\alpha$ coincidences suggests a correlated emission from a Mg compound, leaving an Oxygen residue excited above the threshold for neutron decay. These observations indicate a preferential $\alpha$ emission of $^{24}$Mg at excitation energies well above the threshold for $6-\alpha$ decay.Comment: 21 pages, 17 figures, second paper of a series of tw

Visiones y propuestas hacia un urbanismo emergente: un viaje por la ciudad viva 2006-2016.

1. Introducción – El Proyecto La ciudad viva surge en Andalucía (entre los años 2006 y 2008) como búsqueda de soluciones y herramienta de participación ante las numerosas problemáticas de la ciudad contemporánea, logrando ser el canal de reflexión y comunicación institución-ciudadanía del ámbito urbanístico más utilizado en nuestro país durante años. Su contenido, artículos, revistas y post generados desde su nacimiento hasta 2016 por más de 50 corresponsales repartidos por el todo el mundo, será la fuente documental de esta investigación, que defiende que sus múltiples voces y perspectivas -ordenadas, identificadas y relacionadas- descubren nuevas visiones y propuestas hacia un urbanismo emergente. Su reciente cierre (a principios de 2017) por la Institución que la creó y mi implicación con el proyecto como su Coordinadora, me obligan a rescatar de alguna forma el conocimiento contenido en la plataforma, verdadera inteligencia efectiva y colectiva, y transferirla al conjunto de actores que participamos en la vida y construcción de la ciudad. 2. Métodología – Tras organizar todo el contenido de la plataforma en regiones o ZONAS según temática, elaboro una serie de RELATOS literarios que las recorren referenciando sus numerosas fuentes multidisciplinares. El relato a través de la Zona 1 (Z1), Generación rotonda, la crisis de la habitabilidad contemporánea, son las memorias de una generación cuyo imaginario urbano ha asumido la homogenización que han sufrido las ciudades, las consecuencias de una transformación del paisaje social y cultural a causa de la burbuja inmobiliaria, los efectos de la “zonificación” y las nuevas tecnologías. Zona 2 (Z2), Flânerie es femenino, caminar con perspectiva de género, narra en primera persona cómo se usa y vive la calle y los espacios públicos de la ciudad desde la perspectiva de género y la experiencia de la maternidad. Zona 3 (Z3), Periferias, la intervención pública en barrios europeos de vivienda social 50-80, son diarios de viaje a los barrios analizados en La ciudad viva que incluyen reflexiones de sus corresponsales en estas ciudades y sus políticas públicas de rehabilitación urbana. Zona 4 (Z4), Derecho a techo, alternativas habitacionales; revisa las alternativas habitacionales citadas en La ciudad viva (principalmente latinoamericanas) e incluye varias conversaciones que giran en torno a ellas (Vanesa Valiño, Directora del Observatori Desc; Raúl Robert Oleas, miembro de la Cooperativa de viviendas Sostrecivic; Josefa Domínguez, arquitecta municipal Marinaleda o Raúl Valdés, miembro de la Cooperativa de Ayuda Mutua en Uruguay, entre otros). 3. Conclusiones – Del diagnóstico a la propuesta: Los relatos comienzan centrándose en referencias con carácter más analítico, y terminan en el ámbito propositivo. Las propuestas, identificadas, conectadas y relacionadas, concluyen en ITINERARIOS que, apoyados en una serie de diagramas, permiten identificar nuevos instrumentos “hacia un urbanismo emergente”. Finalmente, mostraré cómo aplico estos nuevos instrumentos derivados de La Ciudad Viva a la praxis, en el ámbito de Sevilla, lugar donde trabajo en planeamiento actualmente en el Plan Reaviva, 2015-2019, Premio Andalucía de Urbanismo) como laboratorio de ensayo urbano

Quasiprojectile breakup and isospin equilibration at Fermi energies: an indication of longer projectile-target contact times?

An investigation of the quasiprojectile breakup channel in semiperipheral and peripheral collisions of $^{58,64}$Ni+$^{58,64}$Ni at 32 and 52 MeV/nucleon is presented. Data have been acquired in the first experimental campaign of the INDRA-FAZIA apparatus in GANIL. The effect of isospin diffusion between projectile and target in the two asymmetric reactions has been highlighted by means of the isospin transport ratio technique, exploiting the neutron-to-proton ratio of the quasiprojectile reconstructed from the two breakup fragments. We found evidence that, for the same reaction centrality, a higher degree of relaxation of the initial isospin imbalance is achieved in the breakup channel with respect to the more populated binary output, possibly indicating the indirect selection of specific dynamical features. We have proposed an interpretation based on different average projectile-target contact times related to the two exit channels under investigation, with a longer interaction for the breakup channel. The time information has been extracted from AMD simulations of the studied systems coupled to GEMINI++: the model calculations support the hypothesis hereby presented

Pre-equilibrium emission and its possible relation to α-clustering in nuclei

The study of nuclear states built on clusters bound by valence neutrons in their molecular configurations is a field of large interest. Clustering becomes particularly important at the dripline, where weakly bound systems prevail. For light nuclei, at an excitation energy close to the particle separation value, there are experimental evidences of such structure effects, but this is still not the case for heavier nuclear systems. Several theoretical efforts have been done in the development of pre-formation alpha-clustering models, but there is still a lack of experimental data capable to give a direct feedback. The search of alpha-cluster evidences in medium-mass systems is therefore a new challenge which can give new hints in this field of research