Light-particle emission from the fissioning nuclei 126Ba, 188Pt and (266,272,278)/110: theoretical predictions and experimental results

We present a comparison of our model treating fission dynamics in conjunction with light-particle (n, p, alpha) evaporation with the available experimental data for the nuclei 126Ba, 188Pt and three isotopes of the element Z=110. The dynamics of the symmetric fission process is described through the solution of a classical Langevin equation for a single collective variable characterizing the nuclear deformation along the fission path. A microscopic approach is used to evaluate the emission rates for pre-fission light particles. Entrance-channel effects are taken into account by generating an initial spin distribution of the compound nucleus formed by the fusion of two deformed nuclei with different relative orientations

O caminho do dzogchen na tradição bön: uma análise histórica e filosófica

This study aims from a hermeneutic point of analysis, a comprehensive aproach about the development of the Bön religion, its interaction with Buddhism through Tibet, and from this meeting, its historical and philosophical developments, centered on the practice of Dzogchen as a possible bridge between Bön and the Nyingma tradition. A survey on the first studies focusing on the Bön religion in the Western academies shows a particular importance, in order to understand the nature of the first historical and philosophical conceptions regarding Bön. The classification of the historical development of Bön in three phases aims at a more pedagogical approach to the understanding of its history. A study of the first centuries from the spreading of Buddhism to Tibet, between VIII and XI centuries A.D., is thought to be particularly important for the understanding of the characteristics that Buddhism would acquire in Tibetan soil, due to the particular nature in which this process was taken. A synthesis of the teachings of the philosophical schools of Mahayana, together with a series of tantric practices, brought from India and Central Asia formed the basis of Tibetan Buddhism. During the first two centuries of the transmission of Buddhism in Tibet, two great masters had a decisive importance in this process, the monk Shantaraksita would be responsible for philosophical synthesis that would be adopted during this period as the basis for the monastic teachings and ordination of monks in Tibet. Next to this philosophical basis, tantric practices were brought, developed and disseminated by the master Padmasambhava, which formed the religious and philosophical basis of Tibetan Buddhism. During this process, the practice of Dzogchen appears as a bridge between the two traditions, Nyingma and Bön, and through a study of its central elements as the mind-base concepts, rigpa and nature-of-mind, we seek to understand the possible similarities and differences between the two traditions.O presente estudo objetiva uma análise de natureza hermenêutica acerca do desenvolvimento da religião Bön, sua interação com o Budismo através do Tibete, e, a partir deste encontro, seus desdobramentos históricos e filosóficos, centrado na prática do Dzogchen como uma possível ponte entre o Bön e a escola Nyingma. Um levantamento acerca dos primeiros estudos tendo como foco as religiões Bön dentro das academias ocidentais se mostra importante, para podermos compreender a natureza das primeiras concepções históricas e filosóficas à respeito do Bön. A classificação do desenvolvimento histórico do Bön em três fases visa uma abordagem mais pedagógica para a compreensão do mesmo. Um estudo dos primeiros séculos da chegada do Budismo ao Tibete, entre os séculos VIII e XI d.C., se mostra particularmente importante para a compreensão das características próprias que o Budismo iria adquirir em solo tibetano, devido à particular natureza na qual se deu este processo. Uma síntese entre os ensinamentos das escolas filosóficas do Mahayana, aliada à uma série de práticas tântricas, trazidas da Índia e da Ásia Central formaram a base do Budismo tibetano. Durante os dois primeiros séculos da transmissão do Budismo no Tibete, dois grandes mestres tiveram importância decisiva no processo, o monge Shantaraksita seria o responsável pela síntese filosófica que seria adotada durante este período como a base para os ensinamentos monásticos e ordenação dos monges no Tibete. Junto à esta base filosófica, as práticas tântricas trazidas, desenvolvidas e difundidas pelo mestre Padmasambhava formam a base religiosa, e filosófica do Budismo no Tibete. Durante este processo, a prática do Dzogchen aparece como uma ponte entre as duas tradições, Nyingma e Bön, e através de um estudo de seus elementos centrais como os conceitos de mente-base, rigpa e natureza-da-mente, buscamos compreender as possíveis semelhanças e diferenças entre ambas as tradições

Halo structure of 14Be

The first kinematically complete breakup reaction study of 14Be was carried out. The two-neutron removal cross sections, neutron angular distributions, and invariant mass spectra for reactions on C and Pb were measured and the electromagnetic component of the dissociation (EMD) contributions deduced. Comparison with model calculations suggest that the configuration of the halo neutrons contains a large v(2s 1/2 )2 admixture.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Two-neutron interferometry as a probe of the nuclear halo

The technique of intensity interferometry is proposed as a probe of the spatial configuration of two-Neutron haloes. After exploring the sensitivity of interferometry to the n-N configuration, it is demonstrated that the application of the standard method for constructing the correlation function is not valid for halo neutrons. A new iterative method is presented and applied to measurements of the dissociation of 6He, 11Li and 14Be. The correlation functions for these systems have thus been extracted for the first time and the corresponding root-Mean-Square n-n separations estimated. The results are in agreement with the predictions of available three-Body models. (C) 2000 Published by Elsevier Science B.V.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Fission and quasifission modes in heavy-ion-induced reactions leading to the formation of Hs*

Mass and energy distributions of binary reaction products obtained in the reactions Ne22+Cf249,Mg26+Cm248, S36+U238, and Fe58+Pb208 have been measured. All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction Mg26+Cm248, is observed. In the reaction S36+U238, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the Fe58+Pb208 reaction the quasifission process dominates at all measured energies. © 2011 American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Fission and quasifission modes in heavy-ion-induced reactions leading to the formation of Hs*

Mass and energy distributions of binary reaction products obtained in the reactions 22Ne+249Cf,26Mg+248Cm, 36S+238U, and 58Fe+208Pb have been measured. All reactions lead to Hs isotopes. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction 26Mg+248Cm, is observed. In the reaction 36S+238U, leading to the formation of a similar compound nucleus, the main part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier fusion-fission is the main process leading to the formation of symmetric fragments for both reactions with Mg and S ions. In the case of the 58Fe+208Pb reaction the quasifission process dominates at all measured energies

Probing fission time scales with neutrons and GDR gamma rays

The time scales for nuclear fission have been explored using both pre- and postfission neutrons and GDR gamma rays. Four systems were investigated: 133-MeV /sup 16/O+/sup 176/Yb and /sup 208/Pb and 104-MeV /sup 4/He+/sup 188/Os and /sup 209/Bi. Fission fragments were measured in coincidence with PPACs. The neutrons were detected using eight detectors from the DEMON array, while gamma rays were measured using the US BaF/sub 2/ array. The pre- and postfission gamma rays were determined using moving source fits parallel and perpendicular to the fission fragment emission directions. The time scales for fission for the neutrons were determined using the neutron clock technique. The gamma-ray data were fitted using a statistical model calculation based on the code CASCADE. The results of the fits from both data types were used to extract nuclear friction coefficients, gamma , and fission time scales. The gamma values ranged from 7 to 20, while the fission times were (31-105)*10/sup -21/s