Effects of Nuclear Structure on Quasi-fission

The quasi-fission mechanism hinders fusion of heavy systems because of a mass flow between the reactants, leading to a re-separation of more symmetric fragments in the exit channel. A good understanding of the competition between fusion and quasi-fission mechanisms is expected to be of great help to optimize the formation and study of heavy and superheavy nuclei. Quantum microscopic models, such as the time-dependent Hartree-Fock approach, allow for a treatment of all degrees of freedom associated to the dynamics of each nucleon. This provides a description of the complex reaction mechanisms, such as quasi-fission, with no parameter adjusted on reaction mechanisms. In particular, the role of the deformation and orientation of a heavy target, as well as the entrance channel magicity and isospin are investigated with theoretical and experimental approaches.Comment: Invited talk to NSRT12. To be published in Eur. Phys. J. Web of Con

Neighbouring Link Travel Time Inference Method Using Artificial Neural Network

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.This paper presents a method for modelling relationship between road segments using feed forward back-propagation neural networks. Unlike most previous papers that focus on travel time estimation of a road based on its traffic information, we proposed the Neighbouring Link Inference Method (NLIM) that can infer travel time of a road segment (link) from travel time its neighbouring segments. It is valuable for links which do not have recent traffic information. The proposed method learns the relationship between travel time of a link and traffic parameters of its nearby links based on sparse historical travel time data. A travel time data outlier detection based on Gaussian mixture model is also proposed in order to reduce the noise of data before they are applied to build NLIM. Results show that the proposed method is capable of estimating the travel time on all traffic link categories. 75% of models can produce travel time data with mean absolute percentage error less than 22%. The proposed method performs better on major than minor links. Performance of the proposed method always dominates performance of traditional methods such as statistic-based and linear least square estimate methods

Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements

Measurements of mass-angle distributions (MADs) for Cr + W reactions, providing a wide range in the neutron-to-proton ratio of the compound system, (N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be determined in a model-independent way. Previous experimental and theoretical studies had produced conflicting conclusions. The experimental MADs reveal an increase in contact time and mass evolution of the quasifission fragments with increasing (N/Z)CN, which is indicative of an increase in the fusion probability. The experimental results are in agreement with microscopic time-dependent Hartree-Fock calculations of the quasifission process. The experimental and theoretical results favor the use of the most neutron-rich projectiles and targets for the production of heavy and superheavy nuclei.Comment: Accepted to PRC as a Rapid Communicatio

Complete Fusion Enhancement and Suppression of Weakly Bound Nuclei at Near Barrier Energies

We consider the influence of breakup channels on the complete fusion of weakly bound systems in terms of dynamic polarization potentials. It is argued that the enhancement of the cross section at sub-barrier energies may be consistent with recent experimental observations that nucleon transfer, often leading to breakup, is dominant compared to direct breakup. The main trends of the experimental complete fusion cross section for $^{6,7}$Li + $^{209}$Bi are analyzed in the framework of the DPP approach.Comment: 12 pages, 2 figure

Assessing decentralised policy implementation in Vietnam : The case of land recovery and resettlement in the Vung Ang Economic Zone

From 2006 plans were implemented to create a deep-sea water port linked to an Economic Zone in the coastal Province of Ha Tinh, located in north central Vietnam. The multi-purpose Zone entitled ‘Vung Ang’, was to attract foreign investors, while the port would provide a link to nearby Laos and Thailand. The project obviously had large implications for the administrations at various levels of governance from Hanoi to the coastal communes and villages, but even more serious impacts on the people living in the affected areas. A large area of about 23,000 hectares was to be cleared, affecting the people of 9 communes, in some of which all inhabitants had to leave their houses and homesteads, to be relocated to completely new settlements about 10 miles inland. These tightly knit communities were not too happy with the prospect to leave their homes and land, the burial places of their ancestors, and the long term comforts of community support networks. While initial decision making process started at the highest levels of Vietnam Governance, the implementation of port and industrial park construction and the related relocation policy was delegated to Ha Tinh province, which is consistent with current decentralisation policies in Vietnam. Actual implementation was carried out by the affected District and Commune level officials – with support from the Communist Party led Mass Organisations – who were in charge of the planning and implementation of the relocation process. This entailed a complex and sensitive series of steps to inform affected households, prepare relocation areas and allocate compensation and alternative housing. This paper describes the implementation dynamics of relocation by depicting and assessing the roles of all stakeholders involved, including the impacts - for better or for worse – of the relocated households. It brings out the way local authorities dealt with affected people, including efforts linked to the ideal of grass-roots democracy. Key areas of contestation are uncovered, such as inadequate infrastructure and low compensation rates. The paper has a second objective to assess the degree to which decentralisation in Vietnam has been actually implemented, and how this affects policy making processes such as the Vung Ang port/industrial zone project. The paper concludes that the relocation policy was implemented in a fairly efficient and harmonious way – with a very intensive engagement of the entire provincial administrative machinery, but that it is too early to assess the livelihood opportunities of the relocated households

Breakup locations: Intertwining effects of nuclear structure and reaction dynamics

Studies at the Australian National University aim to distinguish breakup of the projectile like-nucleus that occurs when approaching the target from that when receding from the target. Helped by breakup simulations, observables have been found that are sensitive to the breakup location, and thus to the mean-lives of unbound states; sensitivity to even sub-zeptosecond lifetime is found. These results provide insights to understand the reaction dynamics of weakly bound nuclei at near barrier energies.The authors acknowledge operations support for the ANU Heavy Ion Accelerator Facility from NCRIS. Financial support from ARC grants DP130101569, DE140100784, and FL110100098 is acknowledged