Roger T.,Grand Accelerateur National dIons Lourds |
Kirsebom O.S.,TRIUMF Laboratory Particle and Nuclear Physics |
Fynbo H.O.U.,University of Aarhus |
Raabe R.,Catholic University of Leuven
Physical Review Letters | Year: 2012
A Reply to the Comment by S. J. Freedman et al.. © 2012 American Physical Society. Source
Hupin G.,Grand Accelerateur National dIons Lourds |
Lacroix D.,Grand Accelerateur National dIons Lourds
Physical Review C - Nuclear Physics | Year: 2010
In nuclear fusion and fission, fluctuation and dissipation arise because of the coupling of collective degrees of freedom with internal excitations. Close to the barrier, quantum, statistical, and non-Markovian effects are expected to be important. In this work, a new approach based on quantum Monte Carlo addressing this problem is presented. The exact dynamics of a system coupled to an environment is replaced by a set of stochastic evolutions of the system density. The quantum Monte Carlo method is applied to systems with quadratic potentials. In all ranges of temperature and coupling, the stochastic method matches the exact evolution, showing that non-Markovian effects can be simulated accurately. A comparison with other theories, such as Nakajima-Zwanzig or time-convolutionless, shows that only the latter can be competitive if the expansion in terms of coupling constant is made at least to fourth order. A systematic study of the inverted parabola case is made at different temperatures and coupling constants. The asymptotic passing probability is estimated by different approaches including the Markovian limit. Large differences with an exact result are seen in the latter case or when only second order in the coupling strength is considered, as is generally assumed in nuclear transport models. In contrast, if fourth order in the coupling or quantum Monte Carlo method is used, a perfect agreement is obtained. © 2010 The American Physical Society. Source
Agency: Cordis | Branch: FP7 | Program: MC-ITN | Phase: FP7-PEOPLE-2011-ITN | Award Amount: 4.58M | Year: 2011
The advancement of science and engineering in the past decades is inherently linked to the development of lasers. Ever higher laser beam powers, brightness and shorter pulse lengths have helped establish them as an invaluable tool for both a wide range of industry and medical applications, such as for example material treatment, precision measurements, laser cutting, display technologies, and laser surgery, and for fundamental research, where many of the most advanced experiments in astrophysics, atomic, molecular and optical physics, as well as in plasma research would be impossible without the latest laser technology. Moreover, lasers have become increasingly important for the successful operation and continuous optimization of particle accelerators: Laser-based particle sources are well suited for delivering the highest quality ion and electron beams, laser acceleration has demonstrated unprecedented accelerating gradients and might be an alternative for conventional particle accelerators in the future, and without laser-based beam diagnostics it would not be possible to unravel the characteristics of many complex particle beams. The LA3-NET consortium proposes to develop laser applications for particle accelerators within an initial training network. The network brings together research centers, universities, and industry partners to jointly train the next generation of researchers. The partners aim at developing long term collaboration and links between the involved teams across sectors and disciplinary boundaries and to thus help defining improved research and training standards in this multi-faceted field
Agency: Cordis | Branch: FP7 | Program: CP-CSA-Infra | Phase: INFRA-2011-2.3.4. | Award Amount: 15.84M | Year: 2011
The objective of the eleven participating Research Infrastructures (RIs) is to build up collaborations and to create long-term synergies to facilitate their implementation and enhance their efficiency and attractiveness. The CRISP proposal focuses on four R&D tasks that are of utmost importance for these RIs: (i) Accelerators, (ii) Instruments & Experiments, (iii) Detectors & Data Acquisition, and (iv) Information Technology (IT) & Data Management. Progress in accelerator technology is essential to provide the RIs with the best possible sources of X-rays, ions and neutrons and to tackle the next challenges in nuclear and high-energy physics. Joint developments for novel experimental schemes and their related instrumentation will create new scientific opportunities at the RIs and offer tremendous potential across all fields of natural sciences. New initiatives and approaches are required to cope with the ever-increasing flow of scientific data, and a joint effort to establish the base elements of adequate platforms for the processing, storage and access to data shall be undertaken. The RIs will exchange know-how and combine complementary expertise, ensuring cost-efficient and coherent development plans. The generated synergies will be crucial to respond to the rapidly evolving and mobile scientific user community. It will allow the RIs to strengthen their role in the advancement of knowledge and to stimulate scientific and technological progress, indispensable to address the grand challenges of our society in health, environment, sustainable energy, transport and communication. The proposed activities will be of enormous benefit as well to other large scale facilities in the European Research Area, such as regional or national light and x-ray sources, high-energy and nuclear facilities.
Agency: Cordis | Branch: FP7 | Program: MC-IEF | Phase: FP7-PEOPLE-2012-IEF | Award Amount: 194.05K | Year: 2013
This project focuses on the theoretical description of low-energy structure of atomic nuclei and the applications to other finite quantum many-body systems. The primary emphasis is on collective excitation and shape phenomena in finite nuclei, and on the structure of exotic nuclei under extreme conditions. Microscopic energy density functionals currently provide an accurate global description of nuclear ground-state properties, while algebraic theories, such as the interacting boson model, are successful in calculating the low-energy structure of medium-heavy and heavy nuclei. To describe spectral properties of nuclei based on a global theory, this project proposes a robust framework constructed by combining algebraic with microscopic theories. This theoretical framework will be used in the study of outstanding open problems in nuclear physics: Microscopic realization of quantum shape phase transition, understanding of the microscopic mechanism behind proton-neutron mixed symmetry, role of pairing correlations in exotic nuclei, the importance of proton-neutron pairing in N~Z nuclei, emergence of symmetries in complex quantum systems, etc. The method will also be used to predict the spectroscopy of exotic nuclei which are extensively studied nowadays at rare-isotope beam facilities around the world, including the planned SPIRAL2 facility in GANIL. The proposed method is general and will be applied to other fields of physics such as the study of analogous excitation modes in molecules or phase structure and low-energy excitations of Bose-Einstein condensates with intrinsic spin. Therefore the project points to giving a comprehensive theory of nuclei under various extreme conditions as well as of general finite quantum systems. In addition, an important component of the project concerns applicants training-through-research and teaching/outreach activities, mainly in the form of training of students and participation at and contribution to advanced summer schools.