Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics
F. Farget, M. Caamano, O. Delaune, O. B. Tarasov, X. Derkx, K. -H. Schmidt, A. M. Amthor, L. Audouin, C. -O. Bacri, G. Barreau, B. Bastin, D. Bazin, B. Blank, J… 展开作者
F. Farget, M. Caamano, O. Delaune, O. B. Tarasov, X. Derkx, K. -H. Schmidt, A. M. Amthor, L. Audouin, C. -O. Bacri, G. Barreau, B. Bastin, D. Bazin, B. Blank, J. Benlliure, L. Caceres, E. Casarejos, A. Chibihi, B. Fernandez-Dominguez, L. Gaudefroy, C. Golabek, S. Grevy, B. Jurado, O. Kamalou, A. Lemasson, S. Lukyanov, W. Mittig, D. J. Morrissey, A. Navin, J. Pereira, L. Perrot, M. Rejmund, T. Roger, M. -G. Saint-Laurent, H. Savajols, C. Schmitt, B. M. Sherill, C. Stodel, J. Taieb, J. -C. Thomas, A. C. Villari
备注：
Invited Plenary Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS)
During the fission process, the nucleus deforms and elongates up to the two fragments inception and their final separation at scission deformation. The evolution of the nucleus energy with deformation is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experimental observation of the potential energy landscape of the deforming nucleus. Very asymmetric fusion-fission reactions at energy close to the Coulomb barrier, produce well-defined conditions of the compound nucleus formation, where processes such as quasi-fission, pre-equilibrium emission and incomplete fusion are negligible. In the same time, the excitation energy is sufficient to reduce significantly structural effects, and mostly the macroscopic part of the potential is responsible for the formation of the fission fragments. We use inverse kinematics combined with spectrometers to select and identify the fission fragments produced in $^{238}$U+$^{12}$C at a bombarding energy close to and well-above the Coulomb barrier. For the first time, the isotopic yields are measured over the complete atomic-number distribution, between Z=30 and Z=63. The experimental set-up also allows to identify transfer-induced reactions, which lead to low-energy fission where the nuclear shell structure shows a strong influence on the fission-fragment distributions. The resulting set of data gives the possibility to observe the fission fragment properties over a wide range of excitation energy, and they reveal the vanishing of the shell effects in the potential energy of the fissioning nucleus, as well as the influence of fission dynamics.
Isotopic fission yields of ${}^{240}$Pu as a function of the excitation energy
GANIL, CNRS/IN2P3, CEA/DRF（GANIL，法国国家科学研究中心/欧洲核子研究组织，法国原子能和替代能源委员会）；IGFAE - Universidade de Santiago de Compostela（圣地亚哥-德孔波斯特拉大学 IGFAE 研究所）；IJC Lab, Université Paris-Saclay, CNRS/IN2P3（巴黎萨克雷大学 IJC 实验室，法国国家科学研究中心/欧洲核子研究组织）；IFIC, Centro Mixto Universidad de Valencia-CSIC（瓦伦西亚大学-西班牙国家科学研究理事会混合中心 IFIC）；CINTECX, Universidade de Vigo（维戈大学 CINTECX 研究中心）；CEA Saclay, DRF/IRFU/SPhN（法国原子能和替代能源委员会萨克雷园区，研究与技术发展部/核物理研究所）
Neutron Induced Fission Fragment Angular Distributions, Anisotropy, and Linear Momentum Transfer Measured with the NIFFTE Fission Time Projection Chamber
Measurement of material isotopics and atom number ratio with alpha-particle spectroscopy for the NIFFTE fission Time Projection Chamber actinide target
Study of fusion-fission in inverse kinematics with a fragment separator
National Superconducting Cyclotron Laboratory, MSU（国家超导回旋加速器实验室，密歇根州立大学）；Grand Accelerateur National d'Ions Lourds, CEA/DSM-CNRS/IN2P3（重离子国家大加速器，CEA/DSM-CNRS/IN2P3）；Department of Chemistry, Michigan State University（密歇根州立大学化学系）；Department of Physics, Bucknell University（巴克内尔大学物理系）；CENBG, UMR 5797 CNRS/IN2P3, Université Bordeaux 2（波尔多大学碳和核物理中心，CNRS/IN2P3联合研究单位5797）；Universidade de Santiago de Compostela（圣地亚哥-德孔波斯特拉大学）；FLNR, JINR（朱诺夫联合核研究所重离子反应实验室）；Department of Physics and Astronomy, MSU（密歇根州立大学物理与天文学系）；IPN Orsay, CNRS/IN2P3（奥赛核物理研究所，CNRS/IN2P3）；Facility for Rare Isotope Beams, MSU（稀有同位素束流设施，密歇根州立大学）
Search for extremely deformed fission fragment in ^{28}Si+^{28}Si with Eurogam Phase II
A high-resolution study of fragment-fragment- $γ$ triple coincident measurements of the symmetric-mass fission exit-channel from the ^{28}Si+^{28}Si reaction has been performed at the VIVITRON Tandem facility by using the EUROGAM Phase II $γ$ -ray spectrometer. The bombarding energy E_{lab} (^{28}Si) = 111.6 MeV has been chosen to populate a well known quasi-molecular resonance in ^{56}Ni. Evidence is presented for a selective population of states in ^{28}Si fragments arising from the symmetric-fission of the ^{56}Ni compound nucleus. In the resonant region the enhanced population of the K^π =…
Isotopic yield in cold binary fission of even-even $^{244-258}$Cf isotopes
采用库仑势与邻近势之和作为相互作用势垒，研究了244- 258 Cf同位素偶偶冷裂变。从冷谷图（驱动电位与碎片质量数的关系图）和通过计算电荷最小化碎片的产率获得有利的碎片组合。发现244、246、248 Cf同位素的最高产率是以Pb（Z=82）为一个碎片的碎片，而250 Cf和252 Cf同位素的最高产率是以Hg（Z=80）为一个碎片的碎片。在254、256、258 Cf同位素的情况下，最高产率是以Sn（Z=50）作为一个片段的片段。因此，具有最大产额的碎片组合揭示了双幻核和近双幻核在二裂变中的作用。发现质量数为A252的Cf同位素有利于不对称分裂< 250 and symmetric splitting is favoured for Cf isotopes with A >.在A=252的Cf同位素的情况下，不对称分裂和对称分裂的概率相等。将252 Cf冷裂变的单个产额与γ- γ- γ符合技术的实验数据进行了比较。
Isoscaling of the Fission Fragments with Langevin Equation
用Langevin方程模拟了$^{112}$ Sn + $^{112}$ Sn和$^{116}$ Sn + $^{116}$ Sn的裂变过程。假设裂变过程为对称裂变或非对称裂变，采用高斯概率抽样，给出了裂变碎片的质量分布。对两个反应的裂变碎片分析都观察到了等标度行为，等标度参数$α$似乎对裂变几率宽度和束流能量敏感。
Measurement of the $^{236}$U fission cross section and angular distributions of fragments from fission of $^{235}$U and $^{236}$U in the neutron energy range of 0.3-500 MeV
