Présidents de session
From Oklo samples to natural core simulations: From Oklo samples to natural core simulations
- F. GAUTHIER-LAFAYE
The emergence of complex life more than five hundred million years ago marked the beginning of change in the Earth’s biosphere. This evolutionary change is associated with numerous events including increasing predation, burrowing, and animal diversity during the so called “Cambrian Explosion” at the Ediacaran-Cambrian boundary. However, several studies have reported that scattered fossils of...
Natural nuclear reactors operated in Oklo (Gabon) about 2.0 billion years ago [1]. This phenomenon was predicted and led to a systematic search for uranium deposits that went critical. Fifty years ago, just a few years after this search was abandonded, the Oklo phenome-non was discovered by chance. Many elements extracted from the Oklo reactor material still carry clear isotopic signatures...
The fission processes for thermal neutron induced 235U and 239Pu fission and for fast neutron induced 238U fission produce fragments with a wide range of mass (72<A<162; A=mass number), and neutrons. As the results of fission events, many elements in the Oklo reactor zones (hereafter, RZs) and the related samples show the variations in the isotopic compositions caused by a combination of...
Paul Dirac is credited with being the first physicist to speculate in print that fundamental constants like the Newtonian gravitational constant G may change over cosmological intervals. Incongruous though this notion may be, it has gained traction among physicists. Modern theoretical frameworks, which attempt to unify all the fundamental forces, accommodate the possibility of varying...
