Speaker
Description
Neutron-induced fission cross sections are among the most fundamental and important nuclear data in nuclear science and engineering. In particular, with the increasing adoption of MOX fuel and the trend toward higher burnup in nuclear reactors, there is a growing demand for accurate nuclear data on minor actinides (Mas) such as americium (Am) and curium (Cm). Despite the importance of these nuclides, the accuracy of fission cross section data for these nuclei remains insufficient, and these nuclides continue to be listed in the High Priority Request List of Nuclear Data by OECD/NEA.
Most experimental studies of fission cross sections have relied on detecting fission fragments using fission ionization chambers. While this method has been widely used, it suffers from several inherent limitations. In particular, uncertainties due to self-absorption of fission fragments within the sample and background contributions from the intense α-decay of MA nuclei would significantly affect measurement accuracy. This issue also imposes constraints on the sample thickness and weight, consequently thereby limiting the achievable counting statistics.
To overcome these issues, the present study focuses on the measurement of prompt neutrons emitted immediately after nuclear fission. Plastic scintillators (EJ276D), which are selectively sensitive to fast neutrons and enable neutron–gamma discrimination, were employed as neutron detectors. A detection system consisting of multiple EJ276D detectors was installed at the ANNRI beamline of the Materials and Life Science Experimental Facility (MLF) in J-PARC. Using the pulsed neutron beam provided by MLF, preliminary neutron-induced fission cross sections of 241Am and 245Cm were measured in the neutron energy range from thermal energies up to several eV. This presentation will provide a detailed description of the experimental setup, analysis procedure and results.
| Session | Nuclear Fission (prompt particle emission, fission yields) |
|---|