Speaker
Description
The FALSTAFF spectrometer [1], designed to detect fission fragments produced in direct kinematics, is a key tool in advancing the understanding of neutron-induced fission, particularly in the MeV energy range. Fission models, both phenomenological and microscopic, have seen significant development over the past decade. However, their ability to accurately predict fission observables such as fragment masses, charges, kinetic energies, and neutrons/gammas, remains an area of active investigation. FALSTAFF employs a 2V-2EV measurement technique to determine the velocity and residual kinetic energy of fission fragments on an event-by-event basis. The velocity is obtained using time-of-flight measurements with a pair Secondary Electron Detectors (SEDs) [3], while the residual energy is measured by calorimetry in an axial ionization chamber.
Recent experiments were conducted at the Neutron For Science (NFS) facility of GANIL/SPIRAL2 [2], focusing on 235 U and 237 Np fission. These experiments spanned a neutron energy range from 0.5 to 40 MeV, providing valuable data on fission fragment mass distributions (FFMDs) and kinetic energies. In this presentation, we will present the results from the 235 U experiments and preliminary data from the 237 Np experiment, taken in October 2024. Comparisons with GEANT4 simulations will be discussed, and
the talk will conclude with an overview of the future FALSTAFF scientific program, which includes the commissioning of the second arm of the spectrometer for coincident detection of both fission fragments. These ongoing developments are expected to significantly enhance the capability of FALSTAFF and contribute to the improvement of nuclear data essential for the simulation of next-generation reactors and hence their design.
References
[1] D. Doré et al., Nucl. Data. Sheets. 119, 346-348 (2014).
[2] X. Ledoux et al., Eur. Phys. J. 57, 257 (2021).
[3] J. Pancin et al., J. Instrum. 4, P12012 (2009).
