In the realm of nuclear physics and energy research, a team of scientists from various institutions, including RIKEN in Japan and the University of Warwick in the UK, has been delving into the intricacies of muon-induced nuclear reactions. Their recent study, published in the journal Physical Review C, focuses on the energy spectra of light charged particles emitted following muon nuclear capture (muNC) on natural silicon.
The researchers, led by Shoichiro Kawase from RIKEN, aimed to measure comprehensive energy spectra of charged particles resulting from muNC on silicon. This process provides valuable insights into the de-excitation dynamics of highly excited nuclei, particularly the interplay between preequilibrium and evaporation processes. While proton emission has been relatively well studied, experimental data on composite charged particles, especially alpha particles at low energies, has been limited.
The experiment was conducted at the RIKEN-RAL Muon Facility. The team used DeltaE-E telescopes and digital pulse-shape analysis with nTD-Si detectors to identify the charged particles. The initial energy spectra were reconstructed through an unfolding procedure and compared with calculations based on the microscopic and evaporation model (MEM) and the PHITS code with surface coalescence and meson-exchange-current extensions.
The results revealed energy spectra of protons, deuterons, tritons, and alpha particles over a broad energy range. Notably, the low-energy alpha-particle spectrum was measured for the first time. The proton spectra were reasonably reproduced by both MEM and PHITS models. For alpha particles, both models described the low-energy evaporation component well, but discrepancies remained at higher energies. The MEM model successfully reproduced the spectral shapes for deuterons and tritons, while PHITS significantly underestimated the yields, especially at high energies.
The study demonstrates clear particle-species-dependent differences in charged-particle emission following muNC. The measured energy spectra provide important constraints on preequilibrium and evaporation processes and highlight the need for improved modeling of composite-particle emission.
For the energy sector, understanding these nuclear processes can have implications for various applications, including nuclear energy production and radiation safety. The insights gained from this research can contribute to the development of more accurate models for nuclear reactions, which are crucial for advancing nuclear energy technologies and ensuring safe and efficient operations.
This article is based on research available at arXiv.