Speaker
Description
In recent years, advances in laser technology have enabled focused intensities on targets to reach up to 10^22~W/cm^2.Within the plasma formed on the target by the laser, ultra-high-density electromagnetic field is generated. High-energy electrons and ions with energies of several tens of MeV have been observed from such laser plasmas, suggesting the possibility that nuclear reactions are induced within the plasma. However, if the granularity is not sufficiently high, the detector cannot perform detailed measurements due to pile-up. This is because reactions in laser plasma occur in extremely short durations and at high densities.
In this study, we aim to establish a γ-ray detection method using nuclear emulsion, which is known for its extremely high granularity. Once established, this method will contribute to a better understanding of phenomena occurring in laser plasma. Furthermore, if laser intensity increases further, it will lead to the development of new research methods that were difficult to perform with conventional acceleration. For example, it will enable the study of nuclear reactions using high-density photons, and under ultra-high electromagnetic field environments, such as inside magnetars.
We analyzed data from an experiment conducted in 2021 using the J-KAREN-P laser at the National Institutes for Quantum Science and Technology (QST), and successfully observed γ-ray events in nuclear emulsion. However, the nuclear emulsions used in this experiment have traditionally been employed in high-energy regions (several GeV and above), such as in cosmic-ray experiments. Therefore, in the typical energy range of nuclear reactions (several tens of MeV), the momentum resolution and detection efficiency may significantly deteriorate. Therefore, we will evaluate the performance of nuclear emulsion at low momentum by analyzing calibration experiments conducted in 2024 using the Electron Linac at the Institute for Chemical Research (ICR).
In this presentation, we will explain the experimental results at QST while comparing them with calibration results at ICR.