Toward new frontiers : Encounter and synergy of state-of-the-art astronomical detectors and exotic quantum beams

Program B02-1	Development of charged particle collection and transportation method
Principal Investigator	OKUTSU, Kenichi (Gakushuin University)

In this project, we aim to observe muons from muon-catalyzed fusion through the development of a charged particle collection and transport system. It is known that negative muons, which are elementary particles, have a negative charge and are about 207 times heavier than electrons. In particular, the molecular orbital of muon in muon molecule is inversely proportional to its mass, therefore its molecular orbital is about 1/207 smaller than that of an electron. This makes the nuclei of the molecule closer, and the wavefunction in the region where the nuclei come into contact with each other due to the tunneling effect has a finite size, which facilitates nuclear reactions.

The nuclear reaction between hydrogen isotopes via muons is known as muon-catalyzed fusion, and unlike thermonuclear fusion, the reaction occurs at low temperatures. In the muon-catalyzed fusion, the fusion products immediately dissociate with high kinetic energy after the nuclear reaction, and the muons that consisted the muon molecule will be released with the kinetic energy of the muon molecular orbital intact. Therefore, direct observation of muons after the nuclear reaction is expected to reveal the molecular orbitals of muon molecules.

The reason this nuclear reaction is called muon “catalyzed” fusion is because the muons released after
Fig. 1. Simulation result of trajectories of charged particles of transport system.

the reaction (recycling muons) help the next nuclear reactions until the muon ends up its lifetime (2.2 μs). Although, muons including recycling muon, play a very important role in the reaction. They are produced in small amounts and have been difficult to observe directly. In this study, we will develop a new device that can transport small amounts of charged particles to distant locations. Detection of the recycling muons using this device is expected to provide information for the applications and fundamental science.

Members

Reference Materials

• 永谷幸則, 奥津賢一 他, 特願 2020-178286.
• P. Strasser et al., Nucl. Instrum. Methods Phys. Res. A 460, 451 (2001).
• K. Okutsu et al., Fusion Eng. Des. 170, 112712 (2021).