arXiv subjects

Y. Kino

Publications and source records attributed to Y. Kino.

3 recordsLinked to original sources

arXiv2024

Few-electron highly charged muonic Ar atoms verified by electronic $K$ x rays

Electronic $K$ x rays emitted by muonic Ar atoms in the gas phase were observed using a superconducting transition-edge-sensor microcalorimeter. The high-precision energy spectra provided a clear signature of the presence of muonic atoms accompanied by a few electrons, which have never been observed before. One-, two-, and three-electron bound, i.e., H-like, He-like, and Li-like, muonic Ar atoms were identified from electronic $K$ x rays and hyper-satellite $K$ x rays. These $K$ x rays are emitted after the charge transfer process by the collisions with surrounding Ar atoms. With the aid of theoretical calculations, we confirmed that the peak positions are consistent with the x-ray energies from highly charged Cl ions, and the intensities reflecting deexcitation dynamics were successfully understood by taking into account the interaction between the muon and bound electrons.

physics.atom-ph↗

arXiv2023

Comprehensive study of muon-catalyzed nuclear reaction processes in the $dtμ$ molecule

Muon catalyzed fusion ($μ$CF) has recently regained considerable research interest owing to several new developments and applications. In this regard, we have performed a comprehensive study of the most important fusion reaction, namely $(dtμ)_{J=v=0}\toα$+$n$+$μ$+17.6 MeV or $(αμ)_{nl}$+$n$+17.6 MeV. The coupled-channels Schrödinger equation for the reaction is thus solved, satisfying the boundary condition for the muonic molecule $(dtμ)_{\rm J=v=0}$ as the initial state and the outgoing $αn μ$ channel with the $α$-$n$ $D$ wave. We employ the $dtμ$- and $αn μ$-channel coupled three-body model. All the $d$-$t$ and $α$-$n$ potentials, and the $d t$-$αn$ channel-coupling nonlocal tensor potential are chosen to reproduce the observed low-energy astrophysical $S$-factor of the reaction $d$+$t\toα$+$n$+17.6 MeV, as well as the total cross section of the $α$+$n$ reaction. The resultant $dtμ$ fusion rate is 1.15x10$^{12}$ s$^{-1}$. Substituting the obtained total wave function into the $T$ matrix, we have calculated absolute values of the fusion rates going to the bound and continuum states of the outgoing $α$-$μ$ pair. We then derived the initial $α$-$μ$ sticking probability $ω_S^0$=0.857%, which is $\sim$7% smaller than the literature values ($\simeq$0.91-0.93%), and can explain the recent observations (2001) at high D-T densities. We also calculate the absolute values for the momentum and energy spectra of the emitted muon. The most important result is that the peak energy is 1.1 keV although the mean energy is 9.5 keV. This is an essential result for the ongoing experimental project to realize the generation of an ultra-slow negative muon beam by utilizing the $μ$CF for various applications e.g., a scanning negative muon microscope and an injection source for the muon collider.

nucl-th↗

arXiv2007

Stau-catalyzed $^6$Li Production in Big-Bang Nucleosynthesis

If the gravitino mass is in the region from a few GeV to a few 10's GeV, the scalar lepton X such as stau is most likely the next lightest supersymmetry particle. The negatively charged and long-lived X^- may form a Coulomb bound state (A X) with a nucleus A and may affect the big-bang nucleosynthesis through catalyzed fusion process. We calculate a production cross section of Li6 from the catalyzed fusion (He4 X^-) + d \to Li6 + X^- by solving the Schrödinger equation exactly for three-body system of He4, d, and X. We utilize the state-of-the-art coupled-channel method, which is known to be very accurate to describe other three-body systems in nuclear and atomic reactions. The importance of the use of appropriate nuclear potential and the exact treatment of the quantum tunneling in the fusion process are emphasized. We find that the astrophysical S-factor at the Gamow peak corresponding to T=10 keV is 0.038 MeV barn. This leads to the Li6 abundance from the catalyzed process as Li6|_{CBBN}\simeq 4.3\times 10^{-11} (D/2.8\times 10^{-5}) ([n_{X^-}/s]/10^{-16}) in the limit of long lifetime of X. Particle physics implication of this result is also discussed.

hep-ph↗