Although a positive muon spin rotation and relaxation (μ+SR) technique is commonly used for materials science, its counterpart technique, μ-SR, has been less common due to its very limited availability and a very slow counting rate. However, a combination between an intense pulsed muon beam, such as, J-PARC and ISIS, and the development of a multi-channel counter system enables us to utilize μ-SR for studying a small nuclear magnetic field in solids. Here, we summarize the advantage and disadvantage of the two μSR techniques and propose μ±SR as a novel tool to identify diffusing species and clarify the ion diffusive nature in battery materials.
We have used muons for an analysis of battery to improve its safety and performance in two ways; one is muon spin rotation and relaxation (μSR) with positive muons to study the diffusion of lithium (Li) in Li-ion battery materials. The dynamics of Li ion can be investigated through the response of muons to the internal magnetic field provided by the nuclear moment of the Li ion. The other is a non-destructive observation using negative muons. Since the muon-characteristic X-rays generated by negative muon irradiation have about 200 times higher energy than fluorescent X-rays, muonic X-rays from Li can penetrate from its housing. Recently, this technology has been successfully applied to the detection of metallic Li in a battery, and we hope that it will be further utilized for safety.
Muonic X-ray analysis is an elemental analysis method by detecting characteristic X-rays emitted from muonic atoms and has various advantages, for example, it can detect light elements such as carbon non-destructively. Our research group has been studying to apply this new analytical method to the sample of the asteroid Ryugu brought back by the asteroid explorer Hayabusa2. This paper outlines the research conducted at J-PARC muon facility so far and the preparation status of the experiment on Ryugu samples scheduled to be conducted from June to July 2021. To make this experiment successful, a device with a glove box has been developed that can analyze microsamples in a helium atmosphere, achieving very low background levels.
In the Materials and Life science experimental Facility (MLF) of J-PARC, the computing group, named “Denno-han”, has been developed, managed and operated the MLF standard software and the computing infrastructures, which are widely covering the neutron event-recording data acquisition (DAQ) system, the device control software framework, data processing software and data management for neutron experimental instruments in MLF. In this article, I introduce the organization of MLF computing group and technical information of a series of MLF standard software as follows: DAQ middleware; IROHA2 instrument control; Manyo library and Utsusemi software. In addition, I report the policies on data management and the remote access from outside of J-PARC.