A new X-ray fluorescence spectroscopy for extraterrestrial materials using a muon beam

Abstract

The recent development of the intense pulsed muon source at J-PARC MUSE, Japan Proton Accelerator Research Complex/MUon Science Establishment (106 s−1 for a momentum of 60 MeV/c), enabled us to pioneer a new frontier in analytical sciences. Here, we report a non-destructive elemental analysis using µ− capture. Controlling muon momentum from 32.5 to 57.5 MeV/c, we successfully demonstrate a depth-profile analysis of light elements (B, C, N, and O) from several mm-thick layered materials and non-destructive bulk analyses of meteorites containing organic materials. Muon beam analysis, enabling a bulk analysis of light to heavy elements without severe radioactivation, is a unique analytical method complementary to other non-destructive analyses. Furthermore, this technology can be used as a powerful tool to identify the content and distribution of organic components in future asteroidal return samples.

Hayabusa2: Scientific importance of samples returned from C-type near-Earth asteroid (162173) 1999 JU3

“…These three categorized samples should be investigated by state-of-the-art laboratory instruments to understand the history of the solar system, especially focusing on (1) galactic chemical evolution and the Sun's parent molecular cloud chemistry, (2) pre-accretional chemical evolution and planetesimal formation in the proto-solar disk, (3) planetesimal processes, such as the final evolutionary stage of volatiles in small early solar system objects prior to possible accretion to planets, (4) geological evolution of asteroids in the solar system, and (5) orbital evolution and surface geological processes of a near-Earth asteroid. In the 2020s, we will have new analytical techniques to reveal the solar system history; fluorescence spectroscopy with muonic X-rays, for instance, may be a new, non-destructive method to identify the content and distribution of organic components in mmto cm-sized pebbles (Terada et al, 2014).…”

Uncontracted basis sets for ab initio calculations of muonic atoms and molecules

“…The free muon's lifetime is 2.2 μ s and it is reduced to some extent in muonic atoms by nuclear capture processes . Recently, there have been interesting developments in muonic X‐ray spectroscopy where nondestructive elemental analysis with several useful properties has been achieved . This in turn has awakened the interest of theoreticians, who can use quantum mechanics to predict properties of muonic atoms and molecules.…”

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex IV: The Muon Facility

“…This capability is particularly useful for light elements, since conventional fluorescent X-ray analysis is insensitive to elements lighter than Na due to the limited penetration depths of X-rays. An example of a muonic X-ray spectrum obtained for a meteorite specimen is shown in Figure 20, where signals from light elements are detected through a wall of glass tube [38].…”