Muonic X-ray Research Articles

Application of Analysis with Muonic X-rays for Battery

Application of Analysis with Muonic X-rays for Battery

Muonic atom X-ray spectroscopy for non-destructive analysis of archeological samples

The implementation in the RIKEN-RAL negative muons facility of a new muon beamline monitoring and novel digital data acquisition system for gamma and X-ray spectroscopy are presented. This work also shows the high potential of the muonic atoms X-ray spectroscopy technique in non-destructive elemental characterization of archaeological samples.

Initial quantum levels of captured muons in CO, CO2, and COS

The role of valence electrons for the muon capture process by molecules is experimentally investigated with the aid of cascade calculations. Low-momentum muons are introduced to gas targets of CO, CO2, and COS below atmospheric pressure. The initial states of captured muons are determined from the measured muonic X-ray structure of the Lyman and Balmer series. We propose that the lone pair electrons in the carbon atom of CO significantly contribute to the capture of a muon with large angular momenta.

Non-destructive, position-selective, and multi-elemental analysis method involving negative muons

Elemental analysis is of fundamental importance in several scientific domains. Many elemental analysis methods have been developed till date, with particular importance having been given to non-destructive analysis methods. In this paper, we review a novel non-destructive, position-selective, and multi-elemental analysis method for bulk material that utilizes a new type of probe, a negative muon. When a muon is stopped by an atom in a material, muonic X-rays are emitted. Due to the large mass of a muon, the energy of muonic X-rays is very high, and the “X-ray fluorescence analysis” method using a muon can solve the problem of self-absorption in an ordinary method using an electron. Two studies involving quantitative and depth-profiling analysis of archeological artifacts by this method are reviewed in this work. We also discuss the scope for future research using this method.

Negative muon capture ratios for nitrogen oxide molecules

Per-atom muon capture ratios are precisely determined from characteristic muonic X-ray measurements of three nitrogen oxide samples (NO, N2O, and NO2) at pressures below 100 kPa. A higher density of covalent electrons at the N atoms relative to the O atoms is required if we explain the experimental results using the proposed muon capture models. From molecular orbit calculations, we found that the electron distributions of only the highest occupied molecular orbitals (HOMO) are dominant at the N atoms, and the electrons in the HOMO significantly contribute to the muon capture phenomena in the nitrogen oxide molecules.

Performance of X-rays crystal detectors with SiPM array readout exposed to the RIKEN-RAL low energy muon beam

Scintillating crystals coupled to SiPM array readout have been proposed to realize compact X-rays detectors for the FAMU experiment, which aims to accurately measure the hyperfine splitting of the ground state of the muonic hydrogen atom. A measurement of the transfer rate of muons from hydrogen to heavier gases is necessary for this purpose. Since 2014, in a series of test runs, a pressurized gas-target was exposed to the pulsed low-energy muon beam at the RIKEN RAL muon facility (Rutherford Appleton Laboratory, U.K.). The main goal of these tests was the characterization of both the background induced by the pulsed beam and the X-ray detectors. Preliminary results are shown on the use of new Pr:LuAG and Ce:GAGG crystals, developed for PET scanners and of more conventional LaBr 3 :Ce crystals, with a SiPM array readout. Energy spectra of the X-rays produced after the de-excitation of muonic atoms formed from the interaction of the beam muons with the gas target in the FAMU apparatus are shown, demonstrating the suitability of these detectors for muonic X-rays spectroscopy.

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

In this work, we investigated muonic atoms and molecules from a quantum chemist's viewpoint by incorporating muons in the CASSCF model. With the aim of predicting muonic X-ray energies, primitive muonic basis sets were developed for a selection of elements. The basis sets were then used in CASSCF calculations of various atoms and molecules to calculate muonic excited states. We described the influence of nuclear charge distribution in predicting muonic X-ray energies. Effects of the electronic wave function on the muonic X-ray energies were also examined. We have computationally demonstrated how the muon can act as a probe for the nuclear charge distribution or electronic wave function by considering lower or higher muonic excited states, respectively. (Less)

Muonic X-ray measurements on mixtures of CaO/MgO and Fe3O4/MnO

Elemental analysis by measurement of muonic X-rays shows great potential for analyzing the elemental composition of a bulk material at a specific depth without sample destruction. For quantitative analysis, muon capture probability is the most important parameter. In this work, the muon capture ratios and muonic X-ray intensity patterns of metal oxides for geochemically and cosmochemically important compounds, MgO, CaO, MnO and Fe3O4, were determined. The muon capture ratios of Ca/Mg and Fe/Mn were proportional to the mixing ratios of CaO/MgO and Fe3O4/MnO. From this relationship, the elemental composition can be determined from the muonic X-ray intensity ratio alone.

Electronic catalogue of muonic X-rays

μX-ray spectra for Z=9-90 were measured with HPGe detectors and muonic beams of PSI (Villigen, Switzerland) [1]. The results are presented as electronic atlas composed of graphic plots. The atlas is available at JINR site [2].

Non-destructive elemental analysis of a carbonaceous chondrite with direct current Muon beam at MuSIC

Electron- or X-ray-induced characteristic X-ray analysis has been widely used to determine chemical compositions of materials in vast research fields. In recent years, analysis of characteristic X-rays from muonic atoms, in which a muon is captured, has attracted attention because both a muon beam and a muon-induced characteristic X-ray have high transmission abilities. Here we report the first non-destructive elemental analysis of a carbonaceous chondrite using one of the world-leading intense direct current muon beam source (MuSIC; MUon Science Innovative Channel). We successfully detected characteristic muonic X-rays of Mg, Si, Fe, O, S and C from Jbilet Winselwan CM chondrite, of which carbon content is about 2 wt%, and the obtained elemental abundance pattern was consistent with that of CM chondrites. Because of its high sensitivity to carbon, non-destructive elemental analysis with a muon beam can be a novel powerful tool to characterize future retuned samples from carbonaceous asteroids.

A compact imaging system with a CdTe double-sided strip detector for non-destructive analysis using negative muonic X-rays

A CdTe double-sided strip detector (CdTe-DSD) is an ideal device for imaging and spectroscopic measurements in the hard X-ray range above 10 keV. Recent development enables us to realize an imager with a detection area of ∼10 cm2. An energy resolution of 1–2 keV (FWHM) and a position resolution of a few hundred μm are available from the detector. This type of imager has been long awaited for non-destructive elemental analysis, especially by using negative muons, because energies of characteristic X-rays from muonic atoms are about 200 time higher than those from normal atoms. With the method that uses negative muons, hard X-ray information gives the spatial distribution of elements in samples at a certain depth defined by the initial momentum of the muon beam. In order to study three-dimensional imaging capability of the method, we have developed a compact imaging system based on CdTe-DSD and a ϕ 3 mm pinhole collimator as the first prototype. We conducted experiments with samples which consist of layers of Al, BN and LiF irradiated by negative muon beams in MUSE/J-PARC and successfully reconstruct hard X-ray images of muonic X-rays from B, N and F at various depths.

Optimal dimension of a layered hydrogen target for muon conversion and muonic x-ray spectroscopy

In spectroscopic studies of nuclei (muonic x-ray spectroscopy and muon conversion), layered solid hydrogen targets are of key importance. The paper develops a mathematical model to optimize the dimension of solid deuterium (degrader) layer in a layered hydrogen structure of H2/T2+sD2 to prepare muon for the creation of muonic atoms. Muonic object balance equations have been constructed and solved. All muonic molecular resonances have been taken into account. The results show good accordance with muon experiments.

Non-destructive Elemental Analysis Using Negative Muon

A negative muon implanted into materials is captured by an atom and forms a muonic atom with emission of muonic X-rays. The X-ray energy is characteristic to the atomic number of the atom which captured the muon. By measuring the energy of the muonic X-ray induced by the negative muon implanted into the sample material with a kinetic energy tuned to stop at a chosen depth from the sample surface, the elemental composition of the sample at the specific depth from the surface is revealed. This elemental analysis method has unique in non-destructive, multi-element, and depth-selective characteristics. The method is being developed at the J-PARC/MUSE facility.

Muonic X-ray spectroscopy: Effect of the presence of protons on X-ray production

The paper deals with muonic X-ray generation by a two-layer solid hydrogen structure of [Formula: see text]. The target has a high efficiency for analyzing characteristic X-rays in ion implantation. To predict the effect of the presence of protons on X-ray production, we have proposed a new kinetic schema. Muonic object equations have been written to descibe all muonic processes. In the case of a low concentration of argon (Ar) ions (5 ppm) in the sD2 layer a proton concentration of about 20% leads to a significant drop in the X-ray yield. However, in the case of a high Ar concentration (500 ppm) this effect is negligible.

Negative muon induced elemental analysis by muonic X-ray and prompt gamma-ray measurements

When a negatively charged muon stopped in a material, muonic atom, which has one muon in place of an electron in the atomic system, is formed. After muon deexcitation process with muonic X-ray emission, the muon reaches to the muonic 1 s state, and the muon is absorbed in the nucleus. As a result, highly excited nucleus is produced, and the nucleus emits neutrons and gamma-rays. In this work, we determined elemental depth profiling of gold concentrations on archeological sample, an old Japanese coin, by measuring gamma-ray intensities emitted from activated nucleus with various incident muon energies.

Nondestructive elemental depth-profiling analysis by muonic X-ray measurement.

Elemental analysis of materials is fundamentally important to science and technology. Many elemental analysis methods have been developed, but three-dimensional nondestructive elemental analysis of bulk materials has remained elusive. Recently, our project team, dreamX (damageless and regioselective elemental analysis with muonic X-rays), developed a nondestructive depth-profiling elemental analysis method after a decade of research. This new method utilizes a new type of probe; a negative muon particle and high-energy muonic X-rays emitted after the muon stops in a material. We performed elemental depth profiling on an old Japanese gold coin (Tempo-Koban) using a low-momentum negative muon beam and successfully determined that the Au concentration in the coin gradually decreased with depth over a micrometer length scale. We believe that this method will be a promising tool for the elemental analysis of valuable samples, such as archeological artifacts.

Observation of Muonic X-rays of Cosmic-Ray Muons Stopped in Al and Fe Targets

We successfully measured muonic X-rays of cosmic-ray muons stopped in Al and Fe targets. In order to identify the events that incoming cosmic-ray muons were stopped in the targets, a coincidence and anticoincidence system of three plastic scintillators was used. The X-rays associated with the atomic muon captures were measured with germanium detectors. Measurements using the Al and Fe targets were carried out for 33 and 16 days, respectively. A sufficient number of muonic X-ray events for identifying the elemental compositions of the target materials were clearly observed. This technique provides a means of nondestructive elemental analysis that does not require the use of particle accelerators.

Development of Elemental Analysis Method for Archeological Artifacts by Characteristic Muonic X-ray Measurement

Development of Elemental Analysis Method for Archeological Artifacts by Characteristic Muonic X-ray Measurement

Muon capture probability of carbon and oxygen for CO, CO2, and COS under low-pressure gas conditions

When a negatively charged muon is stopped in a substance, it is captured by an atom of the substance, and the muonic atom is formed. The muon capture process is significantly affected by the chemical environment of the atom and factors such as molecular structure (chemical effect). In this study, we performed muon irradiation for low-pressure CO, CO2, and COS molecules and measured the muonic X-rays emitted immediately after muon capture by an atom. In this paper, we quantitatively discuss the muon capture probability of each type of atom using the LMM model.

Energy distribution of μd1s muonic atom and its spin states effecting on muonic X-Ray transfer yield in solid thin film method

We have investigated the energy distribution of [Formula: see text] and its spin states (F) effecting on muonic X-ray transfer yield in the solid thin film method. Argon ( Ar ) ion has been considered as the implanted ion in solid deuterium (s D 2) layer at a temperature of T = 3 K. A kinetics model has been used, the corresponding rate equations have been constructed and our results of X-ray yield have been compared with recent measured data. The μd1s muonic atoms, which can take part in resonant molecular formation, have been separated from atoms participating in nonresonant reactions. On this basis, the integrated number of X-rays has been calculated. The results show that the effect of μd1s energy distribution on the number of X-photons is not serious, while its spin states strongly affect the muonic X-ray yield.