Characterization of a Continuous Muon Source for the Non-Destructive and Depth-Selective Elemental Composition Analysis by Muon Induced X- and Gamma-rays

Abstract

The toolbox for material characterization has never been richer than today. Great progress with all kinds of particles and interaction methods provide access to nearly all properties of an object under study. However, a tomographic analysis of the subsurface region remains still a challenge today. In this regard, the Muon Induced X-ray Emission (MIXE) technique has seen rebirth fueled by the availability of high intensity muon beams. We report here a study conducted at the Paul Scherrer Institute (PSI). It demonstrates that the absence of any beam time-structure leads to low pile-up events and a high signal-to-noise ratio (SNR) with less than one hour acquisition time per sample or data point. This performance creates the perspective to open this technique to a wider audience for the routine investigation of non-destructive and depth-sensitive elemental compositions, for example in rare and precious samples. Using a hetero-structured sample of known elements and thicknesses, we successfully detected the characteristic muonic X-rays, emitted during the capture of a negative muon by an atom, and the gamma-rays resulting from the nuclear capture of the muon, characterizing the capabilities of MIXE at PSI. This sample emphasizes the quality of a continuous beam, and the exceptional SNR at high rates. Such sensitivity will enable totally new statistically intense aspects in the field of MIXE, e.g., elemental 3D-tomography and chemical analysis. Therefore, we are currently advancing our proof-of-concept experiments with the goal of creating a full fledged permanently operated user station to make MIXE available to the wider scientific community as well as industry.

The non-destructive investigation of a late antique knob bow fibula (Bügelknopffibel) from Kaiseraugst/CH using Muon Induced X-ray Emission (MIXE)

“…The resulting -X rays and gamma-rays are detected by an appropriate detector setup, arranged around the sample. Further details on the MIXE technique can be found in [ 1 ] and [ 2 ] .…”

“…On the contrary, they continue to be the starting point for all further investigations and considerations. In this context, an ideal route is the application of the Muon Induced X-ray Emission (MIXE) 1 analysis technique, which allows a completely non-destructive elemental determination without detectable radiation damage, and which can measure up to a few centimeters (cm) inside the material due to its high-energy muon induced X-rays.…”

“…Examples of applications of this analysis technique to archaeological metal objects are already available [4,[6][7][8][9][11][12][13], all of which were performed at pulsed muon beam facilities. It was also shown recently [1,2] that the unique experimental setup at the Paul Scherrer Institute (PSI), which utilizes continuous muon beams, enables one to achieve high statistics measurements in short measurement periods.…”

“…This technique is not uniformly named in the literature. In addition to the acronym MIXE[1][2][3][4], other acronyms like MXA (Muonic X-ray Analysis)[5], MAXRS (Muonic Atom X-ray Spectroscopy)[6] and µXES (Muonic X-ray Emission Spectroscopy)[7][8][9] have been used so far.…”

A Novel Non-Destructive Technique for Cultural Heritage: Depth Profiling and Elemental Analysis Underneath the Surface with Negative Muons

“…Muonic X-ray instruments for cultural heritage experiments are currently installed at J-PARC and MuSIC (Japan) and ISIS (UK) muon facilities [24][25][26] and under development at PSI (Switzerland) [27] and TRIUMF (Canada). Generally, the instruments consist of several detectors placed around the sample position, as in Figure 6.…”