Improving the low-energy muon beam quality of the LEM beamline at PSI: Characterisation of ultra-thin carbon foils

The Low-Energy Muon beamline (LEM) at the Paul Scherrer Institute currently stands as the world's only facility providing a continuous beam of low-energy muons with keV energies for conducting muon spin rotation experiments on a nanometer depth scale in heterostructures and near a sample's...

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Bibliographic Details
Published in:arXiv.org 2024-02
Main Authors: Janka, Gianluca, Maria Mendes Martins, Ni, Xiaojie, Zaher Salman, Suter, Andreas, Prokscha, Thomas
Format: Article
Language:English
Subjects:
Carbon
Continuous beams
Foils
Heterostructures
Magnetic properties
Muon spin rotation
Muons
Particle beams
Thickness
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Summary:The Low-Energy Muon beamline (LEM) at the Paul Scherrer Institute currently stands as the world's only facility providing a continuous beam of low-energy muons with keV energies for conducting muon spin rotation experiments on a nanometer depth scale in heterostructures and near a sample's surface. As such, optimizing the beam quality to reach its full potential is of paramount importance. One of the ongoing efforts is dedicated to improving the already applied technique of single muon tagging through the detection of secondary electrons emerging from an ultra-thin carbon foil. In this work, we present the results from installing a thinner foil with a nominal thickness of 0.5 \(\mu g~cm^{-2}\) and compare its performance to that of the previously installed foil with a nominal thickness of 2.0 \(\mu g~cm^{-2}\). Our findings indicate improved beam quality, characterized by smaller beam spots, reduced energy loss and straggling of the muons, and enhanced tagging efficiency. Additionally, we introduce a method utilizing blue laser irradiation for cleaning the carbon foil, further improving and maintaining its characteristics
ISSN:2331-8422