Optical imaging of muons

Seiichi Yamamoto,Kazuhiko Ninomiya,Naritoshi Kawamura,Yoshiyuki Hirano

doi:10.1038/s41598-020-76652-8

Seiichi Yamamoto, Kazuhiko Ninomiya + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-76652-8

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Abstract

Optical imaging of particle beams is a promising method for range and width estimations. However it was not clear that optical imaging was possible for muons. To clarify this, we conducted optical imaging of muons, since high-intensity muons are now available at J-PARC. We irradiated positive muons with different momenta to water or plastic scintillator block, and imaged using a charge-coupled device (CCD) camera during irradiation. The water and plastic scintillator block produced quite different images. The images of water during irradiation of muons produced elliptical shape light distribution at the end of the ranges due to Cherenkov-light from the positrons produced by positive muon decay, while, for the plastic scintillator block, we measured images similar to the dose distributions. We were able to estimate the ranges of muons as well as the measurement of the asymmetry of the direction of the positron emission by the muon decays from the optical images of the water, although the measured ranges were 4 mm to 5 mm larger than the calculated values. The ranges and widths of the beams could also be estimated from the optical images of the plastic scintillator block. We confirmed that optical imaging of muons was possible and is a promising method for the quality assessment, research of muons, and the future muon radiotherapy.

Highlights

Optical imaging of particle beams is a promising method for range and width estimations
Optical imaging is a promising approach for quality assessment (QA) of high energy X-rays from linear accelerators (LINAC)[1,2,3,4,5,6,7]
High-intensity muon beams are available in an experimental facility at the Japan Proton Accelerator Research Complex (J-PARC)[20,21] and pulsed positive or negative muon beams are used in applications such as nondestructive X-ray fluorescence spectroscopy[22,23,24,25,26,27]

Summary

Introduction

Optical imaging of particle beams is a promising method for range and width estimations. A muon has a mean life-time of 2.2 μs and a negative muon decays to one electron and two types of neutrinos ( νe and νμ), while the positive muon decays to one positron and two types of neutrinos (ν e and νμ) Since these characteristics are quite different from familiar radiations such as X-rays, electrons, protons, or carbon ions, new results for such applications for QA, research, or radiation therapy may be obtained by the optical imaging of muons. We previously used Monte Carlo simulation to calculate the dose and light distributions of positive muons in water to determine the feasibility of experimental optical imaging of muons for dose or range measurements[30] In this simulation, dose distribution was given mainly by muons, while the light distribution attributed to the positrons produced by muon d ecay[30]. We show the first optical images measured during irradiation of muons to water and a plastic scintillator block

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