Progress and prospect of MELODY

• Yu Bao (IHEP)

Plan for CiADS Muon Source and Current R&D Progress

• rong wang (IMP)

The Feasibility Study of the GeV-Energy Muon Source Based on HIAF

• 良文 陈 (中国科学院近物所)
• Yu Xu (Institute of Modern Physics, Chinese Academy of Science)

Muon tomography has attracted significant attention in diverse application areas, yet it is currently limited by the low flux and wide energy spread of cosmic ray muons. To overcome these drawbacks, considerable efforts have been made, such as generating a mono-energetic, high-energy muon beam using accelerator facilities. One potential accelerator facility is the High Intensity Heavy-Ion Accelerator Facility (HIAF), which is currently under construction in Huizhou City, China. Considering the projectile energy and beamline length, a high-intensity and GeV-energy muon flux could be produced and delivered by the High Energy Fragment Separator (HFRS) beamline of the HIAF facility. In this paper, the flux intensity and purity of muon beam based on HIAF are discussed in detail. For the $\mu^+$ beam, the highest muon yield reaches $8.2 \times 10^6 ~ \mu$/s with the purity of approximately $2\%$ at a momentum of 3.5 GeV/c; meanwhile, for the $\mu^-$ beam, the maximum muon yield is 4.2 $\times 10^6 ~ \mu$/s with the purity of around $20\%$ at a momentum of 1.5 GeV/c. The results also indicate that, for muon beams with an energy of several GeV, by applying a suitable purification strategy, we can get a muon beam with a purity of 100\% and an intensity of the order of $10^5 ~ \mu$/s. This GeV-energy muon source would unlock the potential of muon tomography, and also provide a unique platform for the exploration of new physics beyond the standard model.

Progress and prospect of the thermal muon source at J-PARC

• Shusei Kamioka (KEK)

Current status of the SHINE muon source

• Yusuke Takeuchi (TDLI/SJTU)

A high-repetition-rate pulsed muon source operating at approximately 50 kHz could improve the sensitivity of various particle physics and material science experiments involving muons. We proposed using the high-repetition-rate pulsed electron beam at the SHINE facility to generate a surface muon beam. Our simulation studies show that an 8 GeV, 100 pC charge pulsed electron beam striking a copper target can produce up to 2 × $10^{3}$ muons per pulse. Through beamline optimization, approximately 60 surface muons per electron bunch can be efficiently transported to the beamline's end. When operated at 50 kHz, the pulsed electron beam yields a surface muon rate of 3 × $10^6 \mu^+$/s—comparable to existing muon facilities. In this talk, the current status and challenges of the SHINE muon source, as well as the preparation status for the upcoming beam test will be reported.

Lattice QCD calculations in Muon $g-2$

• Luchang Jin (University of Connecticut)

Fermilab has measured muon $g-2$ to unprecedented precision. The central value agrees with the previous BNL measurement. On the theory side, the main source of uncertainties are from the two hadronic contributions -- hadronic vacuum polarization (HVP) and hadronic light-by-light scattering (HLbL). Recent lattice QCD calculations have made a lot of contributions in determining these two contributions. These also lead to a significant shift in the theoretical value of the HVP contribution, which brings the final theoretical prediction of muon $g-2$ much closer the experimental measurement. In this talk, I will review these lattice QCD calculations of the hadronic contribution to muon $g-2$.

Studies of hadronic contribution to Muon g-2

• 凌云 戴 (Hunan University)

Searching for a muon EDM and measuring muon g-2 at Fermilab

• Dominika Vasilkova (University of Liverpool)

The Muon g-2 Experiment at Fermilab measures the anomalous part of the muon magnetic dipole moment, a_{\mu}, and searches for a non-zero muon electric dipole moment (EDM). Both are excellent probes of new physics; precise measurements of a_{\mu} can help disentangle current tensions in the Standard Model (SM) prediction, and the predicted muon EDM is beyond current experimental reach. An EDM observation would therefore be a direct sign of new physics, offering a new source of CP violation, otherwise tighter limits can be placed on BSM scenarios. In this talk, I will update on the status of both efforts in the experiment with a focus on the straw tracker-based EDM search.

J-PARC muon g-2/EDM experiment

• Yutaro Sato (Niigata Univ.)

The muon anomalous magnetic moment (g−2)_µ and electric dipole moment are sensitive to new physics beyond the Standard Model (SM). There is a discrepancy between the experimental value of the (g−2)_µ and the SM prediction at more than 5σ level. We aim to measure (g−2)_µ with a precision of 450 parts per billion and to search for electric dipole moment with a sensitivity of 1.5×10^−21 e·cm in the initial phase with a diff erent method from the E821 at BNL and E989 experiment at Fermilab. To achieve unprecedented precision, we utilize high intensity proton beam at J-PARC and newly developed technique of reaccelerated thermal muon beam, which is produced by thermal muonium productions followed by laser ionization and linear acceleration. We report experimental approaches, current status of each component of our experiment, and future prospects.

PKMu-HFRS:  Probing and Knocking with a Gev Muon beam at the HIAF HFRS facility

• Qiang Li (School of physics, Peking University)

Generating a mono-energetic, high-energy muon beam using accelerator facilities can be very attractive for many purposes, for example, searching for muon related new physics beyond the Standard Model. One potential accelerator facility is the High Intensity Heavy-Ion Accelerator Facility (HIAF), which is currently under construction in Huizhou City, China. Considering the projectile energy and beamline length, a high-intensity and GeV-energy muon flux could be produced and delivered by the High Energy Fragment Separator (HFRS) beamline of the HIAF facility. Here we show the roadmap and potential of the PKMu-HFRS program, to search for a muon-philic dark matter or dark boson, and to study the quantum entanglement between scattered leptons, etc.

DREAMuS - Dark Matter REsearch with Advanced Muon Source

• Xiang Chen (Shanghai Jiao Tong University)

我们提出了一个新颖的暗物质探索实验：DREAMuS（利用先进缪子源研究暗物质），使用位于中国的强流重离子加速器装置（HIAF）提供的GeV级缪子束流开展暗物质研究。DREAMuS实验旨在搜寻一种与缪子有特定耦合的暗物质粒子，这类粒子通过带味破坏的重型Z玻色子进行相互作用。该实验将寻找含轻子味破坏的标准模型新物理，并为包括缪子反常磁矩在内的多种实验反常现象提供解释。实验信号特征表现为高横动量的电子，并伴随来自中微子与暗物质粒子的大缺失能量。 本报告将介绍DREAMuS实验的理论框架、模拟研究及预期探测灵敏度，突出其通过缪子相互作用研究暗物质及相关新物理现象的潜力。

Musr Investigation of series magnetic semiconductors isostructual to iron based superconductors

• Fan-Long Ning (ZJU)

Spectrometer development and applications for accelerated muons

• Ziwen Pan (University of Science and Technology of China)

This talk will report the development of muSR spectrometers for the Chinese muon facility.

Muon Production and Acceleration with Ultrafast High Intensity laser

• 锋 张 (Laser Fusion Research Center, CAEP)

Muons, which play a crucial role in both fundamental and applied physics, have traditionally been generated through proton accelerators or from cosmic rays. With the advent of ultra-short high-intensity lasers capable of accelerating electrons to GeV levels, it has become possible to generate muons in laser laboratories. In this work, we show the first proof of principle experiment for novel muon production with an ultra-short, high-intensity laser device through GeV electron beam bombardment on a lead converter target. The muon physical signal is confirmed by measuring its lifetime which is the first clear demonstration of laser-produced muons. Geant4 simulations were employed to investigate the photo-production, electro-production, and Bethe-Heitler processes response for muon generation and their subsequent detection. The results show that the dominant contributions of muons are attributed to the photo-production/electro-production and a significant yield of muons up to 0.01 μ/e- out of the converter target could be achieved. This laser muon source features compact, ultra-short pulse and high flux. Therefore, its implementation in a small laser laboratory is relatively straightforward, significantly reducing the barriers to entry for research in areas such as muonic X-ray elemental analysis, muon spin spectroscopy and so on. Moreover, laser produced muons by the Bethe–Heitler process have velocities close to the laser wakefield. It is possible to accelerate those muons with laser wakefield directly. Therefore for the first time we propose an all-optical ‘Generator and Booster’ scheme to accelerate the produced muons by another laser wakefield. The trapping and acceleration of muons are analyzed by one-dimensional analytic model and verified by two-dimensional particle-in-cell (PIC) simulation. It is shown that muons can be trapped in a broad energy range and accelerated to higher energy than that of electrons for longer dephasing length. We further extrapolate the dependence of the maximum acceleration energy of muons with the laser wakefield relativistic factor γ and the relevant initial energy E0. It is shown that a maximum energy up to 15.2 GeV is promising with γ = 46 and E0 = 1.45 GeV on the existing short pulse laser facilities.

Search for the electric dipole moment of the muon using the frozen-spin technique in a compact storage trap

• Philipp Schmidt-Wellenburg (Paul Scherrer Institute)

Development of the muEDM Muon Trigger Detector

• Guan Ming WONG (Tsung-Dao Lee Institute)

The muEDM experiment at the Paul Scherrer Institut (PSI) aims to measure the muon electric dipole moment (EDM) with unprecedented sensitivity, targeting σ(dμ)​=6×10⁻²³ e·cm, a three-order-of-magnitude improvement over the current limit established by the BNL muon g−2 experiment. Central to this effort is the muon trigger detector (TrigDet), positioned at the solenoid entrance, which provides rapid and precise identification of muons within the solenoid’s storage acceptance. This trigger initiates a pulsed magnetic field to direct muons into stable orbits, where a radial electric field enables the frozen-spin technique for isolating EDM-induced spin precession. The TrigDet utilizes plastic scintillators read out by silicon photomultipliers (SiPMs) and consists of two subsystems: a sub-millimeter-thick Gate detector for minimally invasive muon detection, an Active Aperture detector to veto non-storable muons via anti-coincidence logic. By operating in anti-coincidence, the system ensures selective triggering on storable muons while suppressing background events. A prototype TrigDet was validated at the PSI πE1 beamline using surface muons, with performance assessed through comparative analysis of experimental data and Geant4-based simulations. We present key design principles, prototype test results (including detector response and electronic timing performance), and progress toward achieving the muEDM experiment’s transformative sensitivity goals.

Design of electromagnetic components at MACE and Muon beamline MuST

• Gui-Hao Lu (SUN YAT-SEN UNIVERSITY)

Electromagnetic systems are critical in the design of muon-based beamlines and detectors. This poster shows Positron Transport System (PTS) designed for Muonium-to-Antimuonium Conversion Experiment (MACE) and the beamline device for Accelerator Driven Sub-critical System (CiADS) muon beamline MuST. For MACE, PTS we designed realizes transmission, reconstruction of signal and background rejection. On CiADS MuST beamline, this study presents the front-end design based on radiation-resistant capture solenoids and the deceleration device.

RPC-Scintillator Hybrid Detection System for Muon Scattering Experiments at HIAF-HFRS

• Jinning Li (Peking University)

This work presents a novel detector design enabling muon scattering experiments at the High-energy FRagment Separator[1] (HFRS) at the High Intensity heavy-ion Accelerator Facility[2] (HIAF), offering new capabilities to probe dark matter[3], dark bosons, quantum entanglement phenomena[4], and the charged lepton flavor violation[5] (CLFV). Building upon the muon tomography detector from the Probing and Knocking with Muons (PKMu) initiative, we developed the upgraded detection system specifically adapted for beamline scattering experiments. The core tracking system employs Resistive Plate Chambers[6] (RPCs) inherited from PKMu's architecture, achieving <1 mm spatial resolution for precise muon trajectory reconstruction. To differentiate secondary particles generated through scattering processes and suppress background signals from extraneous particles, we integrated a dedicated particle identification (PID) subsystem combining scintillators and time-of-flight measurements. The detector performance and particle identification efficiency on the beamline have been studied by simulation. And according to the simulation results, dark matter search on high-intensity muon beamline is expected to achieve a detection sensitivity better than the current cosmic-ray muon experiment in even shorter measure time. Additionally, as a preliminary joint tuning of the RPC-scintillator detection system, a performance-test platform made up of two RPCs for scintillators has been trailed, which provides a valuable technical guidance for the complete prototype. Reference: [1] Sheng L N, Zhang X H, Ren H, et al. Ion-optical updates and performance analysis of High energy FRagment Separator (HFRS) at HIAF[J]. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2024, 547: 165214. [2] Yang J C, Xia J W, Xiao G Q, et al. High intensity heavy ion accelerator facility (HIAF) in China[J]. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2013, 317: 263-265. [3] Yu X, Wang Z, Liu C, et al. Proposed Peking University muon experiment for muon tomography and dark matter search[J]. Physical Review D, 2024, 110(1): 016017. [4] Gao L, Ruzi A, Li Q, et al. Testing spooky action between free-traveling electron-positron pairs[J]. arXiv preprint arXiv:2502.07597, 2025. [5] Gao L, Wang Z, Liu C, et al. Probing charged lepton flavor violation in an economical muon on-target experiment[J]. arXiv preprint arXiv:2410.20323, 2024. [6] Li Q, Ye Y, Wen C, et al. Study of spatial resolution properties of a glass RPC[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2012, 663(1): 22-25.

宇宙线缪子成像算法研究

• 群刚 文 (ahu)

宇宙线缪子成像作为一种新兴的探测技术手段，目前主要包括散射成像和透射成像两种主要方法。本报告将重点介绍我们在这两种成像方式中所采用的算法方面的一些创新性探索和实践经验。

Precision Measurements of the Lamb Shift and Fine Structure in Muonium

• Gianluca Janka (PSI)

Due to its lack of internal structure, Muonium is an excellent candidate to provide stringent tests for bound state QED. Furthermore, Muonium is a sensitive probe for the existence of exotic dark-sector particles, new muonic forces, and hidden dimensions. During the Mu-MASS [1] beamtime in December 2019 at the LEM beamline at PSI, we demonstrated the creation of an intense directed beam of metastable Muonium [2]. This opened up the possibility to measure the Muonium Lamb shift to an uncertainty of 2.5 MHz, which is an improvement of around an order of magnitude upon the last measurements [3]. Additionally, by measuring the isolated $2S_{1/2}, F=0 \rightarrow 2P_{1/2}, F=1$ transition for the first time [4], we demonstrated a promising way for an improved determination of the Muonium Lamb shift, provided that the measurement is not limited by statistics anymore. Recently, we also measured the $2S_{1/2} \rightarrow 2P_{3/2}$ fine structure interval in Muonium to an uncertainty of 7.0 MHz for a first time [5]. The experimental setup, the current status and plans for future improvements will be presented. $[1]$ P. Crivelli, "The Mu-MASS (muonium laser spectroscopy) experiment", Hyperfine Interactions 239, 49 (2018) $[2]$ G. Janka et al., "Intense beam of metastable Muonium",Eur. Phys. J. C (2020) $[3]$ B. Ohayon, G. Janka et al., "Precision Measurement of the Lamb Shift in Muonium", Phys. Rev. Lett. 128, 011802 (2022) $[4]$ G. Janka et al., "Measurement of the transition frequency from $2S_{1/2}, F=0$ to $2P_{1/2}, F=1$ states in Muonium", Nat Commun 13, 7273 (2022). $[5]$ P. Blumer, G. Janka et al., Manuscript in preparation.

Nuclear-Structure Effects in High-Precision Spectroscopy of Hydrogen-Like Atoms

• Chen Ji (CCNU)

Muon-related bound-state systems from Gaussian expansion method

• 廷廷 刘 (湖南大学)

Muonic bound states (μ⁺μ⁻, μ⁻p⁺, μ⁺e⁻) serve as important platforms for studying lepton interactions, testing the Standard Model (SM), and probing Beyond the Standard Model (BSM) phenomena, offering unique physical significance. Among these, true muonium (μ⁺μ⁻), composed purely of second-generation leptons, exhibits cleaner and more tractable physical properties due to its purely leptonic composition and larger reduced mass, making it particularly suitable for high-precision tests of quantum electrodynamics (QED) and searches for potential new physics effects. The precise calculation of its energy-level structure especially fine and hyperfine splittings is crucial for understanding fundamental lepton interactions. At the same time, μ⁺e⁻ (muonium) and μ⁻p⁺ (muonic hydrogen) bound states play an irreplaceable role in investigating lepton-matter interactions and low-energy-scale new physics phenomena. In this work, we employ the Gaussian expansion method combined with QED corrections to numerically solve the Schrödinger equation for these muonic bound states, systematically computing their energy spectra and fine-structure splittings. The results provide a theoretical foundation for future high-precision experimental measurements and theoretical validation.

Conceptual Design of the Muonium-to-Antimuonium Conversion Experiment (MACE)

• Shihan Zhao (Sun Yat-Sen University)

The spontaneous conversion of muonium to antimuonium is one of the interesting charged lepton flavor violation phenomena offering a sensitive probe of potential new physics and serving as a tool to constrain the parameter space beyond the Standard Model. The Muonium-to-Antimuonium Conversion Experiment (MACE) is designed to utilize a high-intensity muon beam, a Michel electron magnetic spectrometer, a positron transport system, and a positron detection system, to either discover or constrain this rare process with a conversion probability of $\mathcal{O}(10^{-13})$. In this talk, we will present the experimental design and recent progress on prototyping and validation of MACE.

AI-Enhanced Magnetic Field Measurements

• Bingzhi Li (Zhejiang Lab 之江实验室)

The measurement of the muon anomalous magnetic moment depends on a precise measurement of the muon anomalous precession frequency and the magnetic field. For magnetic field measurement, as the field that muons experience cannot be directly measured, the multipole fitting interpolation method is generally employed. In recent years, integrating physical laws into machine learning has made progress in solving PDE equations. We use a physics informed machine learning method, combining Maxwell's equations with machine learning, to predict magnetic fields in non-directly measurable areas based on a few external field measurements, achieving precise results with simulation data. We have also constructed a Helmholtz coil device to verify the method and obtained some promising results. The method is expected to assist in magnetic field monitoring for the J - PARC muon g - 2 experiment, thereby enabling better control of the muon beam. Furthermore, we aim to refine the method through further research to achieve precise magnetic field measurement and prediction in the future.

Probing Axion-Like Particles with Muons Across High and Low Energies

• Lorenzo Calibbi (Nankai University)

Axion-like particles (ALPs) with lepton flavour violating (LFV) interactions are predicted within a wide range of well-motivated extensions of the Standard Model. The proposed μTRISTAN high-energy e-μ+ and μ+μ+ collider provides a good opportunity to explore flavour physics in the charged lepton sector. In this talk, we discuss the potential of μTRISTAN to probe ALP LFV couplings considering various ALP production and decay modes and compare it with multiple low-energy leptonic constraints and the expected sensitivity at experiments such as MEG-II, Mu3e, MACE.

Search for Dark Photons via Visible Decays at Fixed-Target Experiments

• Zejia Lu (Shanghai Jiao Tong University)

We present dark photon searches via the visible decay mode at fixed-target experiments such as DarkSHINE and MUonE. In DarkSHINE, dark photons are produced through electron bremsstrahlung and they can be identified via displaced vertex signatures from decayed lepton pairs. Detailed studies with full vertex reconstruction are required to enable strong background suppression. We also explore applications to muon beam experiments like MUonE, which offer complementary production channels and sensitivity to muon-philic dark sector scenarios. These efforts highlight the potential of combining electron and muon fixed-target programs to further explore dark sector physics.

Search for light Dark Sectors with the HIAF Muon Beam: HFRS-PKMu experiment proposal

• Zijian Wang (北京大学)

Sub-GeV light dark matter usually requires the existence of new light mediators, such as the dark Z boson in the $L_\mu - L_\tau$ gauge theory. Here we study the search potential for such a Z' boson based on a muon on-target experiment proposal, through $\mu e^- \to \mu e^- X$, with X decays invisibly. The experimental signature would be scattered muon and electron from the target, at large angles compared to backgrounds. Apart from these, activities will be low in the subdetectors located downstream from the interaction point. Here we focus on the usage of the 1-10 GeV muon beam from the HIAF-HFRS facility which is expected to start operation in 2025-2026. Compared with existing experiments or proposals using the CERN 160 GeV muon beam, we find high sensitivity on 10 MeV Z' range.

Probing charged lepton flavor violation and quantum entanglement in muon on-target experiments

• Leyun Gao (Peking University)

Firstly, we'd like to share a novel and cost-effective experiment proposal to probe the charged lepton flavor violation (CLFV) process mediated by an extra massive neutral gauge boson $Z'$ beyond the Standard Model, as a part of the Peking University Muon (PKMuon) Experiment. The considered process can be uniquely sensitive to specific CLFV parameter combinations, such as the coupling coefficient product $\lambda_{e\mu}\lambda_{\mu\mu}$. Additionally, we will present a realistic proposal and a comprehensive study of quantum entanglement in a state composed of different-flavor fermions in muon-electron scattering. Entanglement in the resulting muon-electron qubit system and the violation of the Bell inequality can be observed with a high event rate. This paves the way for performing quantum tomography with muons.

Introduction to “The innovation”

• Lang Pan (HUNAU)

Simulation study of a pixelated CZT MXIE spectrometer for MELODY

• You Lv

Muon-Induced X-ray Emission (MIXE) technique has shown significant application potential in the elemental analysis of cultural heritages, extraterrestrial materials, and energy materials, owing to its non-destructive nature, depth scanning capabilities, and high sensitivity to low-Z elements. As the China‘s first muon source facility, MELODY is currently under construction. A dedicated negative muon beamline and a decay muon beamline have been reserved for the application of the MIXE technique at MELODY. To improve the counting rate of MIXE experiment, we propose developing a pixelated Cadmium Zinc Telluride (CZT) detector-based MIXE spectrometer for MELODY. CZT detector can be fabricated with millimetres-scale pixel readout and operate effectively at room temperature, eliminating the need for cryogenic cooling systems. Moreover, CZT detectors offer relatively high detection efficiency (>95% for 100 keV X-rays) and satisfactory energy resolution (<4% for 100 keV X-rays). This report will introduce the detailed design of the negative muon beamline and decay muon beamline at MELODY, and also the application of MIXE technique. Besides, the preliminary simulation results of the pixelated CZT detector-based MIXE spectrometer will also presented.

Advanced Non-Destructive Element-Sensitive 3D Tomography Using Muon-Induced-Xray-Emission (MIXE)

• Xiao Zhao (PSI)

Muon-Induced X-ray Emission (MIXE) [1-4] is a non-destructive analytical technique that leverages negative muons to probe elemental and isotopic compositions by detecting characteristic muonic X-rays emitted during atomic cascades and gamma rays from nuclear capture processes. By controlling the muon beam momentum, MIXE enables depth-resolved analysis, spanning microns to centimeters, making it ideal for studying compositional variations in fragile, valuable, or operando samples. Significant advancements in MIXE technology have been achieved at the Paul Scherrer Institute (PSI) [5-7], facilitated by the high-rate continuous muon beam. To establish a universal tomographic approach, additional muon tracking was incorporated using a twin GEM-TPC tracker, originally developed for heavy-ion detection at FAIR [8]. This enabled precise reconstruction of muon trajectories and correlation with emitted X-rays, yielding three-dimensional, element-specific information. The resulting technique, MIXE Tomography (MIXE-T), offers high-resolution, depth-resolved elemental analysis for a broad range of applications. [1] Taylor et al., Observation of Muonic X-rays from Bone, Radiat. Res., 1973, 54, 335-342. [2] Hutson et al., Tissue chemical analysis with muonic x rays, Radiology, 1976, 120, 193-198. [3] Köhler et al., Application of muonic X-ray techniques to the elemental analysis of archeological objects, Nucl. Instrum. Methods Phys. Res., 1981, 187, 563-568. [4] Reidy et al., Use of muonic x-rays for nondestructive analysis of bulk samples for low Z constituents, Anal. Chem., 1978, 50, 40-44. [5] Biswas S. et al. The non-destructive investigation of a late antique knob bow fibula (Bügelknopffibel) from Kaiseraugst/CH using Muon Induced X-ray Emission (MIXE), Herit Sci, 2023, 11, 43. [6] Beda A. Hofmann et al., An arrowhead made of meteoritic iron from the late Bronze Age settlement of Mörigen, Switzerland and its possible source, J. Archaeol. Sci., 2023, 157, 105827. [7] Q. Edouard et al., Overcoming the probing-depth dilemma in spectroscopic analyses of batteries with muon-induced X-ray emission (MIXE), J. Mater. Chem. A, 2025, 13, 2275-2284. [8] F. García et al., A GEM-TPC in twin configuration for the Super-FRS tracking of heavy ions at FAIR, NIM-A, 2018, 884, 18-24.

基于缪致X射线的到达时间戳算法的成像方法

• 春添 冯 (南华大学)

人工缪子束流穿透性强，其发射的负缪子束流与靶材料相互作用后会产生特征光子，称缪致X射线，利用其到达灵敏探测器时间、位置及缪子束流信息，可用于对靶材料元素的位置反演。

Muonic X-ray and spherical encoding-based ICF target element imaging

• Dikai Li (SZTU)

The elemental distribution in inertial confinement fusion (ICF) targets critically influences their fusion performance. However, existing detection technologies struggle to simultaneously achieve deep penetration, non-destructive analysis, and micron-level resolution. This project proposes a novel method combining muon-induced X-ray emission (MIXE) with spherical coded imaging to overcome the technical limitations in high-precision elemental distribution detection for ICF targets. The method involves irradiating targets with a muon beam to generate characteristic X-rays, which are modulated by a coded spherical aperture to form encoded signals on the detector. Microscale elemental distribution is then reconstructed through deconvolution and CT algorithms. The research encompasses: 1) establishing a physical model for characteristic X-ray emission induced by muons, based on the design parameters of China’s upcoming high-intensity muon source and typical ICF target elemental distributions; 2) optimizing the spherical coded imaging system and reconstruction algorithms; and 3) quantitative calibration of oxygen distribution in targets (targeting spatial resolution ≤5 μm and density measurement uncertainty ≤0.2 at.%). By integrating the advantages of MIXE and spherical coded imaging, this method enables non-destructive, deep-layer detection of multi-element distributions, addressing the limitations of traditional techniques in surface analysis and sample irradiation damage. The project not only serves the demand for high-precision elemental detection in ICF targets but also provides technical support for China’s first high-intensity muon source facility, driving methodological innovation in particle detection technologies under extreme conditions.

Recent advances in $a_\mu^{HVP,LO}[\pi,\pi] using tau data (online)

• Pablo Roig Garcés (CINVESTAV)

Data-driven calculations of HVP Contribution to Muon g-2 (online)

• Martin Hoferichter (University of Bern)

Dispersive analysis of isospin-breaking corrections to the two-pion contribution to hadronic vacuum polarization for the anomalous magnetic moment of the muon (online)

• Jacobo Ruiz de Elvira (HISKP-Bonn)

Unconventional Superconductivity and Charge Order in Kagome Lattices Revealed by Muon Spin Rotation (online)

• Zurab Guguchia (PSI)

The high-intensity muon beam (HIMB) project at PSI (online)

• Andreas Knecht (PSI)

The Search for Charged Lepton Flavour Violation with the Mu3e detector (online)

• Mark Grimes (University of Bristol)

Simulation study of Imaging widgets with CSNS muon beam

• jifeng hu (South China Normal University)

A detailed simulation and 3D reconstruction of copper and skull are presented in this talk. Imaging performance is compared to that of Xrays tomography.

Cosmic ray muon scattering imaging system based on scintillation detector

• 政 梁 (University of Science and Technology of China)

Cosmic ray muon imaging, as a non-invasive imaging modality, utilizes naturally occurring cosmic ray muons as penetrating probes to reconstruct the distribution of matter. A critical challenge in designing position-sensitive muon detectors lies in optimizing the trade-off among three key parameters: detection area, spatial resolution, and manufacturing cost. Owing to their proven feasibility and operational robustness, scintillator-based detectors remain the preferred choice for muon imaging systems, despite their inherent limitation in achieving sub-centimeter spatial resolution. The primary objective of our project is to develop a large-area, high-position-resolution, and cost-effective cosmic ray muon scattering imaging system based on plastic scintillator detectors. The system achieves an effective detection area of 53 cm × 53 cm, with submillimeter position resolution (<1 mm) under optimized 1.1 cm center-to-center spacing between scintillator strips. Following system assembly, clear imaging results were successfully obtained for 2 cm × 2 cm square lead and tungsten blocks, demonstrating the system's capability for high-Z material identification. Finally, to further reduce detector fabrication costs, an investigation was conducted using organic liquid scintillators as the sensitive medium for muon detection, replacing conventional plastic scintillators. Initial tests of the liquid scintillator prototype demonstrated promising position resolution performance (σ < 1.5 mm).

Cosmic-ray muon polarization and atmospheric neutrino

• Hesheng Liu (Sun Yat-Sen University)

The polarization is a key feature of muons. Not only does it affect background events in high-precision experiments such as JUNO, but it also plays an important role in cosmic ray studies. Understanding muon polarization can provide complementary information to constrain atmospheric neutrino flux modeling. We have developed Cosmic-Ray Muon Spin Spectroscopy (CRmuSR), a scintillator detector, along with Geant4-based Monte Carlo simulations to evaluate the detection efficiency of CRmuSR at various altitudes. Our study will offer a deeper understanding of the correlations between muon polarization and atmospheric neutrinos.

Development and Testing of a Large-Area Cosmic Ray Telescope with Millimeter-Level Positioning Precision

• Yan Niu (ShanDong University)

Cosmic ray muons, as important "natural probes," have been widely used in particle physics experiments. We have developed a cosmic ray telescope with an effective detection cross-section of one square meter to achieve high-precision tracking of high-energy cosmic ray muons. The instrument employs a modular design, innovatively combining a plastic scintillator strip with a layer of scintillating fibers for collaborative detection. The scintillator strip (measuring 1000×55×10 mm) is responsible for muon triggering and coarse positioning, while the fiber layer (with a double-layer structure, each layer densely packed with 54 fibers of 1 mm diameter) accomplishes fine position resolution. The scintillation light signals are read out by photomultiplier tubes (PMTs). Additionally, we developed a dedicated FPGA program for data acquisition. To meet the positional resolution requirements, the width of the fiber group is set to 3 mm, with each single layer measuring one-dimensional coordinates. Two orthogonal single layers form a large layer, and the upper and lower large layers are spaced 1 meter apart, resulting in a tracker capable of achieving millimeter-level spatial resolution. This research encompasses the entire process from the design of the tracker, Geant4 simulation optimization, and systematic testing of key components, to the assembly of the cosmic ray tracker, followed by detailed performance testing. The results indicate that the cosmic ray tracker has a detection efficiency of approximately 85%, and a single-layer fiber detection efficiency of about 95%, with a positional resolution better than 2 mm. This presentation will focus on the cosmic ray telescope's design principles, fabrication processes, and performance testing procedures. Additionally, it will explore the prospects of its applications in cutting-edge particle physics. In collaboration with academic peers, the goal is to advance scientific progress and technological innovation in muon physics and related fields.

基于天然缪子的钻井型缪子探测器的模拟与搭建初步研究

• 思远 罗 (南华大学)

本研究致力于设计一种适用于矿脉勘探的钻井型缪子成像系统，旨在结合地质勘探技术与缪子成像技术，提升矿产资源勘探的精准性与高效性。研究探索并设计的钻井型缪子成像系统，适用于钻探手段，通过弧形塑料闪烁体与双端读出的楔形塑料闪烁体条耦合SiPM，探测系统直径不低于200 mm，长度不小于600 mm，位置分辨为厘米级；

Muonphilic Dark Matter Searches Using an RPC-based Muon Tomography System

• 承恩 刘 (北京大学)

Exploring dark matter remains a central theme in both cosmology and particle physics. Despite compelling cosmological evidence and extensive experimental efforts, no dark matter particle has been directly detected, prompting the search for alternative, theoretically viable approaches. Muons uniquely bridge applied and fundamental research. Cosmic-ray muon tomography has emerged as an effective tool for imaging the internal structure of large-scale objects and has been widely applied in geology and archaeology. In our work, we propose using muon tomography to search for muon-philic dark matter, offering a novel experimental approach. Our detection system employs Resistive Plate Chambers (RPCs) as gas detectors for muon tomography. Each RPC module has a sensitive area of 203×203 mm², achieving a spatial resolution better than σ < 1 mm while maintaining an efficiency above 90%. The tomography system consists of four RPCs, forming a sensitive volume of 203×203×500 mm³. Since January 2024, we have conducted nearly three months of tests on cosmic-ray muon interactions in air. Simultaneously, a GEANT4 simulation—replicating the dimensions, materials, and spacing of our setup—was performed to model the angular distribution of muon events. The experimental data show a significantly higher fraction of large-angle events than predicted, indicating that muon interactions in air and materials require further investigation. Next, we plan to suppress air scattering effects by inserting vacuum chambers between the RPCs, upgrading the system to operate in vacuum mode for dark matter searches. Future efforts will focus on reducing background noise and improving the detection threshold of this method. [1] Phys. Rev. D 110, 016017 [2] arxiv: 2410.20323

Preliminary Design of a Cosmic Ray Veto (CRV) Detector System for the Muonium-to-Antimuonium Conversion Experiment (MACE)

• Zhichao Wang (Sun Yat-Sen University)

The Muonium-to-Antimuonium Conversion Experiment (MACE) aims to search for the charged lepton flavor violation process at an unprecedented level. A significant challenge arises from cosmic-ray-muon-induced background in both the Phase-I and the complete experiment. To address this, a muon detection system with a high efficiency is required. In this work, we focus on a design of Cosmic Ray Veto (CRV) detector system and its expected performace.

MACE Phase-I and Its Detector System

• Yinyuan Huang (SUN YAT-SEN UNIVERSITY)

The Muonium-to-Antimuonium Conversion Experiment (MACE) aims to probe charged lepton flavor violation (cLFV) through an advanced detector system. The MACE calorimeter system could satisfy the requirement in searching for lepton flavor violating $\mathrm{M}\to\gamma\gamma$ and $\mu\to e\gamma\gamma$ decay in the MACE Phase-I. With an inner tracking system comprising a Multigap Resistive Plate Chamber (MRPC) and a Scintillating Fiber (SciFi) tracker, the MACE Phase-I detector aims to achieve unprecedented sensitivity to these cLFV processes. This presentation will outline the experimental design of the MACE Phase-I apparatus and discuss recent progress in prototype development and simulations. The results highlight the experiment’s potential to advance our understanding of fundamental symmetries and physics beyond the Standard Model.

Optimization and Validation of Tiled Timing Counter for Muonium-Antimuonium Conversion Experiments

• Hao Jiang (Sun Yat-Sen University)

Modern particle detection systems increasingly rely on precise timing performance. This work presents the development of a scintillator Tiled Timing Counter (TTC) system optimized for the Muonium-to-Antimuonium Conversion Experiment (MACE). Our study introduces a simulation-guided optimization scheme and a prototype test with cosmic ray muons to validate the design concept. This study will pave the way for similar experiments of interests to measure the time of flight in a high resolution.

对半度规几何与弯曲时空Pati-Salam模型

• UNKNOWN LI Desheng (高能所)

广义相对论的时空背景由度规描述，仿照Dirac将Klein-Gordon方程开根号，这里将度规开根号得到对半度规几何。对半度规几何拥有度规结构还拥有U(4)伴丛结构，可基于自平行输运原理自然给出弯曲时空Pati-Salam模型。这个理论预言了X玻色子与Y玻色子等少量新物理。

Shanghai METRO: A Platform for Muon EducaTion Research and Outreach

• Siew Yan Hoh (TDLI)